nsd - Name Server Daemon (NSD) version 4.1.26.
nsd [-4] [-6] [-a ip-address[@port]]
[-c configfile] [-d] [-f database]
[-h] [-i identity] [-I nsid] [-l
logfile] [-N server-count] [-n
noncurrent-tcp-count] [-P pidfile] [-p
port] [-s seconds] [-t chrootdir]
[-u username] [-V level] [-v]
NSD is a complete implementation of an authoritative DNS nameserver. Upon
startup, NSD will read the database specified with -f
database argument and put itself into background and answers queries on
port 53 or a different port specified with -p port option. The
database is created if it does not exist. By default, NSD will
bind to all local interfaces available. Use the -a
ip-address[@port] option to specify a single particular interface
address to be bound. If this option is given more than once, NSD will
bind its UDP and TCP sockets to all the specified ip-addresses separately. If
IPv6 is enabled when NSD is compiled an IPv6 address can also be
All the options can be specified in the configfile ( -c argument), except
for the -v and -h options. If options are specified on the
commandline, the options on the commandline take precedence over the options
in the configfile.
Normally NSD should be started with the `nsd-control(8)
start` command invoked from a /etc/rc.d/nsd.sh script or similar at
the operating system startup.
- Only listen to IPv4 connections.
- Only listen to IPv6 connections.
- -a ip-address[@port]
- Listen to the specified ip-address. The ip-address must be
specified in numeric format (using the standard IPv4 or IPv6 notation).
Optionally, a port number can be given. This flag can be specified
multiple times to listen to multiple IP addresses. If this flag is not
specified, NSD listens to the wildcard interface.
- -c configfile
- Read specified configfile instead of the default
/var/nsd/etc/nsd.conf. For format description see nsd.conf(5).
- Do not fork, stay in the foreground.
- -f database
- Use the specified database instead of the default of ''. If
a zonesdir: is specified in the config file this path can be
relative to that directory.
- Print help information and exit.
- -i identity
- Return the specified identity when asked for CH TXT
ID.SERVER (This option is used to determine which server is answering
the queries when they are anycast). The default is the name returned by
- -I nsid
- Add the specified nsid to the EDNS section of the answer when
queried with an NSID EDNS enabled packet. As a sequence of hex characters
or with ascii_ prefix and then an ascii string.
- -l logfile
- Log messages to the specified logfile. The default is to log to
stderr and syslog. If a zonesdir: is specified in the config file
this path can be relative to that directory.
- -N count
- Start count NSD servers. The default is 1. Starting more
than a single server is only useful on machines with multiple CPUs and/or
- -n number
- The maximum number of concurrent TCP connection that can be handled
by each server. The default is 100.
- -P pidfile
- Use the specified pidfile instead of the platform specific default,
which is mostly /var/nsd/run/nsd.pid. If a zonesdir: is
specified in the config file, this path can be relative to that
- -p port
- Answer the queries on the specified port. Normally this is port
- -s seconds
- Produce statistics dump every seconds seconds. This is equal to
sending SIGUSR1 to the daemon periodically.
- -t chroot
- Specifies a directory to chroot to upon startup. This option
requires you to ensure that appropriate syslogd(8) socket (e.g.
chrootdir /dev/log) is available, otherwise NSD won't
produce any log output.
- -u username
- Drop user and group privileges to those of username after binding
the socket. The username must be one of: username, id, or id.gid.
For example: nsd, 80, or 80.80.
- -V level
- This value specifies the verbosity level for (non-debug) logging. Default
- Print the version number of NSD to standard error and exit.
NSD reacts to the following signals:
- Stop answering queries, shutdown, and exit normally.
- Reload. Scans zone files and if changed (mtime) reads them in. Also
reopens the logfile (assists logrotation).
- Dump BIND8-style statistics into the log. Ignored otherwise.
NSD will log all the problems via the standard syslog(8) daemon
facility, unless the -d option is specified.
nsd.conf(5), nsd-checkconf(8), nsd-control(8)
NSD was written by NLnet Labs and RIPE NCC joint team. Please see CREDITS
file in the distribution for further details.
- default NSD database
- the process id of the name server.
- default NSD configuration file