Table of Contents
BIND 9 configuration is broadly similar to BIND 8; however, there are a few new areas of configuration, such as views. BIND 8 configuration files should work with few alterations in BIND 9, although more complex configurations should be reviewed to check if they can be more efficiently implemented using the new features found in BIND 9.
BIND 4 configuration files can be
converted to the new format
using the shell script
contrib/named-bootconf/named-bootconf.sh.
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 will be used as
a DNS name, for example " |
|
|
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 delimiter. It is strongly recommended to use string zone names rather than numeric identifiers, in order to be robust against system configuration changes. However, since there is no standard mapping for such names and identifier values, currently 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 the ambiguity, and need to be disambiguated. |
|
|
An |
|
|
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 will match 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 further be limited by the context in which it is used. |
|
|
A quoted string which will be used as
a pathname, such as |
|
|
A number, the word
An
A
The value must be representable as a 64-bit unsigned integer
(0 to 18446744073709551615, inclusive).
Using |
|
|
Either |
|
|
One of |
address_match_list= address_match_list_element ; [ address_match_list_element; ... ]address_match_list_element= [ ! ] (ip_address [/length] | key key_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, and blackhole all use address match lists. Similarly, the listen-on option will cause the server to refuse queries on any of the machine's addresses which do not match the list.
Order of insertion is signficant. If more than one element in an ACL is found to match a given IP address or prefix, preference will be 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 will match 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 having 1.2.3.13 blocked by the negation, but all other 1.2.3.* hosts fall through.
The BIND 9 comment syntax allows for 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, if you prefer) 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.
You cannot use the semicolon (`;') character to start a comment such as you would 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 the server logs, and where the log messages are sent. |
|
lwres |
configures named to also act as a light-weight resolver daemon (lwresd). |
|
masters |
defines a named masters list for inclusion in stub and slave zone masters clauses. |
|
options |
controls global server configuration options and sets defaults for other statements. |
|
statistics-channels |
declares communication channels to get access to named statistics. |
|
server |
sets certain configuration options on a per-server basis. |
|
trusted-keys |
defines trusted DNSSEC keys. |
|
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 a primary use of address match lists: Access Control Lists (ACLs).
Note that an address match list's name must be defined with acl before it can be used elsewhere; no forward references are allowed.
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. |
|
localnets |
Matches any host on an IPv4 or IPv6 network for which the system has an interface. Some systems do not provide a way to determine the prefix lengths of local IPv6 addresses. In such a case, localnets only matches the local IPv6 addresses, just like localhost. |
controls { [ inet ( ip_addr | * ) [ port ip_port ] allow {address_match_list} keys {key_list}; ] [ inet ...; ] [ unixpathpermnumberownernumbergroupnumberkeys {key_list}; ] [ unix ...; ] };
The controls statement declares control channels to be used by system administrators to control 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 will be
accepted on any of the system's IPv4 addresses.
To listen on the IPv6 wildcard address,
use an ip_addr of ::.
If you will only use rndc 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 no controls statement is present,
named will set 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 will attempt to load the command channel key
from the file rndc.key in
/etc (or whatever sysconfdir
was specified as when BIND was built).
To create a rndc.key file, run
rndc-confgen -a.
The rndc.key feature was created to
ease the transition of systems from BIND 8,
which did not have digital signatures on its command channel
messages and thus did not have a keys clause.
It makes it possible to use an existing BIND 8
configuration file in BIND 9 unchanged,
and still have rndc work the same way
ndc worked in BIND 8, simply by executing the
command rndc-confgen -a after BIND 9 is
installed.
Since the rndc.key feature
is only intended to allow the backward-compatible usage of
BIND 8 configuration files, this
feature does not
have a high degree of configurability. You cannot easily change
the key name or the size of the secret, so you should make a
rndc.conf with your own key if you
wish to change
those things. 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.
If you
desire greater flexibility in allowing other users to access
rndc commands, then you need to 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 uniquely identifying 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. Named
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 base-64
encoded string.
logging { [ channelchannel_name{ ( filepath name[ versions (number| unlimited ) ] [ sizesize spec] | syslogsyslog_facility| stderr | null ); [ severity (critical|error|warning|notice|info|debug[level] |dynamic); ] [ print-categoryyesorno; ] [ print-severityyesorno; ] [ print-timeyesorno; ] }; ] [ categorycategory_name{channel_name; [channel_name; ... ] }; ] ... };
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 are wanted. If there is no logging statement, the logging configuration will be:
logging {
category default { default_syslog; default_debug; };
category unmatched { null; };
};
In BIND 9, the logging configuration
is only established when
the entire configuration file has been parsed. In BIND 8, it was
established as soon as the logging
statement
was parsed. When the server is starting 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; you can make as many of them as you want.
Every channel definition must include a destination clause that says whether messages selected for the channel go to a file, to a particular syslog facility, to the standard error stream, or are discarded. It can optionally also limit the message severity level that will be accepted by the channel (the default is info), and whether to include a named-generated time stamp, the category name and/or 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 how many versions of the file will be saved each time the file is opened.
If you use the versions log file
option, then
named will retain that many backup
versions of the file by
renaming them when opening. For example, if you choose to keep
three old versions
of the file lamers.log, then 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.
You can say versions unlimited 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 will stop writing to the file unless it 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 will be 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.
Example usage of 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 will handle messages sent to this facility is described in the syslog.conf man page. If you have a system which uses a very old version of syslog that only uses two arguments to the openlog() function, then this clause is silently ignored.
The severity clause works like syslog's "priorities", except that they can also be used if you are writing straight to a file rather than using syslog. Messages which are not at least of the severity level given will not be selected for the channel; messages of higher severity levels will be accepted.
If you are using syslog, then the syslog.conf priorities will 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 will cause 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, for example when debugging a configuration.
The server can supply extensive debugging information when
it is in debugging mode. If the server's global debug level is
greater
than zero, then debugging mode will be 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, and 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;
};
will 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 has been turned on, then the date and time will be logged. print-time may be specified for a syslog channel, but is usually pointless since syslog also prints the date and time. If print-category is requested, then the category of the message will be logged as well. Finally, if print-severity is on, then the severity level of the message will be logged. The print- options may be used in any combination, and will always be 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
There are four predefined channels that are used for named's default logging as follows. How they are used is described in the section called “The category Phrase”.
channel default_syslog {
syslog daemon; // send to syslog's daemon
// facility
severity info; // only send priority info
// and higher
};
channel default_debug {
file "named.run"; // write to named.run in
// the working directory
// Note: stderr is used instead
// of "named.run"
// if the server is started
// with the '-f' option.
severity dynamic; // log at the server's
// current debug level
};
channel default_stderr {
stderr; // writes to stderr
severity info; // only send priority info
// and higher
};
channel null {
null; // toss anything sent to
// this channel
};
The default_debug channel has the
special
property that it only produces output when the server's debug
level is
nonzero. 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 up and still running as root is discarded. If you need
to capture this output, you must run the server with the "-g"
option and redirect standard error to a file.
Once a channel is defined, it cannot be redefined. Thus you cannot alter the built-in channels directly, but you can modify the default logging by pointing categories at channels you have defined.
There are many categories, so you can send the logs you want to see wherever you want, without seeing logs you don't want. If you don't specify a list of channels for a category, then log messages in that category will be sent to the default category instead. If you don't specify a default category, the following "default default" is used:
category default { default_syslog; default_debug; };
As an example, let's say you want to log security events to a file, but you also want keep the default logging behavior. You'd 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; };
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.
|
default |
The default category defines the logging options for those categories where no specific configuration has been defined. |
|
general |
The catch-all. Many things still aren't classified into categories, and they all end up here. |
|
database |
Messages relating to the databases used internally by the name server to store zone and cache data. |
|
security |
Approval and denial of requests. |
|
config |
Configuration file parsing and processing. |
|
resolver |
DNS resolution, such as the recursive lookups performed on behalf of clients by a caching name server. |
|
xfer-in |
Zone transfers the server is receiving. |
|
xfer-out |
Zone transfers the server is sending. |
|
notify |
The NOTIFY protocol. |
|
client |
Processing of client requests. |
|
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. |
|
network |
Network operations. |
|
update |
Dynamic updates. |
|
update-security |
Approval and denial of update requests. |
|
queries |
Specify where queries should be logged to. At startup, specifying the category queries will also enable query logging unless querylog option has been specified. The query log entry reports the client's IP address and port number, and the query name, class and type. It also reports whether the Recursion Desired flag was set (+ if set, - if not set), if the query was signed (S), EDNS was in use (E), if DO (DNSSEC Ok) was set (D), or if CD (Checking Disabled) was set (C).
|
|
dispatch |
Dispatching of incoming packets to the server modules where they are to be processed. |
|
dnssec |
DNSSEC and TSIG protocol processing. |
|
lame-servers |
Lame servers. These are misconfigurations in remote servers, discovered by BIND 9 when trying to query those servers during resolution. |
|
delegation-only |
Delegation only. Logs queries that have have been forced to NXDOMAIN as the result of a delegation-only zone or a delegation-only in a hint or stub zone declaration. |
|
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 on DNSSEC validation which requires EDNS for the DNSSEC records to be returned. |
This is the grammar of the lwres
statement in the named.conf file:
lwres { [ listen-on {ip_addr[portip_port] ; [ip_addr[portip_port] ; ... ] }; ] [ viewview_name; ] [ search {domain_name; [domain_name; ... ] }; ] [ ndotsnumber; ] };
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 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 will be 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 will be constructed in the same manner as a normal DNS query matching this view. If this statement is omitted, the default view is used, and 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.
mastersname[portip_port] { (masters_list|ip_addr[portip_port] [keykey] ) ; [...] };
masters lists allow for a common set of masters to be easily used by multiple stub and slave zones.
This is the grammar of the options
statement in the named.conf file:
options { [ versionversion_string; ] [ hostnamehostname_string; ] [ server-idserver_id_string; ] [ directorypath_name; ] [ key-directorypath_name; ] [ named-xferpath_name; ] [ tkey-gssapi-credentialprincipal; ] [ tkey-domaindomainname; ] [ tkey-dhkeykey_namekey_tag; ] [ cache-filepath_name; ] [ dump-filepath_name; ] [ memstatisticsyes_or_no; ] [ memstatistics-filepath_name; ] [ pid-filepath_name; ] [ recursing-filepath_name; ] [ statistics-filepath_name; ] [ zone-statisticsyes_or_no; ] [ auth-nxdomainyes_or_no; ] [ deallocate-on-exityes_or_no; ] [ dialupdialup_option; ] [ fake-iqueryyes_or_no; ] [ fetch-glueyes_or_no; ] [ flush-zones-on-shutdownyes_or_no; ] [ has-old-clientsyes_or_no; ] [ host-statisticsyes_or_no; ] [ host-statistics-maxnumber; ] [ minimal-responsesyes_or_no; ] [ multiple-cnamesyes_or_no; ] [ notifyyes_or_no|explicit|master-only; ] [ recursionyes_or_no; ] [ rfc2308-type1yes_or_no; ] [ use-id-poolyes_or_no; ] [ maintain-ixfr-baseyes_or_no; ] [ dnssec-enableyes_or_no; ] [ dnssec-validationyes_or_no; ] [ dnssec-lookasidedomaintrust-anchordomain; ] [ dnssec-must-be-securedomain yes_or_no; ] [ dnssec-accept-expiredyes_or_no; ] [ forward (only|first); ] [ forwarders { [ip_addr[portip_port] ; ... ] }; ] [ dual-stack-servers [portip_port] { (domain_name[portip_port] |ip_addr[portip_port] ) ; ... }; ] [ check-names (master|slave|response) (warn|fail|ignore); ] [ check-mx (warn|fail|ignore); ] [ check-wildcardyes_or_no; ] [ check-integrityyes_or_no; ] [ check-mx-cname (warn|fail|ignore); ] [ check-srv-cname (warn|fail|ignore); ] [ check-siblingyes_or_no; ] [ allow-notify {address_match_list}; ] [ allow-query {address_match_list}; ] [ allow-query-on {address_match_list}; ] [ allow-query-cache {address_match_list}; ] [ allow-query-cache-on {address_match_list}; ] [ allow-transfer {address_match_list}; ] [ allow-recursion {address_match_list}; ] [ allow-recursion-on {address_match_list}; ] [ allow-update {address_match_list}; ] [ allow-update-forwarding {address_match_list}; ] [ update-check-kskyes_or_no; ] [ try-tcp-refreshyes_or_no; ] [ allow-v6-synthesis {address_match_list}; ] [ blackhole {address_match_list}; ] [ avoid-v4-udp-ports {port_list}; ] [ avoid-v6-udp-ports {port_list}; ] [ listen-on [ portip_port] {address_match_list}; ] [ listen-on-v6 [ portip_port] {address_match_list}; ] [ query-source ( (ip4_addr|*) [ port (ip_port|*) ] | [ address (ip4_addr|*) ] [ port (ip_port|*) ] ) ; ] [ query-source-v6 ( (ip6_addr|*) [ port (ip_port|*) ] | [ address (ip6_addr|*) ] [ port (ip_port|*) ] ) ; ] [ use-queryport-poolyes_or_no; ] [ queryport-pool-portsnumber; ] [ queryport-pool-intervalnumber; ] [ max-transfer-time-innumber; ] [ max-transfer-time-outnumber; ] [ max-transfer-idle-innumber; ] [ max-transfer-idle-outnumber; ] [ tcp-clientsnumber; ] [ recursive-clientsnumber; ] [ serial-query-ratenumber; ] [ serial-queriesnumber; ] [ tcp-listen-queuenumber; ] [ transfer-format( one-answer | many-answers ); ] [ transfers-innumber; ] [ transfers-outnumber; ] [ transfers-per-nsnumber; ] [ transfer-source (ip4_addr|*) [portip_port] ; ] [ transfer-source-v6 (ip6_addr|*) [portip_port] ; ] [ alt-transfer-source (ip4_addr|*) [portip_port] ; ] [ alt-transfer-source-v6 (ip6_addr|*) [portip_port] ; ] [ use-alt-transfer-sourceyes_or_no; ] [ notify-delayseconds; ] [ notify-source (ip4_addr|*) [portip_port] ; ] [ notify-source-v6 (ip6_addr|*) [portip_port] ; ] [ notify-to-soayes_or_no; ] [ also-notify {ip_addr[portip_port] ; [ip_addr[portip_port] ; ... ] }; ] [ max-ixfr-log-sizenumber; ] [ max-journal-sizesize_spec; ] [ coresizesize_spec; ] [ datasizesize_spec; ] [ filessize_spec; ] [ stacksizesize_spec; ] [ cleaning-intervalnumber; ] [ heartbeat-intervalnumber; ] [ interface-intervalnumber; ] [ statistics-intervalnumber; ] [ topology {address_match_list}]; [ sortlist {address_match_list}]; [ rrset-order {order_spec; [order_spec; ... ] ] }; [ lame-ttlnumber; ] [ max-ncache-ttlnumber; ] [ max-cache-ttlnumber; ] [ sig-validity-intervalnumber; ] [ min-rootsnumber; ] [ use-ixfryes_or_no; ] [ provide-ixfryes_or_no; ] [ request-ixfryes_or_no; ] [ treat-cr-as-spaceyes_or_no; ] [ min-refresh-timenumber; ] [ max-refresh-timenumber; ] [ min-retry-timenumber; ] [ max-retry-timenumber; ] [ portip_port; ] [ additional-from-authyes_or_no; ] [ additional-from-cacheyes_or_no; ] [ random-devicepath_name; ] [ max-cache-sizesize_spec; ] [ match-mapped-addressesyes_or_no; ] [ preferred-glue (A|AAAA|NONE); ] [ edns-udp-sizenumber; ] [ max-udp-sizenumber; ] [ root-delegation-only [ exclude {namelist} ] ; ] [ querylogyes_or_no; ] [ disable-algorithmsdomain{algorithm; [algorithm; ] }; ] [ acache-enableyes_or_no; ] [ acache-cleaning-intervalnumber; ] [ max-acache-sizesize_spec; ] [ clients-per-querynumber; ] [ max-clients-per-querynumber; ] [ masterfile-format (text|raw) ; ] [ empty-servername; ] [ empty-contactname; ] [ empty-zones-enableyes_or_no; ] [ disable-empty-zonezone_name; ] [ zero-no-soa-ttlyes_or_no; ] [ zero-no-soa-ttl-cacheyes_or_no; ] };
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 will be used.
The working directory of the server.
Any non-absolute pathnames in the configuration file will be
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.
When performing dynamic update of secure zones, the directory where the public and private key files should be found, if different than the current working directory. The directory specified must be an absolute path.
This option is obsolete. It was used in BIND 8 to specify the pathname to the named-xfer program. In BIND 9, no separate named-xfer program is needed; its functionality is built into the name server.
The security credential with which the server should
authenticate keys requested by the GSS-TSIG protocol.
Currently only Kerberos 5 authentication is available
and the credential is a Kerberos principal which
the server can acquire through the default system
key file, normally /etc/krb5.keytab.
Normally this principal is of the form
"dns/server.domain".
To use GSS-TSIG, tkey-domain
must also be set.
The domain 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 will
will be client specified part +
tkey-domain. Otherwise, the
name of the shared key will be random hex
digits + tkey-domain.
In most cases, the domainname
should be the server's domain name, or an otherwise
non-existent subdomain like
"_tkey.domainname". If you are
using GSS-TSIG, this variable must be defined.
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 keyname should be the server's host name.
This is for testing only. Do not use.
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.
The pathname of the file the server writes memory
usage statistics to on exit. If not specified,
the default is named.memstats.
The pathname of the file the server writes its process ID
in. If not specified, the default is /var/run/named.pid.
The pid-file is used by programs that want to send signals to
the running
name server. Specifying pid-file none disables the
use of a PID file — no file will be written and any
existing one will be removed. Note that none
is a keyword, not a filename, and therefore is not enclosed
in
double quotes.
The pathname of the file 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.
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”.
The UDP/TCP port number the server uses for receiving and sending DNS protocol traffic. The default is 53. This option is mainly intended for server testing; a server using a port other than 53 will not be able to communicate with the global DNS.
The 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 options specifies the device (or file) from which
to read
entropy. If this is a file, operations requiring entropy will
fail when the
file has been exhausted. If 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) will be emitted before other glue in the additional section of a query response. The default is not to prefer any type (NONE).
Turn on enforcement of delegation-only in TLDs (top level domains) and root zones with an optional exclude list.
Note some TLDs are not delegation only (e.g. "DE", "LV", "US" and "MUSEUM").
options {
root-delegation-only exclude { "de"; "lv"; "us"; "museum"; };
};
Disable the specified DNSSEC algorithms at and below the specified name. Multiple disable-algorithms statements are allowed. Only the most specific will be applied.
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 will be append to the key name and a DLV record will be 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.
Specify hierarchies which must be or may not be secure (signed and
validated).
If yes, then named will only accept
answers if they
are secure.
If no, then normal dnssec validation
applies
allowing for insecure answers to be accepted.
The specified domain must be under a trusted-key or
dnssec-lookaside must be
active.
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 is
a change from BIND 8. If you
are using very old DNS software, you
may need to set it to yes.
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.
Write memory statistics to the file specfied 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. This has different effects
according
to zone type and concentrates the zone maintenance so that
it all
happens in a short interval, once every heartbeat-interval and
hopefully during the one call. It also suppresses some of
the normal
zone maintenance traffic. The default is no.
The dialup option may also be specified in the view and zone statements, in which case it overrides the global dialup option.
If the zone is a master zone, then the server will send out a NOTIFY request to all the slaves (default). This should trigger the zone serial number check in the slave (providing it supports NOTIFY) allowing the slave 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 slave or stub zone, then the server will suppress the regular "zone up to date" (refresh) queries and only perform 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 just 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
didn't 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 due receiving SIGTERM,
flush or do not flush any pending zone writes. The default
is
flush-zones-on-shutdown no.
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 enables keeping of statistics for every host that the name server interacts with. Not implemented in BIND 9.
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. If you need to disable outgoing
incremental zone
transfers, use provide-ixfr no.
If yes, then when generating
responses the server will only add 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.
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 master 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 master
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 master 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 slaves to crash.
If yes do not check the nameservers
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 master.