1RDISC(8)                            iputils                           RDISC(8)
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NAME

6       rdisc - network router discovery daemon
7

SYNOPSIS

9       rdisc [-abdfrstvV] [-p preference] [-T max_interval] [send_address]
10             [receive_address]
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DESCRIPTION

13       rdisc implements client side of the ICMP router discover protocol.
14       rdisc is invoked at boot time to populate the network routing tables
15       with default routes.
16
17       rdisc listens on the ALL_HOSTS (224.0.0.1) multicast address (or
18       receive_address provided it is given) for ROUTER_ADVERTISE messages
19       from routers. The received messages are handled by first ignoring those
20       listed router addresses with which the host does not share a network.
21       Among the remaining addresses the ones with the highest preference are
22       selected as default routers and a default route is entered in the
23       kernel routing table for each one of them.
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25       Optionally, rdisc can avoid waiting for routers to announce themselves
26       by sending out a few ROUTER_SOLICITATION messages to the ALL_ROUTERS
27       (224.0.0.2) multicast address (or send_address provided it is given)
28       when it is started.
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30       A timer is associated with each router address and the address will no
31       longer be considered for inclusion in the the routing tables if the
32       timer expires before a new advertise message is received from the
33       router. The address will also be excluded from consideration if the
34       host receives an advertise message with the preference being maximally
35       negative.
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37       Server side of router discovery protocol is supported by Cisco IOS and
38       by any more or less complete UNIX routing daemon, f.e gated. Or, rdisc
39       can act as responder, if compiled with ENABLE_RDISC_SERVER.
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OPTIONS

42       -a
43           Accept all routers independently of the preference they have in
44           their advertise messages. Normally rdisc only accepts (and enters
45           in the kernel routing tables) the router or routers with the
46           highest preference.
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48       -b
49           Opposite to -a, i.e. install only router with the best preference
50           value. It is default behaviour.
51
52       -d
53           Send debugging messages to syslog.
54
55       -f
56           Run rdisc forever even if no routers are found. Normally rdisc
57           gives up if it has not received any advertise message after after
58           soliciting three times, in which case it exits with a non-zero exit
59           code. If -f is not specified in the first form then -s must be
60           specified.
61
62       -r
63           Responder mode, available only if compiled with
64           ENABLE_RDISC_SERVER.
65
66       -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.
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72       -p preference
73           Set preference in advertisement. Available only with -r option.
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75       -T max_interval
76           Set maximum advertisement interval in seconds. Default is 600 secs.
77           Available only with -r option.
78
79       -t
80           Test mode. Do not go to background.
81
82       -v
83           Be verbose i.e. send lots of debugging messages to syslog.
84
85       -V
86           Print version and exit.
87

HISTORY

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>.
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SEE ALSO

94       icmp(7), inet(7), ping(8).
95

REFERENCES

97       Deering, S.E.,ed "ICMP Router Discovery Messages", RFC1256, Network
98       Information Center, SRI International, Menlo Park, Calif., September
99       1991.
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SECURITY

102       rdisc requires CAP_NET_RAW to listen and send ICMP messages and
103       capability CAP_NET_ADMIN to update routing tables.
104

AVAILABILITY

106       rdisc is part of iputils package.
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110iputils s20190515                                                     RDISC(8)
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