1RDISC(8) System Manager's Manual: iputils RDISC(8)
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6 rdisc - network router discovery daemon
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9 rdisc [-abdfrstvV] [-p preference] [-T max_interval] [send_address]
10 [receive_address]
11
14 rdisc implements client side of the ICMP router discover protocol.
15 rdisc is invoked at boot time to populate the network routing tables
16 with default routes.
17 rdisc listens on the ALL_HOSTS (224.0.0.1) multicast address (or
19 receive_address provided it is given) for ROUTER_ADVERTISE messages
20 from routers. The received messages are handled by first ignoring those
21 listed router addresses with which the host does not share a network.
22 Among the remaining addresses the ones with the highest preference are
23 selected as default routers and a default route is entered in the ker‐
24 nel routing table for each one of them.
25 Optionally, rdisc can avoid waiting for routers to announce themselves
27 by sending out a few ROUTER_SOLICITATION messages to the ALL_ROUTERS
28 (224.0.0.2) multicast address (or send_address provided it is given)
29 when it is started.
30 A timer is associated with each router address and the address will no
32 longer be considered for inclusion in the the routing tables if the
33 timer expires before a new advertise message is received from the
34 router. The address will also be excluded from consideration if the
35 host receives an advertise message with the preference being maximally
36 negative.
37 Server side of router discovery protocol is supported by Cisco IOS and
39 by any more or less complete UNIX routing daemon, f.e gated. Or, rdisc
40 can act as responder, if compiled with -DRDISC_SERVER.
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43 -a Accept all routers independently of the preference they have in
44 their advertise messages. Normally rdisc only accepts (and
45 enters in the kernel routing tables) the router or routers with
46 the highest preference.
47 -b Opposite to -a, i.e. install only router with the best prefer‐
49 ence value. It is default behaviour.
50 -d Send debugging messages to syslog.
52 -f Run rdisc forever even if no routers are found. Normally rdisc
54 gives up if it has not received any advertise message after
55 after soliciting three times, in which case it exits with a non-
56 zero exit code. If -f is not specified in the first form then
57 -s must be specified.
58 -r Responder mode, available only if compiled with -DRDISC_SERVER.
60 -s Send three solicitation messages initially to quickly discover
62 the routers when the system is booted. When -s is specified
63 rdisc exits with a non-zero exit code if it can not find any
64 routers. This can be overridden with the -f option.
65 -p preference
67 Set preference in advertisement. Available only with -r option.
68 -T max_interval
70 Set maximum advertisement interval in seconds. Default is 600
71 secs. Available only with -r option.
72 -t Test mode. Do not go to background.
74 -v Be verbose i.e. send lots of debugging messages to syslog.
76 -V Print version and exit.
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80 This program was developed by Sun Microsystems (see copyright notice in
81 source file). It was ported to Linux by Alexey Kuznetsov
82 <kuznet@ms2.inr.ac.ru>. It is now maintained by YOSHIFUJI Hideaki
83 <yoshfuji@skbuff.net>.
84
86 icmp(7), inet(7), ping(8).
87
89 Deering, S.E.,ed "ICMP Router Discovery Messages", RFC1256, Network
90 Information Center, SRI International, Menlo Park, Calif., September
91 1991.
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94 rdisc requires CAP_NET_RAW to listen and send ICMP messages and capa‐
95 bility CAP_NET_ADMIN to update routing tables.
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98 rdisc is part of iputils package and the latest versions are available
99 in source form at http://www.skbuff.net/iputils/iputils-cur‐
100 rent.tar.bz2.
101iputils-160308 RDISC(8)