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RDISC(8)               System Manager's Manual: 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 ker-
       nel 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 prefer-
              ence 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>.  It is  now  maintained  by  YOSHIFUJI  Hideaki
       <yoshfuji AT skbuff.net>.
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 capa-
       bility CAP_NET_ADMIN to update routing tables.
AVAILABILITY
       rdisc is part of iputils package and the latest versions are  available
       in    source    form    at   http://www.skbuff.net/iputils/iputils-cur-
       rent.tar.bz2.

iputils-160308                                                        RDISC(8)