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RTADVD(8)                   System Manager's Manual                  RTADVD(8)

     rtadvd - router advertisement daemon

     rtadvd [-CDdfs] [-c configfile] [-p pidfile] interface ...

     rtadvd sends router advertisement packets to the specified interfaces.

     The program will daemonize itself on invocation.  It will then send
     router advertisement packets periodically, as well as in response to
     router solicitation messages sent by end hosts.

     Router advertisements can be configured on a per-interface basis, as
     described in rtadvd.conf(5).

     If there is no configuration file entry for an interface, or if the
     configuration file does not exist at all, rtadvd sets all the parameters
     to their default values.  In particular, rtadvd reads all the interface
     routes from the routing table and advertises them as on-link prefixes.

     rtadvd also watches the routing table.  If an interface direct route is
     added on an advertising interface and no static prefixes are specified by
     the configuration file, rtadvd adds the corresponding prefix to its
     advertising list.

     Similarly, when an interface direct route is deleted, rtadvd will start
     advertising the prefixes with zero valid and preferred lifetimes to help
     the receiving hosts switch to a new prefix when renumbering.  Note,
     however, that the zero valid lifetime cannot invalidate the
     autoconfigured addresses at a receiving host immediately.  According to
     the specification, the host will retain the address for a certain period,
     which will typically be two hours.  The zero lifetimes rather intend to
     make the address deprecated, indicating that a new non-deprecated address
     should be used as the source address of a new connection.  This behavior
     will last for two hours.  Then rtadvd will completely remove the prefix
     from the advertising list, and succeeding advertisements will not contain
     the prefix information.

     Moreover, if the status of an advertising interface changes, rtadvd will
     start or stop sending router advertisements according to the latest

     The -s option may be used to disable this behavior; rtadvd will not watch
     the routing table and the whole functionality described above will be

     Basically, hosts MUST NOT send Router Advertisement messages at any time
     (RFC 2461, Section 6.2.3).  However, it would sometimes be useful to
     allow hosts to advertise some parameters such as prefix information and
     link MTU.  Thus, rtadvd can be invoked if router lifetime is explicitly
     set to zero on every advertising interface.

     The command line options are:

     -C      Don't expire the existing configuration on receipt of SIGHUP.
             This option is only intended to aid the testing of clients that
             consume Router Advertisement messages.

     -c configfile
             Specify an alternate location, configfile, for the configuration
             file.  By default, /etc/rtadvd.conf is used.

     -D      Instead of printing errors using syslog(3) send them to stderr.
             Also when poll(2) fails, exit instead of retrying.

     -d      Print debugging information.  Repeating this option, adds more
             verbose debugging.

     -f      Foreground mode (useful when debugging).  Log messages will be
             dumped to stderr when this option is specified.

     -p pidfile
             Specify an alternate location, pidfile, for the PID file.  By
             default, /var/run/rtadvd.pid is used.

     -s      Do not add or delete prefixes dynamically.  Only statically
             configured prefixes, if any, will be advertised.

     Use SIGHUP to reload the configuration file /etc/rtadvd.conf.  If an
     invalid parameter is found in the configuration file upon the reload, the
     entry will be ignored and the old configuration will be used.  When
     parameters in an existing entry are updated and the -C flag is not used,
     rtadvd will send Router Advertisement messages with the old configuration
     but zero router lifetime to the interface first, and then start to send a
     new message.

     Upon receipt of signal SIGUSR1, rtadvd will dump the current internal
     state into /var/run/rtadvd.dump.

     Use SIGTERM to kill rtadvd gracefully.  In this case, rtadvd will
     transmit router advertisement with router lifetime 0 to all the
     interfaces (in accordance with RFC 2461 6.2.5).

     /etc/rtadvd.conf        The default configuration file.
     /var/run/rtadvd.pid     Contains the PID of the currently running rtadvd.
     /var/run/rtadvd.dump    The file in which rtadvd dumps its internal

     The rtadvd utility exits 0 on success, and >0 if an error occurs.

     rtadvd.conf(5), rtsol(8)

     The rtadvd command first appeared in the WIDE Hydrangea IPv6 protocol
     stack kit.

     There used to be some text that recommended users not to let rtadvd
     advertise Router Advertisement messages on an upstream link to avoid
     undesirable icmp6(4) redirect messages.  However, based on later
     discussion in the IETF IPng working group, all routers should rather
     advertise the messages regardless of the network topology, in order to
     ensure reachability.

NetBSD 9.99                     April 21, 2020                     NetBSD 9.99