huschi.net

RDISC(8)                            iputils                           RDISC(8)
NAME
       rdisc - network router discovery daemon
SYNOPSIS
       rdisc [-abdfrstvV] [-p preference] [-T max_interval] [send_address]
             [receive_address]
DESCRIPTION
       rdisc implements client side of the ICMP router discover protocol.
       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 provided it is given) 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 provided it is given)
       when it is started.
       A timer is associated with each router address and the address will no
       longer be considered for inclusion in the 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
       host receives an advertise message with the preference being maximally
       negative.
       Server side of router discovery protocol is supported by Cisco IOS and
       by any more or less complete UNIX routing daemon, f.e gated. Or, rdisc
       can act as responder, if compiled with -DRDISC_SERVER.
OPTIONS
       -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. It is default behaviour.
       -d
           Send debugging messages to syslog.
       -f
           Run rdisc forever even if no routers are found. Normally rdisc
           gives up if it has not received any advertise message after after
           soliciting three times, in which 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 -DRDISC_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. Available only with -r option.
       -T max_interval
           Set maximum advertisement interval in seconds. Default is 600 secs.
           Available only with -r option.
       -t
           Test mode. Do not go to background.
       -v
           Be verbose i.e. send lots of debugging messages to syslog.
       -V
           Print version and exit.
HISTORY
       This program was developed by Sun Microsystems (see copyright notice in
       source file). It was ported to Linux by Alexey
       Kuznetsov<kuznet AT ms2.ru>.
SEE ALSO
       icmp(7), inet(7), ping(8).
REFERENCES
       Deering, S.E.,ed "ICMP Router Discovery Messages", RFC1256, Network
       Information Center, SRI International, Menlo Park, Calif., September
       1991.
SECURITY
       rdisc requires CAP_NET_RAW to listen and send ICMP messages and
       capability CAP_NET_ADMIN to update routing tables.
AVAILABILITY
       rdisc is part of iputils package.
iputils s20180629                                                     RDISC(8)