rdisc(8) — Linux manual page


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 ( 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

       Optionally, rdisc can avoid waiting for routers to announce
       themselves by sending out a few ROUTER_SOLICITATION messages to
       the ALL_ROUTERS ( 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

           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.

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

           Send debugging messages to syslog.

           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.

           Responder mode, available only if compiled with

           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.

           Test mode. Do not go to background.

           Be verbose and send lots of debugging messages to syslog.

           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 2021-08-27.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2021-08-27.)  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

iputils 20210722                                                RDISC(8)

Pages that refer to this page: icmp(7)