| RTADVD(8) | System Manager's Manual | RTADVD(8) | 
rtadvd —
| rtadvd | [ -CDdfs] [-cconfigfile] [-ppidfile] 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 status.
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 suppressed.
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-c
    configfile-Dstderr. Also when
      poll(2) fails, exit instead of
      retrying.-d-f-p
    pidfile-sUse 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).
rtadvd.rtadvd dumps its internal
    state.rtadvd utility exits 0 on success,
  and >0 if an error occurs.
rtadvd command first appeared in the WIDE Hydrangea
  IPv6 protocol stack kit.
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.
| April 21, 2020 | NetBSD 10.0 |