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
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 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.
24 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.
29 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.
35 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.
39
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.
46 -b
48 Opposite to -a, i.e. install only router with the best preference
49 value. This is the default behaviour.
50 -d
52 Send debugging messages to syslog.
53 -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.
60 -r
62 Responder mode, available only if compiled with
63 ENABLE_RDISC_SERVER.
64 -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.
70 -p preference
72 Set preference in advertisement messages. Available only with -r
73 option.
74 -T max_interval
76 Set maximum advertisement interval in seconds. Default is 600.
77 Available only with -r option.
78 -t
80 Test mode. Do not go to background.
81 -v
83 Be verbose and 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 Kuznetsov
91 <kuznet@ms2.inr.ac.ru>.
92
94 icmp(7), inet(7), ping(8).
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97 RFC1256 ICMP Router Discovery Messages. S. Deering, Ed.. September
98 1991.
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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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105 rdisc is part of iputils package.
106iputils 20210722 RDISC(8)