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 Internet Router Discovery
14       Protocol (IRDP).  rdisc is invoked at boot time to populate the network
15       routing tables with default routes.
16
17       rdisc listens on the ALL_HOSTS (224.0.0.1) multicast address (or
18       receive_address if it is provided) for ROUTER_ADVERTISE messages from
19       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 if it is provided) when
28       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 routing tables if the timer
32       expires before a new advertise message is received from the router. The
33       address will also be excluded from consideration if the received
34       advertise message has a preference of maximum negative.
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36       Server side of router discovery protocol is supported by Cisco IOS and
37       by any more or less complete UNIX routing daemon, for example gated. If
38       compiled with ENABLE_RDISC_SERVER, rdisc can act as responder.
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OPTIONS

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

89       This program was developed by Sun Microsystems (see copyright notice in
90       source file). It was ported to Linux by Alexey Kuznetsov
91       <kuznet@ms2.inr.ac.ru>.
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SEE ALSO

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

REFERENCES

97       RFC1256 ICMP Router Discovery Messages. S. Deering, Ed.. September
98       1991.
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SECURITY

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

105       rdisc is part of iputils package.
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109iputils s20200821                                                     RDISC(8)
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