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1<refentry id="rdisc">
2
3<refmeta>
4<refentrytitle>rdisc</refentrytitle>
5<manvolnum>8</manvolnum>
6<refmiscinfo>iputils-&snapshot;</refmiscinfo>
7</refmeta>
8
9<refnamediv>
10<refname>rdisc</refname>
11<refpurpose>network router discovery daemon</refpurpose>
12</refnamediv>
13
14<refsynopsisdiv>
15<cmdsynopsis>
16<command>rdisc</command>
17<arg choice="opt"><option>-abdfrstvV</option></arg>
18<arg choice="opt">-p <replaceable/preference/</arg>
19<arg choice="opt">-T <replaceable/max_interval/</arg>
20<arg choice="opt"><replaceable/send_address/</arg>
21<arg choice="opt"><replaceable/receive_address/</arg>
22</cmdsynopsis>
23</refsynopsisdiv>
24
25<refsect1><title>DESCRIPTION</title>
26<para>
27<command/rdisc/ implements client side of the ICMP router discover protocol.
28<command/rdisc/ is invoked at boot time to populate the network
29routing tables with default routes.
30</para>
31
32<para>
33<command/rdisc/ listens on the ALL_HOSTS (224.0.0.1) multicast address
34(or <replaceable/receive_address/ provided it is given)
35for ROUTER_ADVERTISE messages from routers. The received
36messages are handled by first ignoring those listed router addresses
37with which the host does not share a network. Among the remaining addresses
38the ones with the highest preference are selected as default routers
39and a default route is entered in the kernel routing table
40for each one of them.
41</para>
42
43<para>
44Optionally, <command/rdisc/ can avoid waiting for routers to announce
45themselves by sending out a few ROUTER_SOLICITATION messages
46to the ALL_ROUTERS (224.0.0.2) multicast address
47(or <replaceable/send_address/ provided it is given)
48when it is started.
49</para>
50
51<para>
52A timer is associated with each router address and the address will
53no longer be considered for inclusion in the the routing tables if the
54timer expires before a new
55<emphasis/advertise/ message is received from the router.
56The address will also be excluded from consideration if the host receives an
57<emphasis/advertise/
58message with the preference being maximally negative.
59</para>
60
61<para>
62Server side of router discovery protocol is supported by Cisco IOS
63and by any more or less complete UNIX routing daemon, f.e <command/gated/.
64Or, <command/rdisc/ can act as responder, if compiled with -DRDISC_SERVER.
65</para>
66
67</refsect1>
68
69<refsect1><title>OPTIONS</title>
70
71<variablelist>
72 <varlistentry>
73  <term><option/-a/</term>
74  <listitem><para>
75Accept all routers independently of the preference they have in their
76<emphasis/advertise/ messages.
77Normally <command/rdisc/ only accepts (and enters in the kernel routing
78tables) the router or routers with the highest preference.
79  </para></listitem>
80 </varlistentry>
81 <varlistentry>
82  <term><option/-b/</term>
83  <listitem><para>
84Opposite to <option/-a/, i.e. install only router with the best
85preference value. It is default behaviour.
86  </para></listitem>
87 </varlistentry>
88 <varlistentry>
89  <term><option/-d/</term>
90  <listitem><para>
91Send debugging messages to syslog.
92  </para></listitem>
93 </varlistentry>
94 <varlistentry>
95  <term><option/-f/</term>
96  <listitem><para>
97Run <command/rdisc/ forever even if no routers are found.
98Normally <command/rdisc/ gives up if it has not received any
99<emphasis/advertise/ message after after soliciting three times,
100in which case it exits with a non-zero exit code.
101If <option/-f/ is not specified in the first form then
102<option/-s/ must be specified.
103  </para></listitem>
104 </varlistentry>
105
106 <varlistentry>
107  <term><option/-r/</term>
108  <listitem><para>
109Responder mode, available only if compiled with -DRDISC_SERVER.
110  </para></listitem>
111 </varlistentry>
112
113 <varlistentry>
114  <term><option/-s/</term>
115  <listitem><para>
116Send three <emphasis/solicitation/ messages initially to quickly discover
117the routers when the system is booted.
118When <option/-s/ is specified <command/rdisc/
119exits with a non-zero exit code if it can not find any routers.
120This can be overridden with the <option/-f/ option.
121  </para></listitem>
122 </varlistentry>
123
124 <varlistentry>
125  <term><option>-p <replaceable/preference/</option></term>
126  <listitem><para>
127Set preference in advertisement.
128Available only with -r option.
129  </para></listitem>
130 </varlistentry>
131
132 <varlistentry>
133  <term><option>-T <replaceable/max_interval/</option></term>
134  <listitem><para>
135Set maximum advertisement interval in seconds.  Default is 600 secs.
136Available only with -r option.
137  </para></listitem>
138 </varlistentry>
139
140 <varlistentry>
141  <term><option/-t/</term>
142  <listitem><para>
143Test mode. Do not go to background.
144  </para></listitem>
145 </varlistentry>
146
147 <varlistentry>
148  <term><option/-v/</term>
149  <listitem><para>
150Be verbose i.e. send lots of debugging messages to syslog.
151  </para></listitem>
152 </varlistentry>
153
154 <varlistentry>
155  <term><option/-V/</term>
156  <listitem><para>
157Print version and exit.
158  </para></listitem>
159 </varlistentry>
160</variablelist>
161</refsect1>
162
163<refsect1><title>HISTORY</title>
164<para>
165This program was developed by Sun Microsystems (see copyright
166notice in source file). It was ported to Linux by
167<ulink url="mailto:kuznet@ms2.inr.ac.ru">Alexey Kuznetsov
168&lt;kuznet@ms2.inr.ac.ru&gt;</ulink>.
169It is now maintained by
170<ulink url="mailto:yoshfuji@skbuff.net">YOSHIFUJI Hideaki
171&lt;yoshfuji@skbuff.net&gt;</ulink>.
172</para>
173</refsect1>
174
175
176<refsect1><title>SEE ALSO</title>
177<para>
178<citerefentry><refentrytitle/icmp/<manvolnum/7/</citerefentry>,
179<citerefentry><refentrytitle/inet/<manvolnum/7/</citerefentry>,
180<link linkend="ping">
181<citerefentry><refentrytitle/ping/<manvolnum/8/</citerefentry></link>.
182</para>
183</refsect1>
184
185<refsect1><title>REFERENCES</title>
186<para>
187Deering, S.E.,ed "ICMP Router Discovery Messages",
188<ulink url="http://tools.ietf.org/rfc/rfc1256.txt">
189RFC1256</ulink>, Network Information Center, SRI International,
190Menlo Park, Calif., September 1991.
191</para>
192</refsect1>
193
194<refsect1><title>SECURITY</title>
195<para>
196<command/rdisc/ requires <constant/CAP_NET_RAW/ to listen
197and send ICMP messages and capability <constant/CAP_NET_ADMIN/
198to update routing tables.
199</para>
200</refsect1>
201
202<refsect1><title>AVAILABILITY</title>
203<para>
204<command/rdisc/ is part of <filename/iputils/ package
205and the latest versions are  available in source form at
206<ulink url="http://www.skbuff.net/iputils/iputils-current.tar.bz2">
207http://www.skbuff.net/iputils/iputils-current.tar.bz2</ulink>.
208</para>
209</refsect1>
210
211<![IGNORE[
212<refsect1><title>COPYING</title>
213<para>
214<literallayout>
215Rdisc (this program) was developed by Sun Microsystems, Inc. and is
216provided for unrestricted use provided that this legend is included on
217all tape media and as a part of the software program in whole or part.
218Users may copy or modify Rdisc without charge, and they may freely
219distribute it.
220
221RDISC IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING THE
222WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
223PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE.
224
225Rdisc is provided with no support and without any obligation on the
226part of Sun Microsystems, Inc. to assist in its use, correction,
227modification or enhancement.
228
229SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE
230INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY RDISC
231OR ANY PART THEREOF.
232
233In no event will Sun Microsystems, Inc. be liable for any lost revenue
234or profits or other special, indirect and consequential damages, even if
235Sun has been advised of the possibility of such damages.
236
237Sun Microsystems, Inc.
2382550 Garcia Avenue
239Mountain View, California  94043
240</literallayout>
241</para>
242</refsect1>
243]]>
244
245
246</refentry>
247