named

, in.named

- Internet domain name server

Synopsis

named [-fgsVv] [-c config-file] [-d debug-level] [-m flag]
     [-n #cpus] [-p port] [-S #max-socks] [-t directory]
     [-u user] [-x cache-file] [-4 | -6]

Description

The named utility is a Domain Name System (DNS) server, part of the BIND 9 distribution from ISC. For more information on the DNS, see RFCs 1033, 1034, and 1035.

When invoked without arguments, named reads the default configuration file /etc/named.conf, reads any initial data, and listens for queries.

in.named is a link to named.

Options

The following options are supported:

-4

Use only IPv4 transport. By default, both IPv4 and IPv6 transports can be used. Options -4 and -6 are mutually exclusive.

-6

Use only IPv6 transport. By default, both IPv4 and IPv6 transports can be used. Options -4 and -6 are mutually exclusive.

-c config-file

Use config-file as the configuration file instead of the default /etc/named.conf. To ensure that reloading the configuration file continues to work after the server has changed its working directory due to to a possible directory option in the configuration file, config-file should be an absolute pathname.

-d debug-level

Set the daemon's debug level to debug-level. Debugging traces from named become more verbose as the debug level increases.

-f

Run the server in the foreground (that is, do not run as a daemon).

-g

Run the server in the foreground and force all logging to stderr.

-m flag

Turn on memory usage debugging flags. Possible flags are usage, trace, and record, size, and mctx. These correspond to the ISC_MEM_DEBUGXXXX flags described in <isc/mem.h>.

-n #cpus

Create #cpus worker threads to take advantage of multiple CPUs. If not specified, named 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.

-p port

Listen for queries on port port. If not specified, the default is port 53.

-S #max-socks

Allow named to use up to #max-socks sockets.

This option should be unnecessary for the vast majority of users. The use of this option could even be harmful, because the specified value might exceed the limitation of the underlying system API. It therefore should be set only when the default configuration causes exhaustion of file descriptors and the operational environment is known to support the specified number of sockets. Note also that the actual maximum number is normally a little smaller than the specified value because named reserves some file descriptors for its internal use.

-s

Write memory usage statistics to stdout on exit.

This option is mainly of interest to BIND 9 developers and might be removed or changed in a future release.

-t directory

Change the root directory using chroot(2) 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 does not enhance security on most systems; the way chroot() is defined allows a process with root privileges to escape a chroot jail.

-u user

Set the real user ID using setuid(2) to user after completing privileged operations, such as creating sockets that listen on privileged ports.

-V

Report the version number and build options, and exit.

-v

Report the version number and exit.

-x cache-file

Load data from cache-file into the cache of the default view.

Do not use this option. It is of interest only to BIND 9 developers and might be removed or changed in a future release.

Extended Description

This section describes additional attributes of named.

SMF Properties

When starting named from the service management facility, smf(5), named configuration is read from the service configuration repository. Use svcprop(1) to list the properties and svccfg(1M) to make changes.

The following application configuration properties are available to administrators:

options/server

Specifies the server executable to be used instead of the default server, /usr/sbin/named.

options/configuration_file

Specifies the configuration file to be used instead of the default, /etc/named.conf. A directory option might be specified in the configuration file. To ensure that reloading the configuration file continues to work in such a situation, configuration_file should be specified as an absolute pathname. This pathname should not include the chroot_dir pathname. This property is the equivalent of the -c option.

options/ip_interfaces

Specifies over which IP transport, IPv4 or IPv6, BIND will transmit. Possible values are IPv4 or IPv6. Any other setting assumes all, the default. This property is the equivalent of command line option -4 or -6

options/listen_on_port

Specifies the default UDP and TCP port to be used for listening to DNS requests. This property is the equivalent of the command line option -p port.

options/debug_level

Specifies the default debug level. The default is 0, which means no debugging. The higher the number the more verbose debug information becomes. Equivalent of the command line option -d debug_level.

options/threads

Specifies the number of CPU worker threads to create. The default of 0 causes named to try and determine the number of CPUs present and create one thread per CPU. Equivalent of command line option -n #cpus.

options/chroot_dir

Specifies the directory to be used as the root directory after processing SMF properties and the command line arguments but before reading the configuration file. Use this property when using a chroot(2) environment. Synonymous to command line option -t pathname.

When using chroot(2), named is unable to disable itself when receiving rndc(1M) stop or halt commands. Instead, you must use the svcadm(1M) disable command.

In the event of a configuration error originating in one of the above SMF application options, named displays a message providing information about the error and the parameters that need correcting. The process then exits with exit code SMF_EXIT_ERR_CONFIG.

At startup, in the event of an error other than a configuration error, named exits with exit code SMF_EXIT_ERR_FATAL. Both of this code and SMF_EXIT_ERR_CONFIG cause the start method, smf_method(5), to place the service in the maintenance state, which can be observed with the svcs(1) command svcs -x.

In addition to the properties listed above, the following property can be used to invoke named as a user other than root:

start/user

Specifies the identity of the user that is invoking named. See smf_method(5) and chroot(2). Note that the user must have solaris.smf.manage.bind authorization. Without this role the named will be unable to manage its SMF FMRI and named will automatically be restarted by the SMF after an rndc(1M) stop or halt command. See EXAMPLES for a sequence of commands that establishes the correct authorization.

SIGNALS

In routine operation, signals should not be used to control the nameserver; rndc(1M) should be used instead.

SIGHUP

Force a reload of the server.

SIGINT, SIGTERM

Shut down the server.

The result of sending any other signals to the server is undefined.

Configuration

The named configuration file is too complex to describe in detail here. A list of configuration options is provided in the named.conf man page shipped with the BIND 9 distribution. A complete description is provided in the BIND 9 Administrator Reference Manual.

Examples

Example 1 Configuring named to Transmit Only over IPv4 Networks

The following command sequence configures named such that it will transmit only over IPv4 networks.

# svccfg -s svc:network/dns/server:default setprop \
> options/ip_interfaces=IPv4
# svcadm refresh svc:network/dns/server:default
#

Example 2 Listing Current Configuration File and Setting an Alternative File

The following sequence of commands lists the current named configuration file and sets an alternative file.

# svcprop -p options/configuration_file dns/server:default 
/etc/named.conf
# svccfg -s dns/server:default setprop \
> options/configuration_file=/var/named/named.conf
# svcadm refresh dns/server:default
# svcprop -p options/configuration_file dns/server:default
/var/named/named.conf

Example 3 Establishing Appropriate Authorization for named

To have named start with the solaris.smf.manage.bind authorization, perform the steps shown below.

Add the user dnsadmin to the solaris.smf.manage.bind role:

# usermod -A solaris.smf.manage.bind dnsadmin
Observe effect of command:
# tail -1 /etc/user_attr
dnsadmin::::type=normal;auths=solaris.smf.manage.bind

Modify the service properties:

# svccfg
svc:> select svc:/network/dns/server:default
svc:/network/dns/server:default> setprop start/user = dnsadmin
svc:/network/dns/server:default> setprop start/group = dnsadmin
svc:/network/dns/server:default> exit
# svcadm refresh svc:/network/dns/server:default
# svcadm restart svc:/network/dns/server:default

Because only root has write access to create the default process-ID file, /var/run/named/named.pid, named must be configured to use an alternative path for the user dnsadmin. Here is an example of how to accomplish this:

# mkdir /var/named/tmp
# chown dnsadmin /var/named/tmp

Shown below is what you must add to named.conf to make use of the directory created above.

# head /etc/named.conf
options {
directory "/var/named";
pid-file "/var/named/tmp/named.pid";
};

Files

/etc/named.conf

default configuration file

/var/run/named/named.pid

default process-ID file

Attributes

See attributes(5) for descriptions of the following attributes:

See Also

svcs(1), named-checkconf(1M), named-checkzone(1M), rndc(1M), rndc-confgen(1M), svcadm(1M), svccfg(1M), svcprop(1), chroot(2), setuid(2), bind(3SOCKET), attributes(5), smf(5), smf_method(5)

RFC 1033, RFC 1034, RFC 1035

See the BIND 9 Administrator's Reference Manual. As of the date of publication of this man page, this document is available at https://www.isc.org/software/bind/documentation.

The named.conf man page shipped with the BIND 9 distribution