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
       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@ms2.inr.ac.ru>.	It is now maintained by YOSHIFUJI Hideaki <yoshfuji@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 capability 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-121221							   10 June 2014 							  RDISC(8)