1RDISC(8) 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
24 kernel 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.
41
43 -a
44 Accept all routers independently of the preference they have in
45 their advertise messages. Normally rdisc only accepts (and enters
46 in the kernel routing tables) the router or routers with the
47 highest preference.
48 -b
50 Opposite to -a, i.e. install only router with the best preference
51 value. It is default behaviour.
52 -d
54 Send debugging messages to syslog.
55 -f
57 Run rdisc forever even if no routers are found. Normally rdisc
58 gives up if it has not received any advertise message after after
59 soliciting three times, in which case it exits with a non-zero exit
60 code. If -f is not specified in the first form then -s must be
61 specified.
62 -r
64 Responder mode, available only if compiled with -DRDISC_SERVER.
65 -s
67 Send three solicitation messages initially to quickly discover the
68 routers when the system is booted. When -s is specified rdisc exits
69 with a non-zero exit code if it can not find any routers. This can
70 be overridden with the -f option.
71 -p preference
73 Set preference in advertisement. Available only with -r option.
74 -T max_interval
76 Set maximum advertisement interval in seconds. Default is 600 secs.
77 Available only with -r option.
78 -t
80 Test mode. Do not go to background.
81 -v
83 Be verbose i.e. send lots of debugging messages to syslog.
84 -V
86 Print version and exit.
87
89 This program was developed by Sun Microsystems (see copyright notice in
90 source file). It was ported to Linux by Alexey
91 Kuznetsov<kuznet@ms2.inr.ac.ru>.
92
94 icmp(7), inet(7), ping(8).
95
97 Deering, S.E.,ed "ICMP Router Discovery Messages", RFC1256, Network
98 Information Center, SRI International, Menlo Park, Calif., September
99 1991.
100
102 rdisc requires CAP_NET_RAW to listen and send ICMP messages and
103 capability CAP_NET_ADMIN to update routing tables.
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106 rdisc is part of iputils package.
107iputils s20180629 RDISC(8)