nslookup — query Internet name servers interactively
nslookup [-option] [name | -] [server]
Nslookup is a program to query Internet domain name servers. Nslookup has two modes: interactive and non-interactive. Interactive mode allows the user to query name servers for information about various hosts and domains or to print a list of hosts in a domain. Non-interactive mode is used to print just the name and requested information for a host or domain.
Interactive mode is entered in the following cases:
when no arguments are given (the default name server will be used)
when the first argument is a hyphen (-) and the second argument is the host name or Internet address of a name server.
Non-interactive mode is used when the name or Internet address of the host to be looked up is given as the first argument. The optional second argument specifies the host name or address of a name server.
Options can also be specified on the command line if they precede the arguments and are prefixed with a hyphen. For example, to change the default query type to host information, and the initial timeout to 10 seconds, type:
nslookup -query=hinfo -timeout=10
The -version option causes
nslookup to print the version
number and immediately exits.
host [server]Look up information for host using the current default server or using server, if specified. If host is an Internet address and the query type is A or PTR, the name of the host is returned. If host is a name and does not have a trailing period, the search list is used to qualify the name.
To look up a host not in the current domain, append a period to the name.
server domainlserver domain
Change the default server to domain; lserver uses the initial
server to look up information about domain, while server uses
the current default server. If an authoritative answer can't be
found, the names of servers that might have the answer are
returned.
rootnot implemented
fingernot implemented
lsnot implemented
viewnot implemented
helpnot implemented
?not implemented
exitExits the program.
set
keyword[=value]This command is used to change state information that affects the lookups. Valid keywords are:
allPrints the current values of the frequently used options to set. Information about the current default server and host is also printed.
class=valueChange the query class to one of:
INthe Internet class
CHthe Chaos class
HSthe Hesiod class
ANYwildcard
The class specifies the protocol group of the information.
(Default = IN; abbreviation = cl)
[no]debugTurn on or off the display of the full response packet and any intermediate response packets when searching.
(Default = nodebug; abbreviation = [no]deb)
[no]d2Turn debugging mode on or off. This displays more about what nslookup is doing.
(Default = nod2)
domain=name
Sets the search list to name.
[no]searchIf the lookup request contains at least one period but doesn't end with a trailing period, append the domain names in the domain search list to the request until an answer is received.
(Default = search)
port=value
Change the default TCP/UDP name server port to value.
(Default = 53; abbreviation = po)
querytype=valuetype=valueChange the type of the information query.
(Default = A and then AAAA; abbreviations = q, ty)
Note: It is only possible to specify one query type, only the default behavior looks up both when an alternative is not specified.
[no]recurseTell the name server to query other servers if it does not have the information.
(Default = recurse; abbreviation = [no]rec)
ndots=numberSet the number of dots (label separators) in a domain that will disable searching. Absolute names always stop searching.
retry=numberSet the number of retries to number.
timeout=numberChange the initial timeout interval for waiting for a reply to number seconds.
[no]vcAlways use a virtual circuit when sending requests to the server.
(Default = novc)
[no]failTry the next nameserver if a nameserver responds with SERVFAIL or a referral (nofail) or terminate query (fail) on such a response.
(Default = nofail)
If nslookup has been built with IDN (internationalized
domain name) support, it can accept and display non-ASCII domain names.
nslookup appropriately converts character encoding of
domain name before sending a request to DNS server or displaying a
reply from the server.
If you'd like to turn off the IDN support for some reason, define
the IDN_DISABLE environment variable.
The IDN support is disabled if the variable is set when
nslookup runs or when the standard output is not
a tty.
BIND 9.11.36 (Extended Support Version)
man.named.conf.html 0000644 00000222062 15253021417 0010220 0 ustar 00named.conf — configuration file for named
named.conf
named.conf is the configuration file
for
named. Statements are enclosed
in braces and terminated with a semi-colon. Clauses in
the statements are also semi-colon terminated. The usual
comment styles are supported:
C style: /* */
C++ style: // to end of line
Unix style: # to end of line
controls{
inet(ipv4_address|ipv6_address|
*)[port(integer|*)]allow
{address_match_element;...}[
keys{string;...}][read-only
boolean];
unixquoted_stringperminteger
ownerintegergroupinteger[
keys{string;...}][read-only
boolean];
};
logging{
categorystring{string;...};
channelstring{
bufferedboolean;
filequoted_string[versions("unlimited"|integer)
][sizesize];
null;
print-categoryboolean;
print-severityboolean;
print-timeboolean;
severitylog_severity;
stderr;
syslog[syslog_facility];
};
};
lwres{
listen-on[portinteger][dscpinteger]{(ipv4_address
|ipv6_address)[portinteger][dscpinteger];...};
lwres-clientsinteger;
lwres-tasksinteger;
ndotsinteger;
search{string;...};
viewstring[class];
};
mastersstring[portinteger][dscp
integer]{(masters|ipv4_address[
portinteger]|ipv6_address[port
integer])[keystring];...};
options{
acache-cleaning-intervalinteger;
acache-enableboolean;
additional-from-authboolean;
additional-from-cacheboolean;
allow-new-zonesboolean;
allow-notify{address_match_element;...};
allow-query{address_match_element;...};
allow-query-cache{address_match_element;...};
allow-query-cache-on{address_match_element;...};
allow-query-on{address_match_element;...};
allow-recursion{address_match_element;...};
allow-recursion-on{address_match_element;...};
allow-transfer{address_match_element;...};
allow-update{address_match_element;...};
allow-update-forwarding{address_match_element;...};
also-notify[portinteger][dscpinteger]{(masters|
ipv4_address[portinteger]|ipv6_address[port
integer])[keystring];...};
alt-transfer-source(ipv4_address|*)[port(integer|*)
][dscpinteger];
alt-transfer-source-v6(ipv6_address|*)[port(integer|
*)][dscpinteger];
answer-cookieboolean;
attach-cachestring;
auth-nxdomainboolean;//defaultchanged
auto-dnssec(allow|maintain|off);
automatic-interface-scanboolean;
avoid-v4-udp-ports{portrange;...};
avoid-v6-udp-ports{portrange;...};
bindkeys-filequoted_string;
blackhole{address_match_element;...};
cache-filequoted_string;
catalog-zones{zonestring[default-masters[portinteger]
[dscpinteger]{(masters|ipv4_address[port
integer]|ipv6_address[portinteger])[key
string];...}][zone-directoryquoted_string][
in-memoryboolean][min-update-intervalinteger];...};
check-dup-records(fail|warn|ignore);
check-integrityboolean;
check-mx(fail|warn|ignore);
check-mx-cname(fail|warn|ignore);
check-names(master|slave|response
)(fail|warn|ignore);
check-siblingboolean;
check-spf(warn|ignore);
check-srv-cname(fail|warn|ignore);
check-wildcardboolean;
cleaning-intervalinteger;
clients-per-queryinteger;
cookie-algorithm(aes|sha1|sha256|siphash24);
cookie-secretstring;
coresize(default|unlimited|sizeval);
datasize(default|unlimited|sizeval);
deny-answer-addresses{address_match_element;...}[
except-from{quoted_string;...}];
deny-answer-aliases{quoted_string;...}[except-from{
quoted_string;...}];
dialup(notify|notify-passive|passive|refresh|boolean);
directoryquoted_string;
disable-algorithmsstring{string;
...};
disable-ds-digestsstring{string;
...};
disable-empty-zonestring;
dns64netprefix{
break-dnssecboolean;
clients{address_match_element;...};
exclude{address_match_element;...};
mapped{address_match_element;...};
recursive-onlyboolean;
suffixipv6_address;
};
dns64-contactstring;
dns64-serverstring;
dnssec-accept-expiredboolean;
dnssec-dnskey-kskonlyboolean;
dnssec-enableboolean;
dnssec-loadkeys-intervalinteger;
dnssec-lookaside(stringtrust-anchor
string|auto|no);
dnssec-must-be-securestringboolean;
dnssec-secure-to-insecureboolean;
dnssec-update-mode(maintain|no-resign);
dnssec-validation(yes|no|auto);
dnstap{(all|auth|client|forwarder|
resolver)[(query|response)];...};
dnstap-identity(quoted_string|none|
hostname);
dnstap-output(file|unix)quoted_string;
dnstap-version(quoted_string|none);
dscpinteger;
dual-stack-servers[portinteger]{(quoted_string[port
integer][dscpinteger]|ipv4_address[port
integer][dscpinteger]|ipv6_address[port
integer][dscpinteger]);...};
dump-filequoted_string;
edns-udp-sizeinteger;
empty-contactstring;
empty-serverstring;
empty-zones-enableboolean;
fetch-quota-paramsintegerfixedpointfixedpointfixedpoint;
fetches-per-serverinteger[(drop|fail)];
fetches-per-zoneinteger[(drop|fail)];
files(default|unlimited|sizeval);
filter-aaaa{address_match_element;...};
filter-aaaa-on-v4(break-dnssec|boolean);
filter-aaaa-on-v6(break-dnssec|boolean);
flush-zones-on-shutdownboolean;
forward(first|only);
forwarders[portinteger][dscpinteger]{(ipv4_address
|ipv6_address)[portinteger][dscpinteger];...};
fstrm-set-buffer-hintinteger;
fstrm-set-flush-timeoutinteger;
fstrm-set-input-queue-sizeinteger;
fstrm-set-output-notify-thresholdinteger;
fstrm-set-output-queue-model(mpsc|spsc);
fstrm-set-output-queue-sizeinteger;
fstrm-set-reopen-intervalinteger;
geoip-directory(quoted_string|none);
geoip-use-ecsboolean;
heartbeat-intervalinteger;
hostname(quoted_string|none);
inline-signingboolean;
interface-intervalinteger;
ixfr-from-differences(master|slave|boolean);
keep-response-order{address_match_element;...};
key-directoryquoted_string;
lame-ttlttlval;
listen-on[portinteger][dscp
integer]{
address_match_element;...};
listen-on-v6[portinteger][dscp
integer]{
address_match_element;...};
lmdb-mapsizesizeval;
lock-file(quoted_string|none);
managed-keys-directoryquoted_string;
masterfile-format(map|raw|text);
masterfile-style(full|relative);
match-mapped-addressesboolean;
max-acache-size(unlimited|sizeval);
max-cache-size(default|unlimited|sizeval|percentage);
max-cache-ttlinteger;
max-clients-per-queryinteger;
max-journal-size(unlimited|sizeval);
max-ncache-ttlinteger;
max-recordsinteger;
max-recursion-depthinteger;
max-recursion-queriesinteger;
max-refresh-timeinteger;
max-retry-timeinteger;
max-rsa-exponent-sizeinteger;
max-transfer-idle-ininteger;
max-transfer-idle-outinteger;
max-transfer-time-ininteger;
max-transfer-time-outinteger;
max-udp-sizeinteger;
max-zone-ttl(unlimited|ttlval);
memstatisticsboolean;
memstatistics-filequoted_string;
message-compressionboolean;
min-refresh-timeinteger;
min-retry-timeinteger;
minimal-anyboolean;
minimal-responses(no-auth|no-auth-recursive|boolean);
multi-masterboolean;
no-case-compress{address_match_element;...};
nocookie-udp-sizeinteger;
notify(explicit|master-only|boolean);
notify-delayinteger;
notify-rateinteger;
notify-source(ipv4_address|*)[port(integer|*)][
dscpinteger];
notify-source-v6(ipv6_address|*)[port(integer|*)]
[dscpinteger];
notify-to-soaboolean;
nta-lifetimettlval;
nta-recheckttlval;
nxdomain-redirectstring;
pid-file(quoted_string|none);
portinteger;
preferred-gluestring;
prefetchinteger[integer];
provide-ixfrboolean;
query-source(([address](ipv4_address|*)[port(
integer|*)])|([[address](ipv4_address|*)]
port(integer|*)))[dscpinteger];
query-source-v6(([address](ipv6_address|*)[port(
integer|*)])|([[address](ipv6_address|*)]
port(integer|*)))[dscpinteger];
querylogboolean;
random-devicequoted_string;
rate-limit{
all-per-secondinteger;
errors-per-secondinteger;
exempt-clients{address_match_element;...};
ipv4-prefix-lengthinteger;
ipv6-prefix-lengthinteger;
log-onlyboolean;
max-table-sizeinteger;
min-table-sizeinteger;
nodata-per-secondinteger;
nxdomains-per-secondinteger;
qps-scaleinteger;
referrals-per-secondinteger;
responses-per-secondinteger;
slipinteger;
windowinteger;
};
recursing-filequoted_string;
recursionboolean;
recursive-clientsinteger;
request-expireboolean;
request-ixfrboolean;
request-nsidboolean;
require-server-cookieboolean;
reserved-socketsinteger;
resolver-query-timeoutinteger;
response-policy{zonestring[logboolean][max-policy-ttl
integer][policy(cname|disabled|drop|given|no-op
|nodata|nxdomain|passthru|tcp-onlyquoted_string)][
recursive-onlyboolean];...}[break-dnssecboolean][
max-policy-ttlinteger][min-ns-dotsinteger][
nsip-wait-recurseboolean][qname-wait-recurseboolean]
[recursive-onlyboolean];
root-delegation-only[exclude{quoted_string;...}];
root-key-sentinelboolean;
rrset-order{[classstring][typestring][name
quoted_string]stringstring;...};
secroots-filequoted_string;
send-cookieboolean;
serial-query-rateinteger;
serial-update-method(date|increment|unixtime);
server-id(quoted_string|none|hostname);
servfail-ttlttlval;
session-keyalgstring;
session-keyfile(quoted_string|none);
session-keynamestring;
sig-signing-nodesinteger;
sig-signing-signaturesinteger;
sig-signing-typeinteger;
sig-validity-intervalinteger[integer];
sortlist{address_match_element;...};
stacksize(default|unlimited|sizeval);
startup-notify-rateinteger;
statistics-filequoted_string;
tcp-clientsinteger;
tcp-listen-queueinteger;
tkey-dhkeyquoted_stringinteger;
tkey-domainquoted_string;
tkey-gssapi-credentialquoted_string;
tkey-gssapi-keytabquoted_string;
transfer-format(many-answers|one-answer);
transfer-message-sizeinteger;
transfer-source(ipv4_address|*)[port(integer|*)][
dscpinteger];
transfer-source-v6(ipv6_address|*)[port(integer|*)
][dscpinteger];
transfers-ininteger;
transfers-outinteger;
transfers-per-nsinteger;
trust-anchor-telemetryboolean;//experimental
try-tcp-refreshboolean;
update-check-kskboolean;
use-alt-transfer-sourceboolean;
use-v4-udp-ports{portrange;...};
use-v6-udp-ports{portrange;...};
v6-biasinteger;
version(quoted_string|none);
zero-no-soa-ttlboolean;
zero-no-soa-ttl-cacheboolean;
zone-statistics(full|terse|none|boolean);
};
servernetprefix{
bogusboolean;
ednsboolean;
edns-udp-sizeinteger;
edns-versioninteger;
keysserver_key;
max-udp-sizeinteger;
notify-source(ipv4_address|*)[port(integer|*)][
dscpinteger];
notify-source-v6(ipv6_address|*)[port(integer|*)]
[dscpinteger];
provide-ixfrboolean;
query-source(([address](ipv4_address|*)[port(
integer|*)])|([[address](ipv4_address|*)]
port(integer|*)))[dscpinteger];
query-source-v6(([address](ipv6_address|*)[port(
integer|*)])|([[address](ipv6_address|*)]
port(integer|*)))[dscpinteger];
request-expireboolean;
request-ixfrboolean;
request-nsidboolean;
send-cookieboolean;
tcp-onlyboolean;
transfer-format(many-answers|one-answer);
transfer-source(ipv4_address|*)[port(integer|*)][
dscpinteger];
transfer-source-v6(ipv6_address|*)[port(integer|*)
][dscpinteger];
transfersinteger;
};
statistics-channels{
inet(ipv4_address|ipv6_address|
*)[port(integer|*)][
allow{address_match_element;...
}];
};
viewstring[class]{
acache-cleaning-intervalinteger;
acache-enableboolean;
additional-from-authboolean;
additional-from-cacheboolean;
allow-new-zonesboolean;
allow-notify{address_match_element;...};
allow-query{address_match_element;...};
allow-query-cache{address_match_element;...};
allow-query-cache-on{address_match_element;...};
allow-query-on{address_match_element;...};
allow-recursion{address_match_element;...};
allow-recursion-on{address_match_element;...};
allow-transfer{address_match_element;...};
allow-update{address_match_element;...};
allow-update-forwarding{address_match_element;...};
also-notify[portinteger][dscpinteger]{(masters|
ipv4_address[portinteger]|ipv6_address[port
integer])[keystring];...};
alt-transfer-source(ipv4_address|*)[port(integer|*)
][dscpinteger];
alt-transfer-source-v6(ipv6_address|*)[port(integer|
*)][dscpinteger];
attach-cachestring;
auth-nxdomainboolean;//defaultchanged
auto-dnssec(allow|maintain|off);
cache-filequoted_string;
catalog-zones{zonestring[default-masters[portinteger]
[dscpinteger]{(masters|ipv4_address[port
integer]|ipv6_address[portinteger])[key
string];...}][zone-directoryquoted_string][
in-memoryboolean][min-update-intervalinteger];...};
check-dup-records(fail|warn|ignore);
check-integrityboolean;
check-mx(fail|warn|ignore);
check-mx-cname(fail|warn|ignore);
check-names(master|slave|response
)(fail|warn|ignore);
check-siblingboolean;
check-spf(warn|ignore);
check-srv-cname(fail|warn|ignore);
check-wildcardboolean;
cleaning-intervalinteger;
clients-per-queryinteger;
deny-answer-addresses{address_match_element;...}[
except-from{quoted_string;...}];
deny-answer-aliases{quoted_string;...}[except-from{
quoted_string;...}];
dialup(notify|notify-passive|passive|refresh|boolean);
disable-algorithmsstring{string;
...};
disable-ds-digestsstring{string;
...};
disable-empty-zonestring;
dlzstring{
databasestring;
searchboolean;
};
dns64netprefix{
break-dnssecboolean;
clients{address_match_element;...};
exclude{address_match_element;...};
mapped{address_match_element;...};
recursive-onlyboolean;
suffixipv6_address;
};
dns64-contactstring;
dns64-serverstring;
dnssec-accept-expiredboolean;
dnssec-dnskey-kskonlyboolean;
dnssec-enableboolean;
dnssec-loadkeys-intervalinteger;
dnssec-lookaside(stringtrust-anchor
string|auto|no);
dnssec-must-be-securestringboolean;
dnssec-secure-to-insecureboolean;
dnssec-update-mode(maintain|no-resign);
dnssec-validation(yes|no|auto);
dnstap{(all|auth|client|forwarder|
resolver)[(query|response)];...};
dual-stack-servers[portinteger]{(quoted_string[port
integer][dscpinteger]|ipv4_address[port
integer][dscpinteger]|ipv6_address[port
integer][dscpinteger]);...};
dyndbstringquoted_string{
unspecified-text};
edns-udp-sizeinteger;
empty-contactstring;
empty-serverstring;
empty-zones-enableboolean;
fetch-quota-paramsintegerfixedpointfixedpointfixedpoint;
fetches-per-serverinteger[(drop|fail)];
fetches-per-zoneinteger[(drop|fail)];
filter-aaaa{address_match_element;...};
filter-aaaa-on-v4(break-dnssec|boolean);
filter-aaaa-on-v6(break-dnssec|boolean);
forward(first|only);
forwarders[portinteger][dscpinteger]{(ipv4_address
|ipv6_address)[portinteger][dscpinteger];...};
inline-signingboolean;
ixfr-from-differences(master|slave|boolean);
keystring{
algorithmstring;
secretstring;
};
key-directoryquoted_string;
lame-ttlttlval;
lmdb-mapsizesizeval;
managed-keys{stringstring
integerintegerinteger
quoted_string;...};
masterfile-format(map|raw|text);
masterfile-style(full|relative);
match-clients{address_match_element;...};
match-destinations{address_match_element;...};
match-recursive-onlyboolean;
max-acache-size(unlimited|sizeval);
max-cache-size(default|unlimited|sizeval|percentage);
max-cache-ttlinteger;
max-clients-per-queryinteger;
max-journal-size(unlimited|sizeval);
max-ncache-ttlinteger;
max-recordsinteger;
max-recursion-depthinteger;
max-recursion-queriesinteger;
max-refresh-timeinteger;
max-retry-timeinteger;
max-transfer-idle-ininteger;
max-transfer-idle-outinteger;
max-transfer-time-ininteger;
max-transfer-time-outinteger;
max-udp-sizeinteger;
max-zone-ttl(unlimited|ttlval);
message-compressionboolean;
min-refresh-timeinteger;
min-retry-timeinteger;
minimal-anyboolean;
minimal-responses(no-auth|no-auth-recursive|boolean);
multi-masterboolean;
no-case-compress{address_match_element;...};
nocookie-udp-sizeinteger;
notify(explicit|master-only|boolean);
notify-delayinteger;
notify-source(ipv4_address|*)[port(integer|*)][
dscpinteger];
notify-source-v6(ipv6_address|*)[port(integer|*)]
[dscpinteger];
notify-to-soaboolean;
nta-lifetimettlval;
nta-recheckttlval;
nxdomain-redirectstring;
preferred-gluestring;
prefetchinteger[integer];
provide-ixfrboolean;
query-source(([address](ipv4_address|*)[port(
integer|*)])|([[address](ipv4_address|*)]
port(integer|*)))[dscpinteger];
query-source-v6(([address](ipv6_address|*)[port(
integer|*)])|([[address](ipv6_address|*)]
port(integer|*)))[dscpinteger];
rate-limit{
all-per-secondinteger;
errors-per-secondinteger;
exempt-clients{address_match_element;...};
ipv4-prefix-lengthinteger;
ipv6-prefix-lengthinteger;
log-onlyboolean;
max-table-sizeinteger;
min-table-sizeinteger;
nodata-per-secondinteger;
nxdomains-per-secondinteger;
qps-scaleinteger;
referrals-per-secondinteger;
responses-per-secondinteger;
slipinteger;
windowinteger;
};
recursionboolean;
request-expireboolean;
request-ixfrboolean;
request-nsidboolean;
require-server-cookieboolean;
resolver-query-timeoutinteger;
response-policy{zonestring[logboolean][max-policy-ttl
integer][policy(cname|disabled|drop|given|no-op
|nodata|nxdomain|passthru|tcp-onlyquoted_string)][
recursive-onlyboolean];...}[break-dnssecboolean][
max-policy-ttlinteger][min-ns-dotsinteger][
nsip-wait-recurseboolean][qname-wait-recurseboolean]
[recursive-onlyboolean];
root-delegation-only[exclude{quoted_string;...}];
root-key-sentinelboolean;
rrset-order{[classstring][typestring][name
quoted_string]stringstring;...};
send-cookieboolean;
serial-update-method(date|increment|unixtime);
servernetprefix{
bogusboolean;
ednsboolean;
edns-udp-sizeinteger;
edns-versioninteger;
keysserver_key;
max-udp-sizeinteger;
notify-source(ipv4_address|*)[port(integer|*
)][dscpinteger];
notify-source-v6(ipv6_address|*)[port(integer
|*)][dscpinteger];
provide-ixfrboolean;
query-source(([address](ipv4_address|*)[port
(integer|*)])|([[address](
ipv4_address|*)]port(integer|*)))[
dscpinteger];
query-source-v6(([address](ipv6_address|*)[
port(integer|*)])|([[address](
ipv6_address|*)]port(integer|*)))[
dscpinteger];
request-expireboolean;
request-ixfrboolean;
request-nsidboolean;
send-cookieboolean;
tcp-onlyboolean;
transfer-format(many-answers|one-answer);
transfer-source(ipv4_address|*)[port(integer|
*)][dscpinteger];
transfer-source-v6(ipv6_address|*)[port(
integer|*)][dscpinteger];
transfersinteger;
};
servfail-ttlttlval;
sig-signing-nodesinteger;
sig-signing-signaturesinteger;
sig-signing-typeinteger;
sig-validity-intervalinteger[integer];
sortlist{address_match_element;...};
transfer-format(many-answers|one-answer);
transfer-source(ipv4_address|*)[port(integer|*)][
dscpinteger];
transfer-source-v6(ipv6_address|*)[port(integer|*)
][dscpinteger];
trust-anchor-telemetryboolean;//experimental
trusted-keys{stringinteger
integerintegerquoted_string;
...};
try-tcp-refreshboolean;
update-check-kskboolean;
use-alt-transfer-sourceboolean;
v6-biasinteger;
zero-no-soa-ttlboolean;
zero-no-soa-ttl-cacheboolean;
zonestring[class]{
allow-notify{address_match_element;...};
allow-query{address_match_element;...};
allow-query-on{address_match_element;...};
allow-transfer{address_match_element;...};
allow-update{address_match_element;...};
allow-update-forwarding{address_match_element;...};
also-notify[portinteger][dscpinteger]{(
masters|ipv4_address[portinteger]|
ipv6_address[portinteger])[keystring];
...};
alt-transfer-source(ipv4_address|*)[port(
integer|*)][dscpinteger];
alt-transfer-source-v6(ipv6_address|*)[port(
integer|*)][dscpinteger];
auto-dnssec(allow|maintain|off);
check-dup-records(fail|warn|ignore);
check-integrityboolean;
check-mx(fail|warn|ignore);
check-mx-cname(fail|warn|ignore);
check-names(fail|warn|ignore);
check-siblingboolean;
check-spf(warn|ignore);
check-srv-cname(fail|warn|ignore);
check-wildcardboolean;
databasestring;
delegation-onlyboolean;
dialup(notify|notify-passive|passive|refresh|
boolean);
dlzstring;
dnssec-dnskey-kskonlyboolean;
dnssec-loadkeys-intervalinteger;
dnssec-secure-to-insecureboolean;
dnssec-update-mode(maintain|no-resign);
filequoted_string;
forward(first|only);
forwarders[portinteger][dscpinteger]{(
ipv4_address|ipv6_address)[portinteger][
dscpinteger];...};
in-viewstring;
inline-signingboolean;
ixfr-from-differencesboolean;
journalquoted_string;
key-directoryquoted_string;
masterfile-format(map|raw|text);
masterfile-style(full|relative);
masters[portinteger][dscpinteger]{(masters
|ipv4_address[portinteger]|ipv6_address[
portinteger])[keystring];...};
max-ixfr-log-size(default|unlimited|
max-journal-size(unlimited|sizeval);
max-recordsinteger;
max-refresh-timeinteger;
max-retry-timeinteger;
max-transfer-idle-ininteger;
max-transfer-idle-outinteger;
max-transfer-time-ininteger;
max-transfer-time-outinteger;
max-zone-ttl(unlimited|ttlval);
min-refresh-timeinteger;
min-retry-timeinteger;
multi-masterboolean;
notify(explicit|master-only|boolean);
notify-delayinteger;
notify-source(ipv4_address|*)[port(integer|*
)][dscpinteger];
notify-source-v6(ipv6_address|*)[port(integer
|*)][dscpinteger];
notify-to-soaboolean;
pubkeyinteger
integer
integer
request-expireboolean;
request-ixfrboolean;
serial-update-method(date|increment|unixtime);
server-addresses{(ipv4_address|ipv6_address);...};
server-names{quoted_string;...};
sig-signing-nodesinteger;
sig-signing-signaturesinteger;
sig-signing-typeinteger;
sig-validity-intervalinteger[integer];
transfer-source(ipv4_address|*)[port(integer|
*)][dscpinteger];
transfer-source-v6(ipv6_address|*)[port(
integer|*)][dscpinteger];
try-tcp-refreshboolean;
type(delegation-only|forward|hint|master|redirect
|slave|static-stub|stub);
update-check-kskboolean;
update-policy(local|{(deny|grant)string(
6to4-self|external|krb5-self|krb5-selfsub|
krb5-subdomain|ms-self|ms-selfsub|ms-subdomain|
name|self|selfsub|selfwild|subdomain|tcp-self
|wildcard|zonesub)[string]rrtypelist;...};
use-alt-transfer-sourceboolean;
zero-no-soa-ttlboolean;
zone-statistics(full|terse|none|boolean);
};
zone-statistics(full|terse|none|boolean);
};
zonestring[class]{
allow-notify{address_match_element;...};
allow-query{address_match_element;...};
allow-query-on{address_match_element;...};
allow-transfer{address_match_element;...};
allow-update{address_match_element;...};
allow-update-forwarding{address_match_element;...};
also-notify[portinteger][dscpinteger]{(masters|
ipv4_address[portinteger]|ipv6_address[port
integer])[keystring];...};
alt-transfer-source(ipv4_address|*)[port(integer|*)
][dscpinteger];
alt-transfer-source-v6(ipv6_address|*)[port(integer|
*)][dscpinteger];
auto-dnssec(allow|maintain|off);
check-dup-records(fail|warn|ignore);
check-integrityboolean;
check-mx(fail|warn|ignore);
check-mx-cname(fail|warn|ignore);
check-names(fail|warn|ignore);
check-siblingboolean;
check-spf(warn|ignore);
check-srv-cname(fail|warn|ignore);
check-wildcardboolean;
databasestring;
delegation-onlyboolean;
dialup(notify|notify-passive|passive|refresh|boolean);
dlzstring;
dnssec-dnskey-kskonlyboolean;
dnssec-loadkeys-intervalinteger;
dnssec-secure-to-insecureboolean;
dnssec-update-mode(maintain|no-resign);
filequoted_string;
forward(first|only);
forwarders[portinteger][dscpinteger]{(ipv4_address
|ipv6_address)[portinteger][dscpinteger];...};
in-viewstring;
inline-signingboolean;
ixfr-from-differencesboolean;
journalquoted_string;
key-directoryquoted_string;
masterfile-format(map|raw|text);
masterfile-style(full|relative);
masters[portinteger][dscpinteger]{(masters|
ipv4_address[portinteger]|ipv6_address[port
integer])[keystring];...};
max-journal-size(unlimited|sizeval);
max-recordsinteger;
max-refresh-timeinteger;
max-retry-timeinteger;
max-transfer-idle-ininteger;
max-transfer-idle-outinteger;
max-transfer-time-ininteger;
max-transfer-time-outinteger;
max-zone-ttl(unlimited|ttlval);
min-refresh-timeinteger;
min-retry-timeinteger;
multi-masterboolean;
notify(explicit|master-only|boolean);
notify-delayinteger;
notify-source(ipv4_address|*)[port(integer|*)][
dscpinteger];
notify-source-v6(ipv6_address|*)[port(integer|*)]
[dscpinteger];
notify-to-soaboolean;
pubkeyintegerinteger
request-expireboolean;
request-ixfrboolean;
serial-update-method(date|increment|unixtime);
server-addresses{(ipv4_address|ipv6_address);...};
server-names{quoted_string;...};
sig-signing-nodesinteger;
sig-signing-signaturesinteger;
sig-signing-typeinteger;
sig-validity-intervalinteger[integer];
transfer-source(ipv4_address|*)[port(integer|*)][
dscpinteger];
transfer-source-v6(ipv6_address|*)[port(integer|*)
][dscpinteger];
try-tcp-refreshboolean;
type(delegation-only|forward|hint|master|redirect|slave
|static-stub|stub);
update-check-kskboolean;
update-policy(local|{(deny|grant)string(6to4-self|
external|krb5-self|krb5-selfsub|krb5-subdomain|ms-self
|ms-selfsub|ms-subdomain|name|self|selfsub|selfwild
|subdomain|tcp-self|wildcard|zonesub)[string]
rrtypelist;...};
use-alt-transfer-sourceboolean;
zero-no-soa-ttlboolean;
zone-statistics(full|terse|none|boolean);
};
BIND 9.11.36 (Extended Support Version)
man.nsupdate.html 0000644 00000066632 15253021417 0010044 0 ustar 00nsupdate — Dynamic DNS update utility
nsupdate [-d] [-D] [-i] [-L ] [[level-g] | [-o] | [-l] | [-y ] | [[hmac:]keyname:secret-k ]] [keyfile-t ] [timeout-u ] [udptimeout-r ] [udpretries-R ] [randomdev-v] [-T] [-P] [-V] [filename]
nsupdate is used to submit Dynamic DNS Update requests as defined in RFC 2136 to a name server. This allows resource records to be added or removed from a zone without manually editing the zone file. A single update request can contain requests to add or remove more than one resource record.
Zones that are under dynamic control via nsupdate or a DHCP server should not be edited by hand. Manual edits could conflict with dynamic updates and cause data to be lost.
The resource records that are dynamically added or removed with nsupdate have to be in the same zone. Requests are sent to the zone's master server. This is identified by the MNAME field of the zone's SOA record.
Transaction signatures can be used to authenticate the Dynamic DNS updates. These use the TSIG resource record type described in RFC 2845 or the SIG(0) record described in RFC 2535 and RFC 2931 or GSS-TSIG as described in RFC 3645.
TSIG relies on
a shared secret that should only be known to
nsupdate and the name server.
For instance, suitable key and
server statements would be added to
/etc/named.conf so that the name server
can associate the appropriate secret key and algorithm with
the IP address of the client application that will be using
TSIG authentication. You can use ddns-confgen
to generate suitable configuration fragments.
nsupdate
uses the -y or -k options
to provide the TSIG shared secret. These options are mutually exclusive.
SIG(0) uses public key cryptography. To use a SIG(0) key, the public key must be stored in a KEY record in a zone served by the name server.
GSS-TSIG uses Kerberos credentials. Standard GSS-TSIG mode
is switched on with the -g flag. A
non-standards-compliant variant of GSS-TSIG used by Windows
2000 can be switched on with the -o flag.
Debug mode. This provides tracing information about the update requests that are made and the replies received from the name server.
Extra debug mode.
Force interactive mode, even when standard input is not a terminal.
keyfile
The file containing the TSIG authentication key.
Keyfiles may be in two formats: a single file containing
a named.conf-format key
statement, which may be generated automatically by
ddns-confgen, or a pair of files whose names are
of the format K{name}.+157.+{random}.key and
K{name}.+157.+{random}.private, which can be
generated by dnssec-keygen.
The -k may also be used to specify a SIG(0) key used
to authenticate Dynamic DNS update requests. In this case, the key
specified is not an HMAC-MD5 key.
Local-host only mode. This sets the server address to
localhost (disabling the server so that the server
address cannot be overridden). Connections to the local server will
use a TSIG key found in /var/run/named/session.key,
which is automatically generated by named if any
local master zone has set update-policy to
local. The location of this key file can be
overridden with the -k option.
levelSet the logging debug level. If zero, logging is disabled.
portSet the port to use for connections to a name server. The default is 53.
Print the list of private BIND-specific resource record
types whose format is understood
by nsupdate. See also
the -T option.
udpretriesThe number of UDP retries. The default is 3. If zero, only one update request will be made.
randomdev
Where to obtain randomness. If the operating system
does not provide a /dev/random or
equivalent device, the default source of randomness is keyboard
input. randomdev specifies the name of
a character device or file containing random data to be used
instead of the default. The special value
keyboard indicates that keyboard input
should be used. This option may be specified multiple times.
timeoutThe maximum time an update request can take before it is aborted. The default is 300 seconds. Zero can be used to disable the timeout.
Print the list of IANA standard resource record types
whose format is understood by nsupdate.
nsupdate will exit after the lists are
printed. The -T option can be combined
with the -P option.
Other types can be entered using "TYPEXXXXX" where "XXXXX" is the decimal value of the type with no leading zeros. The rdata, if present, will be parsed using the UNKNOWN rdata format, (<backslash> <hash> <space> <length> <space> <hexstring>).
udptimeoutThe UDP retry interval. The default is 3 seconds. If zero, the interval will be computed from the timeout interval and number of UDP retries.
Use TCP even for small update requests. By default, nsupdate uses UDP to send update requests to the name server unless they are too large to fit in a UDP request in which case TCP will be used. TCP may be preferable when a batch of update requests is made.
Print the version number and exit.
[hmac:]keyname:secret
Literal TSIG authentication key.
keyname is the name of the key, and
secret is the base64 encoded shared secret.
hmac is the name of the key algorithm;
valid choices are hmac-md5,
hmac-sha1, hmac-sha224,
hmac-sha256, hmac-sha384, or
hmac-sha512. If hmac
is not specified, the default is hmac-md5
or if MD5 was disabled hmac-sha256.
NOTE: Use of the -y option is discouraged because the
shared secret is supplied as a command line argument in clear text.
This may be visible in the output from
ps(1)
or in a history file maintained by the user's shell.
nsupdate
reads input from
filename
or standard input.
Each command is supplied on exactly one line of input.
Some commands are for administrative purposes.
The others are either update instructions or prerequisite checks on the
contents of the zone.
These checks set conditions that some name or set of
resource records (RRset) either exists or is absent from the zone.
These conditions must be met if the entire update request is to succeed.
Updates will be rejected if the tests for the prerequisite conditions
fail.
Every update request consists of zero or more prerequisites and zero or more updates. This allows a suitably authenticated update request to proceed if some specified resource records are present or missing from the zone. A blank input line (or the send command) causes the accumulated commands to be sent as one Dynamic DNS update request to the name server.
The command formats and their meaning are as follows:
Sends all dynamic update requests to the name server
servername.
When no server statement is provided,
nsupdate
will send updates to the master server of the correct zone.
The MNAME field of that zone's SOA record will identify the
master
server for that zone.
port
is the port number on
servername
where the dynamic update requests get sent.
If no port number is specified, the default DNS port number of
53 is
used.
Sends all dynamic update requests using the local
address.
When no local statement is provided,
nsupdate
will send updates using an address and port chosen by the
system.
port
can additionally be used to make requests come from a specific
port.
If no port number is specified, the system will assign one.
Specifies that all updates are to be made to the zone
zonename.
If no
zone
statement is provided,
nsupdate
will attempt determine the correct zone to update based on the
rest of the input.
Specify the default class.
If no class is specified, the
default class is
IN.
Specify the default time to live for records to be added.
The value none will clear the default
ttl.
Specifies that all updates are to be TSIG-signed using the
keyname secret pair.
If hmac is specified, then it sets the
signing algorithm in use; the default is
hmac-md5 or if MD5 was disabled
hmac-sha256. The key
command overrides any key specified on the command line via
-y or -k.
Use GSS-TSIG to sign the updated. This is equivalent to
specifying -g on the command line.
Use the Windows 2000 version of GSS-TSIG to sign the updated.
This is equivalent to specifying -o on the
command line.
When using GSS-TSIG use realm_name rather
than the default realm in krb5.conf. If no
realm is specified the saved realm is cleared.
Turn on or off check-names processing on records to be added. Check-names has no effect on prerequisites or records to be deleted. By default check-names processing is on. If check-names processing fails the record will not be added to the UPDATE message.
Requires that no resource record of any type exists with name
domain-name.
Requires that
domain-name
exists (has as at least one resource record, of any type).
Requires that no resource record exists of the specified
type,
class
and
domain-name.
If
class
is omitted, IN (internet) is assumed.
This requires that a resource record of the specified
type,
class
and
domain-name
must exist.
If
class
is omitted, IN (internet) is assumed.
The
data
from each set of prerequisites of this form
sharing a common
type,
class,
and
domain-name
are combined to form a set of RRs. This set of RRs must
exactly match the set of RRs existing in the zone at the
given
type,
class,
and
domain-name.
The
data
are written in the standard text representation of the resource
record's
RDATA.
Deletes any resource records named
domain-name.
If
type
and
data
is provided, only matching resource records will be removed.
The internet class is assumed if
class
is not supplied. The
ttl
is ignored, and is only allowed for compatibility.
Adds a new resource record with the specified
ttl,
class
and
data.
Displays the current message, containing all of the prerequisites and updates specified since the last send.
Sends the current message. This is equivalent to entering a blank line.
Displays the answer.
Turn on debugging.
Print version number.
Print a list of commands.
Lines beginning with a semicolon are comments and are ignored.
The examples below show how nsupdate could be used to insert and delete resource records from the example.com zone. Notice that the input in each example contains a trailing blank line so that a group of commands are sent as one dynamic update request to the master name server for example.com.
# nsupdate > update delete oldhost.example.com A > update add newhost.example.com 86400 A 172.16.1.1 > send
Any A records for oldhost.example.com are deleted. And an A record for newhost.example.com with IP address 172.16.1.1 is added. The newly-added record has a 1 day TTL (86400 seconds).
# nsupdate > prereq nxdomain nickname.example.com > update add nickname.example.com 86400 CNAME somehost.example.com > send
The prerequisite condition gets the name server to check that there are no resource records of any type for nickname.example.com. If there are, the update request fails. If this name does not exist, a CNAME for it is added. This ensures that when the CNAME is added, it cannot conflict with the long-standing rule in RFC 1034 that a name must not exist as any other record type if it exists as a CNAME. (The rule has been updated for DNSSEC in RFC 2535 to allow CNAMEs to have RRSIG, DNSKEY and NSEC records.)
/etc/resolv.confused to identify default name server
/var/run/named/session.keysets the default TSIG key for use in local-only mode
K{name}.+157.+{random}.keybase-64 encoding of HMAC-MD5 key created by dnssec-keygen(8).
K{name}.+157.+{random}.privatebase-64 encoding of HMAC-MD5 key created by dnssec-keygen(8).
BIND 9.11.36 (Extended Support Version)
Bv9ARM.ch06.html 0000644 00002427774 15253021417 0007220 0 ustar 00Table of Contents
Following is a list of elements used throughout the BIND configuration file documentation:
|
|
The name of an |
|
|
A list of one or more
|
|
|
A named list of one or more |
|
|
A quoted string which is used as
a DNS name; for example, |
|
|
A list of one or more |
|
|
One to four integers valued 0 through 255 separated by dots ("."), such as 123.45.67 or 89.123.45.67. |
|
|
An IPv4 address with exactly four elements
in |
|
|
An IPv6 address, such as 2001:db8::1234. IPv6-scoped addresses that have ambiguity on their scope zones must be disambiguated by an appropriate zone ID with the percent character ("%") as a delimiter. It is strongly recommended to use string zone names rather than numeric identifiers, to be robust against system configuration changes. However, since there is no standard mapping for such names and identifier values, only interface names as link identifiers are supported, assuming one-to-one mapping between interfaces and links. For example, a link-local address fe80::1 on the link attached to the interface ne0 can be specified as fe80::1%ne0. Note that on most systems link-local addresses always have ambiguity and need to be disambiguated. |
|
|
An |
|
|
A |
|
|
An IP port |
|
|
An IP network specified as an When specifying a prefix involving a IPv6-scoped address, the scope may be omitted. In that case, the prefix matches packets from any scope. |
|
|
A |
|
|
A list of one or more
|
|
|
A non-negative 32-bit integer (i.e., a number between 0 and 4294967295, inclusive). Its acceptable value might be further limited by the context in which it is used. |
|
|
A non-negative real number that can be specified to the nearest one-hundredth. Up to five digits can be specified before a decimal point, and up to two digits after, so the maximum value is 99999.99. Acceptable values might be further limited by the contexts in which they are used. |
|
|
A quoted string which is used as
a pathname, such as |
|
|
A list of an |
|
|
A 64-bit unsigned integer, or the keywords
Integers may take values
0 <= value <= 18446744073709551615, though
certain parameters
(such as max-journal-size) may
use a more limited range within these extremes.
In most cases, setting a value to 0 does not
literally mean zero; it means "undefined" or
"as big as possible," depending on the context.
See the explanations of particular parameters
that use
Numeric values can optionally be followed by a
scaling factor:
|
|
|
A
The behavior is exactly the same as
|
|
|
Either |
|
|
One of |
address_match_list=address_match_list_element; ...address_match_list_element= [ ! ] (ip_address|ip_prefix| keykey_id|acl_name| {address_match_list} )
Address match lists are primarily used to determine access control for various server operations. They are also used in the listen-on and sortlist statements. The elements which constitute an address match list can be any of the following:
Elements can be negated with a leading exclamation mark ("!"), and the match list names "any", "none", "localhost", and "localnets" are predefined. More information on those names can be found in the description of the acl statement.
The addition of the key clause made the name of this syntactic element something of a misnomer, since security keys can be used to validate access without regard to a host or network address. Nonetheless, the term "address match list" is still used throughout the documentation.
When a given IP address or prefix is compared to an address match list, the comparison takes place in approximately O(1) time. However, key comparisons require that the list of keys be traversed until a matching key is found, and therefore may be somewhat slower.
The interpretation of a match depends on whether the list is being used for access control, defining listen-on ports, or in a sortlist, and whether the element was negated.
When used as an access control list, a non-negated match allows access and a negated match denies access. If there is no match, access is denied. The clauses allow-notify, allow-recursion, allow-recursion-on, allow-query, allow-query-on, allow-query-cache, allow-query-cache-on, allow-transfer, allow-update, allow-update-forwarding, blackhole, and keep-response-order all use address match lists. Similarly, the listen-on option causes the server to refuse queries on any of the machine's addresses which do not match the list.
Order of insertion is significant. If more than one element in an ACL is found to match a given IP address or prefix, preference is given to the one that came first in the ACL definition. Because of this first-match behavior, an element that defines a subset of another element in the list should come before the broader element, regardless of whether either is negated. For example, in 1.2.3/24; ! 1.2.3.13; the 1.2.3.13 element is completely useless because the algorithm matches any lookup for 1.2.3.13 to the 1.2.3/24 element. Using ! 1.2.3.13; 1.2.3/24 fixes that problem by blocking 1.2.3.13 via the negation, but all other 1.2.3.* hosts pass through.
The BIND 9 comment syntax allows comments to appear anywhere that whitespace may appear in a BIND configuration file. To appeal to programmers of all kinds, they can be written in the C, C++, or shell/perl style.
/* This is a BIND comment as in C */
// This is a BIND comment as in C++
# This is a BIND comment as in common Unix shells # and perl
Comments may appear anywhere that whitespace may appear in a BIND configuration file.
C-style comments start with the two characters /* (slash, star) and end with */ (star, slash). Because they are completely delimited with these characters, they can be used to comment only a portion of a line or to span multiple lines.
C-style comments cannot be nested. For example, the following is not valid because the entire comment ends with the first */:
/* This is the start of a comment. This is still part of the comment. /* This is an incorrect attempt at nesting a comment. */ This is no longer in any comment. */
C++-style comments start with the two characters // (slash, slash) and continue to the end of the physical line. They cannot be continued across multiple physical lines; to have one logical comment span multiple lines, each line must use the // pair. For example:
// This is the start of a comment. The next line // is a new comment, even though it is logically // part of the previous comment.
Shell-style (or perl-style) comments start
with the character # (number sign)
and continue to the end of the
physical line, as in C++ comments.
For example:
# This is the start of a comment. The next line # is a new comment, even though it is logically # part of the previous comment.
The semicolon (";") character cannot start a comment, unlike in a zone file. The semicolon indicates the end of a configuration statement.
A BIND 9 configuration consists of statements and comments. Statements end with a semicolon; statements and comments are the only elements that can appear without enclosing braces. Many statements contain a block of sub-statements, which are also terminated with a semicolon.
The following statements are supported:
|
acl |
Defines a named IP address matching list, for access control and other uses. |
|
controls |
Declares control channels to be used by the rndc utility. |
|
include |
Includes a file. |
|
key |
Specifies key information for use in authentication and authorization using TSIG. |
|
logging |
Specifies what information the server logs and where the log messages are sent. |
|
lwres |
Configures named to also act as a lightweight resolver daemon (lwresd). |
|
masters |
Defines a named list of primary servers for inclusion in stub and secondary zones' masters or also-notify lists. |
|
options |
Controls global server configuration options and sets defaults for other statements. |
|
server |
Sets certain configuration options on a per-server basis. |
|
statistics-channels |
Declares communication channels to get access to named statistics. |
|
trusted-keys |
Defines trusted DNSSEC keys. |
|
managed-keys |
Lists DNSSEC keys to be kept up-to-date using RFC 5011 trust anchor maintenance. |
|
view |
Defines a view. |
|
zone |
Defines a zone. |
The logging and options statements may only occur once per configuration.
The acl statement assigns a symbolic name to an address match list. It gets its name from one of the primary uses of address match lists: Access Control Lists (ACLs).
The following ACLs are built-in:
|
any |
Matches all hosts. |
|
none |
Matches no hosts. |
|
localhost |
Matches the IPv4 and IPv6 addresses of all network interfaces on the system. When addresses are added or removed, the localhost ACL element is updated to reflect the changes. |
|
localnets |
Matches any host on an IPv4 or IPv6 network for which the system has an interface. When addresses are added or removed, the localnets ACL element is updated to reflect the changes. Some systems do not provide a way to determine the prefix lengths of local IPv6 addresses; in such cases, localnets only matches the local IPv6 addresses, just like localhost. |
controls { inet (ipv4_address|ipv6_address| * ) [ port (integer| * ) ] allow {address_match_element; ... } [ keys {string; ... } ] [ read-onlyboolean]; unixquoted_stringpermintegerownerintegergroupinteger[ keys {string; ... } ] [ read-onlyboolean]; };
The controls statement declares control channels to be used by system administrators to manage the operation of the name server. These control channels are used by the rndc utility to send commands to and retrieve non-DNS results from a name server.
An inet control channel is a TCP socket
listening at the specified ip_port on the
specified ip_addr, which can be an IPv4 or IPv6
address. An ip_addr of * (asterisk) is
interpreted as the IPv4 wildcard address; connections are
accepted on any of the system's IPv4 addresses.
To listen on the IPv6 wildcard address,
use an ip_addr of ::.
If rndc is only used on the local host,
using the loopback address (127.0.0.1
or ::1) is recommended for maximum security.
If no port is specified, port 953 is used. The asterisk
"*" cannot be used for ip_port.
The ability to issue commands over the control channel is restricted by the allow and keys clauses. Connections to the control channel are permitted based on the address_match_list. This is for simple IP address-based filtering only; any key_id elements of the address_match_list are ignored.
A unix control channel is a Unix domain socket listening at the specified path in the file system. Access to the socket is specified by the perm, owner, and group clauses. Note on some platforms (SunOS and Solaris), the permissions (perm) are applied to the parent directory as the permissions on the socket itself are ignored.
The primary authorization mechanism of the command channel is the key_list, which contains a list of key_ids. Each key_id in the key_list is authorized to execute commands over the control channel. See Remote Name Daemon Control application in the section called “Administrative Tools”) for information about configuring keys in rndc.
If the read-only clause is enabled, the control channel is limited to the following set of read-only commands: nta -dump, null, status, showzone, testgen, and zonestatus. By default, read-only is not enabled and the control channel allows read-write access.
If no controls statement is present,
named sets up a default
control channel listening on the loopback address 127.0.0.1
and its IPv6 counterpart ::1.
In this case, and also when the controls statement
is present but does not have a keys clause,
named attempts to load the command channel key
from the file rndc.key in
/etc (or whatever sysconfdir
was specified when BIND was built).
To create an rndc.key file, run
rndc-confgen -a.
The key name and the size of the secret cannot be easily changed; if it
is desirable to change those things, make a
rndc.conf with a custom key. The rndc.key file
also has its
permissions set such that only the owner of the file (the user that
named is running as) can access it.
For greater flexibility in allowing other users to access
rndc commands, create
a
rndc.conf file and make it group-readable by a group
that contains the users who should have access.
To disable the command channel, use an empty controls statement: controls { };.
The include statement inserts the specified file at the point where the include statement is encountered. The include statement facilitates the administration of configuration files by permitting the reading or writing of some things but not others. For example, the statement could include private keys that are readable only by the name server.
The key statement defines a shared secret key for use with TSIG (see the section called “TSIG”) or the command channel (see the section called “controls Statement Definition and Usage”).
The key statement can occur at the top level of the configuration file or inside a view statement. Keys defined in top-level key statements can be used in all views. Keys intended for use in a controls statement (see the section called “controls Statement Definition and Usage”) must be defined at the top level.
The key_id, also known as the
key name, is a domain name that uniquely identifies the key. It can
be used in a server
statement to cause requests sent to that
server to be signed with this key, or in address match lists to
verify that incoming requests have been signed with a key
matching this name, algorithm, and secret.
The algorithm_id is a string
that specifies a security/authentication algorithm. The
named server supports hmac-md5,
hmac-sha1, hmac-sha224,
hmac-sha256, hmac-sha384,
and hmac-sha512 TSIG authentication.
Truncated hashes are supported by appending the minimum
number of required bits preceded by a dash, e.g.,
hmac-sha1-80. The
secret_string is the secret
to be used by the algorithm, and is treated as a Base64-encoded string.
logging { categorystring{string; ... }; channelstring{ bufferedboolean; filequoted_string[ versions ( "unlimited" |integer) ] [ sizesize]; null; print-categoryboolean; print-severityboolean; print-timeboolean; severitylog_severity; stderr; syslog [syslog_facility]; }; };
The logging statement configures a wide variety of logging options for the name server. Its channel phrase associates output methods, format options, and severity levels with a name that can then be used with the category phrase to select how various classes of messages are logged.
Only one logging statement is used to define as many channels and categories as desired. If there is no logging statement, the logging configuration is:
logging {
category default { default_syslog; default_debug; };
category unmatched { null; };
};
If named is started with the
-L option, it logs to the specified file
at startup, instead of using syslog. In this case the logging
configuration is:
logging {
category default { default_logfile; default_debug; };
category unmatched { null; };
};
The logging configuration
is only established when
the entire configuration file has been parsed. When the server starts up, all logging messages
regarding syntax errors in the configuration file go to the default
channels, or to standard error if the -g option
was specified.
All log output goes to one or more channels; there is no limit to the number of channels that can be created.
Every channel definition must include a destination clause that says whether messages selected for the channel go to a file, go to a particular syslog facility, go to the standard error stream, or are discarded. The definition can optionally also limit the message severity level that is accepted by the channel (the default is info), and whether to include a named-generated time stamp, the category name, and/or the severity level (the default is not to include any).
The null destination clause causes all messages sent to the channel to be discarded; in that case, other options for the channel are meaningless.
The file destination clause directs the channel to a disk file. It can include limitations both on how large the file is allowed to become, and on how many versions of the file are saved each time the file is opened.
If the versions log file
option is used, then
named retains that many backup
versions of the file by
renaming them when opening. For example, to keep
three old versions
of the file lamers.log, just
before it is opened
lamers.log.1 is renamed to
lamers.log.2, lamers.log.0 is renamed
to lamers.log.1, and lamers.log is
renamed to lamers.log.0.
The versions unlimited option can be set to
not limit
the number of versions.
If a size option is associated with
the log file,
then renaming is only done when the file being opened exceeds the
indicated size. No backup versions are kept by default; any
existing
log file is simply appended.
The size option for files is used to limit log growth. If the file ever exceeds the size, then named stops writing to the file unless it also has a versions option associated with it. If backup versions are kept, the files are rolled as described above and a new one begun. If there is no versions option, no more data is written to the log until some out-of-band mechanism removes or truncates the log to less than the maximum size. The default behavior is not to limit the size of the file.
Here is an example using the size and versions options:
channel an_example_channel {
file "example.log" versions 3 size 20m;
print-time yes;
print-category yes;
};
The syslog destination clause directs the channel to the system log. Its argument is a syslog facility as described in the syslog man page. Known facilities are kern, user, mail, daemon, auth, syslog, lpr, news, uucp, cron, authpriv, ftp, local0, local1, local2, local3, local4, local5, local6, and local7; however, not all facilities are supported on all operating systems. How syslog handles messages sent to this facility is described in the syslog.conf man page. On a system which uses a very old version of syslog, which only uses two arguments to the openlog() function, then this clause is silently ignored.
On Windows machines, syslog messages are directed to the EventViewer.
The severity clause works like syslog's "priorities," except that they can also be used when writing straight to a file rather than using syslog. Messages which are not at least of the severity level given are not selected for the channel; messages of higher severity levels are accepted.
When using syslog, the syslog.conf priorities also determine what eventually passes through. For example, defining a channel facility and severity as daemon and debug, but only logging daemon.warning via syslog.conf, causes messages of severity info and notice to be dropped. If the situation were reversed, with named writing messages of only warning or higher, then syslogd would print all messages it received from the channel.
The stderr destination clause directs the channel to the server's standard error stream. This is intended for use when the server is running as a foreground process, as when debugging a configuration, for example.
The server can supply extensive debugging information when
it is in debugging mode. If the server's global debug level is
greater
than zero, debugging mode is active. The global debug
level is set either by starting the named server
with the -d flag followed by a positive integer,
or by running rndc trace.
The global debug level
can be set to zero, and debugging mode turned off, by running rndc
notrace. All debugging messages in the server have a debug
level; higher debug levels give more detailed output. Channels
that specify a specific debug severity, for example:
channel specific_debug_level {
file "foo";
severity debug 3;
};
get debugging output of level 3 or less any time the server is in debugging mode, regardless of the global debugging level. Channels with dynamic severity use the server's global debug level to determine what messages to print.
If print-time is set to
yes, then the date and time are logged.
print-time may be specified for a
syslog channel, but is usually
unnecessary since syslog also logs
the date and time. If print-category is
set to yes, then the
category of the message is logged as well. Finally, if
print-severity is set, then the severity
level of the message is logged.
The print- options may
be used in any combination, and are always printed in the
following
order: time, category, severity. Here is an example where all
three print- options
are on:
28-Feb-2000 15:05:32.863 general: notice: running
If buffered has been turned on, the output to files is not flushed after each log entry. By default all log messages are flushed.
There are four predefined channels that are used for
named's default logging, as follows.
If named is started with the
-L, then a
fifth channel, default_logfile, is added.
How they are
used is described in the section called “The category Phrase”.
channel default_syslog {
// send to syslog's daemon facility
syslog daemon;
// only send priority info and higher
severity info;
};
channel default_debug {
// write to named.run in the working directory
// Note: stderr is used instead of "named.run" if
// the server is started with the '-g' option.
file "named.run";
// log at the server's current debug level
severity dynamic;
};
channel default_stderr {
// writes to stderr
stderr;
// only send priority info and higher
severity info;
};
channel null {
// toss anything sent to this channel
null;
};
channel default_logfile {
// this channel is only present if named is
// started with the -L option, whose argument
// provides the file name
file "...";
// log at the server's current debug level
severity dynamic;
};
The default_debug channel has the
special
property that it only produces output when the server's debug
level is
non-zero. It normally writes to a file called named.run
in the server's working directory.
For security reasons, when the -u
command-line option is used, the named.run file
is created only after named has
changed to the
new UID, and any debug output generated while named is
starting - and still running as root - is discarded.
To capture this output, run the server with the -L
option to specify a default logfile, or the -g
option to log to standard error which can be redirected to a file.
Once a channel is defined, it cannot be redefined. The built-in channels cannot be altered directly, but the default logging can be modified by pointing categories at defined channels.
There are many categories, so desired logs can be sent anywhere while unwanted logs are ignored. If a list of channels is not specified for a category, log messages in that category are sent to the default category instead. If no default category is specified, the following "default default" is used:
category default { default_syslog; default_debug; };
If named is started with the
-L option, the default category is:
category default { default_logfile; default_debug; };
As an example, let's say a user wants to log security events to a file, but also wants to keep the default logging behavior. They would specify the following:
channel my_security_channel {
file "my_security_file";
severity info;
};
category security {
my_security_channel;
default_syslog;
default_debug;
};
To discard all messages in a category, specify the null channel:
category xfer-out { null; };
category notify { null; };
The following are the available categories and brief descriptions of the types of log information they contain. More categories may be added in future BIND releases.
|
client |
Processing of client requests. |
|
cname |
Name servers that are skipped for being a CNAME rather than A/AAAA records. |
|
config |
Configuration file parsing and processing. |
|
database |
Messages relating to the databases used internally by the name server to store zone and cache data. |
|
default |
Logging options for those categories where no specific configuration has been defined. |
|
delegation-only |
Queries that have been forced to NXDOMAIN as the result of a delegation-only zone or a delegation-only in a forward, hint, or stub zone declaration. |
|
dispatch |
Dispatching of incoming packets to the server modules where they are to be processed. |
|
dnssec |
DNSSEC and TSIG protocol processing. |
|
dnstap |
The "dnstap" DNS traffic capture system. |
|
edns-disabled |
Log queries that have been forced to use plain DNS due to timeouts. This is often due to the remote servers not being RFC 1034-compliant (not always returning FORMERR or similar to EDNS queries and other extensions to the DNS when they are not understood). In other words, this is targeted at servers that fail to respond to DNS queries that they don't understand. Note: the log message can also be due to packet loss. Before reporting servers for non-RFC 1034 compliance they should be re-tested to determine the nature of the non-compliance. This testing should prevent or reduce the number of false-positive reports. Note: eventually named will have to stop treating such timeouts as due to RFC 1034 non-compliance and start treating it as plain packet loss. Falsely classifying packet loss as due to RFC 1034 non-compliance impacts DNSSEC validation, which requires EDNS for the DNSSEC records to be returned. |
|
general |
Catch-all for many things that still are not classified into categories. |
|
lame-servers |
Misconfigurations in remote servers, discovered by BIND 9 when trying to query those servers during resolution. |
|
network |
Network operations. |
|
notify |
The NOTIFY protocol. |
|
queries |
Location where queries should be logged. At startup, specifying the category queries also enables query logging unless querylog option has been specified. The query log entry first reports a client object identifier in @0x<hexadecimal-number> format. Next, it reports the client's IP address and port number, and the query name, class, and type. Next, it reports whether the Recursion Desired flag was set (+ if set, - if not set), whether the query was signed (S), whether EDNS was in use along with the EDNS version number (E(#)), whether TCP was used (T), whether DO (DNSSEC Ok) was set (D), whether CD (Checking Disabled) was set (C), whether a valid DNS Server COOKIE was received (V), and whether a DNS COOKIE option without a valid Server COOKIE was present (K). After this, the destination address the query was sent to is reported.
The first part of this log message, showing the client address/port number and query name, is repeated in all subsequent log messages related to the same query. |
|
query-errors |
Information about queries that resulted in some failure. |
|
rate-limit |
The start, periodic, and final notices of the rate limiting of a stream of responses are logged at info severity in this category. These messages include a hash value of the domain name of the response and the name itself, except when there is insufficient memory to record the name for the final notice. The final notice is normally delayed until about one minute after rate limiting stops. A lack of memory can hurry the final notice, which is indicated by an initial asterisk (*). Various internal events are logged at debug level 1 and higher. Rate limiting of individual requests is logged in the query-errors category. |
|
resolver |
DNS resolution, such as the recursive lookups performed on behalf of clients by a caching name server. |
|
rpz |
Information about errors in response policy zone files, rewritten responses, and, at the highest debug levels, mere rewriting attempts. |
|
security |
Approval and denial of requests. |
|
spill |
Queries that have been terminated, either by dropping or responding with SERVFAIL, as a result of a fetchlimit quota being exceeded. |
|
trust-anchor-telemetry |
Trust-anchor-telemetry requests received by named. |
|
unmatched |
Messages that named was unable to determine the class of, or for which there was no matching view. A one-line summary is also logged to the client category. This category is best sent to a file or stderr; by default it is sent to the null channel. |
|
update |
Dynamic updates. |
|
update-security |
Approval and denial of update requests. |
|
xfer-in |
Zone transfers the server is receiving. |
|
xfer-out |
Zone transfers the server is sending. |
The query-errors category is used to indicate why and how specific queries resulted in responses which indicate an error. Normally, these messages will be logged at debug logging levels; note, however, that if query logging is active, some are logged at info. The logging levels are described below:
At debug level 1 or higher - or at info, when query logging is active - each response with response code SERVFAIL is logged as follows:
client 127.0.0.1#61502: query failed (SERVFAIL) for www.example.com/IN/AAAA at query.c:3880
This means an error resulting in SERVFAIL was detected at line
3880 of source file query.c. Log messages
of this level are particularly helpful in identifying the cause of
SERVFAIL for an authoritative server.
At debug level 2 or higher, detailed context information about recursive resolutions that resulted in SERVFAIL is logged. The log message looks like this:
fetch completed at resolver.c:2970 for www.example.com/A
in 10.000183: timed out/success [domain:example.com,
referral:2,restart:7,qrysent:8,timeout:5,lame:0,quota:0,neterr:0,
badresp:1,adberr:0,findfail:0,valfail:0]
The first part before the colon shows that a recursive
resolution for AAAA records of www.example.com completed
in 10.000183 seconds, and the final result that led to the
SERVFAIL was determined at line 2970 of source file
resolver.c.
The next part shows the detected final result and the latest result of DNSSEC validation. The latter is always "success" when no validation attempt was made. In this example, this query probably resulted in SERVFAIL because all name servers are down or unreachable, leading to a timeout in 10 seconds. DNSSEC validation was probably not attempted.
The last part, enclosed in square brackets, shows statistics
collected for this particular resolution attempt.
The domain field shows the deepest zone that
the resolver reached; it is the zone where the error was
finally detected. The meaning of the other fields is
summarized in the following table.
|
|
The number of referrals the resolver received throughout the resolution process. In the above example there are two, which are most likely com and example.com. |
|
|
The number of cycles that the resolver tried
remote servers at the |
|
|
The number of queries the resolver sent at the
|
|
|
The number of timeouts since the resolver received the last response. |
|
|
The number of lame servers the resolver detected
at the |
|
|
The number of times the resolver was unable to send a query because it had exceeded the permissible fetch quota for a server. |
|
|
The number of erroneous results that the
resolver encountered in sending queries
at the |
|
|
The number of unexpected responses (other than
|
|
|
Failures in finding remote server addresses
of the |
|
|
Failures to resolve remote server addresses. This is a total number of failures throughout the resolution process. |
|
|
Failures of DNSSEC validation.
Validation failures are counted throughout
the resolution process (not limited to
the |
At debug level 3 or higher, the same messages as those at debug level 1 are logged for errors other than SERVFAIL. Note that negative responses such as NXDOMAIN are not errors, and are not logged at this debug level.
At debug level 4 or higher, the detailed context information logged at debug level 2 is logged for errors other than SERVFAIL and for negative responses such as NXDOMAIN.
This is the grammar of the lwres
statement in the named.conf file:
lwres { [ listen-on { (ip_addr[ portip_port] [ dscpip_dscp] ; ) ... }; ] [ viewview_name; ] [ search {domain_name; ... }; ] [ ndotsnumber; ] [ lwres-tasksnumber; ] [ lwres-clientsnumber; ] };
The lwres statement configures the name server to also act as a lightweight resolver server. (See the section called “Running a Resolver Daemon”.) There may be multiple lwres statements configuring lightweight resolver servers with different properties.
The listen-on statement specifies a list of IPv4 addresses (and ports) that this instance of a lightweight resolver daemon should accept requests on. If no port is specified, port 921 is used. If this statement is omitted, requests are accepted on 127.0.0.1, port 921.
The view statement binds this instance of a lightweight resolver daemon to a view in the DNS namespace, so that the response is constructed in the same manner as a normal DNS query matching this view. If this statement is omitted, the default view is used; if there is no default view, an error is triggered.
The search statement is equivalent to
the
search statement in
/etc/resolv.conf. It provides a
list of domains
which are appended to relative names in queries.
The ndots statement is equivalent to
the
ndots statement in
/etc/resolv.conf. It indicates the
minimum
number of dots in a relative domain name that should result in an
exact-match lookup before search path elements are appended.
The lwres-tasks statement specifies the number
of worker threads the lightweight resolver dedicates to serving
clients. By default, the number is the same as the number of CPUs on
the system; this can be overridden using the -n
command-line option when starting the server.
The lwres-clients statement specifies
the number of client objects per thread the lightweight
resolver should create to serve client queries.
By default, if the lightweight resolver runs as a part
of named, 256 client objects are
created for each task; if it runs as lwresd,
1024 client objects are created for each thread. The maximum
value is 32768; higher values are silently ignored and
the maximum is used instead.
Note that setting too high a value may overconsume
system resources.
The maximum number of client queries that the lightweight
resolver can handle at any one time equals
lwres-tasks times lwres-clients.
mastersstring[ portinteger] [ dscpinteger] { (masters|ipv4_address[ portinteger] |ipv6_address[ portinteger] ) [ keystring]; ... };
masters lists allow for a common set of primaries to be easily used by multiple stub and secondary zones in their masters or also-notify lists.
This is the grammar of the options
statement in the named.conf file:
options { acache-cleaning-intervalinteger; acache-enableboolean; additional-from-authboolean; additional-from-cacheboolean; allow-new-zonesboolean; allow-notify {address_match_element; ... }; allow-query {address_match_element; ... }; allow-query-cache {address_match_element; ... }; allow-query-cache-on {address_match_element; ... }; allow-query-on {address_match_element; ... }; allow-recursion {address_match_element; ... }; allow-recursion-on {address_match_element; ... }; allow-transfer {address_match_element; ... }; allow-update {address_match_element; ... }; allow-update-forwarding {address_match_element; ... }; also-notify [ portinteger] [ dscpinteger] { (masters|ipv4_address[ portinteger] |ipv6_address[ portinteger] ) [ keystring]; ... }; alt-transfer-source (ipv4_address| * ) [ port (integer| * ) ] [ dscpinteger]; alt-transfer-source-v6 (ipv6_address| * ) [ port (integer| * ) ] [ dscpinteger]; answer-cookieboolean; attach-cachestring; auth-nxdomainboolean; // default changed auto-dnssec ( allow | maintain | off ); automatic-interface-scanboolean; avoid-v4-udp-ports {portrange; ... }; avoid-v6-udp-ports {portrange; ... }; bindkeys-filequoted_string; blackhole {address_match_element; ... }; cache-filequoted_string; catalog-zones { zonestring[ default-masters [ portinteger] [ dscpinteger] { (masters|ipv4_address[ portinteger] |ipv6_address[ portinteger] ) [ keystring]; ... } ] [ zone-directoryquoted_string] [ in-memoryboolean] [ min-update-intervalinteger]; ... }; check-dup-records ( fail | warn | ignore ); check-integrityboolean; check-mx ( fail | warn | ignore ); check-mx-cname ( fail | warn | ignore ); check-names ( master | slave | response ) ( fail | warn | ignore ); check-siblingboolean; check-spf ( warn | ignore ); check-srv-cname ( fail | warn | ignore ); check-wildcardboolean; cleaning-intervalinteger; clients-per-queryinteger; cookie-algorithm ( aes | sha1 | sha256 | siphash24 ); cookie-secretstring; coresize ( default | unlimited |sizeval); datasize ( default | unlimited |sizeval); deny-answer-addresses {address_match_element; ... } [ except-from {quoted_string; ... } ]; deny-answer-aliases {quoted_string; ... } [ except-from {quoted_string; ... } ]; dialup ( notify | notify-passive | passive | refresh |boolean); directoryquoted_string; disable-algorithmsstring{string; ... }; disable-ds-digestsstring{string; ... }; disable-empty-zonestring; dns64netprefix{ break-dnssecboolean; clients {address_match_element; ... }; exclude {address_match_element; ... }; mapped {address_match_element; ... }; recursive-onlyboolean; suffixipv6_address; }; dns64-contactstring; dns64-serverstring; dnssec-accept-expiredboolean; dnssec-dnskey-kskonlyboolean; dnssec-enableboolean; dnssec-loadkeys-intervalinteger; dnssec-lookaside (stringtrust-anchorstring| auto | no ); dnssec-must-be-securestringboolean; dnssec-secure-to-insecureboolean; dnssec-update-mode ( maintain | no-resign ); dnssec-validation ( yes | no | auto ); dnstap { ( all | auth | client | forwarder | resolver ) [ ( query | response ) ]; ... }; dnstap-identity (quoted_string| none | hostname ); dnstap-output ( file | unix )quoted_string; dnstap-version (quoted_string| none ); dscpinteger; dual-stack-servers [ portinteger] { (quoted_string[ portinteger] [ dscpinteger] |ipv4_address[ portinteger] [ dscpinteger] |ipv6_address[ portinteger] [ dscpinteger] ); ... }; dump-filequoted_string; edns-udp-sizeinteger; empty-contactstring; empty-serverstring; empty-zones-enableboolean; fetch-quota-paramsintegerfixedpointfixedpointfixedpoint; fetches-per-serverinteger[ ( drop | fail ) ]; fetches-per-zoneinteger[ ( drop | fail ) ]; files ( default | unlimited |sizeval); filter-aaaa {address_match_element; ... }; filter-aaaa-on-v4 ( break-dnssec |boolean); filter-aaaa-on-v6 ( break-dnssec |boolean); flush-zones-on-shutdownboolean; forward ( first | only ); forwarders [ portinteger] [ dscpinteger] { (ipv4_address|ipv6_address) [ portinteger] [ dscpinteger]; ... }; fstrm-set-buffer-hintinteger; fstrm-set-flush-timeoutinteger; fstrm-set-input-queue-sizeinteger; fstrm-set-output-notify-thresholdinteger; fstrm-set-output-queue-model ( mpsc | spsc ); fstrm-set-output-queue-sizeinteger; fstrm-set-reopen-intervalinteger; geoip-directory (quoted_string| none ); geoip-use-ecsboolean; heartbeat-intervalinteger; hostname (quoted_string| none ); inline-signingboolean; interface-intervalinteger; ixfr-from-differences ( master | slave |boolean); keep-response-order {address_match_element; ... }; key-directoryquoted_string; lame-ttlttlval; listen-on [ portinteger] [ dscpinteger] {address_match_element; ... }; listen-on-v6 [ portinteger] [ dscpinteger] {address_match_element; ... }; lmdb-mapsizesizeval; lock-file (quoted_string| none ); managed-keys-directoryquoted_string; masterfile-format ( map | raw | text ); masterfile-style ( full | relative ); match-mapped-addressesboolean; max-acache-size ( unlimited |sizeval); max-cache-size ( default | unlimited |sizeval|percentage); max-cache-ttlinteger; max-clients-per-queryinteger; max-journal-size ( unlimited |sizeval); max-ncache-ttlinteger; max-recordsinteger; max-recursion-depthinteger; max-recursion-queriesinteger; max-refresh-timeinteger; max-retry-timeinteger; max-rsa-exponent-sizeinteger; max-transfer-idle-ininteger; max-transfer-idle-outinteger; max-transfer-time-ininteger; max-transfer-time-outinteger; max-udp-sizeinteger; max-zone-ttl ( unlimited |ttlval); memstatisticsboolean; memstatistics-filequoted_string; message-compressionboolean; min-refresh-timeinteger; min-retry-timeinteger; minimal-anyboolean; minimal-responses ( no-auth | no-auth-recursive |boolean); multi-masterboolean; no-case-compress {address_match_element; ... }; nocookie-udp-sizeinteger; notify ( explicit | master-only |boolean); notify-delayinteger; notify-rateinteger; notify-source (ipv4_address| * ) [ port (integer| * ) ] [ dscpinteger]; notify-source-v6 (ipv6_address| * ) [ port (integer| * ) ] [ dscpinteger]; notify-to-soaboolean; nta-lifetimettlval; nta-recheckttlval; nxdomain-redirectstring; pid-file (quoted_string| none ); portinteger; preferred-gluestring; prefetchinteger[integer]; provide-ixfrboolean; query-source ( ( [ address ] (ipv4_address| * ) [ port (integer| * ) ] ) | ( [ [ address ] (ipv4_address| * ) ] port (integer| * ) ) ) [ dscpinteger]; query-source-v6 ( ( [ address ] (ipv6_address| * ) [ port (integer| * ) ] ) | ( [ [ address ] (ipv6_address| * ) ] port (integer| * ) ) ) [ dscpinteger]; querylogboolean; random-devicequoted_string; rate-limit { all-per-secondinteger; errors-per-secondinteger; exempt-clients {address_match_element; ... }; ipv4-prefix-lengthinteger; ipv6-prefix-lengthinteger; log-onlyboolean; max-table-sizeinteger; min-table-sizeinteger; nodata-per-secondinteger; nxdomains-per-secondinteger; qps-scaleinteger; referrals-per-secondinteger; responses-per-secondinteger; slipinteger; windowinteger; }; recursing-filequoted_string; recursionboolean; recursive-clientsinteger; request-expireboolean; request-ixfrboolean; request-nsidboolean; require-server-cookieboolean; reserved-socketsinteger; resolver-query-timeoutinteger; response-policy { zonestring[ logboolean] [ max-policy-ttlinteger] [ policy ( cname | disabled | drop | given | no-op | nodata | nxdomain | passthru | tcp-onlyquoted_string) ] [ recursive-onlyboolean]; ... } [ break-dnssecboolean] [ max-policy-ttlinteger] [ min-ns-dotsinteger] [ nsip-wait-recurseboolean] [ qname-wait-recurseboolean] [ recursive-onlyboolean]; root-delegation-only [ exclude {quoted_string; ... } ]; root-key-sentinelboolean; rrset-order { [ classstring] [ typestring] [ namequoted_string]stringstring; ... }; secroots-filequoted_string; send-cookieboolean; serial-query-rateinteger; serial-update-method ( date | increment | unixtime ); server-id (quoted_string| none | hostname ); servfail-ttlttlval; session-keyalgstring; session-keyfile (quoted_string| none ); session-keynamestring; sig-signing-nodesinteger; sig-signing-signaturesinteger; sig-signing-typeinteger; sig-validity-intervalinteger[integer]; sortlist {address_match_element; ... }; stacksize ( default | unlimited |sizeval); startup-notify-rateinteger; statistics-filequoted_string; tcp-clientsinteger; tcp-listen-queueinteger; tkey-dhkeyquoted_stringinteger; tkey-domainquoted_string; tkey-gssapi-credentialquoted_string; tkey-gssapi-keytabquoted_string; transfer-format ( many-answers | one-answer ); transfer-message-sizeinteger; transfer-source (ipv4_address| * ) [ port (integer| * ) ] [ dscpinteger]; transfer-source-v6 (ipv6_address| * ) [ port (integer| * ) ] [ dscpinteger]; transfers-ininteger; transfers-outinteger; transfers-per-nsinteger; trust-anchor-telemetryboolean; // experimental try-tcp-refreshboolean; update-check-kskboolean; use-alt-transfer-sourceboolean; use-v4-udp-ports {portrange; ... }; use-v6-udp-ports {portrange; ... }; v6-biasinteger; version (quoted_string| none ); zero-no-soa-ttlboolean; zero-no-soa-ttl-cacheboolean; zone-statistics ( full | terse | none |boolean); };
The options statement sets up global options to be used by BIND. This statement may appear only once in a configuration file. If there is no options statement, an options block with each option set to its default is used.
This option allows multiple views to share a single cache database. Each view has its own cache database by default, but if multiple views have the same operational policy for name resolution and caching, those views can share a single cache to save memory, and possibly improve resolution efficiency, by using this option.
The attach-cache option may also be specified in view statements, in which case it overrides the global attach-cache option.
The cache_name specifies
the cache to be shared.
When the named server configures
views which are supposed to share a cache, it
creates a cache with the specified name for the
first view of these sharing views.
The rest of the views simply refer to the
already-created cache.
One common configuration to share a cache is to allow all views to share a single cache. This can be done by specifying attach-cache as a global option with an arbitrary name.
Another possible operation is to allow a subset of all views to share a cache while the others retain their own caches. For example, if there are three views A, B, and C, and only A and B should share a cache, specify the attach-cache option as a view of A (or B)'s option, referring to the other view name:
view "A" {
// this view has its own cache
...
};
view "B" {
// this view refers to A's cache
attach-cache "A";
};
view "C" {
// this view has its own cache
...
};
Views that share a cache must have the same policy on configurable parameters that may affect caching. The current implementation requires the following configurable options be consistent among these views: check-names, cleaning-interval, dnssec-accept-expired, dnssec-validation, max-cache-ttl, max-ncache-ttl, max-cache-size, and zero-no-soa-ttl.
Note that there may be other parameters that may cause confusion if they are inconsistent for different views that share a single cache. For example, if these views define different sets of forwarders that can return different answers for the same question, sharing the answer does not make sense or could even be harmful. It is administrator's responsibility to ensure that configuration differences in different views do not cause disruption with a shared cache.
This sets the working directory of the server.
Any non-absolute pathnames in the configuration file are
taken as relative to this directory. The default
location for most server output files
(e.g., named.run) is this directory.
If a directory is not specified, the working directory
defaults to ".", the directory from
which the server was started. The directory specified
should be an absolute path. It is
strongly recommended
that the directory be writable by the effective user
ID of the named process.
dnstap is a fast, flexible method for capturing and logging DNS traffic. Developed by Robert Edmonds at Farsight Security, Inc., and supported by multiple DNS implementations, dnstap uses libfstrm (a lightweight high-speed framing library, see https://github.com/farsightsec/fstrm) to send event payloads which are encoded using Protocol Buffers (libprotobuf-c, a mechanism for serializing structured data developed by Google, Inc.; see https://developers.google.com/protocol-buffers).
To enable dnstap at compile time,
the fstrm and protobuf-c
libraries must be available, and BIND must be configured with
--enable-dnstap.
The dnstap option is a bracketed list
of message types to be logged. These may be set differently
for each view. Supported types are client,
auth, resolver, and
forwarder. Specifying type
all causes all dnstap
messages to be logged, regardless of type.
Each type may take an additional argument to indicate whether
to log query messages or
response messages; if not specified,
both queries and responses are logged.
Example: To log all authoritative queries and responses, recursive client responses, and upstream queries sent by the resolver, use:
dnstap {
auth;
client response;
resolver query;
};
Logged dnstap messages can be parsed using the dnstap-read utility (see dnstap-read(1) for details).
For more information on dnstap, see http://dnstap.info.
The fstrm library has a number of tunables that are exposed
in named.conf, and can be modified
if necessary to improve performance or prevent loss of data.
These are:
mpsc
(multiple producer, single consumer); the other
option is spsc (single producer,
single consumer).
IOV_MAX,
and the default is 64.
Note that all of the above minimum, maximum, and default values are set by the libfstrm library, and may be subject to change in future versions of the library. See the libfstrm documentation for more information.
This configures the path to which the dnstap frame stream is sent if dnstap is enabled at compile time and active.
The first argument is either file or
unix, indicating whether the destination
is a file or a Unix domain socket. The second argument
is the path of the file or socket. (Note: when using a
socket, dnstap messages are
only sent if another process such as
fstrm_capture
(provided with libfstrm) is listening on
the socket.)
dnstap-output can only be set globally in options. Currently, it can only be set once while named is running; once set, it cannot be changed by rndc reload or rndc reconfig.
This specifies an identity string to send in
dnstap messages. If set to
hostname, which is the default, the
server's hostname is sent. If set to
none, no identity string is sent.
This specifies a version string to send in
dnstap messages. The default is the
version number of the BIND release. If set to
none, no version string is sent.
When named is compiled using the
MaxMind GeoIP2 geolocation API, or the legacy GeoIP API,
this specifies the directory containing GeoIP
database files. By default, the option is set based on
the prefix used to build the libmaxminddb
module; for example, if the library is installed in
/usr/local/lib, then the default
geoip-directory is
/usr/local/share/GeoIP. On Windows,
the default is the named working
directory. See the section called “acl Statement Definition and
Usage” for details about
geoip ACLs.
This is the
directory where the public and private DNSSEC key files
should be found when performing a dynamic update of secure zones, if different than the current working
directory. (Note that this option has no effect on the
paths for files containing non-DNSSEC keys such as
bind.keys,
rndc.key, or
session.key.)
When named is built with liblmdb, this option sets a maximum size for the memory map of the new-zone database (NZD) in LMDB database format. This database is used to store configuration information for zones added using rndc addzone. Note that this is not the NZD database file size, but the largest size that the database may grow to.
Because the database file is memory mapped, its size is limited by the address space of the named process. The default of 32 megabytes was chosen to be usable with 32-bit named builds. The largest permitted value is 1 terabyte. Given typical zone configurations without elaborate ACLs, a 32 MB NZD file ought to be able to hold configurations of about 100,000 zones.
This specifies the directory in which to store the files that track managed DNSSEC keys. By default, this is the working directory. The directory must be writable by the effective user ID of the named process.
If named is not configured to use views,
managed keys for the server are tracked in a single
file called managed-keys.bind.
Otherwise, managed keys are tracked in separate files,
one file per view; each file name is the view name
(or, if it contains characters that are incompatible with
use as a file name, the SHA256 hash of the view name),
followed by the extension
.mkeys.
(Note: in earlier releases, file names for views always used the SHA256 hash of the view name. To ensure compatibility after upgrading, if a file using the old name format is found to exist, it is used instead of the new format.)
This option is obsolete. In BIND 9, no separate named-xfer program is needed; its functionality is built into the name server.
This is the KRB5 keytab file to use for GSS-TSIG updates. If this option is set and tkey-gssapi-credential is not set, updates are allowed with any key matching a principal in the specified keytab.
This is the security credential with which the server should
authenticate keys requested by the GSS-TSIG protocol.
Currently only Kerberos 5 authentication is available;
the credential is a Kerberos principal which the
server can acquire through the default system key
file, normally /etc/krb5.keytab.
The location of the keytab file can be overridden using the
tkey-gssapi-keytab option. Normally this principal is
of the form "DNS/server.domain".
To use GSS-TSIG, tkey-domain must
also be set if a specific keytab is not set with
tkey-gssapi-keytab.
This domain is appended to the names of all shared keys
generated with TKEY. When a
client requests a TKEY exchange,
it may or may not specify the desired name for the
key. If present, the name of the shared key is
client-specified part +
tkey-domain. Otherwise, the
name of the shared key is random hex
digits + tkey-domain.
In most cases, the domainname
should be the server's domain name, or an otherwise
nonexistent subdomain like
"_tkey.domainname". If
using GSS-TSIG, this variable must be defined, unless
a specific keytab is specified using tkey-gssapi-keytab.
This is the Diffie-Hellman key used by the server
to generate shared keys with clients using the Diffie-Hellman
mode
of TKEY. The server must be
able to load the
public and private keys from files in the working directory.
In
most cases, the key_name should be the server's host name.
This is for testing only. Do not use.
This is the pathname of the file the server dumps
the database to, when instructed to do so with
rndc dumpdb.
If not specified, the default is named_dump.db.
This is the pathname of the file the server writes memory
usage statistics to on exit. If not specified,
the default is named.memstats.
This is the pathname of a file on which named
attempts to acquire a file lock when starting for
the first time; if unsuccessful, the server
terminates, under the assumption that another
server is already running. If not specified, the default is
none.
Specifying lock-file none disables the
use of a lock file. lock-file is
ignored if named was run using the -X
option, which overrides it. Changes to
lock-file are ignored if
named is being reloaded or
reconfigured; it is only effective when the server is
first started.
This is the pathname of the file the server writes its process ID
in. If not specified, the default is
/var/run/named/named.pid.
The PID file is used by programs that send signals to
the running
name server. Specifying pid-file none disables the
use of a PID file; no file is written and any
existing one is removed. Note that none
is a keyword, not a filename, and therefore is not enclosed
in
double quotes.
This is the pathname of the file where the server dumps
the queries that are currently recursing, when instructed
to do so with rndc recursing.
If not specified, the default is named.recursing.
This is the pathname of the file the server appends statistics
to, when instructed to do so using rndc stats.
If not specified, the default is named.stats in the
server's current directory. The format of the file is
described
in the section called “The Statistics File”.
This is the pathname of a file to override the built-in trusted
keys provided by named.
See the discussion of dnssec-validation
for details. If not specified, the default is
/etc/bind.keys.
This is the pathname of the file the server dumps
security roots to, when instructed to do so with
rndc secroots.
If not specified, the default is
named.secroots.
This is the pathname of the file into which to write a TSIG
session key generated by named for use by
nsupdate -l. If not specified, the
default is /var/run/named/session.key.
(See the section called “Dynamic Update Policies”, and in
particular the discussion of the
update-policy statement's
local option for more
information about this feature.)
This is the key name to use for the TSIG session key.
If not specified, the default is local-ddns.
This is the algorithm to use for the TSIG session key. Valid values are hmac-sha1, hmac-sha224, hmac-sha256, hmac-sha384, hmac-sha512, and hmac-md5. If not specified, the default is hmac-sha256.
This is the UDP/TCP port number the server uses to receive and send DNS protocol traffic. The default is 53. This option is mainly intended for server testing; a server using a port other than 53 is not able to communicate with the global DNS.
This is the global Differentiated Services Code Point (DSCP) value to classify outgoing DNS traffic, on operating systems that support DSCP. Valid values are 0 through 63. It is not configured by default.
This specifies a source of entropy to be used by the server. Entropy is
primarily needed
for DNSSEC operations, such as TKEY transactions and dynamic
update of signed
zones. This option specifies the device (or file) from which
to read
entropy. If it is a file, operations requiring entropy will
fail when the
file has been exhausted. If random-device is not specified, the default value
is
/dev/random
(or equivalent) when present, and none otherwise. The
random-device option takes
effect during
the initial configuration load at server startup time and
is ignored on subsequent reloads.
If specified, the listed type (A or AAAA) is emitted before other glue in the additional section of a query response. The default is to prefer A records when responding to queries that arrived via IPv4 and AAAA when responding to queries that arrived via IPv6.
This turns on enforcement of delegation-only in TLDs (top-level domains) and root zones with an optional exclude list.
DS queries are expected to be made to and be answered by delegation-only zones. Such queries and responses are treated as an exception to delegation-only processing and are not converted to NXDOMAIN responses, provided a CNAME is not discovered at the query name.
If a delegation-only zone server also serves a child zone, it is not always possible to determine whether an answer comes from the delegation-only zone or the child zone. SOA NS and DNSKEY records are apex-only records and a matching response that contains these records or DS is treated as coming from a child zone. RRSIG records are also examined to see if they are signed by a child zone, and the authority section is examined to see if there is evidence that the answer is from the child zone. Answers that are determined to be from a child zone are not converted to NXDOMAIN responses. Despite all these checks, there is still a possibility of false negatives when a child zone is being served.
Similarly, false positives can arise from empty nodes
(no records at the name) in the delegation-only zone
when the query type is not ANY.
Note that some TLDs are not delegation-only; e.g., "DE", "LV", "US", and "MUSEUM". This list is not exhaustive.
options {
root-delegation-only exclude { "de"; "lv"; "us"; "museum"; };
};
This disables the specified DNSSEC algorithms at and below the specified name. Multiple disable-algorithms statements are allowed. Only the best-match disable-algorithms clause is used to determine the algorithms.
If all supported algorithms are disabled, the zones covered by the disable-algorithms setting are treated as insecure.
Configured trust anchors in trusted-keys or managed-keys that match a disabled algorithm are ignored and treated as if they were not configured.
This disables the specified DS digest types at and below the specified name. Multiple disable-ds-digests statements are allowed. Only the best-match disable-ds-digests clause is used to determine the digest types.
If all supported digest types are disabled, the zones covered by disable-ds-digests are treated as insecure.
When set, dnssec-lookaside provides the validator with an alternate method to validate DNSKEY records at the top of a zone. When a DNSKEY is at or below a domain specified by the deepest dnssec-lookaside, and the normal DNSSEC validation has left the key untrusted, the trust-anchor is appended to the key name and a DLV record is looked up to see if it can validate the key. If the DLV record validates a DNSKEY (similarly to the way a DS record does), the DNSKEY RRset is deemed to be trusted.
If dnssec-lookaside is set to
no, then dnssec-lookaside
is not used.
Note: the ISC-provided DLV service at
dlv.isc.org has been shut down.
The dnssec-lookaside auto;
configuration option, which set named
to use ISC DLV with minimal configuration, has
accordingly been removed.
This specifies hierarchies which must be or may not be secure
(signed and validated). If yes,
then named only accepts answers if
they are secure. If no, then normal
DNSSEC validation applies, allowing insecure answers to
be accepted. The specified domain must be under a
trusted-keys or
managed-keys statement, or
dnssec-validation auto must be active.
This directive instructs named to return mapped IPv4 addresses to AAAA queries when there are no AAAA records. It is intended to be used in conjunction with a NAT64. Each dns64 defines one DNS64 prefix. Multiple DNS64 prefixes can be defined.
Compatible IPv6 prefixes have lengths of 32, 40, 48, 56, 64, and 96, per RFC 6052. Bits 64..71 inclusive must be zero, with the most significant bit of the prefix in position 0.
In addition, a reverse IP6.ARPA zone is created for the prefix to provide a mapping from the IP6.ARPA names to the corresponding IN-ADDR.ARPA names using synthesized CNAMEs. dns64-server and dns64-contact can be used to specify the name of the server and contact for the zones. These can be set at the view/options level but not on a per-prefix basis.
Each dns64 supports an optional
clients ACL that determines which
clients are affected by this directive. If not defined,
it defaults to any;.
Each dns64 supports an optional
mapped ACL that selects which
IPv4 addresses are to be mapped in the corresponding
A RRset. If not defined, it defaults to
any;.
Normally, DNS64 does not apply to a domain name that owns one or more AAAA records; these records are simply returned. The optional exclude ACL allows specification of a list of IPv6 addresses that are ignored if they appear in a domain name's AAAA records; DNS64 is applied to any A records the domain name owns. If not defined, exclude defaults to ::ffff:0.0.0.0/96.
A optional suffix can also
be defined to set the bits trailing the mapped
IPv4 address bits. By default these bits are
set to ::. The bits
matching the prefix and mapped IPv4 address
must be zero.
If recursive-only is set to yes, the DNS64 synthesis only happens for recursive queries. The default is no.
If break-dnssec is set to yes, the DNS64 synthesis happens even if the result, if validated, would cause a DNSSEC validation failure. If this option is set to no (the default), the DO is set on the incoming query, and there are RRSIGs on the applicable records, then synthesis does not happen.
acl rfc1918 { 10/8; 192.168/16; 172.16/12; };
dns64 64:FF9B::/96 {
clients { any; };
mapped { !rfc1918; any; };
exclude { 64:FF9B::/96; ::ffff:0000:0000/96; };
suffix ::;
};
When a zone is configured with auto-dnssec
maintain;, its key repository must be checked
periodically to see if any new keys have been added
or any existing keys' timing metadata has been updated
(see dnssec-keygen(8) and
dnssec-settime(8)). The
dnssec-loadkeys-interval option
sets the frequency of automatic repository checks, in
minutes. The default is 60 (1 hour),
the minimum is 1 (1 minute), and the
maximum is 1440 (24 hours); any higher
value is silently reduced.
If this option is set to its default value of
maintain in a zone of type
master which is DNSSEC-signed
and configured to allow dynamic updates (see
the section called “Dynamic Update Policies”), and
if named has access to the
private signing key(s) for the zone, then
named automatically signs all new
or changed records and maintains signatures for the zone
by regenerating RRSIG records whenever they approach
their expiration date.
If the option is changed to no-resign,
then named signs all new or
changed records, but scheduled maintenance of
signatures is disabled.
With either of these settings, named
rejects updates to a DNSSEC-signed zone when the
signing keys are inactive or unavailable to
named. (A planned third option,
external, will disable all automatic
signing and allow DNSSEC data to be submitted into a zone
via dynamic update; this is not yet implemented.)
This specifies the default lifetime, in seconds, for negative trust anchors added via rndc nta.
A negative trust anchor selectively disables DNSSEC validation for zones that are known to be failing because of misconfiguration, rather than an attack. When data to be validated is at or below an active NTA (and above any other configured trust anchors), named aborts the DNSSEC validation process and treats the data as insecure rather than bogus. This continues until the NTA's lifetime is elapsed. NTAs persist across named restarts.
For convenience, TTL-style time-unit suffixes can be
used to specify the NTA lifetime in seconds, minutes,
or hours. nta-lifetime defaults to
one hour; it cannot exceed one week.
This specifies how often to check whether negative trust anchors added via rndc nta are still necessary.
A negative trust anchor is normally used when a domain has stopped validating due to operator error; it temporarily disables DNSSEC validation for that domain. In the interest of ensuring that DNSSEC validation is turned back on as soon as possible, named periodically sends a query to the domain, ignoring negative trust anchors, to find out whether it can now be validated. If so, the negative trust anchor is allowed to expire early.
Validity checks can be disabled for an individual
NTA by using rndc nta -f, or
for all NTAs by setting nta-recheck
to zero.
For convenience, TTL-style time-unit suffixes can be
used to specify the NTA recheck interval in seconds,
minutes, or hours. The default is five minutes. It
cannot be longer than nta-lifetime,
which cannot be longer than a week.
This specifies a maximum permissible TTL value in seconds.
For convenience, TTL-style time-unit suffixes may be
used to specify the maximum value.
When loading a zone file using a
masterfile-format of
text or raw,
any record encountered with a TTL higher than
max-zone-ttl causes the zone to
be rejected.
This is useful in DNSSEC-signed zones because when
rolling to a new DNSKEY, the old key needs to remain
available until RRSIG records have expired from
caches. The max-zone-ttl option guarantees
that the largest TTL in the zone is no higher
than the set value.
(Note: because map-format files
load directly into memory, this option cannot be
used with them.)
The default value is unlimited.
A max-zone-ttl of zero is treated as
unlimited.
Zones configured for dynamic DNS may use this option to set the update method to be used for the zone serial number in the SOA record.
With the default setting of serial-update-method increment;, the SOA serial number is incremented by one each time the zone is updated.
When set to serial-update-method unixtime;, the SOA serial number is set to the number of seconds since the Unix epoch, unless the serial number is already greater than or equal to that value, in which case it is simply incremented by one.
When set to serial-update-method date;, the new SOA serial number is the current date in the form "YYYYMMDD", followed by two zeroes, unless the existing serial number is already greater than or equal to that value, in which case it is incremented by one.
If full, the server collects
statistical data on all zones, unless specifically
turned off on a per-zone basis by specifying
zone-statistics terse or
zone-statistics none
in the zone statement.
The default is terse, providing
minimal statistics on zones (including name and
current serial number, but not query type
counters).
These statistics may be accessed via the statistics-channel or using rndc stats, which dumps them to the file listed in the statistics-file. See also the section called “The Statistics File”.
For backward compatibility with earlier versions
of BIND 9, the zone-statistics
option can also accept yes
or no; yes
has the same meaning as full.
As of BIND 9.10,
no has the same meaning
as none; previously, it
was the same as terse.
If yes and supported by the operating
system, this automatically rescans network interfaces when the
interface addresses are added or removed. The default is
yes. This configuration option does
not affect the time-based interface-interval
option; it is recommended to set the time-based
interface-interval to 0 when the operator
confirms that automatic interface scanning is supported by the
operating system.
The automatic-interface-scan implementation uses routing sockets for the network interface discovery; therefore, the operating system must support the routing sockets for this feature to work.
If yes, then zones can be
added at runtime via rndc addzone.
The default is no.
Newly added zones' configuration parameters
are stored so that they can persist after the
server is restarted. The configuration information
is saved in a file called
viewname.nzfviewname.nzdviewname is the name of the
view, unless the view name contains characters that are
incompatible with use as a file name, in which case a
cryptographic hash of the view name is used instead.
Configurations for zones added at runtime are stored either in a new-zone file (NZF) or a new-zone database (NZD), depending on whether named was linked with liblmdb at compile time. See rndc(8) for further details about rndc addzone.
If yes, then the AA bit
is always set on NXDOMAIN responses, even if the server is
not actually
authoritative. The default is no.
This option was used in BIND 8 to enable checking for memory leaks on exit. BIND 9 ignores the option and always performs the checks.
This writes memory statistics to the file specified by
memstatistics-file at exit.
The default is no unless
-m record is specified on the command line, in
which case it is yes.
If yes, then the
server treats all zones as if they are doing zone transfers
across
a dial-on-demand dialup link, which can be brought up by
traffic
originating from this server. Although this setting has different effects
according
to zone type, it concentrates the zone maintenance so that
everything
happens quickly, once every heartbeat-interval,
ideally during a single call. It also suppresses some
normal
zone maintenance traffic. The default is no.
If specified in the view and zone statements, the dialup option overrides the global dialup option.
If the zone is a primary zone, the server sends out a NOTIFY request to all the secondaries (default). This should trigger the zone serial number check in the secondary (providing it supports NOTIFY), allowing the secondary to verify the zone while the connection is active. The set of servers to which NOTIFY is sent can be controlled by notify and also-notify.
If the zone is a secondary or stub zone, the server suppresses the regular "zone up to date" (refresh) queries and only performs them when the heartbeat-interval expires, in addition to sending NOTIFY requests.
Finer control can be achieved by using
notify, which only sends NOTIFY
messages;
notify-passive, which sends NOTIFY
messages and
suppresses the normal refresh queries; refresh,
which suppresses normal refresh processing and sends refresh
queries
when the heartbeat-interval
expires; and
passive, which disables normal
refresh
processing.
|
dialup mode |
normal refresh |
heart-beat refresh |
heart-beat notify |
|
no (default) |
yes |
no |
no |
|
yes |
no |
yes |
yes |
|
notify |
yes |
no |
yes |
|
refresh |
no |
yes |
no |
|
passive |
no |
no |
no |
|
notify-passive |
no |
no |
yes |
Note that normal NOTIFY processing is not affected by dialup.
In BIND 8, this option enabled simulating the obsolete DNS query type IQUERY. BIND 9 never does IQUERY simulation.
This option is obsolete.
In BIND 8, fetch-glue yes
caused the server to attempt to fetch glue resource records
it
did not have when constructing the additional
data section of a response. This is now considered a bad
idea
and BIND 9 never does it.
When the nameserver exits upon receiving SIGTERM,
flush or do not flush any pending zone writes. The default
is
flush-zones-on-shutdown no.
When BIND is compiled with GeoIP support and configured
with "geoip" ACL elements, this option indicates whether
the EDNS Client Subnet option, if present in a request,
should be used for matching against the GeoIP database.
The default is
geoip-use-ecs yes.
This option was incorrectly implemented
in BIND 8, and is ignored by BIND 9.
To achieve the intended effect
of
has-old-clients yes, specify
the two separate options auth-nxdomain yes
and rfc2308-type1 no instead.
In BIND 8, this enabled keeping of statistics for every host that the name server interacts with. It is not implemented in BIND 9.
If yes, respond to root key sentinel probes as described in
draft-ietf-dnsop-kskroll-sentinel-08. The default is
yes.
This option is obsolete.
It was used in BIND 8 to
determine whether a transaction log was
kept for Incremental Zone Transfer. BIND 9 maintains a transaction
log whenever possible. To disable outgoing
incremental zone
transfers, use provide-ixfr no.
If yes, DNS name compression is
used in responses to regular queries (not including
AXFR or IXFR, which always use compression). Setting
this option to no reduces CPU
usage on servers and may improve throughput. However,
it increases response size, which may cause more queries
to be processed using TCP; a server with compression
disabled is out of compliance with RFC 1123 Section
6.1.3.2. The default is yes.
If set to yes, then when generating
responses the server only adds records to the authority
and additional data sections when they are required (e.g.
delegations, negative responses). This may improve the
performance of the server.
When set to no-auth, the
server omits records from the authority section
unless they are required, but it may still add
records to the additional section. When set to
no-auth-recursive, this
is only done if the query is recursive. These
settings are useful when answering stub clients,
which usually ignore the authority section.
no-auth-recursive is
designed for mixed-mode servers that handle
both authoritative and recursive queries.
The default is no.
If set to yes, the server replies with only one
of the RRsets for the query name, and its covering
RRSIGs if any, when
generating a positive response to a query of type
ANY over UDP, instead of replying with all known
RRsets for the name. Similarly, a query for type
RRSIG is answered with the RRSIG records covering
only one type. This can reduce the impact of some kinds
of attack traffic, without harming legitimate
clients. (Note, however, that the RRset returned is the
first one found in the database; it is not necessarily
the smallest available RRset.)
Additionally, minimal-responses is
turned on for these queries, so no unnecessary records
are added to the authority or additional sections.
The default is no.
This option was used in BIND 8 to allow a domain name to have multiple CNAME records, in violation of the DNS standards. BIND 9.2 onwards always strictly enforces the CNAME rules both in primary files and dynamic updates.
If yes (the default),
DNS NOTIFY messages are sent when a zone the server is
authoritative for
changes; see the section called “Notify”. The messages are
sent to the
servers listed in the zone's NS records (except the primary
server identified
in the SOA MNAME field), and to any servers listed in the
also-notify option.
If master-only, notifies are only
sent
for primary zones.
If explicit, notifies are sent only
to
servers explicitly listed using also-notify.
If no, no notifies are sent.
The notify option may also be specified in the zone statement, in which case it overrides the options notify statement. It would only be necessary to turn off this option if it caused secondary zones to crash.
If yes, do not check the name servers
in the NS RRset against the SOA MNAME. Normally a NOTIFY
message is not sent to the SOA MNAME (SOA ORIGIN), as it is
supposed to contain the name of the ultimate primary server.
Sometimes, however, a secondary server is listed as the SOA MNAME in
hidden primary configurations; in that case,
the ultimate primary should be set to still send NOTIFY messages to
all the name servers listed in the NS RRset.
If yes, and a
DNS query requests recursion, then the server attempts
to do
all the work required to answer the query. If recursion is
off
and the server does not already know the answer, it
returns a
referral response. The default is
yes.
Note that setting recursion no does not prevent
clients from getting data from the server's cache; it only
prevents new data from being cached as an effect of client
queries.
Caching may still occur as an effect the server's internal
operation, such as NOTIFY address lookups.
If yes, then an empty EDNS(0)
NSID (Name Server Identifier) option is sent with all
queries to authoritative name servers during iterative
resolution. If the authoritative server returns an NSID
option in its response, then its contents are logged in
the resolver category at level
info.
The default is no.
This experimental option is obsolete.
If yes, require a valid server cookie before sending a full
response to a UDP request from a cookie-aware client.
BADCOOKIE is sent if there is a bad or nonexistent
server cookie.
The default is no.
Users wishing to test that DNS COOKIE clients correctly handle BADCOOKIE, or who are
getting a lot of forged DNS requests with DNS COOKIES
present, should set this to yes.
Setting this to yes
results in a reduced amplification effect in a reflection
attack, as the BADCOOKIE response is smaller than
a full response, while also requiring a legitimate client
to follow up with a second query with the new, valid, cookie.
When set to the default value of yes,
COOKIE EDNS options are sent when applicable in
replies to client queries. If set to
no, COOKIE EDNS options are not
sent in replies. This can only be set at the global
options level, not per-view.
answer-cookie no is only intended as a temporary measure, for use when named shares an IP address with other servers that do not yet support DNS COOKIE. A mismatch between servers on the same address is not expected to cause operational problems, but the option to disable COOKIE responses so that all servers have the same behavior is provided out of an abundance of caution. DNS COOKIE is an important security mechanism, and should not be disabled unless absolutely necessary.
If yes, then a COOKIE EDNS
option is sent along with the query. If the
resolver has previously communicated with the server, the
COOKIE returned in the previous transaction is sent.
This is used by the server to determine whether
the resolver has talked to it before. A resolver
sending the correct COOKIE is assumed not to be an
off-path attacker sending a spoofed-source query;
the query is therefore unlikely to be part of a
reflection/amplification attack, so resolvers
sending a correct COOKIE option are not subject to
response rate limiting (RRL). Resolvers which
do not send a correct COOKIE option may be limited
to receiving smaller responses via the
nocookie-udp-size option.
The default is yes.
This sets the maximum size of UDP responses that are sent to queries without a valid server COOKIE. A value below 128 is silently raised to 128. The default value is 4096, but the max-udp-size option may further limit the response size as the default for max-udp-size is 1232.
This experimental option is obsolete.
This sets the algorithm to be used when generating the server cookie; the options are "aes", "sha1", or "sha256". The default is "aes" if supported by the cryptographic library; otherwise, "sha256".
If set, this is a shared secret used for generating and verifying EDNS COOKIE options within an anycast cluster. If not set, the system generates a random secret at startup. The shared secret is encoded as a hex string and needs to be 128 bits for AES128, 160 bits for SHA1, and 256 bits for SHA256.
If there are multiple secrets specified, the first
one listed in named.conf is
used to generate new server cookies. The others
are only used to verify returned cookies.
Setting this to yes
causes the server to send NS records along with the SOA
record for negative
answers. The default is no.
This is not yet implemented in BIND 9.
This causes named to send specially formed queries once per day to domains for which trust anchors have been configured via trusted-keys, managed-keys, or dnssec-validation auto.
The query name used for these queries has the form "_ta-xxxx(-xxxx)(...)".<domain>, where each "xxxx" is a group of four hexadecimal digits representing the key ID of a trusted DNSSEC key. The key IDs for each domain are sorted smallest to largest prior to encoding. The query type is NULL.
By monitoring these queries, zone operators are able to see which resolvers have been updated to trust a new key; this may help them decide when it is safe to remove an old one.
The default is yes.
This option is obsolete. BIND 9 always allocates query IDs from a pool.
This option is obsolete. To disable IXFR to a particular server or servers, see the information on the provide-ixfr option in the section called “server Statement Definition and Usage”. See also the section called “Incremental Zone Transfers (IXFR)”.
See the description of provide-ixfr in the section called “server Statement Definition and Usage”.
See the description of request-ixfr in the section called “server Statement Definition and Usage”.
See the description of request-expire in the section called “server Statement Definition and Usage”.
This option was used in BIND 8 to make the server treat carriage return ("\r") characters the same way as a space or tab character, to facilitate loading of zone files on a Unix system that were generated on an NT or DOS machine. In BIND 9, both UNIX "\n" and NT/DOS "\r\n" newlines are always accepted, and the option is ignored.
These options control the behavior of an authoritative server when answering queries which have additional data, or when following CNAME and DNAME chains.
When both of these options are set to yes
(the default) and a
query is being answered from authoritative data (a zone
configured into the server), the additional data section of
the
reply is filled in using data from other authoritative
zones
and from the cache. In some situations this is undesirable,
such
as when there is concern over the correctness of the cache,
or
in servers where secondary zones may be added and modified by
untrusted third parties. Also, avoiding
the search for this additional data speeds up server
operations
at the possible expense of additional queries to resolve
what would
otherwise be provided in the additional section.
For example, if a query asks for an MX record for host foo.example.com,
and the record found is "MX 10 mail.example.net", normally the address
records (A and AAAA) for mail.example.net are provided as well,
if known, even though they are not in the example.com zone.
Setting these options to no
disables this behavior and makes
the server only search for additional data in the zone it
answers from.
These options are intended for use in authoritative-only servers, or in authoritative-only views. Attempts to set them to no without also specifying recursion no will cause the server to ignore the options and log a warning message.
Specifying additional-from-cache no actually disables the use of the cache not only for additional data lookups but also when looking up the answer. This is usually the desired behavior in an authoritative-only server where the correctness of the cached data is an issue.
When a name server is non-recursively queried for a name that is not below the apex of any served zone, it normally answers with an "upwards referral" to the root servers or the servers of some other known parent of the query name. Since the data in an upwards referral comes from the cache, the server is not able to provide upwards referrals when additional-from-cache no has been specified. Instead, it responds to such queries with REFUSED. This should not cause any problems since upwards referrals are not required for the resolution process.
If yes, then an
IPv4-mapped IPv6 address matches any address-match
list entries that match the corresponding IPv4 address.
This option was introduced to work around a kernel quirk in some operating systems that causes IPv4 TCP connections, such as zone transfers, to be accepted on an IPv6 socket using mapped addresses. This caused address-match lists designed for IPv4 to fail to match. However, named now solves this problem internally. The use of this option is discouraged.
This option is only available when
BIND 9 is compiled with the
--enable-filter-aaaa option on the
"configure" command line. It is intended to help the
transition from IPv4 to IPv6 by not giving IPv6 addresses
to DNS clients unless they have connections to the IPv6
Internet. This is not recommended unless absolutely
necessary. The default is no.
The filter-aaaa-on-v4 option
may also be specified in view statements
to override the global filter-aaaa-on-v4
option.
If yes,
the DNS client is at an IPv4 address, in filter-aaaa,
and if the response does not include DNSSEC signatures,
then all AAAA records are deleted from the response.
This filtering applies to all responses and not only
authoritative responses.
If break-dnssec,
then AAAA records are deleted even when DNSSEC is enabled.
As suggested by the name, this causes the response to not verify,
because the DNSSEC protocol is designed to detect deletions.
This mechanism can erroneously cause other servers to not give AAAA records to their clients. A recursing server with both IPv6 and IPv4 network connections, that queries an authoritative server using this mechanism via IPv4, is denied AAAA records even if its client is using IPv6.
This mechanism is applied to authoritative as well as non-authoritative records. A client using IPv4 that is not allowed recursion can erroneously be given AAAA records because the server is not allowed to check for A records.
Some AAAA records are given to IPv4 clients in glue records. IPv4 clients that are servers can then erroneously answer requests for AAAA records received via IPv4.
This is identical to filter-aaaa-on-v4,
except it filters AAAA responses to queries from IPv6
clients instead of IPv4 clients. To filter all
responses, set both options to yes.
When yes and the server loads a new
version of a primary zone from its zone file or receives a
new version of a secondary file via zone transfer, it
compares the new version to the previous one and calculates
a set of differences. The differences are then logged in
the zone's journal file so that the changes can be
transmitted to downstream secondaries as an incremental zone
transfer.
By allowing incremental zone transfers to be used for non-dynamic zones, this option saves bandwidth at the expense of increased CPU and memory consumption at the primary server. In particular, if the new version of a zone is completely different from the previous one, the set of differences is of a size comparable to the combined size of the old and new zone versions, and the server needs to temporarily allocate memory to hold this complete difference set.
ixfr-from-differences also accepts master and slave at the view and options levels, which causes ixfr-from-differences to be enabled for all primary or secondary zones, respectively. It is off by default.
Note: if inline signing is enabled for a zone, the user-provided ixfr-from-differences setting is ignored for that zone.
This should be set when there are multiple primary servers for a zone
and the
addresses refer to different machines. If yes, named does
not log
when the serial number on the primary is less than what named
currently
has. The default is no.
Zones configured for dynamic DNS may use this option to allow varying levels of automatic DNSSEC key management. There are three possible settings:
auto-dnssec allow; permits
keys to be updated and the zone fully re-signed
whenever the user issues the command rndc sign
zonename.
auto-dnssec maintain; includes the
above, but also automatically adjusts the zone's DNSSEC
keys on a schedule, according to the keys' timing metadata
(see dnssec-keygen(8) and
dnssec-settime(8)). The command
rndc sign
zonename causes
named to load keys from the key
repository and sign the zone with all keys that are
active.
rndc loadkeys
zonename causes
named to load keys from the key
repository and schedule key maintenance events to occur
in the future, but it does not sign the full zone
immediately. Note: once keys have been loaded for a
zone the first time, the repository is searched
for changes periodically, regardless of whether
rndc loadkeys is used. The recheck
interval is defined by
dnssec-loadkeys-interval.)
The default setting is auto-dnssec off.
This indicates whether DNSSEC-related resource
records are to be returned by named.
If set to no,
named does not return DNSSEC-related
resource records unless specifically queried for.
The default is yes.
This option enables DNSSEC validation in named.
Note that dnssec-enable also needs to be
set to yes to be effective.
If set to no, DNSSEC validation
is disabled.
If set to auto, DNSSEC validation
is enabled and a default trust anchor for the DNS root
zone is used. If set to yes,
DNSSEC validation is enabled, but a trust anchor must be
manually configured using a trusted-keys
or managed-keys statement. The default
is yes.
The default root trust anchor is stored in the file
bind.keys.
named loads that key at
startup if dnssec-validation is
set to auto. A copy of the file is
installed along with BIND 9, and is current as of the
release date. If the root key expires, a new copy of
bind.keys can be downloaded
from https://www.isc.org/bind-keys.
(To prevent problems if bind.keys is
not found, the current trust anchor is also compiled in
to named. Relying on this is not
recommended, however, as it requires named
to be recompiled with a new key when the root key expires.)
named loads only
the root key from bind.keys.
The file cannot be used to store keys for other zones.
The root key in bind.keys is ignored
if dnssec-validation auto is not in
use.
Whenever the resolver sends out queries to an EDNS-compliant server, it always sets the DO bit indicating it can support DNSSEC responses, even if dnssec-validation is off.
This accepts expired signatures when verifying DNSSEC signatures.
The default is no.
Setting this option to yes
leaves named vulnerable to
replay attacks.
Query logging provides a complete log of all incoming queries and all query errors. This provides more insight into the server's activity, but with a cost to performance which may be significant on heavily loaded servers.
The querylog option specifies whether query logging should be active when named first starts. If querylog is not specified, then query logging is determined by the presence of the logging category queries. Query logging can also be activated at runtime using the command rndc querylog on, or deactivated with rndc querylog off.
This option is used to restrict the character set and syntax of certain domain names in zone files and/or DNS responses received from the network. The default varies according to usage area. For primary zones (i.e., type master), the default is fail. For secondary zones (type slave), the default is warn. For answers received from the network (response), the default is ignore.
The rules for legal hostnames and mail domains are derived from RFC 952 and RFC 821 as modified by RFC 1123.
check-names applies to the owner names of A, AAAA, and MX records. It also applies to the domain names in the RDATA of NS, SOA, MX, and SRV records. It further applies to the RDATA of PTR records where the owner name indicates that it is a reverse lookup of a hostname (the owner name ends in IN-ADDR.ARPA, IP6.ARPA, or IP6.INT).
This checks primary zones for records that are treated as different by DNSSEC but are semantically equal in plain DNS. The default is to warn. Other possible values are fail and ignore.
This checks whether the MX record appears to refer to a IP address. The default is to warn. Other possible values are fail and ignore.
This option is used to check for non-terminal wildcards. The use of non-terminal wildcards is almost always as a result of a failure to understand the wildcard matching algorithm (RFC 1034). This option affects primary zones. The default (yes) is to check for non-terminal wildcards and issue a warning.
This performs post-load zone integrity checks on primary zones. It checks that MX and SRV records refer to address (A or AAAA) records and that glue address records exist for delegated zones. For MX and SRV records, only in-zone hostnames are checked (for out-of-zone hostnames, use named-checkzone). For NS records, only names below top-of-zone are checked (for out-of-zone names and glue consistency checks, use named-checkzone). The default is yes.
The use of the SPF record to publish Sender Policy Framework is deprecated, as the migration from using TXT records to SPF records was abandoned. Enabling this option also checks that a TXT Sender Policy Framework record exists (starts with "v=spf1") if there is an SPF record. Warnings are emitted if the TXT record does not exist; they can be suppressed with check-spf.
If check-integrity is set, then fail, warn, or ignore MX records that refer to CNAMES. The default is to warn.
If check-integrity is set, then fail, warn, or ignore SRV records that refer to CNAMES. The default is to warn.
When performing integrity checks, also check that sibling glue exists. The default is yes.
If check-integrity is set, check that there is a TXT Sender Policy Framework record present (starts with "v=spf1") if there is an SPF record present. The default is warn.
If yes, when returning authoritative negative responses to
SOA queries, set the TTL of the SOA record returned in
the authority section to zero.
The default is yes.
If yes, when caching a negative response to an SOA query
set the TTL to zero.
The default is no.
When set to the default value of yes,
check the KSK bit in each key to determine how the key
should be used when generating RRSIGs for a secure zone.
Ordinarily, zone-signing keys (that is, keys without the
KSK bit set) are used to sign the entire zone, while
key-signing keys (keys with the KSK bit set) are only
used to sign the DNSKEY RRset at the zone apex.
However, if this option is set to no,
then the KSK bit is ignored; KSKs are treated as if they
were ZSKs and are used to sign the entire zone. This is
similar to the dnssec-signzone -z
command-line option.
When this option is set to yes, there
must be at least two active keys for every algorithm
represented in the DNSKEY RRset: at least one KSK and one
ZSK per algorithm. If there is any algorithm for which
this requirement is not met, this option is ignored
for that algorithm.
When this option and update-check-ksk
are both set to yes, only key-signing
keys (that is, keys with the KSK bit set) are used
to sign the DNSKEY RRset at the zone apex. Zone-signing
keys (keys without the KSK bit set) are used to sign
the remainder of the zone, but not the DNSKEY RRset.
This is similar to the
dnssec-signzone -x command-line option.
The default is no. If
update-check-ksk is set to
no, this option is ignored.
If yes, try to refresh the zone using TCP if UDP queries fail.
The default is
yes.
This allows a dynamic zone to transition from secure to insecure (i.e., signed to unsigned) by deleting all of the DNSKEY records. The default is no. If set to yes, and if the DNSKEY RRset at the zone apex is deleted, all RRSIG and NSEC records are removed from the zone as well.
If the zone uses NSEC3, it is also necessary to delete the NSEC3PARAM RRset from the zone apex; this causes the removal of all corresponding NSEC3 records. (It is expected that this requirement will be eliminated in a future release.)
Note that if a zone has been configured with auto-dnssec maintain and the private keys remain accessible in the key repository, then the zone will be automatically signed again the next time named is started.
The forwarding facility can be used to create a large site-wide cache on a few servers, reducing traffic over links to external name servers. It can also be used to allow queries by servers that do not have direct access to the Internet, but wish to look up exterior names anyway. Forwarding occurs only on those queries for which the server is not authoritative and does not have the answer in its cache.
This option is only meaningful if the
forwarders list is not empty. A value of first is
the default and causes the server to query the forwarders
first;
if that does not answer the question, the server then
looks for
the answer itself. If only is
specified, the
server only queries the forwarders.
This specifies a list of IP addresses to which queries are forwarded. The default is the empty list (no forwarding). Each address in the list can be associated with an optional port number and/or DSCP value, and a default port number and DSCP value can be set for the entire list.
Forwarding can also be configured on a per-domain basis, allowing for the global forwarding options to be overridden in a variety of ways. Particular domains can be set to use different forwarders, or have a different forward only/first behavior, or not forward at all; see the section called “zone Statement Grammar”.
Dual-stack servers are used as servers of last resort, to work around problems in reachability due the lack of support for either IPv4 or IPv6 on the host machine.
This specifies host names or addresses of machines with access to both IPv4 and IPv6 transports. If a hostname is used, the server must be able to resolve the name using only the transport it has. If the machine is dual-stacked, the dual-stack-servers parameter has no effect unless access to a transport has been disabled on the command line (e.g., named -4).
Access to the server can be restricted based on the IP address of the requesting system. See the section called “Address Match Lists” for details on how to specify IP address lists.
This ACL specifies which hosts are allowed to notify this secondary server of zone changes in addition to the zone primaries. allow-notify may also be specified in the zone statement, in which case it overrides the options allow-notify statement. It is only meaningful for a secondary zone. If not specified, the default is to process notify messages only from a zone's primary.
This specifies which hosts are allowed to ask ordinary DNS questions. allow-query may also be specified in the zone statement, in which case it overrides the options allow-query statement. If not specified, the default is to allow queries from all hosts.
allow-query-cache is used to specify access to the cache.
This specifies which local addresses can accept ordinary DNS questions. This makes it possible, for instance, to allow queries on internal-facing interfaces but disallow them on external-facing ones, without necessarily knowing the internal network's addresses.
Note that allow-query-on is only checked for queries that are permitted by allow-query. A query must be allowed by both ACLs, or it is refused.
allow-query-on may also be specified in the zone statement, in which case it overrides the options allow-query-on statement.
If not specified, the default is to allow queries on all addresses.
allow-query-cache is used to specify access to the cache.
This specifies which hosts are allowed to get answers from the cache. If allow-query-cache is not set, BIND checks to see if the following parameters are set, in order: allow-recursion and allow-query (unless recursion no; is set, in which case none; is used). If neither of those parameters is set, the default (localnets; localhost;) is used.
This specifies which local addresses can send answers from the cache. If not specified, the default is to allow cache queries on any address, localnets, and localhost.
This specifies which hosts are allowed to make recursive queries through this server. BIND checks to see if the following parameters are set, in order: allow-recursion, allow-query-cache, and allow-query. If none of those parameters are set, the default (localnets; localhost;) is used.
This specifies which local addresses can accept recursive queries. If not specified, the default is to allow recursive queries on all addresses.
This specifies which hosts are allowed to submit Dynamic DNS updates for primary zones. The default is to deny updates from all hosts. Note that allowing updates based on the requestor's IP address is insecure; see the section called “Dynamic Update Security” for details.
This specifies which hosts are allowed to
submit Dynamic DNS updates to secondary zones to be forwarded to
the
primary. The default is { none; },
which
means that no update forwarding is performed. To
enable
update forwarding, specify
allow-update-forwarding { any; };.
Specifying values other than { none; } or
{ any; } is usually
counterproductive;
the responsibility for update access control should rest
with the
primary server, not the secondaries.
Note that enabling the update forwarding feature on a secondary server may expose primary servers to attacks if they rely on insecure IP-address-based access control; see the section called “Dynamic Update Security” for more details.
This option was introduced for the smooth transition from AAAA to A6 and from "nibble labels" to binary labels. However, since both A6 and binary labels were then deprecated, this option was also deprecated. It is now ignored with some warning messages.
This specifies which hosts are allowed to receive zone transfers from the server. allow-transfer may also be specified in the zone statement, in which case it overrides the options allow-transfer statement. If not specified, the default is to allow transfers to all hosts.
This specifies a list of addresses which the
server does accept queries from or use to resolve a
query. Queries
from these addresses are not responded to. The default
is none.
This specifies a list of addresses to which
filter-aaaa-on-v4
and filter-aaaa-on-v6
apply. The default is any.
This specifies a list of addresses to which the server
sends responses to TCP queries, in the same order
in which they were received. This disables the
processing of TCP queries in parallel. The default
is none.
This specifies a list of addresses which require responses to use case-insensitive compression. This ACL can be used when named needs to work with clients that do not comply with the requirement in RFC 1034 to use case-insensitive name comparisons when checking for matching domain names.
If left undefined, the ACL defaults to none: case-insensitive compression is used for all clients. If the ACL is defined and matches a client, case is ignored when compressing domain names in DNS responses sent to that client.
This can result in slightly smaller responses; if a response contains the names "example.com" and "example.COM", case-insensitive compression treats the second one as a duplicate. It also ensures that the case of the query name exactly matches the case of the owner names of returned records, rather than matches the case of the records entered in the zone file. This allows responses to exactly match the query, which is required by some clients due to incorrect use of case-sensitive comparisons.
Case-insensitive compression is always used in AXFR and IXFR responses, regardless of whether the client matches this ACL.
There are circumstances in which named does not preserve the case of owner names of records: if a zone file defines records of different types with the same name, but the capitalization of the name is different (e.g., "www.example.com/A" and "WWW.EXAMPLE.COM/AAAA"), then all responses for that name use the first version of the name that was used in the zone file. This limitation may be addressed in a future release. However, domain names specified in the rdata of resource records (i.e., records of type NS, MX, CNAME, etc.) always have their case preserved unless the client matches this ACL.
This is the amount of time in seconds that the
resolver spends attempting to resolve a recursive
query before failing. The default and minimum
is 10 and the maximum is
30. Setting it to
0 results in the default
being used.
The interfaces and ports that the server answers queries
from may be specified using the listen-on option. listen-on takes
an optional port and an address_match_list
of IPv4 addresses. (IPv6 addresses are ignored, with a
logged warning.)
The server listens on all interfaces allowed by the address
match list. If a port is not specified, port 53 is used.
Multiple listen-on statements are allowed. For example:
listen-on { 5.6.7.8; };
listen-on port 1234 { !1.2.3.4; 1.2/16; };
enables the name server on port 53 for the IP address 5.6.7.8, and on port 1234 of an address on the machine in net 1.2 that is not 1.2.3.4.
If no listen-on is specified, the server listens on port 53 on all IPv4 interfaces.
The listen-on-v6 option is used to specify the interfaces and the ports on which the server listens for incoming queries sent using IPv6. If not specified, the server listens on port 53 on all IPv6 interfaces.
When
{ any; }
is
specified
as the address_match_list for the
listen-on-v6 option,
the server does not bind a separate socket to each IPv6 interface
address as it does for IPv4, if the operating system has enough API
support for IPv6 (specifically, if it conforms to RFC 3493 and RFC
3542).
Instead, it listens on the IPv6 wildcard address.
If the system only has incomplete API support for IPv6, however,
the behavior is the same as that for IPv4.
A list of particular IPv6 addresses can also be specified, in which case the server listens on a separate socket for each specified address, regardless of whether the desired API is supported by the system. IPv4 addresses specified in listen-on-v6 are ignored, with a logged warning.
Multiple listen-on-v6 options can be used. For example:
listen-on-v6 { any; };
listen-on-v6 port 1234 { !2001:db8::/32; any; };
enables the name server on port 53 for any IPv6 addresses (with a single wildcard socket), and on port 1234 of IPv6 addresses that are not in the prefix 2001:db8::/32 (with separate sockets for each matched address).
To instruct the server not to listen on any IPv6 address, use:
listen-on-v6 { none; };
If the server does not know the answer to a question, it queries other name servers. query-source specifies the address and port used for such queries. For queries sent over IPv6, there is a separate query-source-v6 option. If address is * (asterisk) or is omitted, a wildcard IP address (INADDR_ANY) is used.
If port is * or is omitted, a random port number from a pre-configured range is picked up and used for each query. The port range(s) is specified in the use-v4-udp-ports (for IPv4) and use-v6-udp-ports (for IPv6) options, excluding the ranges specified in the avoid-v4-udp-ports and avoid-v6-udp-ports options, respectively.
The defaults of the query-source and query-source-v6 options are:
query-source address * port *; query-source-v6 address * port *;
If use-v4-udp-ports or use-v6-udp-ports is unspecified, named checks whether the operating system provides a programming interface to retrieve the system's default range for ephemeral ports. If such an interface is available, named uses the corresponding system default range; otherwise, it uses its own defaults:
use-v4-udp-ports { range 1024 65535; };
use-v6-udp-ports { range 1024 65535; };
Note: make sure the ranges are sufficiently large for security. A desirable size depends on several parameters, but we generally recommend it contain at least 16384 ports (14 bits of entropy). Note also that the system's default range when used may be too small for this purpose, and that the range may even be changed while named is running; the new range is automatically applied when named is reloaded. Explicit configuration of use-v4-udp-ports and use-v6-udp-ports is encouraged, so that the ranges are sufficiently large and are reasonably independent from the ranges used by other applications.
Note: the operational configuration where named runs may prohibit the use of some ports. For example, Unix systems do not allow named, if run without root privilege, to use ports less than 1024. If such ports are included in the specified (or detected) set of query ports, the corresponding query attempts will fail, resulting in resolution failures or delay. It is therefore important to configure the set of ports that can be safely used in the expected operational environment.
The defaults of the avoid-v4-udp-ports and avoid-v6-udp-ports options are:
avoid-v4-udp-ports {};
avoid-v6-udp-ports {};
Note: BIND 9.5.0 introduced the use-queryport-pool option to support a pool of such random ports, but this option is now obsolete because reusing the same ports in the pool may not be sufficiently secure. For the same reason, it is generally strongly discouraged to specify a particular port for the query-source or query-source-v6 options; it implicitly disables the use of randomized port numbers.
This option is obsolete.
This option is obsolete.
This option is obsolete.
The address specified in the query-source option is used for both UDP and TCP queries, but the port applies only to UDP queries. TCP queries always use a random unprivileged port.
Solaris 2.5.1 and earlier does not support setting the source address for TCP sockets.
See also transfer-source and notify-source.
BIND has mechanisms in place to facilitate zone transfers and set limits on the amount of load that transfers place on the system. The following options apply to zone transfers.
This option defines a global list of IP addresses of name servers that are also sent NOTIFY messages whenever a fresh copy of the zone is loaded, in addition to the servers listed in the zone's NS records. This helps to ensure that copies of the zones quickly converge on stealth servers. Optionally, a port may be specified with each also-notify address to send the notify messages to a port other than the default of 53. An optional TSIG key can also be specified with each address to cause the notify messages to be signed; this can be useful when sending notifies to multiple views. In place of explicit addresses, one or more named masters lists can be used.
If an also-notify list is given in a zone statement, it overrides the options also-notify statement. When a zone notify statement is set to no, the IP addresses in the global also-notify list are not sent NOTIFY messages for that zone. The default is the empty list (no global notification list).
Inbound zone transfers running longer than this many minutes are terminated. The default is 120 minutes (2 hours). The maximum value is 28 days (40320 minutes).
Inbound zone transfers making no progress in this many minutes are terminated. The default is 60 minutes (1 hour). The maximum value is 28 days (40320 minutes).
Outbound zone transfers running longer than this many minutes are terminated. The default is 120 minutes (2 hours). The maximum value is 28 days (40320 minutes).
Outbound zone transfers making no progress in this many minutes are terminated. The default is 60 minutes (1 hour). The maximum value is 28 days (40320 minutes).
This specifies the rate at which NOTIFY requests are sent during normal zone maintenance operations. (NOTIFY requests due to initial zone loading are subject to a separate rate limit; see below.) The default is 20 per second. The lowest possible rate is one per second; when set to zero, it is silently raised to one.
This is the rate at which NOTIFY requests are sent when the name server is first starting up, or when zones have been newly added to the name server. The default is 20 per second. The lowest possible rate is one per second; when set to zero, it is silently raised to one.
Secondary servers periodically query primary servers to find out if zone serial numbers have changed. Each such query uses a minute amount of the secondary server's network bandwidth. To limit the amount of bandwidth used, BIND 9 limits the rate at which queries are sent. The value of the serial-query-rate option, an integer, is the maximum number of queries sent per second. The default is 20 per second. The lowest possible rate is one per second; when set to zero, it is silently raised to one.
BIND 9 does not limit the number of outstanding serial queries and ignores the serial-queries option. Instead, it limits the rate at which the queries are sent as defined using the serial-query-rate option.
Zone transfers can be sent using two different formats, one-answer and many-answers. The transfer-format option is used on the primary server to determine which format it sends. one-answer uses one DNS message per resource record transferred. many-answers packs as many resource records as possible into one message. many-answers is more efficient; the default is many-answers. The many-answers format is also supported by recent Microsoft Windows name servers. transfer-format may be overridden on a per-server basis by using the server statement.
This is an upper bound on the uncompressed size of DNS messages used in zone transfers over TCP. If a message grows larger than this size, additional messages are used to complete the zone transfer. (Note, however, that this is a hint, not a hard limit; if a message contains a single resource record whose RDATA does not fit within the size limit, a larger message will be permitted so the record can be transferred.)
Valid values are between 512 and 65535 octets; any
values outside that range are adjusted to the nearest
value within it. The default is 20480,
which was selected to improve message compression;
most DNS messages of this size will compress to less
than 16536 bytes. Larger messages cannot be compressed
as effectively, because 16536 is the largest permissible
compression offset pointer in a DNS message.
This option is mainly intended for server testing; there is rarely any benefit in setting a value other than the default.
This is the maximum number of inbound zone transfers
that can run concurrently. The default value is 10.
Increasing transfers-in may
speed up the convergence
of secondary zones, but it also may increase the load on the
local system.
This is the maximum number of outbound zone transfers
that can run concurrently. Zone transfer requests in
excess
of the limit are refused. The default value is 10.
This is the maximum number of inbound zone transfers
that can concurrently transfer from a given remote
name server.
The default value is 2.
Increasing transfers-per-ns
may
speed up the convergence of secondary zones, but it also may
increase
the load on the remote name server. transfers-per-ns may
be overridden on a per-server basis by using the transfers phrase
of the server statement.
transfer-source determines which local address is bound to IPv4 TCP connections used to fetch zones transferred inbound by the server. It also determines the source IPv4 address, and optionally the UDP port, used for the refresh queries and forwarded dynamic updates. If not set, it defaults to a system-controlled value which is usually the address of the interface "closest to" the remote end. This address must appear in the remote end's allow-transfer option for the zone being transferred, if one is specified. This statement sets the transfer-source for all zones, but can be overridden on a per-view or per-zone basis by including a transfer-source statement within the view or zone block in the configuration file.
Solaris 2.5.1 and earlier does not support setting the source address for TCP sockets.
This option is the same as transfer-source, except zone transfers are performed using IPv6.
This indicates an alternate transfer source if the one listed in transfer-source fails and use-alt-transfer-source is set.
To avoid using the alternate transfer source, set use-alt-transfer-source appropriately and do not depend upon getting an answer back to the first refresh query.
This indicates an alternate transfer source if the one listed in transfer-source-v6 fails and use-alt-transfer-source is set.
This indicates whether the alternate transfer sources should be used. If views are specified, this defaults to no; otherwise, it defaults to yes.
notify-source determines which local source address, and optionally UDP port, is used to send NOTIFY messages. This address must appear in the secondary server's masters zone clause or in an allow-notify clause. This statement sets the notify-source for all zones, but can be overridden on a per-zone or per-view basis by including a notify-source statement within the zone or view block in the configuration file.
Solaris 2.5.1 and earlier does not support setting the source address for TCP sockets.
This option acts like notify-source, but applies to notify messages sent to IPv6 addresses.
use-v4-udp-ports, avoid-v4-udp-ports, use-v6-udp-ports, and avoid-v6-udp-ports specify a list of IPv4 and IPv6 UDP ports that are or are not used as source ports for UDP messages. See the section called “Query Address” about how the available ports are determined. For example, with the following configuration:
use-v6-udp-ports { range 32768 65535; };
avoid-v6-udp-ports { 40000; range 50000 60000; };
UDP ports of IPv6 messages sent from named are in one of the following ranges: 32768 to 39999, 40001 to 49999, and 60001 to 65535.
avoid-v4-udp-ports and avoid-v6-udp-ports can be used to prevent named from choosing as its random source port a port that is blocked by a firewall or a port that is used by other applications; if a query went out with a source port blocked by a firewall, the answer would not pass through the firewall and the name server would have to query again. Note: the desired range can also be represented only with use-v4-udp-ports and use-v6-udp-ports, and the avoid- options are redundant in that sense; they are provided for backward compatibility and to possibly simplify the port specification.
The server's usage of many system resources can be limited. Scaled values are allowed when specifying resource limits. For example, 1G can be used instead of 1073741824 to specify a limit of one gigabyte. unlimited requests unlimited use, or the maximum available amount. default uses the limit that was in force when the server was started. See the description of size_spec in the section called “Configuration File Elements”.
The following options set operating system resource limits for the name server process. Some operating systems do not support some or any of the limits; on such systems, a warning is issued if an unsupported limit is used.
This sets the maximum size of a core dump. The default
is default.
This sets the maximum amount of data memory the server
may use. The default is default.
This is a hard limit on server memory usage;
if the server attempts to allocate memory in excess of this
limit, the allocation will fail, which may in turn leave
the server unable to perform DNS service. Therefore,
this option is rarely useful as a way to limit the
amount of memory used by the server, but it can be used
to raise an operating system data size limit that is
too small by default. To limit the amount
of memory used by the server, use the
max-cache-size and
recursive-clients
options instead.
This sets the maximum number of files the server
may have open concurrently. The default is unlimited.
This sets the maximum amount of stack memory the server
may use. The default is default.
The following options set limits on the server's resource consumption that are enforced internally by the server rather than by the operating system.
This option is obsolete; it is accepted and ignored for BIND 8 compatibility. The option max-journal-size performs a similar function in BIND 9.
This sets a maximum size for each journal file
(see the section called “The Journal File”). When the journal file
approaches
the specified size, some of the oldest transactions in the
journal
are automatically removed. The largest permitted
value is 2 gigabytes. The default is
unlimited, which also
means 2 gigabytes.
This option may also be set on a per-zone basis.
This sets the maximum number of records permitted in a zone. The default is zero, which means the maximum is unlimited.
In BIND 8, this specified the maximum number of host statistics entries to be kept. It is not implemented in BIND 9.
This sets the maximum number (a "hard quota") of simultaneous
recursive lookups the server performs on behalf
of clients. The default is
1000. Because each recursing
client uses a fair
bit of memory (on the order of 20 kilobytes), the
value of the
recursive-clients option may
have to be decreased on hosts with limited memory.
recursive-clients defines a "hard
quota" limit for pending recursive clients; when more
clients than this are pending, new incoming requests
are not accepted, and for each incoming request
a previous pending request is dropped.
A "soft quota" is also set. When this lower
quota is exceeded, incoming requests are accepted, but
for each one, a pending request is dropped.
If recursive-clients is greater than
1000, the soft quota is set to
recursive-clients minus 100;
otherwise it is set to 90% of
recursive-clients.
This is the maximum number of simultaneous client TCP
connections that the server accepts.
The default is 150.
These set the initial value (minimum) and maximum number of recursive simultaneous clients for any given query (<qname,qtype,qclass>) that the server accepts before dropping additional clients. named attempts to self-tune this value and changes are logged. The default values are 10 and 100.
This value should reflect how many queries come in for a given name in the time it takes to resolve that name. If the number of queries exceeds this value, named assumes that it is dealing with a non-responsive zone and drops additional queries. If it gets a response after dropping queries, it raises the estimate. The estimate is then lowered in 20 minutes if it has remained unchanged.
If clients-per-query is set to zero, there is no limit on the number of clients per query and no queries are dropped.
If max-clients-per-query is set to zero, there is no upper bound other than imposed by recursive-clients.
This sets the maximum number of simultaneous iterative
queries to any one domain that the server
permits before blocking new queries for data
in or beneath that zone.
This value should reflect how many fetches would
normally be sent to any one zone in the time it
would take to resolve them. It should be smaller
than recursive-clients.
When many clients simultaneously query for the
same name and type, the clients are all attached
to the same fetch, up to the
max-clients-per-query limit,
and only one iterative query is sent.
However, when clients are simultaneously
querying for different names
or types, multiple queries are sent and
max-clients-per-query is not
effective as a limit.
Optionally, this value may be followed by the keyword
drop or fail,
indicating whether queries which exceed the fetch
quota for a zone are dropped with no response,
or answered with SERVFAIL. The default is
drop.
If fetches-per-zone is set to zero, there is no limit on the number of fetches per query and no queries are dropped. The default is zero.
The current list of active fetches can be dumped by
running rndc recursing. The list
includes the number of active fetches for each
domain and the number of queries that have been
passed or dropped as a result of the
fetches-per-zone limit. (Note:
these counters are not cumulative over time; whenever
the number of active fetches for a domain drops to
zero, the counter for that domain is deleted, and the
next time a fetch is sent to that domain, it is
recreated with the counters set to zero.)
This sets the maximum number of simultaneous iterative
queries that the server allows to be sent to
a single upstream name server before blocking
additional queries.
This value should reflect how many fetches would
normally be sent to any one server in the time it
would take to resolve them. It should be smaller
than recursive-clients.
Optionally, this value may be followed by the keyword
drop or fail,
indicating whether queries are dropped with no
response or answered with SERVFAIL, when all of the
servers authoritative for a zone are found to have
exceeded the per-server quota. The default is
fail.
If fetches-per-server is set to zero, there is no limit on the number of fetches per query and no queries are dropped. The default is zero.
The fetches-per-server quota is dynamically adjusted in response to detected congestion. As queries are sent to a server and are either answered or time out, an exponentially weighted moving average is calculated of the ratio of timeouts to responses. If the current average timeout ratio rises above a "high" threshold, then fetches-per-server is reduced for that server. If the timeout ratio drops below a "low" threshold, then fetches-per-server is increased. The fetch-quota-params options can be used to adjust the parameters for this calculation.
This sets the parameters to use for dynamic resizing of
the fetches-per-server quota in
response to detected congestion.
The first argument is an integer value indicating how frequently to recalculate the moving average of the ratio of timeouts to responses for each server. The default is 100, meaning that BIND recalculates the average ratio after every 100 queries have either been answered or timed out.
The remaining three arguments represent the "low" threshold (defaulting to a timeout ratio of 0.1), the "high" threshold (defaulting to a timeout ratio of 0.3), and the discount rate for the moving average (defaulting to 0.7). A higher discount rate causes recent events to weigh more heavily when calculating the moving average; a lower discount rate causes past events to weigh more heavily, smoothing out short-term blips in the timeout ratio. These arguments are all fixed-point numbers with precision of 1/100; at most two places after the decimal point are significant.
This sets the number of file descriptors reserved for TCP, stdio,
etc. This needs to be big enough to cover the number of
interfaces named listens on plus
tcp-clients, as well as
to provide room for outgoing TCP queries and incoming zone
transfers. The default is 512.
The minimum value is 128 and the
maximum value is 128 fewer than
maxsockets (-S). This option may be removed in the future.
This option has little effect on Windows.
This sets the maximum amount of memory to use for the
server's cache, in bytes or percentage of total physical memory.
When the amount of data in the cache
reaches this limit, the server causes records to
expire prematurely, following an LRU-based strategy, so
that the limit is not exceeded.
The keyword unlimited,
or the value 0, places no limit on the cache size;
records are purged from the cache only when their
TTLs expire.
Any positive values less than 2MB are ignored
and reset to 2MB.
In a server with multiple views, the limit applies
separately to the cache of each view.
The default is 90%.
On systems where detection of the amount of physical
memory is not supported, values represented as a percentage
fall back to unlimited.
Note that the detection of physical memory is done only
once at startup, so named does not
adjust the cache size if the amount of physical memory
is changed during runtime.
This sets the listen-queue depth. The default and minimum is 10. If the kernel supports the accept filter "dataready", this also controls how many TCP connections are queued in kernel space waiting for some data before being passed to accept. Non-zero values less than 10 are silently raised. A value of 0 may also be used; on most platforms this sets the listen-queue length to a system-defined default value.
This interval is effectively obsolete. Previously, the server removed expired resource records from the cache every cleaning-interval minutes. BIND 9 now manages cache memory in a more sophisticated manner and does not rely on periodic cleaning anymore. Specifying this option therefore has no effect on the server's behavior.
The server performs zone maintenance tasks for all zones marked as dialup whenever this interval expires. The default is 60 minutes. Reasonable values are up to 1 day (1440 minutes). The maximum value is 28 days (40320 minutes). If set to 0, no zone maintenance for these zones occurs.
The server scans the network interface list every interface-interval minutes. The default is 60 minutes; the maximum value is 28 days (40320 minutes). If set to 0, interface scanning only occurs when the configuration file is loaded, or when automatic-interface-scan is enabled and supported by the operating system. After the scan, the server begins listening for queries on any newly discovered interfaces (provided they are allowed by the listen-on configuration), and stops listening on interfaces that have gone away.
Name server statistics are logged every statistics-interval minutes. The default is 60, and the maximum value is 28 days (40320 minutes). If set to 0, no statistics are logged.
This option is not implemented in BIND 9.
In BIND 8, this option indicated network topology so that preferential treatment could be given to the topologically closest name servers when sending queries. It is not implemented in BIND 9.
The response to a DNS query may consist of multiple resource records (RRs) forming a resource record set (RRset). The name server normally returns the RRs within the RRset in an indeterminate order (but see the rrset-order statement in the section called “RRset Ordering”). The client resolver code should rearrange the RRs as appropriate: that is, using any addresses on the local net in preference to other addresses. However, not all resolvers can do this or are correctly configured. When a client is using a local server, the sorting can be performed in the server, based on the client's address. This only requires configuring the name servers, not all the clients.
The sortlist statement (see below) takes an address_match_list and interprets it in a special way. Each top-level statement in the sortlist must itself be an explicit address_match_list with one or two elements. The first element (which may be an IP address, an IP prefix, an ACL name, or a nested address_match_list) of each top-level list is checked against the source address of the query until a match is found. When the addresses in the first element overlap, the first rule to match is selected.
Once the source address of the query has been matched, if the top-level statement contains only one element, the actual primitive element that matched the source address is used to select the address in the response to move to the beginning of the response. If the statement is a list of two elements, then the second element is interpreted as a topology preference list. Each top-level element is assigned a distance, and the address in the response with the minimum distance is moved to the beginning of the response.
In the following example, any queries received from any of the addresses of the host itself get responses preferring addresses on any of the locally connected networks. Next most preferred are addresses on the 192.168.1/24 network, and after that either the 192.168.2/24 or 192.168.3/24 network, with no preference shown between these two networks. Queries received from a host on the 192.168.1/24 network prefer other addresses on that network to the 192.168.2/24 and 192.168.3/24 networks. Queries received from a host on the 192.168.4/24 or the 192.168.5/24 network only prefer other addresses on their directly connected networks.
sortlist {
// IF the local host
// THEN first fit on the following nets
{ localhost;
{ localnets;
192.168.1/24;
{ 192.168.2/24; 192.168.3/24; }; }; };
// IF on class C 192.168.1 THEN use .1, or .2 or .3
{ 192.168.1/24;
{ 192.168.1/24;
{ 192.168.2/24; 192.168.3/24; }; }; };
// IF on class C 192.168.2 THEN use .2, or .1 or .3
{ 192.168.2/24;
{ 192.168.2/24;
{ 192.168.1/24; 192.168.3/24; }; }; };
// IF on class C 192.168.3 THEN use .3, or .1 or .2
{ 192.168.3/24;
{ 192.168.3/24;
{ 192.168.1/24; 192.168.2/24; }; }; };
// IF .4 or .5 THEN prefer that net
{ { 192.168.4/24; 192.168.5/24; };
};
};
The following example illustrates reasonable behavior for the local host and hosts on directly connected networks. Responses sent to queries from the local host favor any of the directly connected networks. Responses sent to queries from any other hosts on a directly connected network prefer addresses on that same network. Responses to other queries are not sorted.
sortlist {
{ localhost; localnets; };
{ localnets; };
};
While alternating the order of records in a DNS response between subsequent queries is a known load distribution technique, certain caveats apply (mostly stemming from caching) which usually make it a suboptimal choice for load balancing purposes when used on its own.
The rrset-order statement permits configuration of the ordering of the records in a multiple-record response. See also: the section called “The sortlist Statement”.
Each rule in an rrset-order statement is defined as follows:
[class <class_name>]
[type <type_name>]
[name "<domain_name>"]
order <ordering>
The default qualifiers for each rule are:
<domain_name> only matches the name
itself, not any of its subdomains. To make a rule match all
subdomains of a given name, a wildcard name
(*.<domain_name>) must be used.
Note that *.<domain_name> does
not match
<domain_name> itself; to specify
RRset ordering for a name and all of its subdomains, two separate
rules must be defined: one for
<domain_name> and one for
*.<domain_name>.
The legal values for <ordering>
are:
Records are returned in the order they are defined in the zone file.
The fixed option is only available if BIND is configured with --enable-fixed-rrset at compile time.
Records are returned in a random order.
Records are returned in a cyclic round-robin order, rotating by one record per query.
By default, records are returned in random order.
Note that if multiple rrset-order statements are present in the configuration file (at both the options and view levels), they are not combined; instead, the more-specific one (view) replaces the less-specific one (options).
If multiple rules within a single rrset-order statement match a given RRset, the first matching rule is applied.
Example:
rrset-order {
type A name "foo.isc.org" order random;
type AAAA name "foo.isc.org" order cyclic;
name "bar.isc.org" order fixed;
name "*.bar.isc.org" order random;
name "*.baz.isc.org" order cyclic;
};
With the above configuration, the following RRset ordering is used:
QNAME |
QTYPE |
RRset Order |
|---|---|---|
|
|
random |
|
|
cyclic |
|
|
random |
|
all |
random |
|
all |
fixed |
|
all |
random |
|
all |
random |
|
all |
cyclic |
This is always set to 0. More information is available in the security advisory for CVE-2021-25219.
This sets the number of seconds to cache a
SERVFAIL response due to DNSSEC validation failure or
other general server failure. If set to
0, SERVFAIL caching is disabled.
The SERVFAIL cache is not consulted if a query has
the CD (Checking Disabled) bit set; this allows a
query that failed due to DNSSEC validation to be retried
without waiting for the SERVFAIL TTL to expire.
The maximum value is 30
seconds; any higher value is silently
reduced. The default is 1
second.
To reduce network traffic and increase performance,
the server stores negative answers. max-ncache-ttl is
used to set a maximum retention time for these answers in
the server,
in seconds. The default
max-ncache-ttl is 10800 seconds (3 hours).
max-ncache-ttl cannot exceed
7 days and is
silently truncated to 7 days if set to a greater value.
This sets the maximum time for which the server caches ordinary (positive) answers, in seconds. The default is 604800 (one week). A value of zero may cause all queries to return SERVFAIL, because of lost caches of intermediate RRsets (such as NS and glue AAAA/A records) in the resolution process.
This sets the minimum number of root servers that
is required for a request for the root servers to be
accepted. The default
is 2.
This is not implemented in BIND 9.
This specifies the number of days into the future that
DNSSEC signatures that are automatically generated as a
result of dynamic updates (the section called “Dynamic Update”) will expire. There
is an optional second field which specifies how
long before expiry that the signatures are
regenerated. If not specified, the signatures are
regenerated at 1/4 of base interval. The second
field is specified in days if the base interval is
greater than 7 days; otherwise it is specified in hours.
The default base interval is 30 days,
giving a re-signing interval of 7 1/2 days. The maximum
value is 10 years (3660 days).
The signature inception time is unconditionally set to one hour before the current time, to allow for a limited amount of clock skew.
The sig-validity-interval should be at least several multiples of the SOA expire interval, to allow for reasonable interaction between the various timer and expiry dates.
This specifies the maximum number of nodes to be
examined in each quantum, when signing a zone with
a new DNSKEY. The default is
100.
This specifies a threshold number of signatures that
terminates processing a quantum, when signing
a zone with a new DNSKEY. The default is
10.
This specifies a private RDATA type to be used when generating
signing-state records. The default is
65534.
This parameter may be removed in a future version, once there is a standard type.
Signing-state records are used internally by
named to track the current state of
a zone-signing process, i.e., whether it is still active
or has been completed. The records can be inspected
using the command
rndc signing -list zone.
Once named has finished signing
a zone with a particular key, the signing-state
record associated with that key can be removed from
the zone by running
rndc signing -clear keyid/algorithm zone.
To clear all of the completed signing-state
records for a zone, use
rndc signing -clear all zone.
These options control the server's behavior on refreshing a zone (querying for SOA changes) or retrying failed transfers. Usually the SOA values for the zone are used, up to a hard-coded maximum expiry of 24 weeks. However, these values are set by the primary, giving secondary server administrators little control over their contents.
These options allow the administrator to set a minimum and maximum refresh and retry time in seconds per-zone, per-view, or globally. These options are valid for secondary and stub zones, and clamp the SOA refresh and retry times to the specified values.
The following defaults apply: min-refresh-time 300 seconds, max-refresh-time 2419200 seconds (4 weeks), min-retry-time 500 seconds, and max-retry-time 1209600 seconds (2 weeks).
This sets the maximum advertised EDNS UDP buffer size, in bytes, to control the size of packets received from authoritative servers in response to recursive queries. Valid values are 512 to 4096; values outside this range are silently adjusted to the nearest value within it. The default value is 1232.
The usual reason for setting edns-udp-size to a non-default value is to get UDP answers to pass through broken firewalls that block fragmented packets and/or block UDP DNS packets that are greater than 512 bytes.
When named first queries a remote server, it advertises a UDP buffer size of 512, as this has the greatest chance of success on the first try.
If the initial response times out, named tries again with plain DNS; if that is successful, it is taken as evidence that the server does not support EDNS. After enough failures using EDNS and successes using plain DNS, named defaults to plain DNS for future communications with that server. If that happens, named periodically sends an EDNS query to see if the situation has improved.
However, if the initial query is successful with EDNS advertising a buffer size of 512, then named advertises progressively larger buffer sizes on successive queries, until responses begin timing out or edns-udp-size is reached.
The default buffer sizes used by named are 512, 1232, 1432, and 4096, but never exceed edns-udp-size. (The values 1232 and 1432 are chosen to allow for an IPv4-/IPv6-encapsulated UDP message to be sent without fragmentation at the minimum MTU sizes for Ethernet and IPv6 networks.)
This sets the maximum EDNS UDP message size that named sends, in bytes. Valid values are 512 to 4096; values outside this range are silently adjusted to the nearest value within it. The default value is 1232.
This value applies to responses sent by a server; to set the advertised buffer size in queries, see edns-udp-size.
The usual reason for setting max-udp-size to a non-default value is to allow UDP answers to pass through broken firewalls that block fragmented packets and/or block UDP packets that are greater than 512 bytes. This is independent of the advertised receive buffer (edns-udp-size).
Setting this to a low value encourages additional TCP traffic to the name server.
This specifies
the file format of zone files (see
the section called “Additional File Formats”).
The default value is text, which is the
standard textual representation, except for secondary zones,
in which the default value is raw.
Files in formats other than text are
typically expected to be generated by the
named-compilezone tool, or dumped by
named.
Note that when a zone file in a format other than
text is loaded, named
may omit some of the checks which would be performed for a
file in text format. In particular,
check-names checks do not apply
for the raw format. This means
a zone file in the raw format
must be generated with the same check level as that
specified in the named configuration
file. Also, map format files are
loaded directly into memory via memory mapping, with only
minimal checking.
This statement sets the masterfile-format for all zones, but can be overridden on a per-zone or per-view basis by including a masterfile-format statement within the zone or view block in the configuration file.
This specifies the formatting of zone files during dump,
when the masterfile-format is
text. This option is ignored
with any other masterfile-format.
When set to relative,
records are printed in a multi-line format, with owner
names expressed relative to a shared origin. When set
to full, records are printed in
a single-line format with absolute owner names.
The full format is most suitable
when a zone file needs to be processed automatically
by a script. The relative format
is more human-readable, and is thus suitable when a
zone is to be edited by hand. The default is
relative.
This sets the maximum number of levels of recursion that are permitted at any one time while servicing a recursive query. Resolving a name may require looking up a name server address, which in turn requires resolving another name, etc.; if the number of recursions exceeds this value, the recursive query is terminated and returns SERVFAIL. The default is 7.
This sets the maximum number of iterative queries that may be sent while servicing a recursive query. If more queries are sent, the recursive query is terminated and returns SERVFAIL. The default is 100.
This sets the delay, in seconds, between sending sets of NOTIFY messages for a zone. The default is 5 seconds.
The overall rate at which NOTIFY messages are sent for all zones is controlled by serial-query-rate.
This sets the maximum RSA exponent size, in bits, that is accepted when validating. Valid values are 35 to 4096 bits. The default, zero, is also accepted and is equivalent to 4096.
When a query is received for cached data which is to expire shortly, named can refresh the data from the authoritative server immediately, ensuring that the cache always has an answer available.
prefetch specifies the
"trigger" TTL value at which prefetch of the current
query takes place; when a cache record with a
lower TTL value is encountered during query processing,
it is refreshed. Valid trigger TTL values are 1 to
10 seconds. Values larger than 10 seconds are silently
reduced to 10.
Setting a trigger TTL to zero causes
prefetch to be disabled.
The default trigger TTL is 2.
An optional second argument specifies the "eligibility"
TTL: the smallest original
TTL value that is accepted for a record to be
eligible for prefetching. The eligibility TTL must
be at least six seconds longer than the trigger TTL;
if not, named silently
adjusts it upward.
The default eligibility TTL is 9.
When determining the next name server to try,
this indicates by how many milliseconds to prefer IPv6 name servers.
The default is 50 milliseconds.
The server provides some helpful diagnostic information
through a number of built-in zones under the
pseudo-top-level-domain bind in the
CHAOS class. These zones are part
of a
built-in view (see the section called “view Statement Grammar”) of
class
CHAOS, which is separate from the
default view of class IN. Most global
configuration options (allow-query,
etc.) apply to this view, but some are locally
overridden: notify,
recursion, and
allow-new-zones are
always set to no, and
rate-limit is set to allow
three responses per second.
To disable these zones, use the options below or hide the built-in CHAOS view by defining an explicit view of class CHAOS that matches all clients.
This is the version the server should report
via a query of the name version.bind
with type TXT and class CHAOS.
The default is the real version number of this server.
Specifying version none
disables processing of the queries.
Setting version to any value
(including none) also
disables queries for authors.bind TXT CH.
This is the hostname the server should report via a query of
the name hostname.bind
with type TXT and class CHAOS.
This defaults to the hostname of the machine hosting the
name server, as
found by the gethostname() function. The primary purpose of such queries
is to
identify which of a group of anycast servers is actually
answering the queries. Specifying hostname none;
disables processing of the queries.
This is the ID the server should report when receiving a Name
Server Identifier (NSID) query, or a query of the name
ID.SERVER with type
TXT and class CHAOS.
The primary purpose of such queries is to
identify which of a group of anycast servers is actually
answering the queries. Specifying server-id none;
disables processing of the queries.
Specifying server-id hostname; causes named to
use the hostname as found by the gethostname() function.
The default server-id is none.
The named server has some built-in empty zones, for SOA and NS records only. These are for zones that should normally be answered locally and which queries should not be sent to the Internet's root servers. The official servers which cover these namespaces return NXDOMAIN responses to these queries. In particular, these cover the reverse namespaces for addresses from RFC 1918, RFC 4193, RFC 5737, and RFC 6598. They also include the reverse namespace for the IPv6 local address (locally assigned), IPv6 link local addresses, the IPv6 loopback address, and the IPv6 unknown address.
The server attempts to determine if a built-in zone already exists or is active (covered by a forward-only forwarding declaration) and does not create an empty zone if either is true.
The current list of empty zones is:
Empty zones can be set at the view level and only apply to views of class IN. Disabled empty zones are only inherited from options if there are no disabled empty zones specified at the view level. To override the options list of disabled zones, disable the root zone at the view level. For example:
disable-empty-zone ".";
If using the address ranges covered here, reverse zones covering the addresses should already be in place. In practice this appears to not be the case, with many queries being made to the infrastructure servers for names in these spaces. So many, in fact, that sacrificial servers had to be deployed to channel the query load away from the infrastructure servers.
The real parent servers for these zones should disable all empty zones under the parent zone they serve. For the real root servers, this is all built-in empty zones. This enables them to return referrals to deeper in the tree.
This specifies the server name that appears in the returned SOA record for empty zones. If none is specified, the zone's name is used.
This specifies the contact name that appears in the returned SOA record for empty zones. If none is specified, "." is used.
This enables or disables all empty zones. By default, they are enabled.
This disables individual empty zones. By default, none are disabled. This option can be specified multiple times.
The additional section cache, also called acache, is an internal cache to improve the response performance of BIND 9. When additional section caching is enabled, BIND 9 caches an internal shortcut to the additional section content for each answer RR. Note that acache is an internal caching mechanism of BIND 9, and is not related to the DNS caching server function.
Additional section caching does not change the response content (except the RRsets ordering of the additional section; see below), but can improve the response performance significantly. It is particularly effective when BIND 9 acts as an authoritative server for a zone that has many delegations with many glue RRs.
To obtain the maximum performance improvement from additional section caching, setting additional-from-cache to no is recommended, since the current implementation of acache does not shortcut additional section information from the DNS cache data.
One obvious disadvantage of acache is that it requires much more memory for the internal cached data. Thus, if the response performance does not matter and memory consumption is more critical, the acache mechanism can be disabled by setting acache-enable to no. It is also possible to specify the upper limit of memory consumption for acache by using max-acache-size.
Additional section caching also has a minor effect on the RRset ordering in the additional section. Without acache, cyclic order is effective for the additional section as well as for the answer and authority sections. However, additional section caching fixes the ordering when it first caches an RRset for the additional section, and the same ordering is kept in succeeding responses, regardless of the setting of rrset-order. The effect of this should be minor, however, since an RRset in the additional section typically only contains a small number of RRs (and in many cases only a single RR), so the ordering is not significant.
The following is a summary of options related to acache.
If yes, additional section caching is enabled. The default value is no.
The server removes stale cache entries, based on an LRU-based algorithm, every acache-cleaning-interval minutes. The default is 60 minutes. If set to 0, no periodic cleaning occurs.
This is the maximum amount of memory, in bytes, to use for the server's acache.
When the amount of data in the acache reaches this limit,
the server
cleans more aggressively so that the limit is not
exceeded.
In a server with multiple views, the limit applies
separately to the
acache of each view.
The default is 16M.
BIND 9 provides the ability to filter
out responses from external DNS servers containing
certain types of data in the answer section.
Specifically, it can reject address (A or AAAA) records if
the corresponding IPv4 or IPv6 addresses match the given
address_match_list of the
deny-answer-addresses option.
It can also reject CNAME or DNAME records if the "alias"
name (i.e., the CNAME alias or the substituted query name
due to DNAME) matches the
given namelist of the
deny-answer-aliases option, where
"match" means the alias name is a subdomain of one of
the name_list elements.
If the optional namelist is specified
with except-from, records whose query name
matches the list are accepted regardless of the filter
setting.
Likewise, if the alias name is a subdomain of the
corresponding zone, the deny-answer-aliases
filter does not apply;
for example, even if "example.com" is specified for
deny-answer-aliases,
www.example.com. CNAME xxx.example.com.
returned by an "example.com" server is accepted.
In the address_match_list of the
deny-answer-addresses option, only
ip_addr
and ip_prefix
are meaningful;
any key_id is silently ignored.
If a response message is rejected due to the filtering, the entire message is discarded without being cached, and a SERVFAIL error is returned to the client.
This filtering is intended to prevent "DNS rebinding attacks," in which an attacker, in response to a query for a domain name the attacker controls, returns an IP address within the user's own network or an alias name within the user's own domain. A naive web browser or script could then serve as an unintended proxy, allowing the attacker to get access to an internal node of the local network that could not be externally accessed otherwise. See the paper available at https://dl.acm.org/doi/10.1145/1315245.1315298 for more details about these attacks.
For example, with a domain named "example.net" and an internal network using an IPv4 prefix 192.0.2.0/24, an administrator might specify the following rules:
deny-answer-addresses { 192.0.2.0/24; } except-from { "example.net"; };
deny-answer-aliases { "example.net"; };
If an external attacker let a web browser in the local network look up an IPv4 address of "attacker.example.com", the attacker's DNS server would return a response like this:
attacker.example.com. A 192.0.2.1
in the answer section. Since the rdata of this record (the IPv4 address) matches the specified prefix 192.0.2.0/24, this response would be ignored.
On the other hand, if the browser looked up a legitimate internal web server "www.example.net" and the following response were returned to the BIND 9 server:
www.example.net. A 192.0.2.2
it would be accepted, since the owner name "www.example.net" matches the except-from element, "example.net".
Note that this is not really an attack on the DNS per se. In fact, there is nothing wrong with having an "external" name mapped to an "internal" IP address or domain name from the DNS point of view; it might actually be provided for a legitimate purpose, such as for debugging. As long as the mapping is provided by the correct owner, it either is not possible or does not make sense to detect whether the intent of the mapping is legitimate within the DNS. The "rebinding" attack must primarily be protected at the application that uses the DNS. For a large site, however, it may be difficult to protect all possible applications at once. This filtering feature is provided only to help such an operational environment; turning it on is generally discouraged unless there is no other choice and the attack is a real threat to applications.
Care should be particularly taken if using this option for addresses within 127.0.0.0/8. These addresses are obviously "internal," but many applications conventionally rely on a DNS mapping from some name to such an address. Filtering out DNS records containing this address spuriously can break such applications.
BIND 9 includes a limited mechanism to modify DNS responses for requests analogous to email anti-spam DNS rejection lists. Responses can be changed to deny the existence of domains (NXDOMAIN), deny the existence of IP addresses for domains (NODATA), or contain other IP addresses or data.
Response policy zones are named in the response-policy option for the view or among the global options if there is no response-policy option for the view. Response policy zones are ordinary DNS zones containing RRsets that can be queried normally if allowed. It is usually best to restrict those queries with something like allow-query { localhost; };. Note that zones using masterfile-format map cannot be used as policy zones.
A response-policy option can support multiple policy zones. To maximize performance, a radix tree is used to quickly identify response policy zones containing triggers that match the current query. This imposes an upper limit of 32 on the number of policy zones in a single response-policy option; more than that is a configuration error.
Rules encoded in response policy zones are processed after those defined in Access Control Lists (ACLs). All queries from clients which are not permitted access to the resolver are answered with a status code of REFUSED, regardless of configured RPZ rules.
Five policy triggers can be encoded in RPZ records.
IP records are triggered by the IP address of the
DNS client.
Client IP address triggers are encoded in records that have
owner names that are subdomains of
rpz-client-ip, relativized to the
policy zone origin name,
and encode an address or address block.
IPv4 addresses are represented as
prefixlength.B4.B3.B2.B1.rpz-client-ip.
The IPv4 prefix length must be between 1 and 32.
All four bytes - B4, B3, B2, and B1 - must be present.
B4 is the decimal value of the least significant byte of the
IPv4 address as in IN-ADDR.ARPA.
IPv6 addresses are encoded in a format similar
to the standard IPv6 text representation,
prefixlength.W8.W7.W6.W5.W4.W3.W2.W1.rpz-client-ip.
Each of W8,...,W1 is a one- to four-digit hexadecimal number
representing 16 bits of the IPv6 address as in the standard
text representation of IPv6 addresses, but reversed as in
IP6.ARPA. (Note that this representation of IPv6
address is different from IP6.ARPA where each hex
digit occupies a label.)
All 8 words must be present except when one set of consecutive
zero words is replaced with .zz.,
analogous to double colons (::) in standard IPv6 text
encodings.
The IPv6 prefix length must be between 1 and 128.
QNAME policy records are triggered by query names of requests and targets of CNAME records resolved to generate the response. The owner name of a QNAME policy record is the query name relativized to the policy zone.
IP triggers are IP addresses in an A or AAAA record in the ANSWER section of a response. They are encoded like client-IP triggers, except as subdomains of rpz-ip.
NSDNAME triggers match names of authoritative servers for the query name, a parent of the query name, a CNAME for the query name, or a parent of a CNAME. They are encoded as subdomains of rpz-nsdname, relativized to the RPZ origin name. NSIP triggers match IP addresses in A and AAAA RRsets for domains that can be checked against NSDNAME policy records. The nsdname-enable phrase turns NSDNAME triggers off or on for a single policy zone or for all zones.
If authoritative nameservers for the query name are not
yet known, named recursively
looks up the authoritative servers for the query name
before applying an RPZ-NSDNAME rule,
which can cause a processing delay. To speed up
processing at the cost of precision, the
nsdname-wait-recurse option
can be used; when set to no,
RPZ-NSDNAME rules are only applied when authoritative
servers for the query name have already been looked up and
cached. If authoritative servers for the query name
are not in the cache, the RPZ-NSDNAME rule is
ignored, but the authoritative servers for the query name
are looked up in the background and the rule is
applied to subsequent queries. The default is
yes, meaning RPZ-NSDNAME
rules are always applied, even if authoritative
servers for the query name need to be looked up first.
NSIP triggers match the IP addresses of authoritative servers. They are enncoded like IP triggers, except as subdomains of rpz-nsip. NSDNAME and NSIP triggers are checked only for names with at least min-ns-dots dots. The default value of min-ns-dots is 1, to exclude top-level domains.
If a name server's IP address is not yet known,
named recursively looks up
the IP address before applying an RPZ-NSIP rule,
which can cause a processing delay. To speed up
processing at the cost of precision, the
nsip-wait-recurse option
can be used: when set to no,
RPZ-NSIP rules are only applied when a name
server's IP address has already been looked up and
cached. If a server's IP address is not in the
cache, the RPZ-NSIP rule is ignored,
but the address is looked up in the
background and the rule is applied
to subsequent queries. The default is
yes, meaning RPZ-NSIP
rules are always applied, even if an
address needs to be looked up first.
The query response is checked against all response policy zones, so two or more policy records can be triggered by a response. Because DNS responses are rewritten according to at most one policy record, a single record encoding an action (other than DISABLED actions) must be chosen. Triggers, or the records that encode them, are chosen for rewriting in the following order:
When the processing of a response is restarted to resolve DNAME or CNAME records and a policy record set has not been triggered, all response policy zones are again consulted for the DNAME or CNAME names and addresses.
RPZ record sets are any types of DNS record, except DNAME or DNSSEC, that encode actions or responses to individual queries. Any of the policies can be used with any of the triggers. For example, while the TCP-only policy is commonly used with client-IP triggers, it can be used with any type of trigger to force the use of TCP for responses with owner names in a zone.
The auto-acceptance policy is specified by a CNAME whose target is rpz-passthru. It causes the response to not be rewritten and is most often used to "poke holes" in policies for CIDR blocks.
The auto-rejection policy is specified by a CNAME whose target is rpz-drop. It causes the response to be discarded. Nothing is sent to the DNS client.
The "slip" policy is specified by a CNAME whose target is rpz-tcp-only. It changes UDP responses to short, truncated DNS responses that require the DNS client to try again with TCP. It is used to mitigate distributed DNS reflection attacks.
The "domain undefined" response is encoded by a CNAME whose target is the root domain (.)
The empty set of resource records is specified by a
CNAME whose target is the wildcard top-level
domain (*.).
It rewrites the response to NODATA or ANCOUNT=0.
A set of ordinary DNS records can be used to answer queries. Queries for record types not the set are answered with NODATA.
A special form of local data is a CNAME whose target is a wildcard such as *.example.com. It is used as if an ordinary CNAME after the asterisk (*) has been replaced with the query name. This special form is useful for query logging in the walled garden's authoritative DNS server.
All of the actions specified in all of the individual records in a policy zone can be overridden with a policy clause in the response-policy option. An organization using a policy zone provided by another organization might use this mechanism to redirect domains to its own walled garden.
The placeholder policy says "do not override but perform the action specified in the zone."
The testing override policy causes policy zone records to do nothing but log what they would have done if the policy zone were not disabled. The response to the DNS query is written (or not) according to any triggered policy records that are not disabled. Disabled policy zones should appear first, because they are often not logged if a higher-precedence trigger is found first.
each override the corresponding per-record policy.
causes all RPZ policy records to act as if they were "cname domain" records.
By default, the actions encoded in a response policy zone are applied only to queries that ask for recursion (RD=1). That default can be changed for a single policy zone, or for all response policy zones in a view, with a recursive-only no clause. This feature is useful for serving the same zone files both inside and outside an RFC 1918 cloud and using RPZ to delete answers that would otherwise contain RFC 1918 values on the externally visible name server or view.
Also by default, RPZ actions are applied only to DNS requests that either do not request DNSSEC metadata (DO=0) or when no DNSSEC records are available for the requested name in the original zone (not the response policy zone). This default can be changed for all response policy zones in a view with a break-dnssec yes clause. In that case, RPZ actions are applied regardless of DNSSEC. The name of the clause option reflects the fact that results rewritten by RPZ actions cannot verify.
No DNS records are needed for a QNAME or Client-IP trigger; the name or IP address itself is sufficient, so in principle the query name need not be recursively resolved. However, not resolving the requested name can leak the fact that response policy rewriting is in use, and that the name is listed in a policy zone, to operators of servers for listed names. To prevent that information leak, by default any recursion needed for a request is done before any policy triggers are considered. Because listed domains often have slow authoritative servers, this behavior can cost significant time. The qname-wait-recurse no option overrides that default behavior when recursion cannot change a non-error response. The option does not affect QNAME or client-IP triggers in policy zones listed after other zones containing IP, NSIP, and NSDNAME triggers, because those may depend on the A, AAAA, and NS records that would be found during recursive resolution. It also does not affect DNSSEC requests (DO=1) unless break-dnssec yes is in use, because the response would depend on whether RRSIG records were found during resolution. Using this option can cause error responses such as SERVFAIL to appear to be rewritten, since no recursion is being done to discover problems at the authoritative server.
The TTL of a record modified by RPZ policies is set from the TTL of the relevant record in the policy zone. It is then limited to a maximum value. The max-policy-ttl clause changes the maximum number of seconds from its default of 5.
For example, an administrator might use this option statement:
response-policy { zone "badlist"; };
and this zone statement:
zone "badlist" {type master; file "master/badlist"; allow-query {none;}; };
with this zone file:
$TTL 1H
@ SOA LOCALHOST. named-mgr.example.com (1 1h 15m 30d 2h)
NS LOCALHOST.
; QNAME policy records. There are no periods (.) after the owner names.
nxdomain.domain.com CNAME . ; NXDOMAIN policy
*.nxdomain.domain.com CNAME . ; NXDOMAIN policy
nodata.domain.com CNAME *. ; NODATA policy
*.nodata.domain.com CNAME *. ; NODATA policy
bad.domain.com A 10.0.0.1 ; redirect to a walled garden
AAAA 2001:2::1
bzone.domain.com CNAME garden.example.com.
; do not rewrite (PASSTHRU) OK.DOMAIN.COM
ok.domain.com CNAME rpz-passthru.
; redirect x.bzone.domain.com to x.bzone.domain.com.garden.example.com
*.bzone.domain.com CNAME *.garden.example.com.
; IP policy records that rewrite all responses containing A records in 127/8
; except 127.0.0.1
8.0.0.0.127.rpz-ip CNAME .
32.1.0.0.127.rpz-ip CNAME rpz-passthru.
; NSDNAME and NSIP policy records
ns.domain.com.rpz-nsdname CNAME .
48.zz.2.2001.rpz-nsip CNAME .
; auto-reject and auto-accept some DNS clients
112.zz.2001.rpz-client-ip CNAME rpz-drop.
8.0.0.0.127.rpz-client-ip CNAME rpz-drop.
; force some DNS clients and responses in the example.com zone to TCP
16.0.0.1.10.rpz-client-ip CNAME rpz-tcp-only.
example.com CNAME rpz-tcp-only.
*.example.com CNAME rpz-tcp-only.
RPZ can affect server performance. Each configured response policy zone requires the server to perform one to four additional database lookups before a query can be answered. For example, a DNS server with four policy zones, each with all four kinds of response triggers (QNAME, IP, NSIP, and NSDNAME), requires a total of 17 times as many database lookups as a similar DNS server with no response policy zones. A BIND 9 server with adequate memory and one response policy zone with QNAME and IP triggers might achieve a maximum queries-per-second (QPS) rate about 20% lower. A server with four response policy zones with QNAME and IP triggers might have a maximum QPS rate about 50% lower.
Responses rewritten by RPZ are counted in the RPZRewrites statistics.
The log clause can be used to optionally turn off rewrite logging for a particular response policy zone. By default, all rewrites are logged.
Excessive, almost identical UDP responses can be controlled by configuring a rate-limit clause in an options or view statement. This mechanism keeps authoritative BIND 9 from being used to amplify reflection denial of service (DoS) attacks. Short, truncated (TC=1) responses can be sent to provide rate-limited responses to legitimate clients within a range of forged, attacked IP addresses. Legitimate clients react to dropped or truncated responses by retrying with UDP or with TCP, respectively.
This mechanism is intended for authoritative DNS servers. It can be used on recursive servers, but can slow applications such as SMTP servers (mail receivers) and HTTP clients (web browsers) that repeatedly request the same domains. When possible, closing "open" recursive servers is better.
Response rate limiting uses a "credit" or "token bucket" scheme. Each combination of identical response and client has a conceptual "account" that earns a specified number of credits every second. A prospective response debits its account by one. Responses are dropped or truncated while the account is negative. Responses are tracked within a rolling window of time which defaults to 15 seconds, but which can be configured with the window option to any value from 1 to 3600 seconds (1 hour). The account cannot become more positive than the per-second limit or more negative than window times the per-second limit. When the specified number of credits for a class of responses is set to 0, those responses are not rate-limited.
The notions of "identical response" and "DNS client" for rate limiting are not simplistic. All responses to an address block are counted as if to a single client. The prefix lengths of address blocks are specified with ipv4-prefix-length (default 24) and ipv6-prefix-length (default 56).
All non-empty responses for a valid domain name (qname) and record type (qtype) are identical and have a limit specified with responses-per-second (default 0 or no limit). All empty (NODATA) responses for a valid domain, regardless of query type, are identical. Responses in the NODATA class are limited by nodata-per-second (default responses-per-second). Requests for any and all undefined subdomains of a given valid domain result in NXDOMAIN errors, and are identical regardless of query type. They are limited by nxdomains-per-second (default responses-per-second). This controls some attacks using random names, but can be relaxed or turned off (set to 0) on servers that expect many legitimate NXDOMAIN responses, such as from anti-spam rejection lists. Referrals or delegations to the server of a given domain are identical and are limited by referrals-per-second (default responses-per-second).
Responses generated from local wildcards are counted and limited as if they were for the parent domain name. This controls flooding using random.wild.example.com.
All requests that result in DNS errors other than NXDOMAIN, such as SERVFAIL and FORMERR, are identical regardless of requested name (qname) or record type (qtype). This controls attacks using invalid requests or distant, broken authoritative servers. By default the limit on errors is the same as the responses-per-second value, but it can be set separately with errors-per-second.
Many attacks using DNS involve UDP requests with forged source addresses. Rate limiting prevents the use of BIND 9 to flood a network with responses to requests with forged source addresses, but could let a third party block responses to legitimate requests. There is a mechanism that can answer some legitimate requests from a client whose address is being forged in a flood. Setting slip to 2 (its default) causes every other UDP request to be answered with a small truncated (TC=1) response. The small size and reduced frequency, and resulting lack of amplification, of "slipped" responses make them unattractive for reflection DoS attacks. slip must be between 0 and 10. A value of 0 does not "slip"; no truncated responses are sent due to rate limiting. Rather, all responses are dropped. A value of 1 causes every response to slip; values between 2 and 10 cause every nth response to slip. Some error responses, including REFUSED and SERVFAIL, cannot be replaced with truncated responses and are instead leaked at the slip rate.
(Note: dropped responses from an authoritative server may reduce the difficulty of a third party successfully forging a response to a recursive resolver. The best security against forged responses is for authoritative operators to sign their zones using DNSSEC and for resolver operators to validate the responses. When this is not an option, operators who are more concerned with response integrity than with flood mitigation may consider setting slip to 1, causing all rate-limited responses to be truncated rather than dropped. This reduces the effectiveness of rate-limiting against reflection attacks.)
When the approximate query-per-second rate exceeds the qps-scale value, the responses-per-second, errors-per-second, nxdomains-per-second, and all-per-second values are reduced by the ratio of the current rate to the qps-scale value. This feature can tighten defenses during attacks. For example, with qps-scale 250; responses-per-second 20; and a total query rate of 1000 queries/second for all queries from all DNS clients including via TCP, then the effective responses/second limit changes to (250/1000)*20, or 5. Responses sent via TCP are not limited but are counted to compute the query-per-second rate.
Communities of DNS clients can be given their own parameters or no rate limiting by putting rate-limit statements in view statements instead of in the global option statement. A rate-limit statement in a view replaces, rather than supplements, a rate-limit statement among the main options. DNS clients within a view can be exempted from rate limits with the exempt-clients clause.
UDP responses of all kinds can be limited with the all-per-second phrase. This rate limiting is unlike the rate limiting provided by responses-per-second, errors-per-second, and nxdomains-per-second on a DNS server, which are often invisible to the victim of a DNS reflection attack. Unless the forged requests of the attack are the same as the legitimate requests of the victim, the victim's requests are not affected. Responses affected by an all-per-second limit are always dropped; the slip value has no effect. An all-per-second limit should be at least 4 times as large as the other limits, because single DNS clients often send bursts of legitimate requests. For example, the receipt of a single mail message can prompt requests from an SMTP server for NS, PTR, A, and AAAA records as the incoming SMTP/TCP/IP connection is considered. The SMTP server can need additional NS, A, AAAA, MX, TXT, and SPF records as it considers the SMTP Mail From command. Web browsers often repeatedly resolve the same names that are duplicated in HTML <IMG> tags in a page. all-per-second is similar to the rate limiting offered by firewalls but is often inferior. Attacks that justify ignoring the contents of DNS responses are likely to be attacks on the DNS server itself. They usually should be discarded before the DNS server spends resources make TCP connections or parsing DNS requests, but that rate limiting must be done before the DNS server sees the requests.
The maximum size of the table used to track requests and rate-limit responses is set with max-table-size. Each entry in the table is between 40 and 80 bytes. The table needs approximately as many entries as the number of requests received per second. The default is 20,000. To reduce the cold start of growing the table, min-table-size (default 500) can set the minimum table size. Enable rate-limit category logging to monitor expansions of the table and inform choices for the initial and maximum table size.
Use log-only yes to test rate-limiting parameters without actually dropping any requests.
Responses dropped by rate limits are included in the RateDropped and QryDropped statistics. Responses that truncated by rate limits are included in RateSlipped and RespTruncated.
named supports NXDOMAIN redirection via two methods:
With either method, when named gets an NXDOMAIN response it examines a separate namespace to see if the NXDOMAIN response should be replaced with an alternative response.
With a redirect zone (zone "." { type redirect; };), the data used to replace the NXDOMAIN is held in a single zone which is not part of the normal namespace. All the redirect information is contained in the zone; there are no delegations.
With a redirect namespace (option { nxdomain-redirect <suffix> };), the data used to replace the NXDOMAIN is part of the normal namespace and is looked up by appending the specified suffix to the original query name. This roughly doubles the cache required to process NXDOMAIN responses, as both the original NXDOMAIN response and the replacement data (or a NXDOMAIN indicating that there is no replacement) must be stored.
If both a redirect zone and a redirect namespace are configured, the redirect zone is tried first.
servernetprefix{ bogusboolean; ednsboolean; edns-udp-sizeinteger; edns-versioninteger; keysserver_key; max-udp-sizeinteger; notify-source (ipv4_address| * ) [ port (integer| * ) ] [ dscpinteger]; notify-source-v6 (ipv6_address| * ) [ port (integer| * ) ] [ dscpinteger]; provide-ixfrboolean; query-source ( ( [ address ] (ipv4_address| * ) [ port (integer| * ) ] ) | ( [ [ address ] (ipv4_address| * ) ] port (integer| * ) ) ) [ dscpinteger]; query-source-v6 ( ( [ address ] (ipv6_address| * ) [ port (integer| * ) ] ) | ( [ [ address ] (ipv6_address| * ) ] port (integer| * ) ) ) [ dscpinteger]; request-expireboolean; request-ixfrboolean; request-nsidboolean; send-cookieboolean; tcp-onlyboolean; transfer-format ( many-answers | one-answer ); transfer-source (ipv4_address| * ) [ port (integer| * ) ] [ dscpinteger]; transfer-source-v6 (ipv6_address| * ) [ port (integer| * ) ] [ dscpinteger]; transfersinteger; };
The server statement defines
characteristics
to be associated with a remote name server. If a prefix length is
specified, then a range of servers is covered. Only the most
specific
server clause applies, regardless of the order in
named.conf.
The server statement can occur at the top level of the configuration file or inside a view statement. If a view statement contains one or more server statements, only those apply to the view and any top-level ones are ignored. If a view contains no server statements, any top-level server statements are used as defaults.
If a remote server is giving out bad data, marking it as bogus prevents further queries to it. The default value of bogus is no.
The provide-ixfr clause determines whether the local server, acting as primary, responds with an incremental zone transfer when the given remote server, a secondary, requests it. If set to yes, incremental transfer is provided whenever possible. If set to no, all transfers to the remote server are non-incremental. If not set, the value of the provide-ixfr option in the view or global options block is used as a default.
The request-ixfr clause determines whether the local server, acting as a secondary, requests incremental zone transfers from the given remote server, a primary. If not set, the value of the request-ixfr option in the view or global options block is used as a default. It may also be set in the zone block; if set there, it overrides the global or view setting for that zone.
IXFR requests to servers that do not support IXFR automatically fall back to AXFR. Therefore, there is no need to manually list which servers support IXFR and which ones do not; the global default of yes should always work. The purpose of the provide-ixfr and request-ixfr clauses is to make it possible to disable the use of IXFR even when both primary and secondary claim to support it: for example, if one of the servers is buggy and crashes or corrupts data when IXFR is used.
The request-expire clause determines whether the local server, when acting as a secondary, requests the EDNS EXPIRE value. The EDNS EXPIRE value indicates the remaining time before the zone data expires and needs to be refreshed. This is used when a secondary server transfers a zone from another secondary server; when transferring from the primary, the expiration timer is set from the EXPIRE field of the SOA record instead. The default is yes.
The edns clause determines whether the local server attempts to use EDNS when communicating with the remote server. The default is yes.
The edns-udp-size option sets the EDNS UDP size that is advertised by named when querying the remote server. Valid values are 512 to 4096 bytes; values outside this range are silently adjusted to the nearest value within it. This option is useful when advertising a different value to this server than the value advertised globally: for example, when there is a firewall at the remote site that is blocking large replies. Note: currently, this sets a single UDP size for all packets sent to the server; named does not deviate from this value. This differs from the behavior of edns-udp-size in options or view statements, where it specifies a maximum value. The server statement behavior may be brought into conformance with the options/view behavior in future releases.
The edns-version option sets the maximum EDNS VERSION that is sent to the server(s) by the resolver. The actual EDNS version sent is still subject to normal EDNS version-negotiation rules (see RFC 6891), the maximum EDNS version supported by the server, and any other heuristics that indicate that a lower version should be sent. This option is intended to be used when a remote server reacts badly to a given EDNS version or higher; it should be set to the highest version the remote server is known to support. Valid values are 0 to 255; higher values are silently adjusted. This option is not needed until higher EDNS versions than 0 are in use.
The max-udp-size option sets the maximum EDNS UDP message size named sends. Valid values are 512 to 4096 bytes; values outside this range are silently adjusted. This option is useful when there is a firewall that is blocking large replies from named.
The tcp-only option sets the transport protocol to TCP. The default is to use the UDP transport and to fallback on TCP only when a truncated response is received.
The server supports two zone transfer methods. The first, one-answer, uses one DNS message per resource record transferred. many-answers packs as many resource records as possible into a single message, which is more efficient. It is possible to specify which method to use for a server via the transfer-format option; If not set there, the transfer-format specified by the options statement is used.
transfers is used to limit the number of concurrent inbound zone transfers from the specified server. If no transfers clause is specified, the limit is set according to the transfers-per-ns option.
The keys clause identifies a key_id defined by the key statement, to be used for transaction security (TSIG, the section called “TSIG”) when talking to the remote server. When a request is sent to the remote server, a request signature is generated using the key specified here and appended to the message. A request originating from the remote server is not required to be signed by this key.
Only a single key per server is currently supported.
The transfer-source and transfer-source-v6 clauses specify the IPv4 and IPv6 source address, respectively, to be used for zone transfer with the remote server. For an IPv4 remote server, only transfer-source can be specified. Similarly, for an IPv6 remote server, only transfer-source-v6 can be specified. For more details, see the description of transfer-source and transfer-source-v6 in the section called “Zone Transfers”.
The notify-source and notify-source-v6 clauses specify the IPv4 and IPv6 source address, respectively, to be used for notify messages sent to remote servers. For an IPv4 remote server, only notify-source can be specified. Similarly, for an IPv6 remote server, only notify-source-v6 can be specified.
The query-source and query-source-v6 clauses specify the IPv4 and IPv6 source address, respectively, to be used for queries sent to remote servers. For an IPv4 remote server, only query-source can be specified. Similarly, for an IPv6 remote server, only query-source-v6 can be specified.
The request-nsid clause determines whether the local server adds an NSID EDNS option to requests sent to the server. This overrides request-nsid set at the view or option level.
The send-cookie clause determines whether the local server adds a COOKIE EDNS option to requests sent to the server. This overrides send-cookie set at the view or option level. The named server may determine that COOKIE is not supported by the remote server and not add a COOKIE EDNS option to requests.
statistics-channels { inet (ipv4_address|ipv6_address| * ) [ port (integer| * ) ] [ allow {address_match_element; ... } ]; };
The statistics-channels statement declares communication channels to be used by system administrators to get access to statistics information on the name server.
This statement is intended to be flexible to support multiple communication protocols in the future, but currently only HTTP access is supported. It requires that BIND 9 be compiled with libxml2 and/or json-c (also known as libjson0); the statistics-channels statement is still accepted even if it is built without the library, but any HTTP access fails with an error.
An inet control channel is a TCP socket
listening at the specified ip_port on the
specified ip_addr, which can be an IPv4 or IPv6
address. An ip_addr of *
(asterisk) is
interpreted as the IPv4 wildcard address; connections are
accepted on any of the system's IPv4 addresses.
To listen on the IPv6 wildcard address,
use an ip_addr of ::.
If no port is specified, port 80 is used for HTTP channels.
The asterisk (*) cannot be used for
ip_port.
Attempts to open a statistics channel are restricted by the optional allow clause. Connections to the statistics channel are permitted based on the address_match_list. If no allow clause is present, named accepts connection attempts from any address; since the statistics may contain sensitive internal information, it is highly recommended to restrict the source of connection requests appropriately.
If no statistics-channels statement is present, named does not open any communication channels.
The statistics are available in various formats and views, depending on the URI used to access them. For example, if the statistics channel is configured to listen on 127.0.0.1 port 8888, then the statistics are accessible in XML format at http://127.0.0.1:8888/ or http://127.0.0.1:8888/xml. A CSS file is included, which can format the XML statistics into tables when viewed with a stylesheet-capable browser, and into charts and graphs using the Google Charts API when using a JavaScript-capable browser.
Broken-out subsets of the statistics can be viewed at http://127.0.0.1:8888/xml/v3/status (server uptime and last reconfiguration time), http://127.0.0.1:8888/xml/v3/server (server and resolver statistics), http://127.0.0.1:8888/xml/v3/zones (zone statistics), http://127.0.0.1:8888/xml/v3/net (network status and socket statistics), http://127.0.0.1:8888/xml/v3/mem (memory manager statistics), http://127.0.0.1:8888/xml/v3/tasks (task manager statistics), and http://127.0.0.1:8888/xml/v3/traffic (traffic sizes).
The full set of statistics can also be read in JSON format at http://127.0.0.1:8888/json, with the broken-out subsets at http://127.0.0.1:8888/json/v1/status (server uptime and last reconfiguration time), http://127.0.0.1:8888/json/v1/server (server and resolver statistics), http://127.0.0.1:8888/json/v1/zones (zone statistics), http://127.0.0.1:8888/json/v1/net (network status and socket statistics), http://127.0.0.1:8888/json/v1/mem (memory manager statistics), http://127.0.0.1:8888/json/v1/tasks (task manager statistics), and http://127.0.0.1:8888/json/v1/traffic (traffic sizes).
The trusted-keys statement defines DNSSEC security roots. DNSSEC is described in the section called “DNSSEC”. A security root is defined when the public key for a non-authoritative zone is known, but cannot be securely obtained through DNS, either because it is the DNS root zone or because its parent zone is unsigned. Once a key has been configured as a trusted key, it is treated as if it has been validated and proven secure. The resolver attempts DNSSEC validation on all DNS data in subdomains of a security root.
All keys (and corresponding zones) listed in trusted-keys are deemed to exist regardless of what parent zones say. Similarly, for all keys listed in trusted-keys, only those keys are used to validate the DNSKEY RRset. The parent's DS RRset is not used.
The trusted-keys statement can contain multiple key entries, each consisting of the key's domain name, flags, protocol, and algorithm, and the Base64 representation of the key data. Spaces, tabs, newlines, and carriage returns are ignored in the key data, so the configuration may be split into multiple lines.
trusted-keys may be set at the top level
of named.conf or within a view. If it is
set in both places, they are additive; keys defined at the top
level are inherited by all views, but keys defined in a view
are only used within that view.
Validation below specified names can be temporarily disabled by using rndc nta.
managed-keys {stringstringintegerintegerintegerquoted_string; ... };
The managed-keys statement, like trusted-keys, defines DNSSEC security roots. The difference is that managed-keys can be kept up-to-date automatically, without intervention from the resolver operator.
Suppose, for example, that a zone's key-signing key was compromised, and the zone owner had to revoke and replace the key. A resolver which had the old key in a trusted-keys statement would be unable to validate this zone; it would reply with a SERVFAIL response code. This would continue until the resolver operator updated the trusted-keys statement with the new key.
If, however, the zone were listed in a managed-keys statement instead, the zone owner could add a "stand-by" key to the zone in advance. named would store the stand-by key, and when the original key was revoked, named would be able to transition smoothly to the new key. It would also recognize that the old key had been revoked and cease using that key to validate answers, minimizing the damage that the compromised key could do.
A managed-keys statement contains a list of
the keys to be managed, along with information about how the
keys are to be initialized for the first time. The only
initialization method currently supported is
initial-key.
This means the managed-keys statement must
contain a copy of the initializing key. (Future releases may
allow keys to be initialized by other methods, eliminating this
requirement.)
Consequently, a managed-keys statement
appears similar to a trusted-keys statement, differing
by the presence of the second field, which contains the keyword
initial-key. The difference is, whereas the
keys listed in a trusted-keys continue to be
trusted until they are removed from
named.conf, an initializing key listed
in a managed-keys statement is only trusted
once: for as long as it takes to load the
managed-key database and start the RFC 5011 key-maintenance
process.
The first time named runs with a managed key
configured in named.conf, it fetches the
DNSKEY RRset directly from the zone apex, and validates it
using the key specified in the managed-keys
statement. If the DNSKEY RRset is validly signed, then it is
used as the basis for a new managed-keys database.
From that point on, whenever named runs, it sees the managed-keys statement, checks to make sure RFC 5011 key maintenance has already been initialized for the specified domain, and if so, simply moves on. The key specified in the managed-keys statement is not used to validate answers; it is superseded by the key or keys stored in the managed-keys database.
The next time named runs after a name has been removed from the managed-keys statement, the corresponding zone is removed from the managed-keys database, and RFC 5011 key maintenance is no longer used for that domain.
In the current implementation, the managed-keys database is stored as a master-format zone file.
On servers which do not use views, this file is named
managed-keys.bind. When views are in
use, there is a separate managed-keys database for each
view; the filename is the view name (or, if a view name
contains characters which would make it illegal as a filename,
a hash of the view name), followed by
the suffix .mkeys.
When the key database is changed, the zone is updated.
As with any other dynamic zone, changes are written
into a journal file, e.g.,
managed-keys.bind.jnl or
internal.mkeys.jnl.
Changes are committed to the zone file as soon as
possible afterward, usually within 30
seconds. Whenever named is using
automatic key maintenance, the zone file and journal file
can be expected to exist in the working directory.
(For this reason, among others, the working directory
should be always be writable by named.)
If the dnssec-validation option is
set to auto, named
automatically initializes a managed key for the
root zone. The key that is used to initialize the
key-maintenance process is stored in bind.keys;
the location of this file can be overridden with the
bindkeys-file option. As a fallback
in the event no bind.keys can be
found, the initializing key is also compiled directly
into named.
viewview_name[class] { match-clients {address_match_list} ; match-destinations {address_match_list} ; match-recursive-onlyyes_or_no; [view_option; ... ] [zone_statement; ... ] } ;
The view statement is a powerful feature of BIND 9 that lets a name server answer a DNS query differently depending on who is asking. It is particularly useful for implementing split DNS setups without having to run multiple servers.
Each view statement defines a view
of the
DNS namespace that is seen by a subset of clients. A client
matches
a view if its source IP address matches the
address_match_list of the view's
match-clients clause and its
destination IP address matches
the address_match_list of the
view's
match-destinations clause. If not
specified, both
match-clients and match-destinations
default to matching all addresses. In addition to checking IP
addresses,
match-clients and match-destinations
can also take keys which provide an
mechanism for the
client to select the view. A view can also be specified
as match-recursive-only, which
means that only recursive
requests from matching clients match that view.
The order of the view statements is
significant;
a client request is resolved in the context of the first
view that it matches.
Zones defined within a view statement are only accessible to clients that match the view. By defining a zone of the same name in multiple views, different zone data can be given to different clients: for example, "internal" and "external" clients in a split DNS setup.
Many of the options given in the options statement can also be used within a view statement, and then apply only when resolving queries with that view. When no view-specific value is given, the value in the options statement is used as a default. Also, zone options can have default values specified in the view statement; these view-specific defaults take precedence over those in the options statement.
Views are class-specific. If no class is given, class IN is assumed. Note that all non-IN views must contain a hint zone, since only the IN class has compiled-in default hints.
If there are no view statements in the config file, a default view that matches any client is automatically created in class IN. Any zone statements specified on the top level of the configuration file are considered to be part of this default view, and the options statement applies to the default view. If any explicit view statements are present, all zone statements must occur inside view statements.
Here is an example of a typical split DNS setup implemented using view statements:
view "internal" {
// This should match our internal networks.
match-clients { 10.0.0.0/8; };
// Provide recursive service to internal
// clients only.
recursion yes;
// Provide a complete view of the example.com
// zone including addresses of internal hosts.
zone "example.com" {
type master;
file "example-internal.db";
};
};
view "external" {
// Match all clients not matched by the
// previous view.
match-clients { any; };
// Refuse recursive service to external clients.
recursion no;
// Provide a restricted view of the example.com
// zone containing only publicly accessible hosts.
zone "example.com" {
type master;
file "example-external.db";
};
};
zonestring[class] { type ( master | primary ); allow-query {address_match_element; ... }; allow-query-on {address_match_element; ... }; allow-transfer {address_match_element; ... }; allow-update {address_match_element; ... }; also-notify [ portinteger] [ dscpinteger] { (masters|ipv4_address[ portinteger] |ipv6_address[ portinteger] ) [ keystring]; ... }; alt-transfer-source (ipv4_address| * ) [ port (integer| * ) ] [ dscpinteger]; alt-transfer-source-v6 (ipv6_address| * ) [ port (integer| * ) ] [ dscpinteger]; auto-dnssec ( allow | maintain | off ); check-dup-records ( fail | warn | ignore ); check-integrityboolean; check-mx ( fail | warn | ignore ); check-mx-cname ( fail | warn | ignore ); check-names ( fail | warn | ignore ); check-siblingboolean; check-spf ( warn | ignore ); check-srv-cname ( fail | warn | ignore ); check-wildcardboolean; databasestring; dialup ( notify | notify-passive | passive | refresh |boolean); dlzstring; dnssec-dnskey-kskonlyboolean; dnssec-loadkeys-intervalinteger; dnssec-secure-to-insecureboolean; dnssec-update-mode ( maintain | no-resign ); filequoted_string; forward ( first | only ); forwarders [ portinteger] [ dscpinteger] { (ipv4_address|ipv6_address) [ portinteger] [ dscpinteger]; ... }; inline-signingboolean; ixfr-from-differencesboolean; journalquoted_string; key-directoryquoted_string; masterfile-format ( map | raw | text ); masterfile-style ( full | relative ); max-journal-size ( unlimited |sizeval); max-recordsinteger; max-transfer-idle-outinteger; max-transfer-time-outinteger; max-zone-ttl ( unlimited |ttlval); notify ( explicit | master-only |boolean); notify-delayinteger; notify-source (ipv4_address| * ) [ port (integer| * ) ] [ dscpinteger]; notify-source-v6 (ipv6_address| * ) [ port (integer| * ) ] [ dscpinteger]; notify-to-soaboolean; serial-update-method ( date | increment | unixtime ); sig-signing-nodesinteger; sig-signing-signaturesinteger; sig-signing-typeinteger; sig-validity-intervalinteger[integer]; update-check-kskboolean; update-policy ( local | { ( deny | grant )string( 6to4-self | external | krb5-self | krb5-selfsub | krb5-subdomain | ms-self | ms-selfsub | ms-subdomain | name | self | selfsub | selfwild | subdomain | tcp-self | wildcard | zonesub ) [string]rrtypelist; ... }; zero-no-soa-ttlboolean; zone-statistics ( full | terse | none |boolean); };
zonestring[class] { type ( slave | secondary ); allow-notify {address_match_element; ... }; allow-query {address_match_element; ... }; allow-query-on {address_match_element; ... }; allow-transfer {address_match_element; ... }; allow-update-forwarding {address_match_element; ... }; also-notify [ portinteger] [ dscpinteger] { (masters|ipv4_address[ portinteger] |ipv6_address[ portinteger] ) [ keystring]; ... }; alt-transfer-source (ipv4_address| * ) [ port (integer| * ) ] [ dscpinteger]; alt-transfer-source-v6 (ipv6_address| * ) [ port (integer| * ) ] [ dscpinteger]; auto-dnssec ( allow | maintain | off ); check-names ( fail | warn | ignore ); databasestring; dialup ( notify | notify-passive | passive | refresh |boolean); dlzstring; dnssec-dnskey-kskonlyboolean; dnssec-loadkeys-intervalinteger; dnssec-update-mode ( maintain | no-resign ); filequoted_string; forward ( first | only ); forwarders [ portinteger] [ dscpinteger] { (ipv4_address|ipv6_address) [ portinteger] [ dscpinteger]; ... }; inline-signingboolean; ixfr-from-differencesboolean; journalquoted_string; key-directoryquoted_string; masterfile-format ( map | raw | text ); masterfile-style ( full | relative ); masters [ portinteger] [ dscpinteger] { (masters|ipv4_address[ portinteger] |ipv6_address[ portinteger] ) [ keystring]; ... }; max-journal-size ( unlimited |sizeval); max-recordsinteger; max-refresh-timeinteger; max-retry-timeinteger; max-transfer-idle-ininteger; max-transfer-idle-outinteger; max-transfer-time-ininteger; max-transfer-time-outinteger; min-refresh-timeinteger; min-retry-timeinteger; multi-masterboolean; notify ( explicit | master-only |boolean); notify-delayinteger; notify-source (ipv4_address| * ) [ port (integer| * ) ] [ dscpinteger]; notify-source-v6 (ipv6_address| * ) [ port (integer| * ) ] [ dscpinteger]; notify-to-soaboolean; request-expireboolean; request-ixfrboolean; sig-signing-nodesinteger; sig-signing-signaturesinteger; sig-signing-typeinteger; sig-validity-intervalinteger[integer]; transfer-source (ipv4_address| * ) [ port (integer| * ) ] [ dscpinteger]; transfer-source-v6 (ipv6_address| * ) [ port (integer| * ) ] [ dscpinteger]; try-tcp-refreshboolean; update-check-kskboolean; use-alt-transfer-sourceboolean; zero-no-soa-ttlboolean; zone-statistics ( full | terse | none |boolean); };
zonestring[class] { type hint; check-names ( fail | warn | ignore ); delegation-onlyboolean; filequoted_string; };
zonestring[class] { type stub; allow-query {address_match_element; ... }; allow-query-on {address_match_element; ... }; check-names ( fail | warn | ignore ); databasestring; delegation-onlyboolean; dialup ( notify | notify-passive | passive | refresh |boolean); filequoted_string; forward ( first | only ); forwarders [ portinteger] [ dscpinteger] { (ipv4_address|ipv6_address) [ portinteger] [ dscpinteger]; ... }; masterfile-format ( map | raw | text ); masterfile-style ( full | relative ); masters [ portinteger] [ dscpinteger] { (masters|ipv4_address[ portinteger] |ipv6_address[ portinteger] ) [ keystring]; ... }; max-recordsinteger; max-refresh-timeinteger; max-retry-timeinteger; max-transfer-idle-ininteger; max-transfer-time-ininteger; min-refresh-timeinteger; min-retry-timeinteger; multi-masterboolean; transfer-source (ipv4_address| * ) [ port (integer| * ) ] [ dscpinteger]; transfer-source-v6 (ipv6_address| * ) [ port (integer| * ) ] [ dscpinteger]; use-alt-transfer-sourceboolean; zone-statistics ( full | terse | none |boolean); };
zonestring[class] { type static-stub; allow-query {address_match_element; ... }; allow-query-on {address_match_element; ... }; forward ( first | only ); forwarders [ portinteger] [ dscpinteger] { (ipv4_address|ipv6_address) [ portinteger] [ dscpinteger]; ... }; max-recordsinteger; server-addresses { (ipv4_address|ipv6_address); ... }; server-names {quoted_string; ... }; zone-statistics ( full | terse | none |boolean); };
zonestring[class] { type forward; delegation-onlyboolean; forward ( first | only ); forwarders [ portinteger] [ dscpinteger] { (ipv4_address|ipv6_address) [ portinteger] [ dscpinteger]; ... }; };
zonestring[class] { type redirect; allow-query {address_match_element; ... }; allow-query-on {address_match_element; ... }; dlzstring; filequoted_string; masterfile-format ( map | raw | text ); masterfile-style ( full | relative ); masters [ portinteger] [ dscpinteger] { (masters|ipv4_address[ portinteger] |ipv6_address[ portinteger] ) [ keystring]; ... }; max-recordsinteger; max-zone-ttl ( unlimited |ttlval); zone-statistics ( full | terse | none |boolean); };
zonestring[class] { type delegation-only; };
zonestring[class] { in-viewstring; };
The type keyword is required
for the zone configuration unless
it is an in-view configuration. Its
acceptable values are: master,
slave, hint,
stub, static-stub,
forward, redirect,
or delegation-only.
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The server has a master copy of the data for the zone and is able to provide authoritative answers for it. |
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A secondary zone, replicating a primary zone
provided by another authoritative server.
The masters list
specifies one or more IP addresses
of primary servers that the secondary contacts to update
its copy of the zone.
Masters list elements can also be names of other
masters lists.
By default, transfers are made from port 53 on the
servers; this can
be changed for all servers by specifying a port number
before the
list of IP addresses, or on a per-server basis after
the IP address.
Authentication to the primary can also be done with
per-server TSIG keys.
If a file is specified, then the
replica is written to this file whenever the zone
is changed,
and reloaded from this file on a server restart. Use
of a file is
recommended, since it often speeds server startup and
eliminates
a needless waste of bandwidth. Note that for large
numbers (in the
tens or hundreds of thousands) of zones per server, it
is best to
use a two-level naming scheme for zone filenames. For
example,
a secondary server for the zone |
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The initial set of root name servers is specified using a hint zone. When the server starts, it uses the root hints to find a root name server and get the most recent list of root name servers. If no hint zone is specified for class IN, the server uses a compiled-in default set of root servers hints. Classes other than IN have no built-in default hints. |
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A stub zone is similar to a secondary zone, except that it replicates only the NS records of a primary zone instead of the entire zone. Stub zones are not a standard part of the DNS; they are a feature specific to the BIND implementation.
Stub zones can be used to eliminate the need for a glue
NS record
in a parent zone, at the expense of maintaining a stub
zone entry and
a set of name server addresses in
Stub zones can also be used as a way to force the
resolution
of a given domain to use a particular set of
authoritative servers.
For example, the caching name servers on a private
network using
RFC 1918 addressing may be configured with stub zones
for
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A static-stub zone is similar to a stub zone with the following exceptions: the zone data is statically configured, rather than transferred from a primary server; and when recursion is necessary for a query that matches a static-stub zone, the locally configured data (name server names and glue addresses) is always used, even if different authoritative information is cached. Zone data is configured via the server-addresses and server-names zone options. The zone data is maintained in the form of NS and (if necessary) glue A or AAAA RRs internally, which can be seen by dumping zone databases by rndc dumpdb -all. The configured RRs are considered local configuration parameters rather than public data. Non-recursive queries (i.e., those with the RD bit off) to a static-stub zone are therefore prohibited and are responded to with REFUSED. Since the data is statically configured, no zone maintenance action takes place for a static-stub zone. For example, there is no periodic refresh attempt, and an incoming notify message will be rejected with an rcode of NOTAUTH. Each static-stub zone is configured with internally generated NS and (if necessary) glue A or AAAA RRs. |
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A forward zone is a way to configure forwarding on a per-domain basis. A zone statement of type forward can contain a forward and/or forwarders statement, which applies to queries within the domain given by the zone name. If no forwarders statement is present, or an empty list for forwarders is given, then no forwarding is done for the domain, canceling the effects of any forwarders in the options statement. Thus, to use this type of zone to change the behavior of the global forward option (that is, "forward first" to, then "forward only", or vice versa), but use the same servers as set globally, re-specify the global forwarders. |
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Redirect zones are used to provide answers to queries when normal resolution would result in NXDOMAIN being returned. Only one redirect zone is supported per view. allow-query can be used to restrict which clients see these answers. If the client has requested DNSSEC records (DO=1) and the NXDOMAIN response is signed, no substitution occurs.
To redirect all NXDOMAIN responses to
100.100.100.2 and
2001:ffff:ffff::100.100.100.2,
configure a type As another example, to redirect all Spanish names (under .ES), use similar entries but with the names "*.ES." instead of "*.". To redirect all commercial Spanish names (under COM.ES), use wildcard entries called "*.COM.ES.". Note that the redirect zone supports all possible types; it is not limited to A and AAAA records.
Because redirect zones are not referenced
directly by name, they are not kept in the
zone lookup table with normal primary and secondary
zones. Consequently, it is not currently possible
to use
rndc reload
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This zone type is used to enforce the delegation-only status of infrastructure zones (e.g., COM, NET, ORG). Any answer that is received without an explicit or implicit delegation in the authority section is treated as NXDOMAIN. This does not apply to the zone apex, and should not be applied to leaf zones.
See caveats in root-delegation-only. |
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When using multiple views, a primary or secondary zone
configured in one view can be referenced in a
subsequent view. This allows both views to serve the
same zone without the overhead of loading it more
than once. This is configured using a
See the section called “Multiple Views” for more information. |
The zone's name may optionally be followed by a class. If
a class is not specified, class IN (for Internet),
is assumed. This is correct for the vast majority of cases.
The hesiod class is
named for an information service from MIT's Project Athena. It was
used to share information about various systems databases, such
as users, groups, printers, and so on. The keyword
HS is
a synonym for hesiod.
Another MIT development is Chaosnet, a LAN protocol created
in the mid-1970s. Zone data for it can be specified with the CHAOS class.
See the description of allow-notify in the section called “Access Control”.
See the description of allow-query in the section called “Access Control”.
See the description of allow-query-on in the section called “Access Control”.
See the description of allow-transfer in the section called “Access Control”.
See the description of allow-update in the section called “Access Control”.
This specifies a "Simple Secure Update" policy. See the section called “Dynamic Update Policies”.
See the description of allow-update-forwarding in the section called “Access Control”.
This option is only meaningful if notify
is
active for this zone. The set of machines that
receive a
DNS NOTIFY message
for this zone is made up of all the listed name servers
(other than
the primary) for the zone, plus any IP addresses
specified
with also-notify. A port
may be specified
with each also-notify
address to send the notify
messages to a port other than the default of 53.
A TSIG key may also be specified to cause the
NOTIFY to be signed by the
given key.
also-notify is not
meaningful for stub zones.
The default is the empty list.
This option is used to restrict the character set and syntax of certain domain names in zone files and/or DNS responses received from the network. The default varies according to zone type. For primary zones the default is fail; for secondary zones the default is warn. It is not implemented for hint zones.
See the description of check-mx in the section called “Boolean Options”.
See the description of check-spf in the section called “Boolean Options”.
See the description of check-wildcard in the section called “Boolean Options”.
See the description of check-integrity in the section called “Boolean Options”.
See the description of check-sibling in the section called “Boolean Options”.
See the description of zero-no-soa-ttl in the section called “Boolean Options”.
See the description of update-check-ksk in the section called “Boolean Options”.
See the description of dnssec-loadkeys-interval in the section called “options Statement Definition and Usage”.
See the description of dnssec-update-mode in the section called “options Statement Definition and Usage”.
See the description of dnssec-dnskey-kskonly in the section called “Boolean Options”.
See the description of try-tcp-refresh in the section called “Boolean Options”.
This specifies the type of database to be used to store the zone data. The string following the database keyword is interpreted as a list of whitespace-delimited words. The first word identifies the database type, and any subsequent words are passed as arguments to the database to be interpreted in a way specific to the database type.
The default is "rbt", BIND 9's
native in-memory
red-black tree database. This database does not take
arguments.
Other values are possible if additional database drivers have been linked into the server. Some sample drivers are included with the distribution but none are linked in by default.
See the description of dialup in the section called “Boolean Options”.
This flag only applies to forward, hint, and stub
zones. If set to yes,
then the zone is treated as if it is
also a delegation-only type zone.
See caveats in root-delegation-only.
This sets the zone's filename. In master, hint, and redirect zones which do not have masters defined, zone data is loaded from this file. In slave, stub, and redirect zones which do have masters defined, zone data is retrieved from another server and saved in this file. This option is not applicable to other zone types.
This option is only meaningful if the zone has a forwarders list. The only value causes the lookup to fail after trying the forwarders and getting no answer, while first allows a normal lookup to be tried.
This is used to override the list of global forwarders. If it is not specified in a zone of type forward, no forwarding is done for the zone and the global options are not used.
This was used in BIND 8 to
specify the name
of the transaction log (journal) file for dynamic update
and IXFR.
BIND 9 ignores the option
and constructs the name of the journal
file by appending ".jnl"
to the name of the
zone file.
This was an undocumented option in BIND 8. It is ignored in BIND 9.
This allows the default journal's filename to be overridden.
The default is the zone's filename with ".jnl" appended.
This is applicable to primary (master)
and secondary (slave) zones.
See the description of max-journal-size in the section called “Server Resource Limits”.
See the description of max-records in the section called “Server Resource Limits”.
See the description of max-transfer-time-in in the section called “Zone Transfers”.
See the description of max-transfer-idle-in in the section called “Zone Transfers”.
See the description of max-transfer-time-out in the section called “Zone Transfers”.
See the description of max-transfer-idle-out in the section called “Zone Transfers”.
See the description of notify in the section called “Boolean Options”.
See the description of notify-delay in the section called “Tuning”.
See the description of notify-to-soa in the section called “Boolean Options”.
In BIND 8, this option was intended to specify a public zone key for verification of signatures in DNSSEC-signed zones when they were loaded from disk. BIND 9 does not verify signatures on load and ignores the option.
See the description of zone-statistics in the section called “options Statement Definition and Usage”.
This option is only meaningful for static-stub zones. This is a list of IP addresses to which queries should be sent in recursive resolution for the zone. A non-empty list for this option internally configures the apex NS RR with associated glue A or AAAA RRs.
For example, if "example.com" is configured as a static-stub zone with 192.0.2.1 and 2001:db8::1234 in a server-addresses option, the following RRs are internally configured:
example.com. NS example.com. example.com. A 192.0.2.1 example.com. AAAA 2001:db8::1234
These records are used internally to resolve names under the static-stub zone. For instance, if the server receives a query for "www.example.com" with the RD bit on, the server initiates recursive resolution and sends queries to 192.0.2.1 and/or 2001:db8::1234.
This option is only meaningful for static-stub zones. This is a list of domain names of name servers that act as authoritative servers of the static-stub zone. These names are resolved to IP addresses when named needs to send queries to these servers. For this supplemental resolution to be successful, these names must not be a subdomain of the origin name of the static-stub zone. That is, when "example.net" is the origin of a static-stub zone, "ns.example" and "master.example.com" can be specified in the server-names option, but "ns.example.net" cannot; it is rejected by the configuration parser.
A non-empty list for this option internally configures the apex NS RR with the specified names. For example, if "example.com" is configured as a static-stub zone with "ns1.example.net" and "ns2.example.net" in a server-names option, the following RRs are internally configured:
example.com. NS ns1.example.net. example.com. NS ns2.example.net.
These records are used internally to resolve names under the static-stub zone. For instance, if the server receives a query for "www.example.com" with the RD bit on, the server initiates recursive resolution, resolves "ns1.example.net" and/or "ns2.example.net" to IP addresses, and then sends queries to one or more of these addresses.
See the description of sig-validity-interval in the section called “Tuning”.
See the description of sig-signing-nodes in the section called “Tuning”.
See the description of sig-signing-signatures in the section called “Tuning”.
See the description of sig-signing-type in the section called “Tuning”.
See the description of transfer-source in the section called “Zone Transfers”.
See the description of transfer-source-v6 in the section called “Zone Transfers”.
See the description of alt-transfer-source in the section called “Zone Transfers”.
See the description of alt-transfer-source-v6 in the section called “Zone Transfers”.
See the description of use-alt-transfer-source in the section called “Zone Transfers”.
See the description of notify-source in the section called “Zone Transfers”.
See the description of notify-source-v6 in the section called “Zone Transfers”.
See the descriptions in the section called “Tuning”.
See the description of
ixfr-from-differences in the section called “Boolean Options”.
(Note that the ixfr-from-differences
choices of master and
slave are not
available at the zone level.)
See the description of key-directory in the section called “options Statement Definition and Usage”.
See the description of auto-dnssec in the section called “options Statement Definition and Usage”.
See the description of serial-update-method in the section called “options Statement Definition and Usage”.
If yes, this enables
"bump in the wire" signing of a zone, where an
unsigned zone is transferred in or loaded from
disk and a signed version of the zone is served,
with, possibly, a different serial number. This
behavior is disabled by default.
See the description of multi-master in the section called “Boolean Options”.
See the description of masterfile-format in the section called “Tuning”.
See the description of max-zone-ttl in the section called “options Statement Definition and Usage”.
See the description of dnssec-secure-to-insecure in the section called “Boolean Options”.
BIND 9 supports two methods of granting clients the right to perform dynamic updates to a zone, configured by the allow-update and update-policy options.
The allow-update clause is a simple access control list. Any client that matches the ACL is granted permission to update any record in the zone.
The update-policy clause allows more fine-grained control over which updates are allowed. It specifies a set of rules, in which each rule either grants or denies permission for one or more names in the zone to be updated by one or more identities. Identity is determined by the key that signed the update request, using either TSIG or SIG(0). In most cases, update-policy rules only apply to key-based identities. There is no way to specify update permissions based on client source address.
update-policy rules are only meaningful for primary zones (type master), and are not allowed in any other zone type. It is a configuration error to specify both allow-update and update-policy at the same time.
A pre-defined update-policy rule can be
switched on with the command
update-policy local;.
named automatically generates a TSIG session
key when starting and stores it in a file; this key can then
be used by local clients to update the zone while
named is running.
By default, the session key is stored in the file
/var/run/named/session.key, the key name
is "local-ddns", and the key algorithm is HMAC-SHA256.
These values are configurable with the
session-keyfile,
session-keyname, and
session-keyalg options, respectively.
A client running on the local system, if run with appropriate
permissions, may read the session key from the key file and
use it to sign update requests. The zone's update
policy is set to allow that key to change any record
within the zone. Assuming the key name is "local-ddns",
this policy is equivalent to:
update-policy { grant local-ddns zonesub any; };
with the additional restriction that only clients connecting from the local system are permitted to send updates.
Note that only one session key is generated by named; all zones configured to use update-policy local accept the same key.
The command nsupdate -l implements this feature, sending requests to localhost and signing them using the key retrieved from the session key file.
Other rule definitions look like this:
( grant | deny )identityruletype[name] [types]
Each rule grants or denies privileges. Rules are checked in the order in which they are specified in the update-policy statement. Once a message has successfully matched a rule, the operation is immediately granted or denied, and no further rules are examined. There are 13 types of rules; the rule type is specified by the ruletype field, and the interpretation of other fields varies depending on the rule type.
In general, a rule is matched when the key that signed an update request matches the identity field, the name of the record to be updated matches the name field (in the manner specified by the ruletype field), and the type of the record to be updated matches the types field. Details for each rule type are described below.
The identity field must be set to
a fully qualified domain name. In most cases, this
represents the name of the TSIG or SIG(0) key that must be
used to sign the update request. If the specified name is a
wildcard, it is subject to DNS wildcard expansion, and the
rule may apply to multiple identities. When a TKEY exchange
has been used to create a shared secret, the identity of
the key used to authenticate the TKEY exchange is
used as the identity of the shared secret. Some rule types
use identities matching the client's Kerberos principal
(e.g, "host/machine@REALM") or
Windows realm (machine$@REALM).
The name field also specifies
a fully qualified domain name. This often
represents the name of the record to be updated.
Interpretation of this field is dependent on rule type.
If no types are explicitly specified, then a rule matches all types except RRSIG, NS, SOA, NSEC, and NSEC3. Types may be specified by name, including "ANY"; ANY matches all types except NSEC and NSEC3, which can never be updated. Note that when an attempt is made to delete all records associated with a name, the rules are checked for each existing record type.
The ruletype field has 16
values:
name, subdomain,
zonesub, wildcard,
self, selfsub,
selfwild, ms-self,
ms-selfsub, ms-subdomain,
krb5-self, krb5-selfsub,
krb5-subdomain, tcp-self,
6to4-self, and external.
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With exact-match semantics, this rule matches
when the name being updated is identical
to the contents of the
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This rule matches when the name being updated
is a subdomain of, or identical to, the
contents of the |
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This rule is similar to subdomain, except that it matches when the name being updated is a subdomain of the zone in which the update-policy statement appears. This obviates the need to type the zone name twice, and enables the use of a standard update-policy statement in multiple zones without modification.
When this rule is used, the
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The |
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This rule matches when the name of the record
being updated matches the contents of the
The |
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This rule is similar to |
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This rule is similar to |
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When a client sends an UPDATE using a Windows machine principal (for example, "machine$@REALM"), this rule allows records with the absolute name of "machine.REALM" to be updated.
The realm to be matched is specified in the
The
For example,
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This is similar to ms-self, except it also allows updates to any subdomain of the name specified in the Windows machine principal, not just to the name itself. |
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When a client sends an UPDATE using a Windows machine principal (for example, "machine$@REALM"), this rule allows any machine in the specified realm to update any record in the zone or in a specified subdomain of the zone.
The realm to be matched is specified in the
The
For example, if update-policy
for the zone "example.com" includes
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When a client sends an UPDATE using a Kerberos machine principal (for example, "host/machine@REALM"), this rule allows records with the absolute name of "machine" to be updated, provided it has been authenticated by REALM. This is similar but not identical to ms-self, due to the "machine" part of the Kerberos principal being an absolute name instead of an unqualified name.
The realm to be matched is specified in the
The
For example,
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This is similar to krb5-self, except it also allows updates to any subdomain of the name specified in the "machine" part of the Kerberos principal, not just to the name itself. |
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This rule is identical to ms-subdomain, except that it works with Kerberos machine principals (i.e., "host/machine@REALM") rather than Windows machine principals. |
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This rule allows updates that have been sent via
TCP and for which the standard mapping from the
client's IP address into the
NoteIt is theoretically possible to spoof these TCP sessions. |
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This allows the name matching a 6to4 IPv6 prefix,
as specified in RFC 3056, to be updated by any
TCP connection from either the 6to4 network or
from the corresponding IPv4 address. This is
intended to allow NS or DNAME RRsets to be added
to the
The identity field must match
the 6to4 prefix in
In addition, if specified for an
NoteIt is theoretically possible to spoof these TCP sessions. |
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This rule allows named to defer the decision of whether to allow a given update to an external daemon.
The method of communicating with the daemon is
specified in the Requests to the external daemon are sent over the Unix-domain socket as datagrams with the following format: Protocol version number (4 bytes, network byte order, currently 1) Request length (4 bytes, network byte order) Signer (null-terminated string) Name (null-terminated string) TCP source address (null-terminated string) Rdata type (null-terminated string) Key (null-terminated string) TKEY token length (4 bytes, network byte order) TKEY token (remainder of packet) The daemon replies with a four-byte value in network byte order, containing either 0 or 1; 0 indicates that the specified update is not permitted, and 1 indicates that it is. |
When multiple views are in use, a zone may be referenced by more than one of them. Often, the views contain different zones with the same name, allowing different clients to receive different answers for the same queries. At times, however, it is desirable for multiple views to contain identical zones. The in-view zone option provides an efficient way to do this; it allows a view to reference a zone that was defined in a previously configured view. Example:
view internal {
match-clients { 10/8; };
zone example.com {
type master;
file "example-external.db";
};
};
view external {
match-clients { any; };
zone example.com {
in-view internal;
};
};
An in-view option cannot refer to a view that is configured later in the configuration file.
A zone statement which uses the in-view option may not use any other , with the exception of forward and forwarders. (These options control the behavior of the containing view, rather than change the zone object itself.)
Zone-level ACLs (e.g., allow-query, allow-transfer), and other configuration details of the zone, are all set in the view the referenced zone is defined in. Be careful to ensure that ACLs are wide enough for all views referencing the zone.
An in-view zone cannot be used as a response policy zone.
An in-view zone is not intended to reference a forward zone.
This section, largely borrowed from RFC 1034, describes the concept of a Resource Record (RR) and explains when each type is used. Since the publication of RFC 1034, several new RRs have been identified and implemented in the DNS. These are also included.
A domain name identifies a node. Each node has a set of resource information, which may be empty. The set of resource information associated with a particular name is composed of separate RRs. The order of RRs in a set is not significant and need not be preserved by name servers, resolvers, or other parts of the DNS. However, sorting of multiple RRs is permitted for optimization purposes: for example, to specify that a particular nearby server be tried first. See the section called “The sortlist Statement” and the section called “RRset Ordering”.
The components of a Resource Record are:
|
owner name |
The domain name where the RR is found. |
|
type |
An encoded 16-bit value that specifies the type of the resource record. |
|
TTL |
The time-to-live of the RR. This field is a 32-bit integer in units of seconds, and is primarily used by resolvers when they cache RRs. The TTL describes how long a RR can be cached before it should be discarded. |
|
class |
An encoded 16-bit value that identifies a protocol family or an instance of a protocol. |
|
RDATA |
The resource data. The format of the data is type- and sometimes class-specific. |
For a complete list of types of valid RRs, including those that have been obsoleted, please refer to https://en.wikipedia.org/wiki/List_of_DNS_record_types.
The following classes of resource records are currently valid in the DNS:
|
IN |
The Internet. |
|
CH |
Chaosnet, a LAN protocol created at MIT in the
mid-1970s.
It was rarely used for its historical purpose, but was reused for
BIND's
built-in server information zones, e.g.,
|
|
HS |
Hesiod, an information service developed by MIT's Project Athena. It was used to share information about various systems databases, such as users, groups, printers, etc. |
The owner name is often implicit, rather than forming an integral part of the RR. For example, many name servers internally form tree or hash structures for the name space, and chain RRs off nodes. The remaining RR parts are the fixed header (type, class, TTL), which is consistent for all RRs, and a variable part (RDATA) that fits the needs of the resource being described.
The TTL field is a time limit on how long an RR can be kept in a cache. This limit does not apply to authoritative data in zones; that also times out, but follows the refreshing policies for the zone. The TTL is assigned by the administrator for the zone where the data originates. While short TTLs can be used to minimize caching, and a zero TTL prohibits caching, the realities of Internet performance suggest that these times should be on the order of days for the typical host. If a change can be anticipated, the TTL can be reduced prior to the change to minimize inconsistency, and then increased back to its former value following the change.
The data in the RDATA section of RRs is carried as a combination of binary strings and domain names. The domain names are frequently used as "pointers" to other data in the DNS.
RRs are represented in binary form in the packets of the DNS protocol, and are usually represented in highly encoded form when stored in a name server or resolver. In the examples provided in RFC 1034, a style similar to that used in zone files was employed in order to show the contents of RRs. In this format, most RRs are shown on a single line, although continuation lines are possible using parentheses.
The start of the line gives the owner of the RR. If a line begins with a blank, then the owner is assumed to be the same as that of the previous RR. Blank lines are often included for readability.
Following the owner are list the TTL, type, and class of the RR. Class and type use the mnemonics defined above, and TTL is an integer before the type field. To avoid ambiguity in parsing, type and class mnemonics are disjoint, TTLs are integers, and the type mnemonic is always last. The IN class and TTL values are often omitted from examples in the interest of clarity.
The resource data or RDATA section of the RR is given using knowledge of the typical representation for the data.
For example, the RRs carried in a message might be shown as:
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The MX RRs have an RDATA section which consists of a 16-bit number followed by a domain name. The address RRs use a standard IP address format to contain a 32-bit Internet address.
The above example shows six RRs, with two RRs at each of three domain names.
Here is another possible example:
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This example shows two addresses for
XX.LCS.MIT.EDU, each of a different class.
As described above, domain servers store information as a series of resource records, each of which contains a particular piece of information about a given domain name (which is usually, but not always, a host). The simplest way to think of a RR is as a typed pair of data, a domain name matched with a relevant datum and stored with some additional type information, to help systems determine when the RR is relevant.
MX records are used to control delivery of email. The data specified in the record is a priority and a domain name. The priority controls the order in which email delivery is attempted, with the lowest number first. If two priorities are the same, a server is chosen randomly. If no servers at a given priority are responding, the mail transport agent falls back to the next largest priority. Priority numbers do not have any absolute meaning; they are relevant only respective to other MX records for that domain name. The domain name given is the machine to which the mail is delivered. It must have an associated address record (A or AAAA); CNAME is not sufficient.
For a given domain, if there is both a CNAME record and an MX record, the MX record is in error, and is ignored. Instead, the mail is delivered to the server specified in the MX record pointed to by the CNAME. For example:
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Mail delivery is attempted to mail.example.com and
mail2.example.com (in
any order); if neither of those succeeds, delivery to mail.backup.org
is attempted.
The time-to- (TTL) of the RR field is a 32-bit integer represented in units of seconds, and is primarily used by resolvers when they cache RRs. The TTL describes how long an RR can be cached before it should be discarded. The following three types of TTLs are currently used in a zone file.
|
SOA |
The last field in the SOA is the negative caching TTL. This controls how long other servers cache no-such-domain (NXDOMAIN) responses from this server. The maximum time for negative caching is 3 hours (3h). |
|
$TTL |
The $TTL directive at the top of the zone file (before the SOA) gives a default TTL for every RR without a specific TTL set. |
|
RR TTLs |
Each RR can have a TTL as the second field in the RR, which controls how long other servers can cache it. |
All of these TTLs default to units of seconds, though units
can be explicitly specified: for example, 1h30m.
Reverse name resolution (that is, translation from IP address to name) is achieved by means of the in-addr.arpa domain and PTR records. Entries in the in-addr.arpa domain are made in least-to-most significant order, read left to right. This is the opposite order to the way IP addresses are usually written. Thus, a machine with an IP address of 10.1.2.3 would have a corresponding in-addr.arpa name of 3.2.1.10.in-addr.arpa. This name should have a PTR resource record whose data field is the name of the machine or, optionally, multiple PTR records if the machine has more than one name. For example, in the [example.com] domain:
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The $ORIGIN line in this example is only to provide context; it does not necessarily appear in the actual usage. It is only used here to indicate that the example is relative to the listed origin.
The DNS "master file" format was initially defined in RFC 1035 and has subsequently been extended. While the format itself is class-independent, all records in a zone file must be of the same class.
Master file directives include $ORIGIN, $INCLUDE, and $TTL.
When used in the label (or name) field, the asperand or
at-sign (@) symbol represents the current origin.
At the start of the zone file, it is the
<zone_name>, followed by a
trailing dot (.).
Syntax: $ORIGIN
domain-name
[comment]
$ORIGIN
sets the domain name that is appended to any
unqualified records. When a zone is first read, there
is an implicit $ORIGIN
<zone_name>.;
note the trailing dot.
The current $ORIGIN is appended to
the domain specified in the $ORIGIN
argument if it is not absolute.
$ORIGIN example.com. WWW CNAME MAIN-SERVER
is equivalent to
WWW.EXAMPLE.COM. CNAME MAIN-SERVER.EXAMPLE.COM.
Syntax: $INCLUDE
filename
[
origin ]
[ comment ]
This reads and processes the file filename as
if it were included in the file at this point. If origin is
specified, the file is processed with $ORIGIN set
to that value; otherwise, the current $ORIGIN is
used.
The origin and the current domain name revert to the values they had prior to the $INCLUDE once the file has been read.
RFC 1035 specifies that the current origin should be restored after an $INCLUDE, but it is silent on whether the current domain name should also be restored. BIND 9 restores both of them. This could be construed as a deviation from RFC 1035, a feature, or both.
Syntax: $GENERATE
range
lhs
[ttl]
[class]
type
rhs
[comment]
$GENERATE is used to create a series of resource records that only differ from each other by an iterator. $GENERATE can be used to easily generate the sets of records required to support sub-/24 reverse delegations described in RFC 2317: Classless IN-ADDR.ARPA delegation.
$ORIGIN 0.0.192.IN-ADDR.ARPA. $GENERATE 1-2 @ NS SERVER$.EXAMPLE. $GENERATE 1-127 $ CNAME $.0
is equivalent to
0.0.0.192.IN-ADDR.ARPA. NS SERVER1.EXAMPLE. 0.0.0.192.IN-ADDR.ARPA. NS SERVER2.EXAMPLE. 1.0.0.192.IN-ADDR.ARPA. CNAME 1.0.0.0.192.IN-ADDR.ARPA. 2.0.0.192.IN-ADDR.ARPA. CNAME 2.0.0.0.192.IN-ADDR.ARPA. ... 127.0.0.192.IN-ADDR.ARPA. CNAME 127.0.0.0.192.IN-ADDR.ARPA.
Both generate a set of A and MX records. Note the MX's right-hand side is a quoted string. The quotes are stripped when the right-hand side is processed.
$ORIGIN EXAMPLE. $GENERATE 1-127 HOST-$ A 1.2.3.$ $GENERATE 1-127 HOST-$ MX "0 ."
is equivalent to
HOST-1.EXAMPLE. A 1.2.3.1 HOST-1.EXAMPLE. MX 0 . HOST-2.EXAMPLE. A 1.2.3.2 HOST-2.EXAMPLE. MX 0 . HOST-3.EXAMPLE. A 1.2.3.3 HOST-3.EXAMPLE. MX 0 . ... HOST-127.EXAMPLE. A 1.2.3.127 HOST-127.EXAMPLE. MX 0 .
|
range |
This can be one of two forms: start-stop or start-stop/step. If the first form is used, then step is set to 1. "start", "stop", and "step" must be positive integers between 0 and (2^31)-1. "start" must not be larger than "stop". |
|
lhs |
This describes the owner name of the resource records to be created. Any single $ (dollar sign) symbols within the lhs string are replaced by the iterator value. To get a $ in the output, escape the $ using a backslash \, e.g., \$. The $ may optionally be followed by modifiers which change the offset from the iterator, field width, and base. Modifiers are introduced by a { (left brace) immediately following the $, as in ${offset[,width[,base]]}. For example, ${-20,3,d} subtracts 20 from the current value and prints the result as a decimal in a zero-padded field of width 3. Available output forms are decimal (d), octal (o), hexadecimal (x or X for uppercase), and nibble (n or N for uppercase). The default modifier is ${0,0,d}. If the lhs is not absolute, the current $ORIGIN is appended to the name. In nibble mode, the value is treated as if it were a reversed hexadecimal string, with each hexadecimal digit as a separate label. The width field includes the label separator. For compatibility with earlier versions, $$ is still recognized as indicating a literal $ in the output. |
|
ttl |
This specifies the time-to-live of the generated records. If not specified, this is inherited using the normal TTL inheritance rules. class and ttl can be entered in either order. |
|
class |
This specifies the class of the generated records. This must match the zone class if it is specified. class and ttl can be entered in either order. |
|
type |
This can be any valid type. |
|
rhs |
rhs is an optionally quoted string. |
The $GENERATE directive is a BIND extension and not part of the standard zone file format.
BIND 8 did not support the optional TTL and CLASS fields.
In addition to the standard text format, BIND 9 supports the ability to read or dump to zone files in other formats.
The raw format is
a binary representation of zone data in a manner similar
to that used in zone transfers. Since it does not require
parsing text, load time is significantly reduced.
An even faster alternative is the map
format, which is an image of a BIND 9
in-memory zone database; it can be loaded
directly into memory via the mmap()
function and the zone can begin serving queries almost
immediately.
For a primary server, a zone file in
raw or map
format is expected to be generated from a textual zone
file by the named-compilezone command.
For a secondary server or for a dynamic zone, the zone file is automatically
generated when
named dumps the zone contents after
zone transfer or when applying prior updates, if one of these formats is specified by the
masterfile-format option.
If a zone file in a binary format needs manual modification, it first must be converted to a textual form by the named-compilezone command. Make any necessary modifications to the text file, and then convert it to the binary form via the named-compilezone command again.
Note that map format is extremely
architecture-specific. A map
file cannot be used on a system
with different pointer size, endianness, or data alignment
than the system on which it was generated, and should in
general be used only inside a single system.
While raw format uses
network byte order and avoids architecture-dependent
data alignment so that it is as portable as
possible, it is also primarily expected to be used
inside the same single system. To export a
zone file in either raw or
map format, or make a
portable backup of such a file, conversion to
text format is recommended.
BIND 9 maintains lots of statistics information and provides several interfaces for users to access those statistics. The available statistics include all statistics counters that are meaningful in BIND 9, and other information that is considered useful.
The statistics information is categorized into the following sections:
|
Incoming Requests |
The number of incoming DNS requests for each OPCODE. |
|
Incoming Queries |
The number of incoming queries for each RR type. |
|
Outgoing Queries |
The number of outgoing queries for each RR type sent from the internal resolver, maintained per view. |
|
Name Server Statistics |
Statistics counters for incoming request processing. |
|
Zone Maintenance Statistics |
Statistics counters regarding zone maintenance operations, such as zone transfers. |
|
Resolver Statistics |
Statistics counters for name resolutions performed in the internal resolver, maintained per view. |
|
Cache DB RRsets |
Statistics counters related to cache contents, maintained per view. The "NXDOMAIN" counter is the number of names that have been cached as nonexistent. Counters named for RR types indicate the number of active RRsets for each type in the cache database. If an RR type name is preceded by an exclamation point (!), it represents the number of records in the cache which indicate that the type does not exist for a particular name; this is also known as "NXRRSET". If an RR type name is preceded by a hash mark (#), it represents the number of RRsets for this type that are present in the cache but whose TTLs have expired; these RRsets may only be used if stale answers are enabled. If an RR type name is preceded by a tilde (~), it represents the number of RRsets for this type that are present in the cache database but are marked for garbage collection; these RRsets cannot be used. |
|
Socket I/O Statistics |
Statistics counters for network-related events. |
A subset of Name Server Statistics is collected and shown
per zone for which the server has the authority, when
zone-statistics is set to
full (or yes),
for backward compatibility. See the description of
zone-statistics in the section called “options Statement Definition and
Usage”
for further details.
These statistics counters are shown with their zone and view names. The view name is omitted when the server is not configured with explicit views.
There are currently two user interfaces to get access to the statistics. One is in plain-text format, dumped to the file specified by the statistics-file configuration option; the other is remotely accessible via a statistics channel when the statistics-channels statement is specified in the configuration file (see the section called “statistics-channels Statement Grammar”.)
The text format statistics dump begins with a line, like:
+++ Statistics Dump +++ (973798949)
The number in parentheses is a standard Unix-style timestamp, measured in seconds since January 1, 1970. Following that line is a set of statistics information, which is categorized as described above. Each section begins with a line, like:
++ Name Server Statistics ++
Each section consists of lines, each containing the statistics counter value followed by its textual description; see below for available counters. For brevity, counters that have a value of 0 are not shown in the statistics file.
The statistics dump ends with the line where the number is identical to the number in the beginning line; for example:
--- Statistics Dump --- (973798949)
The following tables summarize the statistics counters that BIND 9 provides. For each row of the tables, the leftmost column is the abbreviated symbol name of that counter; these symbols are shown in the statistics information accessed via an HTTP statistics channel. The rightmost column gives the description of the counter, which is also shown in the statistics file, but, in this document, may be slightly modified for better readability. Additional notes may also be provided in this column. When a middle column exists between these two columns, it gives the corresponding counter name of the BIND 8 statistics, if applicable.
|
Symbol |
BIND 8 Symbol |
Description |
|
Requestv4 |
RQ |
This indicates the number of IPv4 requests received. Note: this also counts non-query requests. |
|
Requestv6 |
RQ |
This indicates the number of IPv6 requests received. Note: this also counts non-query requests. |
|
ReqEdns0 |
|
This indicates the number of requests received with EDNS(0). |
|
ReqBadEDNSVer |
|
This indicates the number of requests received with an unsupported EDNS version. |
|
ReqTSIG |
|
This indicates the number of requests received with TSIG. |
|
ReqSIG0 |
|
This indicates the number of requests received with SIG(0). |
|
ReqBadSIG |
|
This indicates the number of requests received with an invalid (TSIG or SIG(0)) signature. |
|
ReqTCP |
RTCP |
This indicates the number of TCP requests received. |
|
AuthQryRej |
RUQ |
This indicates the number of rejected authoritative (non-recursive) queries. |
|
RecQryRej |
RURQ |
This indicates the number of rejected recursive queries. |
|
XfrRej |
RUXFR |
This indicates the number of rejected zone transfer requests. |
|
UpdateRej |
RUUpd |
This indicates the number of rejected dynamic update requests. |
|
Response |
SAns |
This indicates the number of responses sent. |
|
RespTruncated |
|
This indicates the number of truncated responses sent. |
|
RespEDNS0 |
|
This indicates the number of responses sent with EDNS(0). |
|
RespTSIG |
|
This indicates the number of responses sent with TSIG. |
|
RespSIG0 |
|
This indicates the number of responses sent with SIG(0). |
|
QrySuccess |
|
This indicates the number of queries that resulted in a successful answer, meaning queries which return a NOERROR response with at least one answer RR. This corresponds to the success counter of previous versions of BIND 9. |
|
QryAuthAns |
|
This indicates the number of queries that resulted in an authoritative answer. |
|
QryNoauthAns |
SNaAns |
This indicates the number of queries that resulted in a non-authoritative answer. |
|
QryReferral |
|
This indicates the number of queries that resulted in a referral answer. This corresponds to the referral counter of previous versions of BIND 9. |
|
QryNxrrset |
|
This indicates the number of queries that resulted in NOERROR responses with no data. This corresponds to the nxrrset counter of previous versions of BIND 9. |
|
QrySERVFAIL |
SFail |
This indicates the number of queries that resulted in SERVFAIL. |
|
QryFORMERR |
SFErr |
This indicates the number of queries that resulted in FORMERR. |
|
QryNXDOMAIN |
SNXD |
This indicates the number of queries that resulted in NXDOMAIN. This corresponds to the nxdomain counter of previous versions of BIND 9. |
|
QryRecursion |
RFwdQ |
This indicates the number of queries that caused the server to perform recursion in order to find the final answer. This corresponds to the recursion counter of previous versions of BIND 9. |
|
QryDuplicate |
RDupQ |
This indicates the number of queries which the server attempted to recurse but for which it discovered an existing query with the same IP address, port, query ID, name, type, and class already being processed. This corresponds to the duplicate counter of previous versions of BIND 9. |
|
QryDropped |
|
This indicates the number of recursive queries for which the server discovered an excessive number of existing recursive queries for the same name, type, and class, and which were subsequently dropped. This is the number of dropped queries due to the reason explained with the clients-per-query and max-clients-per-query options (see the description about clients-per-query.) This corresponds to the dropped counter of previous versions of BIND 9. |
|
QryFailure |
|
This indicates the number of query failures. This corresponds to the failure counter of previous versions of BIND 9. Note: this counter is provided mainly for backward compatibility with the previous versions; normally, more fine-grained counters such as AuthQryRej and RecQryRej that would also fall into this counter are provided, so this counter is not of much interest in practice. |
|
QryNXRedir |
|
This indicates the number of queries that resulted in NXDOMAIN that were redirected. |
|
QryNXRedirRLookup |
|
This indicates the number of queries that resulted in NXDOMAIN that were redirected and resulted in a successful remote lookup. |
|
XfrReqDone |
|
This indicates the number of requested and completed zone transfers. |
|
UpdateReqFwd |
|
This indicates the number of forwarded update requests. |
|
UpdateRespFwd |
|
This indicates the number of forwarded update responses. |
|
UpdateFwdFail |
|
This indicates the number of forwarded dynamic updates that failed. |
|
UpdateDone |
|
This indicates the number of completed dynamic updates. |
|
UpdateFail |
|
This indicates the number of failed dynamic updates. |
|
UpdateBadPrereq |
|
This indicates the number of dynamic updates rejected due to a prerequisite failure. |
|
RateDropped |
|
This indicates the number of responses dropped due to rate limits. |
|
RateSlipped |
|
This indicates the number of responses truncated by rate limits. |
|
RPZRewrites |
|
This indicates the number of response policy zone rewrites. |
|
Symbol |
Description |
|
NotifyOutv4 |
This indicates the number of IPv4 notifies sent. |
|
NotifyOutv6 |
This indicates the number of IPv6 notifies sent. |
|
NotifyInv4 |
This indicates the number of IPv4 notifies received. |
|
NotifyInv6 |
This indicates the number of IPv6 notifies received. |
|
NotifyRej |
This indicates the number of incoming notifies rejected. |
|
SOAOutv4 |
This indicates the number of IPv4 SOA queries sent. |
|
SOAOutv6 |
This indicates the number of IPv6 SOA queries sent. |
|
AXFRReqv4 |
This indicates the number of requested IPv4 AXFRs. |
|
AXFRReqv6 |
This indicates the number of requested IPv6 AXFRs. |
|
IXFRReqv4 |
This indicates the number of requested IPv4 IXFRs. |
|
IXFRReqv6 |
This indicates the number of requested IPv6 IXFRs. |
|
XfrSuccess |
This indicates the number of successful zone transfer requests. |
|
XfrFail |
This indicates the number of failed zone transfer requests. |
|
Symbol |
BIND 8 Symbol |
Description |
|
Queryv4 |
SFwdQ |
This indicates the number of IPv4 queries sent. |
|
Queryv6 |
SFwdQ |
This indicates the number of IPv6 queries sent. |
|
Responsev4 |
RR |
This indicates the number of IPv4 responses received. |
|
Responsev6 |
RR |
This indicates the number of IPv6 responses received. |
|
NXDOMAIN |
RNXD |
This indicates the number of NXDOMAINs received. |
|
SERVFAIL |
RFail |
This indicates the number of SERVFAILs received. |
|
FORMERR |
RFErr |
This indicates the number of FORMERRs received. |
|
OtherError |
RErr |
This indicates the number of other errors received. |
|
EDNS0Fail |
|
This indicates the number of EDNS(0) query failures. |
|
Mismatch |
RDupR |
This indicates the number of mismatched responses received, meaning the DNS ID, response's source address, and/or the response's source port does not match what was expected. (The port must be 53 or as defined by the port option.) This may be an indication of a cache poisoning attempt. |
|
Truncated |
|
This indicates the number of truncated responses received. |
|
Lame |
RLame |
This indicates the number of lame delegations received. |
|
Retry |
SDupQ |
This indicates the number of query retries performed. |
|
QueryAbort |
|
This indicates the number of queries aborted due to quota control. |
|
QuerySockFail |
|
This indicates the number of failures in opening query sockets. One common reason for such failures is a due to a limitation on file descriptors. |
|
QueryTimeout |
|
This indicates the number of query timeouts. |
|
GlueFetchv4 |
SSysQ |
This indicates the number of IPv4 NS address fetches invoked. |
|
GlueFetchv6 |
SSysQ |
This indicates the number of IPv6 NS address fetches invoked. |
|
GlueFetchv4Fail |
|
This indicates the number of failed IPv4 NS address fetches. |
|
GlueFetchv6Fail |
|
This indicates the number of failed IPv6 NS address fetches. |
|
ValAttempt |
|
This indicates the number of attempted DNSSEC validations. |
|
ValOk |
|
This indicates the number of successful DNSSEC validations. |
|
ValNegOk |
|
This indicates the number of successful DNSSEC validations on negative information. |
|
ValFail |
|
This indicates the number of failed DNSSEC validations. |
|
QryRTTnn |
|
This provides a frequency table on query round-trip times (RTTs). Each nn specifies the corresponding frequency. In the sequence of nn_1, nn_2, ..., nn_m, the value of nn_i is the number of queries whose RTTs are between nn_(i-1) (inclusive) and nn_i (exclusive) milliseconds. For the sake of convenience, we define nn_0 to be 0. The last entry should be represented as nn_m+, which means the number of queries whose RTTs are equal to or greater than nn_m milliseconds. |
Socket I/O statistics counters are defined per socket type, which are UDP4 (UDP/IPv4), UDP6 (UDP/IPv6), TCP4 (TCP/IPv4), TCP6 (TCP/IPv6), Unix (Unix Domain), and FDwatch (sockets opened outside the socket module). In the following table, <TYPE> represents a socket type. Not all counters are available for all socket types; exceptions are noted in the description field.
|
Symbol |
Description |
|
<TYPE>Open |
This indicates the number of sockets opened successfully. This counter does not apply to the FDwatch type. |
|
<TYPE>OpenFail |
This indicates the number of failures to open sockets. This counter does not apply to the FDwatch type. |
|
<TYPE>Close |
This indicates the number of closed sockets. |
|
<TYPE>BindFail |
This indicates the number of failures to bind sockets. |
|
<TYPE>ConnFail |
This indicates the number of failures to connect sockets. |
|
<TYPE>Conn |
This indicates the number of connections established successfully. |
|
<TYPE>AcceptFail |
This indicates the number of failures to accept incoming connection requests. This counter does not apply to the UDP and FDwatch types. |
|
<TYPE>Accept |
This indicates the number of incoming connections successfully accepted. This counter does not apply to the UDP and FDwatch types. |
|
<TYPE>SendErr |
This indicates the number of errors in socket send operations. This counter corresponds to the SErr counter of BIND 8. |
|
<TYPE>RecvErr |
This indicates the number of errors in socket receive operations, including errors of send operations on a connected UDP socket, notified by an ICMP error message. |
Most statistics counters that were available in BIND 8 are also supported in BIND 9, as shown in the above tables. Here are notes about other counters that do not appear in these tables.
These counters are not supported, because BIND 9 does not adopt the notion of forwarding as BIND 8 did.
This counter is accessible in the Incoming Queries section.
This counter is accessible in the Incoming Requests section.
This counter is not supported, because BIND 9 does not care about IP options.
BIND 9.11.36 (Extended Support Version)
man.named-nzd2nzf.html 0000644 00000007352 15253021417 0010670 0 ustar 00named-nzd2nzf — Convert an NZD database to NZF text format
named-nzd2nzf {filename}
named-nzd2nzf converts an NZD database to NZF format and prints it to standard output. This can be used to review the configuration of zones that were added to named via rndc addzone. It can also be used to restore the old file format when rolling back from a newer version of BIND to an older version.
BIND 9.11.36 (Extended Support Version)
man.host.html 0000644 00000031374 15253021417 0007171 0 ustar 00host — DNS lookup utility
host [-aCdlnrsTUwv] [-c ] [class-N ] [ndots-p ] [port-R ] [number-t ] [type-W ] [wait-m ] [[flag-4] | [-6]] [-v] [-V] {name} [server]
host is a simple utility for performing DNS lookups. It is normally used to convert names to IP addresses and vice versa. When no arguments or options are given, host prints a short summary of its command line arguments and options.
name is the domain name that is to be
looked
up. It can also be a dotted-decimal IPv4 address or a colon-delimited
IPv6 address, in which case host will by
default
perform a reverse lookup for that address.
server is an optional argument which
is either
the name or IP address of the name server that host
should query instead of the server or servers listed in
/etc/resolv.conf.
Use IPv4 only for query transport.
See also the -6 option.
Use IPv6 only for query transport.
See also the -4 option.
"All". The -a option is normally equivalent
to -v -t .
It also affects the behaviour of the ANY-l
list zone option.
classQuery class: This can be used to lookup HS (Hesiod) or CH (Chaosnet) class resource records. The default class is IN (Internet).
Check consistency: host will query the
SOA records for zone name from all
the listed authoritative name servers for that zone. The
list of name servers is defined by the NS records that are
found for the zone.
Print debugging traces.
Equivalent to the -v verbose option.
Obsolete. Use the IP6.INT domain for reverse lookups of IPv6 addresses as defined in RFC1886 and deprecated in RFC4159. The default is to use IP6.ARPA as specified in RFC3596.
List zone:
The host command performs a zone transfer of
zone name and prints out the NS,
PTR and address records (A/AAAA).
Together, the -l -a
options print all records in the zone.
ndots
The number of dots that have to be
in name for it to be considered
absolute. The default value is that defined using the
ndots statement in /etc/resolv.conf,
or 1 if no ndots statement is present. Names with fewer
dots are interpreted as relative names and will be
searched for in the domains listed in
the search or domain directive
in /etc/resolv.conf.
portSpecify the port on the server to query. The default is 53.
Non-recursive query:
Setting this option clears the RD (recursion desired) bit
in the query. This should mean that the name server
receiving the query will not attempt to
resolve name.
The -r option
enables host to mimic the behavior of a
name server by making non-recursive queries and expecting
to receive answers to those queries that can be
referrals to other name servers.
number
Number of retries for UDP queries:
If number is negative or zero, the
number of retries will default to 1. The default value is
1, or the value of the attempts
option in /etc/resolv.conf, if set.
Do not send the query to the next nameserver if any server responds with a SERVFAIL response, which is the reverse of normal stub resolver behavior.
type
Query type:
The type argument can be any
recognized query type: CNAME, NS, SOA, TXT, DNSKEY, AXFR, etc.
When no query type is specified, host
automatically selects an appropriate query type. By default, it
looks for A, AAAA, and MX records.
If the -C option is given, queries will
be made for SOA records.
If name is a dotted-decimal IPv4
address or colon-delimited IPv6
address, host will query for PTR
records.
If a query type of IXFR is chosen the starting serial
number can be specified by appending an equal followed by
the starting serial number
(like -t ).
IXFR=12345678
TCP/UDP:
By default, host uses UDP when making
queries. The -T option makes it use a TCP
connection when querying the name server. TCP will be
automatically selected for queries that require it, such
as zone transfer (AXFR) requests. Type ANY queries default
to TCP but can be forced to UDP initially using -U.
flag
Memory usage debugging: the flag can
be record, usage,
or trace. You can specify
the -m option more than once to set
multiple flags.
Verbose output.
Equivalent to the -d debug option.
Verbose output can also be enabled by setting
the debug option
in /etc/resolv.conf.
Print the version number and exit.
Wait forever: The query timeout is set to the maximum possible.
See also the -W option.
wait
Timeout: Wait for up to wait
seconds for a reply. If wait is
less than one, the wait interval is set to one second.
By default, host will wait for 5
seconds for UDP responses and 10 seconds for TCP
connections. These defaults can be overridden by
the timeout option
in /etc/resolv.conf.
See also the -w option.
If host has been built with IDN (internationalized
domain name) support, it can accept and display non-ASCII domain names.
host appropriately converts character encoding of
domain name before sending a request to DNS server or displaying a
reply from the server.
If you'd like to turn off the IDN support for some reason, defines
the IDN_DISABLE environment variable.
The IDN support is disabled if the variable is set when
host runs.
BIND 9.11.36 (Extended Support Version)
man.dnssec-keyfromlabel.html 0000644 00000044654 15253021417 0012152 0 ustar 00dnssec-keyfromlabel — DNSSEC key generation tool
dnssec-keyfromlabel {-l label} [-3] [-a ] [algorithm-A ] [date/offset-c ] [class-D ] [date/offset-D sync ] [date/offset-E ] [engine-f ] [flag-G] [-I ] [date/offset-i ] [interval-k] [-K ] [directory-L ] [ttl-n ] [nametype-P ] [date/offset-P sync ] [date/offset-p ] [protocol-R ] [date/offset-S ] [key-t ] [type-v ] [level-V] [-y] {name}
dnssec-keyfromlabel generates a key pair of files that referencing a key object stored in a cryptographic hardware service module (HSM). The private key file can be used for DNSSEC signing of zone data as if it were a conventional signing key created by dnssec-keygen, but the key material is stored within the HSM, and the actual signing takes place there.
The name of the key is specified on the command
line. This must match the name of the zone for which the key is
being generated.
algorithm
Selects the cryptographic algorithm. The value of
algorithm must be one of RSAMD5, RSASHA1,
DSA, NSEC3RSASHA1, NSEC3DSA, RSASHA256, RSASHA512, ECCGOST,
ECDSAP256SHA256, ECDSAP384SHA384, ED25519 or ED448.
These values are case insensitive.
If no algorithm is specified, then RSASHA1 will be used by
default, unless the -3 option is specified,
in which case NSEC3RSASHA1 will be used instead. (If
-3 is used and an algorithm is specified,
that algorithm will be checked for compatibility with NSEC3.)
Note 1: that for DNSSEC, RSASHA1 is a mandatory to implement algorithm, and DSA is recommended.
Note 2: DH automatically sets the -k flag.
Use an NSEC3-capable algorithm to generate a DNSSEC key. If this option is used and no algorithm is explicitly set on the command line, NSEC3RSASHA1 will be used by default.
engineSpecifies the cryptographic hardware to use.
When BIND is built with OpenSSL PKCS#11 support, this defaults to the string "pkcs11", which identifies an OpenSSL engine that can drive a cryptographic accelerator or hardware service module. When BIND is built with native PKCS#11 cryptography (--enable-native-pkcs11), it defaults to the path of the PKCS#11 provider library specified via "--with-pkcs11".
labelSpecifies the label for a key pair in the crypto hardware.
When BIND 9 is built with OpenSSL-based PKCS#11 support, the label is an arbitrary string that identifies a particular key.
When BIND 9 is built with native PKCS#11
support, the label is a PKCS#11 URI string in the format
"pkcs11:keyword=value[;keyword=value;...]"
Keywords include "token", which identifies the HSM; "object", which
identifies the key; and "pin-source", which identifies a file from
which the HSM's PIN code can be obtained. The label will be
stored in the on-disk "private" file.
If the label contains a
pin-source field, tools using the generated
key files will be able to use the HSM for signing and other
operations without any need for an operator to manually enter
a PIN. Note: Making the HSM's PIN accessible in this manner
may reduce the security advantage of using an HSM; be sure
this is what you want to do before making use of this feature.
nametype
Specifies the owner type of the key. The value of
nametype must either be ZONE (for a DNSSEC
zone key (KEY/DNSKEY)), HOST or ENTITY (for a key associated with
a host (KEY)),
USER (for a key associated with a user(KEY)) or OTHER (DNSKEY).
These values are case insensitive.
Compatibility mode: generates an old-style key, without
any metadata. By default, dnssec-keyfromlabel
will include the key's creation date in the metadata stored
with the private key, and other dates may be set there as well
(publication date, activation date, etc). Keys that include
this data may be incompatible with older versions of BIND; the
-C option suppresses them.
classIndicates that the DNS record containing the key should have the specified class. If not specified, class IN is used.
flagSet the specified flag in the flag field of the KEY/DNSKEY record. The only recognized flags are KSK (Key Signing Key) and REVOKE.
Generate a key, but do not publish it or sign with it. This option is incompatible with -P and -A.
Prints a short summary of the options and arguments to dnssec-keyfromlabel.
directorySets the directory in which the key files are to be written.
Generate KEY records rather than DNSKEY records.
ttl
Sets the default TTL to use for this key when it is converted
into a DNSKEY RR. If the key is imported into a zone,
this is the TTL that will be used for it, unless there was
already a DNSKEY RRset in place, in which case the existing TTL
would take precedence. Setting the default TTL to
0 or none removes it.
protocolSets the protocol value for the key. The protocol is a number between 0 and 255. The default is 3 (DNSSEC). Other possible values for this argument are listed in RFC 2535 and its successors.
keyGenerate a key as an explicit successor to an existing key. The name, algorithm, size, and type of the key will be set to match the predecessor. The activation date of the new key will be set to the inactivation date of the existing one. The publication date will be set to the activation date minus the prepublication interval, which defaults to 30 days.
type
Indicates the use of the key. type must be
one of AUTHCONF, NOAUTHCONF, NOAUTH, or NOCONF. The default
is AUTHCONF. AUTH refers to the ability to authenticate
data, and CONF the ability to encrypt data.
levelSets the debugging level.
Prints version information.
Allows DNSSEC key files to be generated even if the key ID would collide with that of an existing key, in the event of either key being revoked. (This is only safe to use if you are sure you won't be using RFC 5011 trust anchor maintenance with either of the keys involved.)
Dates can be expressed in the format YYYYMMDD or YYYYMMDDHHMMSS. If the argument begins with a '+' or '-', it is interpreted as an offset from the present time. For convenience, if such an offset is followed by one of the suffixes 'y', 'mo', 'w', 'd', 'h', or 'mi', then the offset is computed in years (defined as 365 24-hour days, ignoring leap years), months (defined as 30 24-hour days), weeks, days, hours, or minutes, respectively. Without a suffix, the offset is computed in seconds. To explicitly prevent a date from being set, use 'none' or 'never'.
date/offsetSets the date on which a key is to be published to the zone. After that date, the key will be included in the zone but will not be used to sign it. If not set, and if the -G option has not been used, the default is "now".
date/offsetSets the date on which the CDS and CDNSKEY records which match this key are to be published to the zone.
date/offsetSets the date on which the key is to be activated. After that date, the key will be included in the zone and used to sign it. If not set, and if the -G option has not been used, the default is "now".
date/offsetSets the date on which the key is to be revoked. After that date, the key will be flagged as revoked. It will be included in the zone and will be used to sign it.
date/offsetSets the date on which the key is to be retired. After that date, the key will still be included in the zone, but it will not be used to sign it.
date/offsetSets the date on which the key is to be deleted. After that date, the key will no longer be included in the zone. (It may remain in the key repository, however.)
date/offsetSets the date on which the CDS and CDNSKEY records which match this key are to be deleted.
intervalSets the prepublication interval for a key. If set, then the publication and activation dates must be separated by at least this much time. If the activation date is specified but the publication date isn't, then the publication date will default to this much time before the activation date; conversely, if the publication date is specified but activation date isn't, then activation will be set to this much time after publication.
If the key is being created as an explicit successor to another key, then the default prepublication interval is 30 days; otherwise it is zero.
As with date offsets, if the argument is followed by one of the suffixes 'y', 'mo', 'w', 'd', 'h', or 'mi', then the interval is measured in years, months, weeks, days, hours, or minutes, respectively. Without a suffix, the interval is measured in seconds.
When dnssec-keyfromlabel completes
successfully,
it prints a string of the form Knnnn.+aaa+iiiii
to the standard output. This is an identification string for
the key files it has generated.
nnnn is the key name.
aaa is the numeric representation
of the algorithm.
iiiii is the key identifier (or
footprint).
dnssec-keyfromlabel
creates two files, with names based
on the printed string. Knnnn.+aaa+iiiii.key
contains the public key, and
Knnnn.+aaa+iiiii.private contains the
private key.
The .key file contains a DNS KEY record
that
can be inserted into a zone file (directly or with a $INCLUDE
statement).
The .private file contains
algorithm-specific
fields. For obvious security reasons, this file does not have
general read permission.
BIND 9.11.36 (Extended Support Version)
Bv9ARM.ch08.html 0000644 00000013774 15253021417 0007207 0 ustar 00Table of Contents
The best solution to installation and configuration issues is to take preventive measures by setting up logging files beforehand. The log files provide a source of hints and information that can be used to identify what went wrong and fix the problem.
Zone serial numbers are just numbers — they are not date-related. However, many people set them to a number that represents a date, usually of the form YYYYMMDDRR. Occasionally they make a mistake and set the serial number to a date in the future, then try to correct it by setting it to the current date. This causes problems because serial numbers are used to indicate that a zone has been updated. If the serial number on the secondary server is lower than the serial number on the primary, the secondary server attempts to update its copy of the zone.
Setting the serial number to a lower number on the primary server than the one on the secondary server means that the secondary will not perform updates to its copy of the zone.
The solution to this is to add 2147483647 (2^31-1) to the number, reload the zone and make sure all secondaries have updated to the new zone serial number, then reset it to the desired number and reload the zone again.
The BIND-users mailing list, at https://lists.isc.org/mailman/listinfo/bind-users, is an excellent resource for peer user support. In addition, ISC maintains a Knowledgebase of helpful articles at https://kb.isc.org.
Internet Systems Consortium (ISC) offers annual support agreements for BIND9, ISC DHCP, and Kea DHCP. All paid support contracts include advance security notifications; some levels include service level agreements (SLAs), premium software features, and increased priority on bug fixes and feature requests.
Please contact info@isc.org or visit https://www.isc.org/contact/ for more information.
BIND 9.11.36 (Extended Support Version)
Bv9ARM.ch09.html 0000644 00000352033 15253021417 0007202 0 ustar 00Table of Contents
BIND 9.11 (Extended Support Version) is a stable branch of BIND. This document summarizes significant changes since the last production release on that branch.
Please see the file CHANGES for a more
detailed list of changes and bug fixes.
The latest versions of BIND 9 software can always be found at https://www.isc.org/download/. There you will find additional information about each release, source code, and pre-compiled versions for Microsoft Windows operating systems.
With the release of BIND 9.11.0, ISC changed to the open source license for BIND from the ISC license to the Mozilla Public License (MPL 2.0).
The MPL-2.0 license requires that if you make changes to licensed software (e.g. BIND) and distribute them outside your organization, that you publish those changes under that same license. It does not require that you publish or disclose anything other than the changes you made to our software.
This requirement will not affect anyone who is using BIND, with or without modifications, without redistributing it, nor anyone redistributing it without changes. Therefore, this change will be without consequence for most individuals and organizations who are using BIND.
Those unsure whether or not the license change affects their use of BIND, or who wish to discuss how to comply with the license may contact ISC at https://www.isc.org/mission/contact/.
The lame-ttl option controls how long named caches certain types of broken responses from authoritative servers (see the security advisory for details). This caching mechanism could be abused by an attacker to significantly degrade resolver performance. The vulnerability has been mitigated by changing the default value of lame-ttl to 0 and overriding any explicitly set value with 0, effectively disabling this mechanism altogether. ISC's testing has determined that doing that has a negligible impact on resolver performance while also preventing abuse. Administrators may observe more traffic towards servers issuing certain types of broken responses than in previous BIND 9 releases, depending on client query patterns. (CVE-2021-25219)
ISC would like to thank Kishore Kumar Kothapalli of Infoblox for bringing this vulnerability to our attention. [GL #2899]
named failed to check the opcode of responses when performing zone refreshes, stub zone updates, and UPDATE forwarding. This could lead to an assertion failure under certain conditions and has been addressed by rejecting responses whose opcode does not match the expected value. [GL #2762]
This maintenance release of BIND 9.11 contains no significant changes, although some minor updates have been made (for example, to fix build issues on Solaris 11).
This maintenance release of BIND 9.11 contains no significant changes, although some minor updates have been made (for example, to eliminate compiler warnings emitted by GCC 11).
DNSSEC responses containing NSEC3 records with iteration counts greater than 150 are now treated as insecure. [GL #2445]
The maximum supported number of NSEC3 iterations that can be configured for a zone has been reduced to 150. [GL #2642]
The implementation of the ZONEMD RR type has been updated to match RFC 8976. [GL #2658]
A malformed incoming IXFR transfer could trigger an assertion failure in named, causing it to quit abnormally. (CVE-2021-25214)
ISC would like to thank Greg Kuechle of SaskTel for bringing this vulnerability to our attention. [GL #2467]
named crashed when a DNAME record placed in the ANSWER section during DNAME chasing turned out to be the final answer to a client query. (CVE-2021-25215)
ISC would like to thank Siva Kakarla for bringing this vulnerability to our attention. [GL #2540]
When a server's configuration set the tkey-gssapi-keytab or tkey-gssapi-credential option, a specially crafted GSS-TSIG query could cause a buffer overflow in the ISC implementation of SPNEGO (a protocol enabling negotiation of the security mechanism used for GSSAPI authentication). This flaw could be exploited to crash named binaries compiled for 64-bit platforms, and could enable remote code execution when named was compiled for 32-bit platforms. (CVE-2021-25216)
This vulnerability was reported to us as ZDI-CAN-13347 by Trend Micro Zero Day Initiative. [GL #2604]
The ISC implementation of SPNEGO was removed from BIND 9 source code. Instead, BIND 9 now always uses the SPNEGO implementation provided by the system GSSAPI library when it is built with GSSAPI support. All major contemporary Kerberos/GSSAPI libraries contain an implementation of the SPNEGO mechanism. [GL #2607]
The BIND 9.11.30 release was withdrawn after a backporting bug was discovered during pre-release testing. ISC would like to acknowledge the assistance of Natan Segal of Bluecat Networks.
When tkey-gssapi-keytab or tkey-gssapi-credential was configured, a specially crafted GSS-TSIG query could cause a buffer overflow in the ISC implementation of SPNEGO (a protocol enabling negotiation of the security mechanism to use for GSSAPI authentication). This flaw could be exploited to crash named. Theoretically, it also enabled remote code execution, but achieving the latter is very difficult in real-world conditions. (CVE-2020-8625)
This vulnerability was responsibly reported to us as ZDI-CAN-12302 by Trend Micro Zero Day Initiative. [GL #2354]
The default value of max-recursion-queries was increased from 75 to 100. Since the queries sent towards root and TLD servers are now included in the count (as a result of the fix for CVE-2020-8616), max-recursion-queries has a higher chance of being exceeded by non-attack queries, which is the main reason for increasing its default value. [GL #2305]
The default value of nocookie-udp-size was restored back to 4096 bytes. Since max-udp-size is the upper bound for nocookie-udp-size, this change relieves the operator from having to change nocookie-udp-size together with max-udp-size in order to increase the default EDNS buffer size limit. nocookie-udp-size can still be set to a value lower than max-udp-size, if desired. [GL #2250]
Handling of missing DNS COOKIE responses over UDP was tightened by falling back to TCP. [GL #2275]
The CNAME synthesized from a DNAME was incorrectly followed when the QTYPE was CNAME or ANY. [GL #2280]
Building with native PKCS#11 support for AEP Keyper has been broken since BIND 9.11.22. This has been fixed. [GL #2315]
named acting as a resolver could incorrectly treat signed zones with no DS record at the parent as bogus. Such zones should be treated as insecure. This has been fixed. [GL #2236]
After a Negative Trust Anchor (NTA) is added, BIND performs periodic checks to see if it is still necessary. If BIND encountered a failure while creating a query to perform such a check, it attempted to dereference a NULL pointer, resulting in a crash. [GL #2244]
A problem obtaining glue records could prevent a stub zone from functioning properly, if the authoritative server for the zone were configured for minimal responses. [GL #1736]
DNS Flag Day 2020: The default EDNS buffer size has been changed from 4096 to 1232 bytes. According to measurements done by multiple parties, this should not cause any operational problems as most of the Internet "core" is able to cope with IP message sizes between 1400-1500 bytes; the 1232 size was picked as a conservative minimal number that could be changed by the DNS operator to an estimated path MTU minus the estimated header space. In practice, the smallest MTU witnessed in the operational DNS community is 1500 octets, the maximum Ethernet payload size, so a useful default for maximum DNS/UDP payload size on reliable networks would be 1400 bytes. [GL #2183]
named reported an invalid memory size when running in an environment that did not properly report the number of available memory pages and/or the size of each memory page. [GL #2166]
With multiple forwarders configured, named could
fail the REQUIRE(msg->state == (-1)) assertion in
lib/dns/message.c, causing it to crash. This has
been fixed. [GL #2124]
Parsing of LOC records was made more strict by rejecting a sole period
(.) and/or m as a value.
These changes prevent zone files using such values from being loaded.
Handling of negative altitudes which are not integers was also
corrected. [GL #2074]
Several problems found by OSS-Fuzz were fixed. (None of these are security issues.) [GL !3953] [GL !3975]
It was possible to trigger an assertion failure when verifying the response to a TSIG-signed request. This was disclosed in CVE-2020-8622.
ISC would like to thank Dave Feldman, Jeff Warren, and Joel Cunningham of Oracle for bringing this vulnerability to our attention. [GL #2028]
When BIND 9 was compiled with native PKCS#11 support, it was possible to trigger an assertion failure in code determining the number of bits in the PKCS#11 RSA public key with a specially crafted packet. This was disclosed in CVE-2020-8623.
ISC would like to thank Lyu Chiy for bringing this vulnerability to our attention. [GL #2037]
update-policy rules of type subdomain were incorrectly treated as zonesub rules, which allowed keys used in subdomain rules to update names outside of the specified subdomains. The problem was fixed by making sure subdomain rules are again processed as described in the ARM. This was disclosed in CVE-2020-8624.
ISC would like to thank Joop Boonen of credativ GmbH for bringing this vulnerability to our attention. [GL #2055]
Wildcard RPZ passthru rules could incorrectly be overridden by other rules that were loaded from RPZ zones which appeared later in the response-policy statement. This has been fixed. [GL #1619]
LMDB locking code was revised to make rndc reconfig work properly on FreeBSD and with LMDB >= 0.9.26. [GL #1976]
named could crash when cleaning dead nodes in
lib/dns/rbtdb.c that were being reused.
[GL #1968]
Properly handle missing kyua command so that make check does not fail unexpectedly when CMocka is installed, but Kyua is not. [GL #1950]
The validator could fail to accept a properly signed RRset if an unsupported algorithm appeared earlier in the DNSKEY RRset than a supported algorithm. It could also stop if it detected a malformed public key. [GL #1689]
It was possible to trigger an INSIST failure when a zone with an interior wildcard label was queried in a certain pattern. This was disclosed in CVE-2020-8619. [GL #1111] [GL #1718]
dig and other tools can now print the Extended DNS Error (EDE) option when it appears in a request or a response. [GL #1835]
When fully updating the NSEC3 chain for a large zone via IXFR, a temporary loss of performance could be experienced on the secondary server when answering queries for nonexistent data that required DNSSEC proof of non-existence (in other words, queries that required the server to find and to return NSEC3 data). The unnecessary processing step that was causing this delay has now been removed. [GL #1834]
A data race in lib/dns/resolver.c:log_formerr()
that could lead to an assertion failure was fixed. [GL #1808]
Previously, provide-ixfr no; failed to return up-to-date responses when the serial number was greater than or equal to the current serial number. [GL #1714]
named-checkconf -p could include spurious text in server-addresses statements due to an uninitialized DSCP value. This has been fixed. [GL #1812]
The ARM has been updated to indicate that the TSIG session key is generated when named starts, regardless of whether it is needed. [GL #1842]
To prevent exhaustion of server resources by a maliciously configured domain, the number of recursive queries that can be triggered by a request before aborting recursion has been further limited. Root and top-level domain servers are no longer exempt from the max-recursion-queries limit. Fetches for missing name server address records are limited to 4 for any domain. This issue was disclosed in CVE-2020-8616. [GL #1388]
Replaying a TSIG BADTIME response as a request could trigger an assertion failure. This was disclosed in CVE-2020-8617. [GL #1703]
Message IDs in inbound AXFR transfers are now checked for consistency. Log messages are emitted for streams with inconsistent message IDs. [GL #1674]
When running on a system with support for Linux capabilities, named drops root privileges very soon after system startup. This was causing a spurious log message, "unable to set effective uid to 0: Operation not permitted", which has now been silenced. [GL #1042] [GL #1090]
When named-checkconf -z was run, it would sometimes incorrectly set its exit code. It reflected the status of the last view found; if zone-loading errors were found in earlier configured views but not in the last one, the exit code indicated success. Thanks to Graham Clinch. [GL #1807]
When built without LMDB support, named failed to restart after a zone with a double quote (") in its name was added with rndc addzone. Thanks to Alberto Fernndez. [GL #1695]
DNS rebinding protection was ineffective when BIND 9 is configured as a forwarding DNS server. Found and responsibly reported by Tobias Klein. [GL #1574]
We have received reports that in some circumstances, receipt of an IXFR can cause the processing of queries to slow significantly. Some of these are related to RPZ processing, others appear to occur where there are NSEC3-related changes (such as an operator changing the NSEC3 salt used in the hash calculation). These are being investigated. [GL #1685]
The configure option --with-libxml2 now uses pkg-config to detect libxml2 library availability. You will either have to install pkg-config or specify the exact path where libxml2 has been installed on your system. [GL #1635]
Set a limit on the number of concurrently served pipelined TCP queries. This flaw is disclosed in CVE-2019-6477. [GL #1264]
A SipHash 2-4 based DNS Cookie (RFC 7873) algorithm has been added. [GL #605]
If you are running multiple DNS Servers (different versions of BIND 9 or DNS server from multiple vendors) responding from the same IP address (anycast or load-balancing scenarios), you'll have to make sure that all the servers are configured with the same DNS Cookie algorithm and same Server Secret for the best performance.
DS records included in DNS referral messages can now be validated and cached immediately, reducing the number of queries needed for a DNSSEC validation. [GL #964]
Interaction between DNS64 and RPZ No Data rule (CNAME *.) could cause unexpected results; this has been fixed. [GL #1106]
named-checkconf now checks DNS64 prefixes to ensure bits 64-71 are zero. [GL #1159]
named-checkconf could crash during configuration if configured to use "geoip continent" ACLs with legacy GeoIP. [GL #1163]
named-checkconf now correctly reports a missing dnstap-output option when dnstap is set. [GL #1136]
Handle ETIMEDOUT error on connect() with a non-blocking socket. [GL #1133]
The new GeoIP2 API from MaxMind is now supported when BIND is compiled using configure --with-geoip2. The legacy GeoIP API can be used by compiling with configure --with-geoip instead. (Note that the databases for the legacy API are no longer maintained by MaxMind.)
The default path to the GeoIP2 databases will be set based
on the location of the libmaxminddb library;
for example, if it is in /usr/local/lib,
then the default path will be
/usr/local/share/GeoIP.
This value can be overridden in named.conf
using the geoip-directory option.
Some geoip ACL settings that were available with legacy GeoIP, including searches for netspeed, org, and three-letter ISO country codes, will no longer work when using GeoIP2. Supported GeoIP2 database types are country, city, domain, isp, and as. All of the databases support both IPv4 and IPv6 lookups. [GL #182]
The TCP client quota set using the tcp-clients option could be exceeded in some cases. This could lead to exhaustion of file descriptors. This flaw is disclosed in CVE-2018-5743. [GL #615]
When trusted-keys and
managed-keys are both configured for the
same name, or when trusted-keys is used to
configure a trust anchor for the root zone and
dnssec-validation is set to
auto, automatic RFC 5011 key
rollovers will fail.
This combination of settings was never intended to work, but there was no check for it in the parser. This has been corrected; a warning is now logged. (In BIND 9.15 and higher this error will be fatal.) [GL #868]
Code change #4964, intended to prevent double signatures when deleting an inactive zone DNSKEY in some situations, introduced a new problem during zone processing in which some delegation glue RRsets are incorrectly identified as needing RRSIGs, which are then created for them using the current active ZSK for the zone. In some, but not all cases, the newly-signed RRsets are added to the zone's NSEC/NSEC3 chain, but incompletely -- this can result in a broken chain, affecting validation of proof of nonexistence for records in the zone. [GL #771]
named could crash if it managed a DNSSEC security root with managed-keys and the authoritative zone rolled the key to an algorithm not supported by BIND 9. This flaw is disclosed in CVE-2018-5745. [GL #780]
named leaked memory when processing a request with multiple Key Tag EDNS options present. ISC would like to thank Toshifumi Sakaguchi for bringing this to our attention. This flaw is disclosed in CVE-2018-5744. [GL #772]
Zone transfer controls for writable DLZ zones were not effective as the allowzonexfr method was not being called for such zones. This flaw is disclosed in CVE-2019-6465. [GL #790]
When compiled with IDN support, the dig and the nslookup commands now disable IDN processing when the standard output is not a tty (e.g. not used by human). The command line options +idnin and +idnout need to be used to enable IDN processing when dig or nslookup is used from the shell scripts.
named could crash during recursive processing of DNAME records when deny-answer-aliases was in use. This flaw is disclosed in CVE-2018-5740. [GL #387]
Two new update policy rule types have been added krb5-selfsub and ms-selfsub which allow machines with Kerberos principals to update the name space at or below the machine names identified in the respective principals.
The rndc nta command could not differentiate between views of the same name but different class; this has been corrected with the addition of a -class option. [GL #105]
When recursion is enabled but the allow-recursion and allow-query-cache ACLs are not specified, they should be limited to local networks, but they were inadvertently set to match the default allow-query, thus allowing remote queries. This flaw is disclosed in CVE-2018-5738. [GL #309]
named now supports the "root key sentinel"
mechanism. This enables validating resolvers to indicate
which trust anchors are configured for the root, so that
information about root key rollover status can be gathered.
To disable this feature, add
root-key-sentinel no; to
named.conf.
Added the ability not to return a DNS COOKIE option when one
is present in the request. To prevent a cookie being returned,
add answer-cookie no; to
named.conf. [GL #173]
answer-cookie no is only intended as a temporary measure, for use when named shares an IP address with other servers that do not yet support DNS COOKIE. A mismatch between servers on the same address is not expected to cause operational problems, but the option to disable COOKIE responses so that all servers have the same behavior is provided out of an abundance of caution. DNS COOKIE is an important security mechanism, and should not be disabled unless absolutely necessary.
named will now log a warning if the old BIND now can be compiled against libidn2 library to add IDNA2008 support. Previously BIND only supported IDNA2003 using (now obsolete) idnkit-1 library.
dig +noidnin can be used to disable IDN processing on the input domain name, when BIND is compiled with IDN support.
Multiple cookie-secret clause are now
supported. The first cookie-secret in
named.conf is used to generate new
server cookies. Any others are used to accept old server
cookies or those generated by other servers using the
matching cookie-secret.
named now rejects excessively large incremental (IXFR) zone transfers in order to prevent possible corruption of journal files which could cause named to abort when loading zones. [GL #339]
rndc reload could cause named to leak memory if it was invoked before the zone loading actions from a previous rndc reload command were completed. [RT #47076]
Addresses could be referenced after being freed during resolver processing, causing an assertion failure. The chances of this happening were remote, but the introduction of a delay in resolution increased them. This bug is disclosed in CVE-2017-3145. [RT #46839]
update-policy rules that otherwise ignore the name field now require that it be set to "." to ensure that any type list present is properly interpreted. If the name field was omitted from the rule declaration and a type list was present it wouldn't be interpreted as expected.
The ISC DNSSEC Lookaside Validation (DLV) service has
been shut down; all DLV records in the dlv.isc.org zone
have been removed. References to the service have been
removed from BIND documentation. Lookaside validation
is no longer used by default by delv.
The DLV key has been removed from bind.keys.
Setting dnssec-lookaside to
auto or to use dlv.isc.org as a trust
anchor results in a warning being issued.
named will now log a warning if the old root DNSSEC key is explicitly configured and has not been updated. [RT #43670]
BIND can now use the Ed25519 and Ed448 Edwards Curve DNSSEC signing algorithms described in RFC 8080. Note, however, that these algorithms must be supported in OpenSSL; currently they are only available in the development branch of OpenSSL at https://github.com/openssl/openssl. [RT #44696]
When parsing DNS messages, EDNS KEY TAG options are checked for correctness. When printing messages (for example, in dig), EDNS KEY TAG options are printed in readable format.
named will no longer start or accept reconfiguration if managed-keys or dnssec-validation auto are in use and the managed-keys directory (specified by managed-keys-directory, and defaulting to the working directory if not specified), is not writable by the effective user ID. [RT #46077]
Previously, update-policy local; accepted updates from any source so long as they were signed by the locally-generated session key. This has been further restricted; updates are now only accepted from locally configured addresses. [RT #45492]
Attempting to validate improperly unsigned CNAME responses from secure zones could cause a validator loop. This caused a delay in returning SERVFAIL and also increased the chances of encountering the crash bug described in CVE-2017-3145. [RT #46839]
When named was reconfigured, failure of some zones to load correctly could leave the system in an inconsistent state; while generally harmless, this could lead to a crash later when using rndc addzone. Reconfiguration changes are now fully rolled back in the event of failure. [RT #45841]
Some header files included <isc/util.h> incorrectly as it pollutes with namespace with non ISC_ macros and this should only be done by explicitly including <isc/util.h>. This has been corrected. Some code may depend on <isc/util.h> being implicitly included via other header files. Such code should explicitly include <isc/util.h>.
Zones created with rndc addzone could
temporarily fail to inherit the allow-transfer
ACL set in the options section of
named.conf. [RT #46603]
named failed to properly determine whether there were active KSK and ZSK keys for an algorithm when update-check-ksk was true (which is the default setting). This could leave records unsigned when rolling keys. [RT #46743] [RT #46754] [RT #46774]
An error in TSIG handling could permit unauthorized zone transfers or zone updates. These flaws are disclosed in CVE-2017-3142 and CVE-2017-3143. [RT #45383]
The BIND installer on Windows used an unquoted service path, which can enable privilege escalation. This flaw is disclosed in CVE-2017-3141. [RT #45229]
With certain RPZ configurations, a response with TTL 0 could cause named to go into an infinite query loop. This flaw is disclosed in CVE-2017-3140. [RT #45181]
dig +ednsopt now accepts the names for EDNS options in addition to numeric values. For example, an EDNS Client-Subnet option could be sent using dig +ednsopt=ecs:.... Thanks to John Worley of Secure64 for the contribution. [RT #44461]
Threads in named are now set to human-readable names to assist debugging on operating systems that support that. Threads will have names such as "isc-timer", "isc-sockmgr", "isc-worker0001", and so on. This will affect the reporting of subsidiary thread names in ps and top, but not the main thread. [RT #43234]
DiG now warns about .local queries which are reserved for Multicast DNS. [RT #44783]
Fixed a bug that was introduced in an earlier development release which caused multi-packet AXFR and IXFR messages to fail validation if not all packets contained TSIG records; this caused interoperability problems with some other DNS implementations. [RT #45509]
Reloading or reconfiguring named could fail on some platforms when LMDB was in use. [RT #45203]
Due to some incorrectly deleted code, when BIND was built with LMDB, zones that were deleted via rndc delzone were removed from the running server but were not removed from the new zone database, so that deletion did not persist after a server restart. This has been corrected. [RT #45185]
Semicolons are no longer escaped when printing CAA and URI records. This may break applications that depend on the presence of the backslash before the semicolon. [RT #45216]
AD could be set on truncated answer with no records present in the answer and authority sections. [RT #45140]
rndc "" could trigger an assertion failure in named. This flaw is disclosed in (CVE-2017-3138). [RT #44924]
Some chaining (i.e., type CNAME or DNAME) responses to upstream queries could trigger assertion failures. This flaw is disclosed in CVE-2017-3137. [RT #44734]
dns64 with break-dnssec yes; can result in an assertion failure. This flaw is disclosed in CVE-2017-3136. [RT #44653]
If a server is configured with a response policy zone (RPZ) that rewrites an answer with local data, and is also configured for DNS64 address mapping, a NULL pointer can be read triggering a server crash. This flaw is disclosed in CVE-2017-3135. [RT #44434]
A coding error in the nxdomain-redirect
feature could lead to an assertion failure if the redirection
namespace was served from a local authoritative data source
such as a local zone or a DLZ instead of via recursive
lookup. This flaw is disclosed in CVE-2016-9778. [RT #43837]
named could mishandle authority sections with missing RRSIGs, triggering an assertion failure. This flaw is disclosed in CVE-2016-9444. [RT #43632]
named mishandled some responses where covering RRSIG records were returned without the requested data, resulting in an assertion failure. This flaw is disclosed in CVE-2016-9147. [RT #43548]
named incorrectly tried to cache TKEY records which could trigger an assertion failure when there was a class mismatch. This flaw is disclosed in CVE-2016-9131. [RT #43522]
It was possible to trigger assertions when processing responses containing answers of type DNAME. This flaw is disclosed in CVE-2016-8864. [RT #43465]
Added the ability to specify the maximum number of records
permitted in a zone (max-records #;).
This provides a mechanism to block overly large zone
transfers, which is a potential risk with slave zones from
other parties, as described in CVE-2016-6170.
[RT #42143]
dnstap now stores both the local and remote addresses for all messages, instead of only the remote address. The default output format for dnstap-read has been updated to include these addresses, with the initiating address first and the responding address second, separated by "-%gt;" or "%lt;-" to indicate in which direction the message was sent. [RT #43595]
Expanded and improved the YAML output from dnstap-read -y: it now includes packet size and a detailed breakdown of message contents. [RT #43622] [RT #43642]
If an ACL is specified with an address prefix in which the prefix length is longer than the address portion (for example, 192.0.2.1/8), named will now log a warning. In future releases this will be a fatal configuration error. [RT #43367]
A synthesized CNAME record appearing in a response before the associated DNAME could be cached, when it should not have been. This was a regression introduced while addressing CVE-2016-8864. [RT #44318]
named could deadlock if multiple changes to NSEC/NSEC3 parameters for the same zone were being processed at the same time. [RT #42770]
named could trigger an assertion when sending NOTIFY messages. [RT #44019]
Referencing a nonexistent zone in a response-policy statement could cause an assertion failure during configuration. [RT #43787]
rndc addzone could cause a crash when attempting to add a zone with a type other than master or slave. Such zones are now rejected. [RT #43665]
named could hang when encountering log file names with large apparent gaps in version number (for example, when files exist called "logfile.0", "logfile.1", and "logfile.1482954169"). This is now handled correctly. [RT #38688]
If a zone was updated while named was processing a query for nonexistent data, it could return out-of-sync NSEC3 records causing potential DNSSEC validation failure. [RT #43247]
The built-in root hints have been updated to include an IPv6 address (2001:500:12::d0d) for G.ROOT-SERVERS.NET.
Authoritative server support for the EDNS Client Subnet option (ECS), introduced in BIND 9.11.0, was based on an early version of the specification, and is now known to have incompatibilities with other ECS implementations. It is also inefficient, requiring a separate view for each answer, and is unable to correct for overlapping subnets in the configuration. It is intended for testing purposes but is not recommended for for production use. This was not made sufficiently clear in the documentation at the time of release.
It was possible to trigger a assertion when rendering a message using a specially crafted request. This flaw is disclosed in CVE-2016-2776. [RT #43139]
getrrsetbyname with a non absolute name could trigger an infinite recursion bug in lwresd and named with lwres configured if when combined with a search list entry the resulting name is too long. This flaw is disclosed in CVE-2016-2775. [RT #42694]
A new method of provisioning secondary servers called "Catalog Zones" has been added. This is an implementation of draft-muks-dnsop-dns-catalog-zones/ .
A catalog zone is a regular DNS zone which contains a list of "member zones", along with the configuration options for each of those zones. When a server is configured to use a catalog zone, all the zones listed in the catalog zone are added to the local server as slave zones. When the catalog zone is updated (e.g., by adding or removing zones, or changing configuration options for existing zones) those changes will be put into effect. Since the catalog zone is itself a DNS zone, this means configuration changes can be propagated to slaves using the standard AXFR/IXFR update mechanism.
This feature should be considered experimental. It currently supports only basic features; more advanced features such as ACLs and TSIG keys are not yet supported. Example catalog zone configurations can be found in the Chapter 9 of the BIND Administrator Reference Manual.
Support for master entries with TSIG keys has been added to catalog zones, as well as support for allow-query and allow-transfer.
Added an isc.rndc Python module, which allows rndc commands to be sent from Python programs.
Added support for DynDB, a new interface for loading zone data from an external database, developed by Red Hat for the FreeIPA project. (Thanks in particular to Adam Tkac and Petr Spacek of Red Hat for the contribution.)
Unlike the existing DLZ and SDB interfaces, which provide a limited subset of database functionality within BIND - translating DNS queries into real-time database lookups with relatively poor performance and with no ability to handle DNSSEC-signed data - DynDB is able to fully implement and extend the database API used natively by BIND.
A DynDB module could pre-load data from an external data source, then serve it with the same performance and functionality as conventional BIND zones, and with the ability to take advantage of database features not available in BIND, such as multi-master replication.
Fetch quotas are now compiled in by default: they no longer require BIND to be configured with --enable-fetchlimit, as was the case when the feature was introduced in BIND 9.10.3.
These quotas limit the queries that are sent by recursive resolvers to authoritative servers experiencing denial-of-service attacks. They can both reduce the harm done to authoritative servers and also avoid the resource exhaustion that can be experienced by recursive servers when they are being used as a vehicle for such an attack.
fetches-per-server limits the number of
simultaneous queries that can be sent to any single
authoritative server. The configured value is a starting
point; it is automatically adjusted downward if the server is
partially or completely non-responsive. The algorithm used to
adjust the quota can be configured via the
fetch-quota-params option.
fetches-per-zone limits the number of
simultaneous queries that can be sent for names within a
single domain. (Note: Unlike "fetches-per-server", this
value is not self-tuning.)
Statistics counters have also been added to track the number of queries affected by these quotas.
Added support for dnstap, a fast, flexible method for capturing and logging DNS traffic, developed by Robert Edmonds at Farsight Security, Inc., whose assistance is gratefully acknowledged.
To enable dnstap at compile time,
the fstrm and protobuf-c
libraries must be available, and BIND must be configured with
--enable-dnstap.
A new utility dnstap-read has been added to allow dnstap data to be presented in a human-readable format.
rndc dnstap -roll causes dnstap
output files to be rolled like log files -- the most recent output
file is renamed with a .0 suffix, the next
most recent with .1, etc. (Note that this
only works when dnstap output is being written
to a file, not to a UNIX domain socket.) An optional numerical
argument specifies how many backup log files to retain; if not
specified or set to 0, there is no limit.
rndc dnstap -reopen simply closes and reopens the dnstap output channel without renaming the output file.
For more information on dnstap, see https://dnstap.info.
New statistics counters have been added to track traffic sizes, as specified in RSSAC002. Query and response message sizes are broken up into ranges of histogram buckets: TCP and UDP queries of size 0-15, 16-31, ..., 272-288, and 288+, and TCP and UDP responses of size 0-15, 16-31, ..., 4080-4095, and 4096+. These values can be accessed via the XML and JSON statistics channels at, for example, http://localhost:8888/xml/v3/traffic or http://localhost:8888/json/v1/traffic.
Statistics for RSSAC02v3 traffic-volume, traffic-sizes and rcode-volume reporting are now collected.
A new DNSSEC key management utility,
dnssec-keymgr, has been added. This tool
is meant to run unattended (e.g., under cron).
It reads a policy definition file
(default /etc/dnssec-policy.conf)
and creates or updates DNSSEC keys as necessary to ensure that a
zone's keys match the defined policy for that zone. New keys are
created whenever necessary to ensure rollovers occur correctly.
Existing keys' timing metadata is adjusted as needed to set the
correct rollover period, prepublication interval, etc. If
the configured policy changes, keys are corrected automatically.
See the dnssec-keymgr man page for full details.
Note: dnssec-keymgr depends on Python and on the Python lex/yacc module, PLY. The other Python-based tools, dnssec-coverage and dnssec-checkds, have been refactored and updated as part of this work.
dnssec-keymgr now takes a -r
randomfile option.
(Many thanks to Sebastin Castro for his assistance in developing this tool at the IETF 95 Hackathon in Buenos Aires, April 2016.)
The serial number of a dynamically updatable zone can
now be set using
rndc signing -serial number zonename.
This is particularly useful with inline-signing
zones that have been reset. Setting the serial number to a value
larger than that on the slaves will trigger an AXFR-style
transfer.
When answering recursive queries, SERVFAIL responses can now be
cached by the server for a limited time; subsequent queries for
the same query name and type will return another SERVFAIL until
the cache times out. This reduces the frequency of retries
when a query is persistently failing, which can be a burden
on recursive servers. The SERVFAIL cache timeout is controlled
by servfail-ttl, which defaults to 1 second
and has an upper limit of 30.
The new rndc nta command can now be used to
set a "negative trust anchor" (NTA), disabling DNSSEC validation for
a specific domain; this can be used when responses from a domain
are known to be failing validation due to administrative error
rather than because of a spoofing attack. NTAs are strictly
temporary; by default they expire after one hour, but can be
configured to last up to one week. The default NTA lifetime
can be changed by setting the nta-lifetime in
named.conf. When added, NTAs are stored in a
file (viewname.nta
The EDNS Client Subnet (ECS) option is now supported for
authoritative servers; if a query contains an ECS option then
ACLs containing geoip or ecs
elements can match against the address encoded in the option.
This can be used to select a view for a query, so that different
answers can be provided depending on the client network.
The EDNS EXPIRE option has been implemented on the client side, allowing a slave server to set the expiration timer correctly when transferring zone data from another slave server.
A new masterfile-style zone option controls
the formatting of text zone files: When set to
full, the zone file will dumped in
single-line-per-record format.
dig +ednsopt can now be used to set arbitrary EDNS options in DNS requests.
dig +ednsflags can now be used to set yet-to-be-defined EDNS flags in DNS requests.
dig +[no]ednsnegotiation can now be used enable / disable EDNS version negotiation.
dig +header-only can now be used to send queries without a question section.
dig +ttlunits causes dig to print TTL values with time-unit suffixes: w, d, h, m, s for weeks, days, hours, minutes, and seconds.
dig +zflag can be used to set the last unassigned DNS header flag bit. This bit is normally zero.
dig +dscp=value
can now be used to set the DSCP code point in outgoing query
packets.
dig +mapped can now be used to determine if mapped IPv4 addresses can be used.
nslookup will now look up IPv6 as well as IPv4 addresses by default. [RT #40420]
serial-update-method can now be set to
date. On update, the serial number will
be set to the current date in YYYYMMDDNN format.
dnssec-signzone -N date also sets the serial number to YYYYMMDDNN.
named -L filename
causes named to send log messages to the
specified file by default instead of to the system log.
The rate limiter configured by the
serial-query-rate option no longer covers
NOTIFY messages; those are now separately controlled by
notify-rate and
startup-notify-rate (the latter of which
controls the rate of NOTIFY messages sent when the server
is first started up or reconfigured).
The default number of tasks and client objects available
for serving lightweight resolver queries have been increased,
and are now configurable via the new lwres-tasks
and lwres-clients options in
named.conf. [RT #35857]
Log output to files can now be buffered by specifying buffered yes; when creating a channel.
delv +tcp will exclusively use TCP when sending queries.
named will now check to see whether
other name server processes are running before starting up.
This is implemented in two ways: 1) by refusing to start
if the configured network interfaces all return "address
in use", and 2) by attempting to acquire a lock on a file
specified by the lock-file option or
the -X command line option. The
default lock file is
/var/run/named/named.lock.
Specifying none will disable the lock
file check.
rndc delzone can now be applied to zones
which were configured in named.conf;
it is no longer restricted to zones which were added by
rndc addzone. (Note, however, that
this does not edit named.conf; the zone
must be removed from the configuration or it will return
when named is restarted or reloaded.)
rndc modzone can be used to reconfigure a zone, using similar syntax to rndc addzone.
rndc showzone displays the current configuration for a specified zone.
When BIND is built with the lmdb library (Lightning Memory-Mapped Database), named will store the configuration information for zones that are added via rndc addzone in a database, rather than in a flat "NZF" file. This dramatically improves performance for rndc delzone and rndc modzone: deleting or changing the contents of a database is much faster than rewriting a text file.
On startup, if named finds an existing NZF file, it will automatically convert it to the new NZD database format.
To view the contents of an NZD, or to convert an NZD back to an NZF file (for example, to revert back to an earlier version of BIND which did not support the NZD format), use the new command named-nzd2nzf [RT #39837]
Added server-side support for pipelined TCP queries. Clients may continue sending queries via TCP while previous queries are processed in parallel. Responses are sent when they are ready, not necessarily in the order in which the queries were received.
To revert to the former behavior for a particular client address or range of addresses, specify the address prefix in the "keep-response-order" option. To revert to the former behavior for all clients, use "keep-response-order { any; };".
The new mdig command is a version of dig that sends multiple pipelined queries and then waits for responses, instead of sending one query and waiting the response before sending the next. [RT #38261]
To enable better monitoring and troubleshooting of RFC 5011 trust anchor management, the new rndc managed-keys can be used to check status of trust anchors or to force keys to be refreshed. Also, the managed-keys data file now has easier-to-read comments. [RT #38458]
An --enable-querytrace configure switch is now available to enable very verbose query trace logging. This option can only be set at compile time. This option has a negative performance impact and should be used only for debugging. [RT #37520]
A new tcp-only option can be specified in server statements to force named to connect to the specified server via TCP. [RT #37800]
The nxdomain-redirect option specifies a DNS namespace to use for NXDOMAIN redirection. When a recursive lookup returns NXDOMAIN, a second lookup is initiated with the specified name appended to the query name. This allows NXDOMAIN redirection data to be supplied by multiple zones configured on the server, or by recursive queries to other servers. (The older method, using a single type redirect zone, has better average performance but is less flexible.) [RT #37989]
The following types have been implemented: CSYNC, NINFO, RKEY, SINK, TA, TALINK.
A new message-compression option can be
used to specify whether or not to use name compression when
answering queries. Setting this to no
results in larger responses, but reduces CPU consumption and
may improve throughput. The default is yes.
A read-only option is now available in the controls statement to grant non-destructive control channel access. In such cases, a restricted set of rndc commands are allowed, which can report information from named, but cannot reconfigure or stop the server. By default, the control channel access is not restricted to these read-only operations. [RT #40498]
When loading a signed zone, named will now check whether an RRSIG's inception time is in the future, and if so, it will regenerate the RRSIG immediately. This helps when a system's clock needs to be reset backwards.
The new minimal-any option reduces the size of answers to UDP queries for type ANY by implementing one of the strategies in "draft-ietf-dnsop-refuse-any": returning a single arbitrarily-selected RRset that matches the query name rather than returning all of the matching RRsets. Thanks to Tony Finch for the contribution. [RT #41615]
named now provides feedback to the owners of zones which have trust anchors configured (trusted-keys, managed-keys, dnssec-validation auto; and dnssec-lookaside auto;) by sending a daily query which encodes the keyids of the configured trust anchors for the zone. This is controlled by trust-anchor-telemetry and defaults to yes.
The logging format used for querylog has been altered. It now includes an additional field indicating the address in memory of the client object processing the query.
The ISC DNSSEC Lookaside Validation (DLV) service is scheduled
to be disabled in 2017. A warning is now logged when
named is configured to use this service,
either explicitly or via dnssec-lookaside auto;.
[RT #42207]
The timers returned by the statistics channel (indicating current time, server boot time, and most recent reconfiguration time) are now reported with millisecond accuracy. [RT #40082]
Updated the compiled-in addresses for H.ROOT-SERVERS.NET and L.ROOT-SERVERS.NET.
ACLs containing geoip asnum elements were not correctly matched unless the full organization name was specified in the ACL (as in geoip asnum "AS1234 Example, Inc.";). They can now match against the AS number alone (as in geoip asnum "AS1234";).
When using native PKCS#11 cryptography (i.e., configure --enable-native-pkcs11) HSM PINs of up to 256 characters can now be used.
NXDOMAIN responses to queries of type DS are now cached separately from those for other types. This helps when using "grafted" zones of type forward, for which the parent zone does not contain a delegation, such as local top-level domains. Previously a query of type DS for such a zone could cause the zone apex to be cached as NXDOMAIN, blocking all subsequent queries. (Note: This change is only helpful when DNSSEC validation is not enabled. "Grafted" zones without a delegation in the parent are not a recommended configuration.)
Update forwarding performance has been improved by allowing a single TCP connection to be shared between multiple updates.
By default, nsupdate will now check the correctness of hostnames when adding records of type A, AAAA, MX, SOA, NS, SRV or PTR. This behavior can be disabled with check-names no.
Added support for OPENPGPKEY type.
The names of the files used to store managed keys and added
zones for each view are no longer based on the SHA256 hash
of the view name, except when this is necessary because the
view name contains characters that would be incompatible with use
as a file name. For views whose names do not contain forward
slashes ('/'), backslashes ('\'), or capital letters - which
could potentially cause namespace collision problems on
case-insensitive filesystems - files will now be named
after the view (for example, internal.mkeys
or external.nzf). However, to ensure
consistent behavior when upgrading, if a file using the old
name format is found to exist, it will continue to be used.
"rndc" can now return text output of arbitrary size to the caller. (Prior to this, certain commands such as "rndc tsig-list" and "rndc zonestatus" could return truncated output.)
Errors reported when running rndc addzone (e.g., when a zone file cannot be loaded) have been clarified to make it easier to diagnose problems.
When encountering an authoritative name server whose name is an alias pointing to another name, the resolver treats this as an error and skips to the next server. Previously this happened silently; now the error will be logged to the newly-created "cname" log category.
If named is not configured to validate answers, then allow fallback to plain DNS on timeout even when we know the server supports EDNS. This will allow the server to potentially resolve signed queries when TCP is being blocked.
Large inline-signing changes should be less disruptive.
Signature generation is now done incrementally; the number
of signatures to be generated in each quantum is controlled
by "sig-signing-signatures number;".
[RT #37927]
The experimental SIT option (code point 65001) of BIND 9.10.0 through BIND 9.10.2 has been replaced with the COOKIE option (code point 10). It is no longer experimental, and is sent by default, by both named and dig.
The SIT-related named.conf options have been marked as obsolete, and are otherwise ignored.
When dig receives a truncated (TC=1) response or a BADCOOKIE response code from a server, it will automatically retry the query using the server COOKIE that was returned by the server in its initial response. [RT #39047]
Retrieving the local port range from net.ipv4.ip_local_port_range on Linux is now supported.
A new nsip-wait-recurse directive has been
added to RPZ, specifying whether to look up unknown name server
IP addresses and wait for a response before applying RPZ-NSIP rules.
The default is yes. If set to
no, named will only
apply RPZ-NSIP rules to servers whose addresses are already cached.
The addresses will be looked up in the background so the rule can
be applied on subsequent queries. This improves performance when
the cache is cold, at the cost of temporary imprecision in applying
policy directives. [RT #35009]
Within the response-policy option, it is now
possible to configure RPZ rewrite logging on a per-zone basis
using the log clause.
The default preferred glue is now the address type of the transport the query was received over.
On machines with 2 or more processors (CPU), the default value for the number of UDP listeners has been changed to the number of detected processors minus one.
Zone transfers now use smaller message sizes to improve message compression. This results in reduced network usage.
Added support for the AVC resource record type (Application Visibility and Control).
Changed rndc reconfig behavior so that newly added zones are loaded asynchronously and the loading does not block the server.
minimal-responses now takes two new
arguments: no-auth suppresses
populating the authority section but not the additional
section; no-auth-recursive
does the same but only when answering recursive queries.
At server startup time, the queues for processing notify and zone refresh queries are now processed in LIFO rather than FIFO order, to speed up loading of newly added zones. [RT #42825]
When answering queries of type MX or SRV, TLSA records for the target name are now included in the additional section to speed up DANE processing. [RT #42894]
named can now use the TCP Fast Open mechanism on the server side, if supported by the local operating system. [RT #42866]
Fixed a crash when calling rndc stats on some Windows builds: some Visual Studio compilers generate code that crashes when the "%z" printf() format specifier is used. [RT #42380]
Windows installs were failing due to triggering UAC without the installation binary being signed.
A change in the internal binary representation of the RBT database node structure enabled a race condition to occur (especially when BIND was built with certain compilers or optimizer settings), leading to inconsistent database state which caused random assertion failures. [RT #42380]
BIND 9.11 (Extended Support Version) will be supported until at least December, 2021.
See https://kb.isc.org/docs/aa-00896 for details of ISC's software support policy.
BIND 9.11.36 (Extended Support Version)
man.delv.html 0000644 00000056400 15253021417 0007143 0 ustar 00delv — DNS lookup and validation utility
delv [@server] [[-4] | [-6]] [-a ] [anchor-file-b ] [address-c ] [class-d ] [level-i] [-m] [-p ] [port#-q ] [name-t ] [type-x ] [name] [type] [class] [queryopt...]addr
delv [-h]
delv [-v]
delv [queryopt...] [query...]
delv is a tool for sending DNS queries and validating the results, using the same internal resolver and validator logic as named.
delv will send to a specified name server all queries needed to fetch and validate the requested data; this includes the original requested query, subsequent queries to follow CNAME or DNAME chains, and queries for DNSKEY, DS and DLV records to establish a chain of trust for DNSSEC validation. It does not perform iterative resolution, but simulates the behavior of a name server configured for DNSSEC validating and forwarding.
By default, responses are validated using built-in DNSSEC trust anchor for the root zone ("."). Records returned by delv are either fully validated or were not signed. If validation fails, an explanation of the failure is included in the output; the validation process can be traced in detail. Because delv does not rely on an external server to carry out validation, it can be used to check the validity of DNS responses in environments where local name servers may not be trustworthy.
Unless it is told to query a specific name server,
delv will try each of the servers listed in
/etc/resolv.conf. If no usable server
addresses are found, delv will send
queries to the localhost addresses (127.0.0.1 for IPv4, ::1
for IPv6).
When no command line arguments or options are given, delv will perform an NS query for "." (the root zone).
A typical invocation of delv looks like:
delv @server name type
where:
server
is the name or IP address of the name server to query. This
can be an IPv4 address in dotted-decimal notation or an IPv6
address in colon-delimited notation. When the supplied
server argument is a hostname,
delv resolves that name before
querying that name server (note, however, that this
initial lookup is not validated
by DNSSEC).
If no server argument is
provided, delv consults
/etc/resolv.conf; if an
address is found there, it queries the name server at
that address. If either of the -4 or
-6 options are in use, then
only addresses for the corresponding transport
will be tried. If no usable addresses are found,
delv will send queries to
the localhost addresses (127.0.0.1 for IPv4,
::1 for IPv6).
nameis the domain name to be looked up.
type
indicates what type of query is required —
ANY, A, MX, etc.
type can be any valid query
type. If no
type argument is supplied,
delv will perform a lookup for an
A record.
anchor-file
Specifies a file from which to read DNSSEC trust anchors.
The default is /etc/bind.keys, which
is included with BIND 9 and contains
one or more trust anchors for the root zone (".").
Keys that do not match the root zone name are ignored.
An alternate key name can be specified using the
+root=NAME options. DNSSEC Lookaside
Validation can also be turned on by using the
+dlv=NAME to specify the name of a
zone containing DLV records.
Note: When reading the trust anchor file,
delv treats managed-keys
statements and trusted-keys statements
identically. That is, for a managed key, it is the
initial key that is trusted; RFC 5011
key management is not supported. delv
will not consult the managed-keys database maintained by
named. This means that if either of the
keys in /etc/bind.keys is revoked
and rolled over, it will be necessary to update
/etc/bind.keys to use DNSSEC
validation in delv.
address
Sets the source IP address of the query to
address. This must be a valid address
on one of the host's network interfaces or "0.0.0.0" or "::".
An optional source port may be specified by appending
"#<port>"
classSets the query class for the requested data. Currently, only class "IN" is supported in delv and any other value is ignored.
level
Set the systemwide debug level to level.
The allowed range is from 0 to 99.
The default is 0 (no debugging).
Debugging traces from delv become
more verbose as the debug level increases.
See the +mtrace, +rtrace,
and +vtrace options below for additional
debugging details.
Display the delv help usage output and exit.
Insecure mode. This disables internal DNSSEC validation. (Note, however, this does not set the CD bit on upstream queries. If the server being queried is performing DNSSEC validation, then it will not return invalid data; this can cause delv to time out. When it is necessary to examine invalid data to debug a DNSSEC problem, use dig +cd.)
Enables memory usage debugging.
port#Specifies a destination port to use for queries instead of the standard DNS port number 53. This option would be used with a name server that has been configured to listen for queries on a non-standard port number.
name
Sets the query name to name.
While the query name can be specified without using the
-q, it is sometimes necessary to disambiguate
names from types or classes (for example, when looking up the
name "ns", which could be misinterpreted as the type NS,
or "ch", which could be misinterpreted as class CH).
type
Sets the query type to type, which
can be any valid query type supported in BIND 9 except
for zone transfer types AXFR and IXFR. As with
-q, this is useful to distinguish
query name type or class when they are ambiguous.
it is sometimes necessary to disambiguate names from types.
The default query type is "A", unless the -x
option is supplied to indicate a reverse lookup, in which case
it is "PTR".
Print the delv version and exit.
addr
Performs a reverse lookup, mapping an addresses to
a name. addr is an IPv4 address in
dotted-decimal notation, or a colon-delimited IPv6 address.
When -x is used, there is no need to provide
the name or type
arguments. delv automatically performs a
lookup for a name like 11.12.13.10.in-addr.arpa
and sets the query type to PTR. IPv6 addresses are looked up
using nibble format under the IP6.ARPA domain.
Forces delv to only use IPv4.
Forces delv to only use IPv6.
delv provides a number of query options which affect the way results are displayed, and in some cases the way lookups are performed.
Each query option is identified by a keyword preceded by a plus sign
(+). Some keywords set or reset an
option. These may be preceded by the string
no to negate the meaning of that keyword.
Other keywords assign values to options like the timeout interval.
They have the form +keyword=value.
The query options are:
+[no]cdflagControls whether to set the CD (checking disabled) bit in queries sent by delv. This may be useful when troubleshooting DNSSEC problems from behind a validating resolver. A validating resolver will block invalid responses, making it difficult to retrieve them for analysis. Setting the CD flag on queries will cause the resolver to return invalid responses, which delv can then validate internally and report the errors in detail.
+[no]classControls whether to display the CLASS when printing a record. The default is to display the CLASS.
+[no]ttlControls whether to display the TTL when printing a record. The default is to display the TTL.
+[no]rtraceToggle resolver fetch logging. This reports the name and type of each query sent by delv in the process of carrying out the resolution and validation process: this includes including the original query and all subsequent queries to follow CNAMEs and to establish a chain of trust for DNSSEC validation.
This is equivalent to setting the debug level to 1 in
the "resolver" logging category. Setting the systemwide
debug level to 1 using the -d option will
product the same output (but will affect other logging
categories as well).
+[no]mtraceToggle message logging. This produces a detailed dump of the responses received by delv in the process of carrying out the resolution and validation process.
This is equivalent to setting the debug level to 10
for the "packets" module of the "resolver" logging
category. Setting the systemwide debug level to 10 using
the -d option will produce the same output
(but will affect other logging categories as well).
+[no]vtraceToggle validation logging. This shows the internal process of the validator as it determines whether an answer is validly signed, unsigned, or invalid.
This is equivalent to setting the debug level to 3
for the "validator" module of the "dnssec" logging
category. Setting the systemwide debug level to 3 using
the -d option will produce the same output
(but will affect other logging categories as well).
+[no]shortProvide a terse answer. The default is to print the answer in a verbose form.
+[no]commentsToggle the display of comment lines in the output. The default is to print comments.
+[no]rrcommentsToggle the display of per-record comments in the output (for example, human-readable key information about DNSKEY records). The default is to print per-record comments.
+[no]cryptoToggle the display of cryptographic fields in DNSSEC records. The contents of these field are unnecessary to debug most DNSSEC validation failures and removing them makes it easier to see the common failures. The default is to display the fields. When omitted they are replaced by the string "[omitted]" or in the DNSKEY case the key id is displayed as the replacement, e.g. "[ key id = value ]".
+[no]trustControls whether to display the trust level when printing a record. The default is to display the trust level.
+[no]split[=W]
Split long hex- or base64-formatted fields in resource
records into chunks of W characters
(where W is rounded up to the nearest
multiple of 4).
+nosplit or
+split=0 causes fields not to be
split at all. The default is 56 characters, or 44 characters
when multiline mode is active.
+[no]all
Set or clear the display options
+[no]comments,
+[no]rrcomments, and
+[no]trust as a group.
+[no]multilinePrint long records (such as RRSIG, DNSKEY, and SOA records) in a verbose multi-line format with human-readable comments. The default is to print each record on a single line, to facilitate machine parsing of the delv output.
+[no]dnssec
Indicates whether to display RRSIG records in the
delv output. The default is to
do so. Note that (unlike in dig)
this does not control whether to
request DNSSEC records or whether to validate them.
DNSSEC records are always requested, and validation
will always occur unless suppressed by the use of
-i or +noroot and
+nodlv.
+[no]root[=ROOT]
Indicates whether to perform conventional (non-lookaside)
DNSSEC validation, and if so, specifies the
name of a trust anchor. The default is to validate using
a trust anchor of "." (the root zone), for which there is
a built-in key. If specifying a different trust anchor,
then -a must be used to specify a file
containing the key.
+[no]dlv[=DLV]
Indicates whether to perform DNSSEC lookaside validation,
and if so, specifies the name of the DLV trust anchor.
The -a option must also be used to specify
a file containing the DLV key.
+[no]tcpControls whether to use TCP when sending queries. The default is to use UDP unless a truncated response has been received.
+[no]unknownformatPrint all RDATA in unknown RR type presentation format (RFC 3597). The default is to print RDATA for known types in the type's presentation format.
BIND 9.11.36 (Extended Support Version)
man.lwresd.html 0000644 00000027422 15253021417 0007513 0 ustar 00lwresd — lightweight resolver daemon
lwresd [-c ] [config-file-C ] [config-file-d ] [debug-level-f] [-g] [-i ] [pid-file-m ] [flag-n ] [#cpus-P ] [port-p ] [port-s] [-t ] [directory-u ] [user-v] [[-4] | [-6]]
lwresd is the daemon providing name lookup services to clients that use the BIND 9 lightweight resolver library. It is essentially a stripped-down, caching-only name server that answers queries using the BIND 9 lightweight resolver protocol rather than the DNS protocol.
lwresd listens for resolver queries on a UDP port on the IPv4 loopback interface, 127.0.0.1. This means that lwresd can only be used by processes running on the local machine. By default, UDP port number 921 is used for lightweight resolver requests and responses.
Incoming lightweight resolver requests are decoded by the server which then resolves them using the DNS protocol. When the DNS lookup completes, lwresd encodes the answers in the lightweight resolver format and returns them to the client that made the request.
If /etc/resolv.conf contains any
nameserver entries, lwresd
sends recursive DNS queries to those servers. This is similar
to the use of forwarders in a caching name server. If no
nameserver entries are present, or if
forwarding fails, lwresd resolves the
queries autonomously starting at the root name servers, using
a built-in list of root server hints.
Use IPv4 only even if the host machine is capable of IPv6.
-4 and -6 are mutually
exclusive.
Use IPv6 only even if the host machine is capable of IPv4.
-4 and -6 are mutually
exclusive.
config-file
Use config-file as the
configuration file instead of the default,
/etc/lwresd.conf.
-c can not be used with -C.
config-file
Use config-file as the
configuration file instead of the default,
/etc/resolv.conf.
-C can not be used with -c.
debug-level
Set the daemon's debug level to debug-level.
Debugging traces from lwresd become
more verbose as the debug level increases.
Run the server in the foreground (i.e. do not daemonize).
Run the server in the foreground and force all logging
to stderr.
pid-file
Use pid-file as the
PID file instead of the default,
/var/run/lwresd/lwresd.pid.
flag
Turn on memory usage debugging flags. Possible flags are
usage,
trace,
record,
size, and
mctx.
These correspond to the ISC_MEM_DEBUGXXXX flags described in
<isc/mem.h>.
#cpus
Create #cpus worker threads
to take advantage of multiple CPUs. If not specified,
lwresd will try to determine the
number of CPUs present and create one thread per CPU.
If it is unable to determine the number of CPUs, a
single worker thread will be created.
port
Listen for lightweight resolver queries on port
port. If
not specified, the default is port 921.
port
Send DNS lookups to port port. If not
specified, the default is port 53. This provides a
way of testing the lightweight resolver daemon with a
name server that listens for queries on a non-standard
port number.
Write memory usage statistics to stdout
on exit.
This option is mainly of interest to BIND 9 developers and may be removed or changed in a future release.
directoryChroot
to directory after
processing the command line arguments, but before
reading the configuration file.
This option should be used in conjunction with the
-u option, as chrooting a process
running as root doesn't enhance security on most
systems; the way chroot(2) is
defined allows a process with root privileges to
escape a chroot jail.
userSetuid
to user after completing
privileged operations, such as creating sockets that
listen on privileged ports.
Report the version number and exit.
BIND 9.11.36 (Extended Support Version)
Bv9ARM.ch13.html 0000644 00000023253 15253021417 0007174 0 ustar 00Table of Contents
named.conf — configuration file for named
rndc.conf — rndc configuration file
BIND 9.11.36 (Extended Support Version)
man.dnssec-coverage.html 0000644 00000025606 15253021417 0011265 0 ustar 00dnssec-coverage — checks future DNSKEY coverage for a zone
dnssec-coverage [-K ] [directory-l ] [length-f ] [file-d ] [DNSKEY TTL-m ] [max TTL-r ] [interval-c ] [compilezone path-k] [-z] [zone...]
dnssec-coverage verifies that the DNSSEC keys for a given zone or a set of zones have timing metadata set properly to ensure no future lapses in DNSSEC coverage.
If zone is specified, then keys found in
the key repository matching that zone are scanned, and an ordered
list is generated of the events scheduled for that key (i.e.,
publication, activation, inactivation, deletion). The list of
events is walked in order of occurrence. Warnings are generated
if any event is scheduled which could cause the zone to enter a
state in which validation failures might occur: for example, if
the number of published or active keys for a given algorithm drops
to zero, or if a key is deleted from the zone too soon after a new
key is rolled, and cached data signed by the prior key has not had
time to expire from resolver caches.
If zone is not specified, then all keys in the
key repository will be scanned, and all zones for which there are
keys will be analyzed. (Note: This method of reporting is only
accurate if all the zones that have keys in a given repository
share the same TTL parameters.)
directorySets the directory in which keys can be found. Defaults to the current working directory.
file
If a file is specified, then the zone is
read from that file; the largest TTL and the DNSKEY TTL are
determined directly from the zone data, and the
-m and -d options do
not need to be specified on the command line.
duration
The length of time to check for DNSSEC coverage. Key events
scheduled further into the future than duration
will be ignored, and assumed to be correct.
The value of duration can be set in seconds,
or in larger units of time by adding a suffix: 'mi' for minutes,
'h' for hours, 'd' for days, 'w' for weeks, 'mo' for months,
'y' for years.
maximum TTLSets the value to be used as the maximum TTL for the zone or zones being analyzed when determining whether there is a possibility of validation failure. When a zone-signing key is deactivated, there must be enough time for the record in the zone with the longest TTL to have expired from resolver caches before that key can be purged from the DNSKEY RRset. If that condition does not apply, a warning will be generated.
The length of the TTL can be set in seconds, or in larger units of time by adding a suffix: 'mi' for minutes, 'h' for hours, 'd' for days, 'w' for weeks, 'mo' for months, 'y' for years.
This option is not necessary if the -f has
been used to specify a zone file. If -f has
been specified, this option may still be used; it will override
the value found in the file.
If this option is not used and the maximum TTL cannot be retrieved from a zone file, a warning is generated and a default value of 1 week is used.
DNSKEY TTLSets the value to be used as the DNSKEY TTL for the zone or zones being analyzed when determining whether there is a possibility of validation failure. When a key is rolled (that is, replaced with a new key), there must be enough time for the old DNSKEY RRset to have expired from resolver caches before the new key is activated and begins generating signatures. If that condition does not apply, a warning will be generated.
The length of the TTL can be set in seconds, or in larger units of time by adding a suffix: 'mi' for minutes, 'h' for hours, 'd' for days, 'w' for weeks, 'mo' for months, 'y' for years.
This option is not necessary if -f has
been used to specify a zone file from which the TTL
of the DNSKEY RRset can be read, or if a default key TTL was
set using ith the -L to
dnssec-keygen. If either of those is true,
this option may still be used; it will override the values
found in the zone file or the key file.
If this option is not used and the key TTL cannot be retrieved from the zone file or the key file, then a warning is generated and a default value of 1 day is used.
resign interval
Sets the value to be used as the resign interval for the zone
or zones being analyzed when determining whether there is a
possibility of validation failure. This value defaults to
22.5 days, which is also the default in
named. However, if it has been changed
by the sig-validity-interval option in
named.conf, then it should also be
changed here.
The length of the interval can be set in seconds, or in larger units of time by adding a suffix: 'mi' for minutes, 'h' for hours, 'd' for days, 'w' for weeks, 'mo' for months, 'y' for years.
Only check KSK coverage; ignore ZSK events. Cannot be
used with -z.
Only check ZSK coverage; ignore KSK events. Cannot be
used with -k.
compilezone pathSpecifies a path to a named-compilezone binary. Used for testing.
BIND 9.11.36 (Extended Support Version)
man.pkcs11-list.html 0000644 00000012257 15253021417 0010266 0 ustar 00pkcs11-list — list PKCS#11 objects
pkcs11-list [-P] [-m ] [module-s ] [-i slotID] [-l label] [-p ]PIN
pkcs11-list
lists the PKCS#11 objects with ID or
label or by default all objects.
The object class, label, and ID are displayed for all
keys. For private or secret keys, the extractability
attribute is also displayed, as either true,
false, or never.
List only the public objects. (Note that on some PKCS#11 devices, all objects are private.)
moduleSpecify the PKCS#11 provider module. This must be the full path to a shared library object implementing the PKCS#11 API for the device.
slotOpen the session with the given PKCS#11 slot. The default is slot 0.
IDList only key objects with the given object ID.
labelList only key objects with the given label.
PINSpecify the PIN for the device. If no PIN is provided on the command line, pkcs11-list will prompt for it.
BIND 9.11.36 (Extended Support Version)
Bv9ARM.ch10.html 0000644 00000015757 15253021417 0007203 0 ustar 00Although the Domain Name System "officially" began in 1984 with the publication of RFC 920, the core of the new system was described in 1983 in RFCs 882 and 883. From 1984 to 1987, the ARPAnet (the precursor to today's Internet) became a testbed of experimentation for developing the new naming/addressing scheme in a rapidly expanding, operational network environment. New RFCs were written and published in 1987 that modified the original documents to incorporate improvements based on the working model. RFC 1034, "Domain Names-Concepts and Facilities," and RFC 1035, "Domain Names-Implementation and Specification," were published and became the standards upon which all DNS implementations are built.
The first working domain name server, called "Jeeves," was written in 1983-84 by Paul Mockapetris for operation on DEC Tops-20 machines located at the University of Southern California's Information Sciences Institute (USC-ISI) and SRI International's Network Information Center (SRI-NIC). A DNS server for Unix machines, the Berkeley Internet Name Domain (BIND) package, was written soon after by a group of graduate students at the University of California at Berkeley under a grant from the US Defense Advanced Research Projects Administration (DARPA).
Versions of BIND through 4.8.3 were maintained by the Computer Systems Research Group (CSRG) at UC Berkeley. Douglas Terry, Mark Painter, David Riggle, and Songnian Zhou made up the initial BIND project team. After that, additional work on the software package was done by Ralph Campbell. Kevin Dunlap, a Digital Equipment Corporation employee on loan to the CSRG, worked on BIND for 2 years, from 1985 to 1987. Many other people also contributed to BIND development during that time: Doug Kingston, Craig Partridge, Smoot Carl-Mitchell, Mike Muuss, Jim Bloom and Mike Schwartz. BIND maintenance was subsequently handled by Mike Karels and ivind Kure.
BIND versions 4.9 and 4.9.1 were released by Digital Equipment Corporation (which became Compaq Computer Corporation and eventually merged with Hewlett-Packard). Paul Vixie, then a DEC employee, became BIND's primary caretaker. He was assisted by Phil Almquist, Robert Elz, Alan Barrett, Paul Albitz, Bryan Beecher, Andrew Partan, Andy Cherenson, Tom Limoncelli, Berthold Paffrath, Fuat Baran, Anant Kumar, Art Harkin, Win Treese, Don Lewis, Christophe Wolfhugel, and others.
In 1994, BIND version 4.9.2 was sponsored by Vixie Enterprises. Paul Vixie became BIND's principal architect/programmer.
BIND versions from 4.9.3 onward have been developed and maintained by Internet Systems Consortium and its predecessor, the Internet Software Consortium, with support provided by ISC's sponsors.
As co-architects/programmers, Bob Halley and Paul Vixie released the first production-ready version of BIND version 8 in May 1997.
BIND version 9 was released in September 2000 and is a major rewrite of nearly all aspects of the underlying BIND architecture.
BIND versions 4 and 8 are officially deprecated. No additional development is done on BIND version 4 or BIND version 8.
BIND development work is made possible today by the sponsorship of corporations who purchase professional support services from ISC (https://www.isc.org/contact/) and/or donate to our mission, and by the tireless efforts of numerous individuals.
BIND 9.11.36 (Extended Support Version)
man.dnssec-verify.html 0000644 00000016206 15253021417 0010772 0 ustar 00dnssec-verify — DNSSEC zone verification tool
dnssec-verify [-c ] [class-E ] [engine-I ] [input-format-o ] [origin-v ] [level-V] [-x] [-z] {zonefile}
dnssec-verify verifies that a zone is fully signed for each algorithm found in the DNSKEY RRset for the zone, and that the NSEC / NSEC3 chains are complete.
classSpecifies the DNS class of the zone.
engineSpecifies the cryptographic hardware to use, when applicable.
When BIND is built with OpenSSL PKCS#11 support, this defaults to the string "pkcs11", which identifies an OpenSSL engine that can drive a cryptographic accelerator or hardware service module. When BIND is built with native PKCS#11 cryptography (--enable-native-pkcs11), it defaults to the path of the PKCS#11 provider library specified via "--with-pkcs11".
input-formatThe format of the input zone file. Possible formats are "text" (default) and "raw". This option is primarily intended to be used for dynamic signed zones so that the dumped zone file in a non-text format containing updates can be verified independently. The use of this option does not make much sense for non-dynamic zones.
originThe zone origin. If not specified, the name of the zone file is assumed to be the origin.
levelSets the debugging level.
Prints version information.
Only verify that the DNSKEY RRset is signed with key-signing
keys. Without this flag, it is assumed that the DNSKEY RRset
will be signed by all active keys. When this flag is set,
it will not be an error if the DNSKEY RRset is not signed
by zone-signing keys. This corresponds to the -x
option in dnssec-signzone.
Ignore the KSK flag on the keys when determining whether the zone if correctly signed. Without this flag it is assumed that there will be a non-revoked, self-signed DNSKEY with the KSK flag set for each algorithm and that RRsets other than DNSKEY RRset will be signed with a different DNSKEY without the KSK flag set.
With this flag set, we only require that for each algorithm,
there will be at least one non-revoked, self-signed DNSKEY,
regardless of the KSK flag state, and that other RRsets
will be signed by a non-revoked key for the same algorithm
that includes the self-signed key; the same key may be used
for both purposes. This corresponds to the -z
option in dnssec-signzone.
The file containing the zone to be signed.
BIND 9.11.36 (Extended Support Version)
man.named-rrchecker.html 0000644 00000010101 15253021417 0011227 0 ustar 00named-rrchecker — syntax checker for individual DNS resource records
named-rrchecker [-h] [-o ] [origin-p] [-u] [-C] [-T] [-P]
named-rrchecker read a individual DNS resource record from standard input and checks if it is syntactically correct.
The -h prints out the help menu.
The -o
option specifies a origin to be used when interpreting the record.
origin
The -p prints out the resulting record in canonical
form. If there is no canonical form defined then the record will be
printed in unknown record format.
The -u prints out the resulting record in unknown record
form.
The -C, -T and -P
print out the known class, standard type and private type mnemonics
respectively.
BIND 9.11.36 (Extended Support Version)
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