4 <refentrytitle>rdisc</refentrytitle>
5 <manvolnum>8</manvolnum>
6 <refmiscinfo>iputils-&snapshot;</refmiscinfo>
10 <refname>rdisc</refname>
11 <refpurpose>network router discovery daemon</refpurpose>
16 <command>rdisc</command>
17 <arg choice="opt"><option>-abdfstvV</option></arg>
18 <arg choice="opt"><replaceable/send_address/</arg>
19 <arg choice="opt"><replaceable/receive_address/</arg>
23 <refsect1><title>DESCRIPTION</title>
25 <command/rdisc/ implements client side of the ICMP router discover protocol.
26 <command/rdisc/ is invoked at boot time to populate the network
27 routing tables with default routes.
31 <command/rdisc/ listens on the ALL_HOSTS (224.0.0.1) multicast address
32 (or <replaceable/receive_address/ provided it is given)
33 for ROUTER_ADVERTISE messages from routers. The received
34 messages are handled by first ignoring those listed router addresses
35 with which the host does not share a network. Among the remaining addresses
36 the ones with the highest preference are selected as default routers
37 and a default route is entered in the kernel routing table
42 Optionally, <command/rdisc/ can avoid waiting for routers to announce
43 themselves by sending out a few ROUTER_SOLICITATION messages
44 to the ALL_ROUTERS (224.0.0.2) multicast address
45 (or <replaceable/send_address/ provided it is given)
50 A timer is associated with each router address and the address will
51 no longer be considered for inclusion in the the routing tables if the
52 timer expires before a new
53 <emphasis/advertise/ message is received from the router.
54 The address will also be excluded from consideration if the host receives an
56 message with the preference being maximally negative.
60 Server side of router discovery protocol is supported by Cisco IOS
61 and by any more or less complete UNIX routing daemon, f.e <command/gated/.
66 <refsect1><title>OPTIONS</title>
70 <term><option/-a/</term>
72 Accept all routers independently of the preference they have in their
73 <emphasis/advertise/ messages.
74 Normally <command/rdisc/ only accepts (and enters in the kernel routing
75 tables) the router or routers with the highest preference.
79 <term><option/-b/</term>
81 Opposite to <option/-a/, i.e. install only router with the best
82 preference value. It is default behaviour.
86 <term><option/-d/</term>
88 Send debugging messages to syslog.
92 <term><option/-f/</term>
94 Run <command/rdisc/ forever even if no routers are found.
95 Normally <command/rdisc/ gives up if it has not received any
96 <emphasis/advertise/ message after after soliciting three times,
97 in which case it exits with a non-zero exit code.
98 If <option/-f/ is not specified in the first form then
99 <option/-s/ must be specified.
104 <term><option/-s/</term>
106 Send three <emphasis/solicitation/ messages initially to quickly discover
107 the routers when the system is booted.
108 When <option/-s/ is specified <command/rdisc/
109 exits with a non-zero exit code if it can not find any routers.
110 This can be overridden with the <option/-f/ option.
115 <term><option/-t/</term>
117 Test mode. Do not go to background.
123 <term><option/-v/</term>
125 Be verbose i.e. send lots of debugging messages to syslog.
130 <term><option/-V/</term>
132 Print version and exit.
138 <refsect1><title>HISTORY</title>
140 This program was developed by Sun Microsystems (see copyright
141 notice in source file). It was ported to Linux by
142 <ulink url="mailto:kuznet@ms2.inr.ac.ru">Alexey Kuznetsov
143 <kuznet@ms2.inr.ac.ru></ulink>.
144 It is now maintained by
145 <ulink url="mailto:yoshfuji@skbuff.net">YOSHIFUJI Hideaki
146 <yoshfuji@skbuff.net></ulink>.
151 <refsect1><title>SEE ALSO</title>
153 <citerefentry><refentrytitle/icmp/<manvolnum/7/</citerefentry>,
154 <citerefentry><refentrytitle/inet/<manvolnum/7/</citerefentry>,
155 <link linkend="ping">
156 <citerefentry><refentrytitle/ping/<manvolnum/8/</citerefentry></link>.
160 <refsect1><title>REFERENCES</title>
162 Deering, S.E.,ed "ICMP Router Discovery Messages",
163 <ulink url="ftp://ftp.isi.edu/in-notes/rfc1256.txt">
164 RFC1256</ulink>, Network Information Center, SRI International,
165 Menlo Park, Calif., September 1991.
169 <refsect1><title>SECURITY</title>
171 <command/rdisc/ requires <constant/CAP_NET_RAWIO/ to listen
172 and send ICMP messages and capability <constant/CAP_NET_ADMIN/
173 to update routing tables.
177 <refsect1><title>AVAILABILITY</title>
179 <command/rdisc/ is part of <filename/iputils/ package
180 and the latest versions are available in source form at
181 <ulink url="http://www.skbuff.net/iputils/iputils-current.tar.bz2">
182 http://www.skbuff.net/iputils/iputils-current.tar.bz2</ulink>.
187 <refsect1><title>COPYING</title>
190 Rdisc (this program) was developed by Sun Microsystems, Inc. and is
191 provided for unrestricted use provided that this legend is included on
192 all tape media and as a part of the software program in whole or part.
193 Users may copy or modify Rdisc without charge, and they may freely
196 RDISC IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING THE
197 WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
198 PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE.
200 Rdisc is provided with no support and without any obligation on the
201 part of Sun Microsystems, Inc. to assist in its use, correction,
202 modification or enhancement.
204 SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE
205 INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY RDISC
208 In no event will Sun Microsystems, Inc. be liable for any lost revenue
209 or profits or other special, indirect and consequential damages, even if
210 Sun has been advised of the possibility of such damages.
212 Sun Microsystems, Inc.
214 Mountain View, California 94043