.\" Copyright (C) 2000, 2001, 2003-2009, 2011, 2013-2020 Internet Systems Consortium, Inc. ("ISC")
.\" 
.\" This Source Code Form is subject to the terms of the Mozilla Public
.\" License, v. 2.0. If a copy of the MPL was not distributed with this
.\" file, You can obtain one at http://mozilla.org/MPL/2.0/.
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'\" t
.\"     Title: named
.\"    Author: 
.\" Generator: DocBook XSL Stylesheets v1.78.1 <http://docbook.sf.net/>
.\"      Date: 2014-02-19
.\"    Manual: BIND9
.\"    Source: ISC
.\"  Language: English
.\"
.TH "NAMED" "8" "2014\-02\-19" "ISC" "BIND9"
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.SH "NAME"
named \- Internet domain name server
.SH "SYNOPSIS"
.HP \w'\fBnamed\fR\ 'u
\fBnamed\fR [[\fB\-4\fR] | [\fB\-6\fR]] [\fB\-c\ \fR\fB\fIconfig\-file\fR\fR] [\fB\-d\ \fR\fB\fIdebug\-level\fR\fR] [\fB\-D\ \fR\fB\fIstring\fR\fR] [\fB\-E\ \fR\fB\fIengine\-name\fR\fR] [\fB\-f\fR] [\fB\-g\fR] [\fB\-L\ \fR\fB\fIlogfile\fR\fR] [\fB\-M\ \fR\fB\fIoption\fR\fR] [\fB\-m\ \fR\fB\fIflag\fR\fR] [\fB\-n\ \fR\fB\fI#cpus\fR\fR] [\fB\-p\ \fR\fB\fIport\fR\fR] [\fB\-s\fR] [\fB\-S\ \fR\fB\fI#max\-socks\fR\fR] [\fB\-t\ \fR\fB\fIdirectory\fR\fR] [\fB\-U\ \fR\fB\fI#listeners\fR\fR] [\fB\-u\ \fR\fB\fIuser\fR\fR] [\fB\-v\fR] [\fB\-V\fR] [\fB\-X\ \fR\fB\fIlock\-file\fR\fR] [\fB\-x\ \fR\fB\fIcache\-file\fR\fR]
.SH "DESCRIPTION"
.PP
\fBnamed\fR
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\&.
.PP
When invoked without arguments,
\fBnamed\fR
will read the default configuration file
/etc/named\&.conf, read any initial data, and listen for queries\&.
.SH "OPTIONS"
.PP
\-4
.RS 4
Use IPv4 only even if the host machine is capable of IPv6\&.
\fB\-4\fR
and
\fB\-6\fR
are mutually exclusive\&.
.RE
.PP
\-6
.RS 4
Use IPv6 only even if the host machine is capable of IPv4\&.
\fB\-4\fR
and
\fB\-6\fR
are mutually exclusive\&.
.RE
.PP
\-c \fIconfig\-file\fR
.RS 4
Use
\fIconfig\-file\fR
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
\fBdirectory\fR
option in the configuration file,
\fIconfig\-file\fR
should be an absolute pathname\&.
.RE
.PP
\-d \fIdebug\-level\fR
.RS 4
Set the daemon\*(Aqs debug level to
\fIdebug\-level\fR\&. Debugging traces from
\fBnamed\fR
become more verbose as the debug level increases\&.
.RE
.PP
\-D \fIstring\fR
.RS 4
Specifies a string that is used to identify a instance of
\fBnamed\fR
in a process listing\&. The contents of
\fIstring\fR
are not examined\&.
.RE
.PP
\-E \fIengine\-name\fR
.RS 4
When applicable, specifies the hardware to use for cryptographic operations, such as a secure key store used for signing\&.
.sp
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"\&.
.RE
.PP
\-f
.RS 4
Run the server in the foreground (i\&.e\&. do not daemonize)\&.
.RE
.PP
\-g
.RS 4
Run the server in the foreground and force all logging to
stderr\&.
.RE
.PP
\-L \fIlogfile\fR
.RS 4
Log to the file
\fBlogfile\fR
by default instead of the system log\&.
.RE
.PP
\-M \fIoption\fR
.RS 4
Sets the default memory context options\&. Currently the only supported option is
\fIexternal\fR, which causes the internal memory manager to be bypassed in favor of system\-provided memory allocation functions\&.
.RE
.PP
\-m \fIflag\fR
.RS 4
Turn on memory usage debugging flags\&. Possible flags are
\fIusage\fR,
\fItrace\fR,
\fIrecord\fR,
\fIsize\fR, and
\fImctx\fR\&. These correspond to the ISC_MEM_DEBUGXXXX flags described in
<isc/mem\&.h>\&.
.RE
.PP
\-n \fI#cpus\fR
.RS 4
Create
\fI#cpus\fR
worker threads to take advantage of multiple CPUs\&. If not specified,
\fBnamed\fR
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\&.
.RE
.PP
\-p \fIport\fR
.RS 4
Listen for queries on port
\fIport\fR\&. If not specified, the default is port 53\&.
.RE
.PP
\-s
.RS 4
Write memory usage statistics to
stdout
on exit\&.
.if n \{\
.sp
.\}
.RS 4
.it 1 an-trap
.nr an-no-space-flag 1
.nr an-break-flag 1
.br
.ps +1
\fBNote\fR
.ps -1
.br
This option is mainly of interest to BIND 9 developers and may be removed or changed in a future release\&.
.sp .5v
.RE
.RE
.PP
\-S \fI#max\-socks\fR
.RS 4
Allow
\fBnamed\fR
to use up to
\fI#max\-socks\fR
sockets\&. The default value is 4096 on systems built with default configuration options, and 21000 on systems built with "configure \-\-with\-tuning=large"\&.
.if n \{\
.sp
.\}
.RS 4
.it 1 an-trap
.nr an-no-space-flag 1
.nr an-break-flag 1
.br
.ps +1
\fBWarning\fR
.ps -1
.br
This option should be unnecessary for the vast majority of users\&. The use of this option could even be harmful because the specified value may exceed the limitation of the underlying system API\&. It is therefore 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 fewer than the specified value because
\fBnamed\fR
reserves some file descriptors for its internal use\&.
.sp .5v
.RE
.RE
.PP
\-t \fIdirectory\fR
.RS 4
Chroot to
\fIdirectory\fR
after processing the command line arguments, but before reading the configuration file\&.
.if n \{\
.sp
.\}
.RS 4
.it 1 an-trap
.nr an-no-space-flag 1
.nr an-break-flag 1
.br
.ps +1
\fBWarning\fR
.ps -1
.br
This option should be used in conjunction with the
\fB\-u\fR
option, as chrooting a process running as root doesn\*(Aqt enhance security on most systems; the way
\fBchroot(2)\fR
is defined allows a process with root privileges to escape a chroot jail\&.
.sp .5v
.RE
.RE
.PP
\-U \fI#listeners\fR
.RS 4
Use
\fI#listeners\fR
worker threads to listen for incoming UDP packets on each address\&. If not specified,
\fBnamed\fR
will calculate a default value based on the number of detected CPUs: 1 for 1 CPU, and the number of detected CPUs minus one for machines with more than 1 CPU\&. This cannot be increased to a value higher than the number of CPUs\&. If
\fB\-n\fR
has been set to a higher value than the number of detected CPUs, then
\fB\-U\fR
may be increased as high as that value, but no higher\&. On Windows, the number of UDP listeners is hardwired to 1 and this option has no effect\&.
.RE
.PP
\-u \fIuser\fR
.RS 4
Setuid to
\fIuser\fR
after completing privileged operations, such as creating sockets that listen on privileged ports\&.
.if n \{\
.sp
.\}
.RS 4
.it 1 an-trap
.nr an-no-space-flag 1
.nr an-break-flag 1
.br
.ps +1
\fBNote\fR
.ps -1
.br
On Linux,
\fBnamed\fR
uses the kernel\*(Aqs capability mechanism to drop all root privileges except the ability to
\fBbind(2)\fR
to a privileged port and set process resource limits\&. Unfortunately, this means that the
\fB\-u\fR
option only works when
\fBnamed\fR
is run on kernel 2\&.2\&.18 or later, or kernel 2\&.3\&.99\-pre3 or later, since previous kernels did not allow privileges to be retained after
\fBsetuid(2)\fR\&.
.sp .5v
.RE
.RE
.PP
\-v
.RS 4
Report the version number and exit\&.
.RE
.PP
\-V
.RS 4
Report the version number and build options, and exit\&.
.RE
.PP
\-X \fIlock\-file\fR
.RS 4
Acquire a lock on the specified file at runtime; this helps to prevent duplicate
\fBnamed\fR
instances from running simultaneously\&. Use of this option overrides the
\fBlock\-file\fR
option in
named\&.conf\&. If set to
none, the lock file check is disabled\&.
.RE
.PP
\-x \fIcache\-file\fR
.RS 4
Load data from
\fIcache\-file\fR
into the cache of the default view\&.
.if n \{\
.sp
.\}
.RS 4
.it 1 an-trap
.nr an-no-space-flag 1
.nr an-break-flag 1
.br
.ps +1
\fBWarning\fR
.ps -1
.br
This option must not be used\&. It is only of interest to BIND 9 developers and may be removed or changed in a future release\&.
.sp .5v
.RE
.RE
.SH "SIGNALS"
.PP
In routine operation, signals should not be used to control the nameserver;
\fBrndc\fR
should be used instead\&.
.PP
SIGHUP
.RS 4
Force a reload of the server\&.
.RE
.PP
SIGINT, SIGTERM
.RS 4
Shut down the server\&.
.RE
.PP
The result of sending any other signals to the server is undefined\&.
.SH "CONFIGURATION"
.PP
The
\fBnamed\fR
configuration file is too complex to describe in detail here\&. A complete description is provided in the
BIND 9 Administrator Reference Manual\&.
.PP
\fBnamed\fR
inherits the
\fBumask\fR
(file creation mode mask) from the parent process\&. If files created by
\fBnamed\fR, such as journal files, need to have custom permissions, the
\fBumask\fR
should be set explicitly in the script used to start the
\fBnamed\fR
process\&.
.SH "FILES"
.PP
/etc/named\&.conf
.RS 4
The default configuration file\&.
.RE
.PP
/var/run/named/named\&.pid
.RS 4
The default process\-id file\&.
.PP
.SH "NOTES"
.PP
.TP
\fBRed Hat SELinux BIND Security Profile:\fR
.PP
By default, Red Hat ships BIND with the most secure SELinux policy
that will not prevent normal BIND operation and will prevent exploitation
of all known BIND security vulnerabilities . See the selinux(8) man page
for information about SElinux.
.PP
It is not necessary to run named in a chroot environment if the Red Hat
SELinux policy for named is enabled. When enabled, this policy is far
more secure than a chroot environment. Users are recommended to enable
SELinux and remove the bind-chroot package.
.PP
With this extra security comes some restrictions:
.PP
By default, the SELinux policy does not allow named to write any master
zone database files. Only the root user may create files in the $ROOTDIR/var/named
zone database file directory (the options { "directory" } option), where
$ROOTDIR is set in /etc/sysconfig/named.
.PP
The "named" group must be granted read privelege to
these files in order for named to be enabled to read them.
.PP
Any file created in the zone database file directory is automatically assigned
the SELinux file context named_zone_t .
.PP
By default, SELinux prevents any role from modifying named_zone_t files; this
means that files in the zone database directory cannot be modified by dynamic
DNS (DDNS) updates or zone transfers.
.PP
The Red Hat BIND distribution and SELinux policy creates three directories where
named is allowed to create and modify files: /var/named/slaves, /var/named/dynamic
/var/named/data. By placing files you want named to modify, such as
slave or DDNS updateable zone files and database / statistics dump files in
these directories, named will work normally and no further operator action is
required. Files in these directories are automatically assigned the 'named_cache_t'
file context, which SELinux allows named to write.
.PP
\fBRed Hat BIND SDB support:\fR
.PP
Red Hat ships named with compiled in Simplified Database Backend modules that ISC
provides in the "contrib/sdb" directory. Install bind-sdb package if you want use them
.PP
The SDB modules for LDAP, PostGreSQL, DirDB and SQLite are compiled into named-sdb.
.PP
See the documentation for the various SDB modules in /usr/share/doc/bind-sdb-*/ .
.br
.PP
.RE
.SH "SEE ALSO"
.PP
RFC 1033,
RFC 1034,
RFC 1035,
\fBnamed-checkconf\fR(8),
\fBnamed-checkzone\fR(8),
\fBrndc\fR(8),
\fBlwresd\fR(8),
\fBnamed.conf\fR(5),
BIND 9 Administrator Reference Manual\&.
.SH "AUTHOR"
.PP
\fBInternet Systems Consortium, Inc\&.\fR
.SH "COPYRIGHT"
.br
Copyright \(co 2000, 2001, 2003-2009, 2011, 2013-2020 Internet Systems Consortium, Inc. ("ISC")
.br