rdisc(8) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | HISTORY | SEE ALSO | REFERENCES | SECURITY | AVAILABILITY | COLOPHON

RDISC(8)                           iputils                          RDISC(8)

NAME         top

       rdisc - network router discovery daemon

SYNOPSIS         top

       rdisc [-abdfrstvV] [-p preference] [-T max_interval] [send_address]
             [receive_address]

DESCRIPTION         top

       rdisc implements client side of the ICMP Internet Router Discovery
       Protocol (IRDP).  rdisc is invoked at boot time to populate the
       network routing tables with default routes.

       rdisc listens on the ALL_HOSTS (224.0.0.1) multicast address (or
       receive_address if it is provided) for ROUTER_ADVERTISE messages from
       routers. The received messages are handled by first ignoring those
       listed router addresses with which the host does not share a network.
       Among the remaining addresses the ones with the highest preference
       are selected as default routers and a default route is entered in the
       kernel routing table for each one of them.

       Optionally, rdisc can avoid waiting for routers to announce
       themselves by sending out a few ROUTER_SOLICITATION messages to the
       ALL_ROUTERS (224.0.0.2) multicast address (or send_address if it is
       provided) when it is started.

       A timer is associated with each router address and the address will
       no longer be considered for inclusion in the routing tables if the
       timer expires before a new advertise message is received from the
       router. The address will also be excluded from consideration if the
       received advertise message has a preference of maximum negative.

       Server side of router discovery protocol is supported by Cisco IOS
       and by any more or less complete UNIX routing daemon, for example
       gated. If compiled with ENABLE_RDISC_SERVER, rdisc can act as
       responder.

OPTIONS         top

       -a
           Accept all routers independently of the preference they have in
           their advertise messages. Normally rdisc only accepts (and enters
           in the kernel routing tables) the router or routers with the
           highest preference.

       -b
           Opposite to -a, i.e. install only router with the best preference
           value. This is the default behaviour.

       -d
           Send debugging messages to syslog.

       -f
           Keep rdisc running in the background even if no routers are
           found. Normally rdisc gives up if it has not received any
           advertise message after soliciting three times. In this case it
           exits with a non-zero exit code. If -f is not specified in the
           first form then -s must be specified.

       -r
           Responder mode, available only if compiled with
           ENABLE_RDISC_SERVER.

       -s
           Send three solicitation messages initially to quickly discover
           the routers when the system is booted. When -s is specified rdisc
           exits with a non-zero exit code if it can not find any routers.
           This can be overridden with the -f option.

       -p preference
           Set preference in advertisement messages. Available only with -r
           option.

       -T max_interval
           Set maximum advertisement interval in seconds. Default is 600.
           Available only with -r option.

       -t
           Test mode. Do not go to background.

       -v
           Be verbose and send lots of debugging messages to syslog.

       -V
           Print version and exit.

HISTORY         top

       This program was developed by Sun Microsystems (see copyright notice
       in source file). It was ported to Linux by Alexey Kuznetsov
       <kuznet@ms2.inr.ac.ru>.

SEE ALSO         top

       icmp(7), inet(7), ping(8).

REFERENCES         top

       RFC1256 ICMP Router Discovery Messages. S. Deering, Ed.. September
       1991.

SECURITY         top

       rdisc requires CAP_NET_RAW to listen and send ICMP messages and
       capability CAP_NET_ADMIN to update routing tables.

AVAILABILITY         top

       rdisc is part of iputils package.

COLOPHON         top

       This page is part of the iputils (IP utilities) project.  Information
       about the project can be found at ⟨http://www.skbuff.net/iputils/⟩.
       If you have a bug report for this manual page, send it to
       yoshfuji@skbuff.net, netdev@vger.kernel.org.  This page was obtained
       from the project's upstream Git repository
       ⟨https://github.com/iputils/iputils.git⟩ on 2020-09-18.  (At that
       time, the date of the most recent commit that was found in the repos‐
       itory was 2020-08-29.)  If you discover any rendering problems in
       this HTML version of the page, or you believe there is a better or
       more up-to-date source for the page, or you have corrections or
       improvements to the information in this COLOPHON (which is not part
       of the original manual page), send a mail to man-pages@man7.org

iputils s20200821                                                   RDISC(8)

Pages that refer to this page: icmp(7)