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>-abdfstvV</option></arg> 18<arg choice="opt"><replaceable/send_address/</arg> 19<arg choice="opt"><replaceable/receive_address/</arg> 20</cmdsynopsis> 21</refsynopsisdiv> 22 23<refsect1><title>DESCRIPTION</title> 24<para> 25<command/rdisc/ implements client side of the ICMP router discover protocol. 26<command/rdisc/ is invoked at boot time to populate the network 27routing tables with default routes. 28</para> 29 30<para> 31<command/rdisc/ listens on the ALL_HOSTS (224.0.0.1) multicast address 32(or <replaceable/receive_address/ provided it is given) 33for ROUTER_ADVERTISE messages from routers. The received 34messages are handled by first ignoring those listed router addresses 35with which the host does not share a network. Among the remaining addresses 36the ones with the highest preference are selected as default routers 37and a default route is entered in the kernel routing table 38for each one of them. 39</para> 40 41<para> 42Optionally, <command/rdisc/ can avoid waiting for routers to announce 43themselves by sending out a few ROUTER_SOLICITATION messages 44to the ALL_ROUTERS (224.0.0.2) multicast address 45(or <replaceable/send_address/ provided it is given) 46when it is started. 47</para> 48 49<para> 50A timer is associated with each router address and the address will 51no longer be considered for inclusion in the the routing tables if the 52timer expires before a new 53<emphasis/advertise/ message is received from the router. 54The address will also be excluded from consideration if the host receives an 55<emphasis/advertise/ 56message with the preference being maximally negative. 57</para> 58 59<para> 60Server side of router discovery protocol is supported by Cisco IOS 61and by any more or less complete UNIX routing daemon, f.e <command/gated/. 62</para> 63 64</refsect1> 65 66<refsect1><title>OPTIONS</title> 67 68<variablelist> 69 <varlistentry> 70 <term><option/-a/</term> 71 <listitem><para> 72Accept all routers independently of the preference they have in their 73<emphasis/advertise/ messages. 74Normally <command/rdisc/ only accepts (and enters in the kernel routing 75tables) the router or routers with the highest preference. 76 </para></listitem> 77 </varlistentry> 78 <varlistentry> 79 <term><option/-b/</term> 80 <listitem><para> 81Opposite to <option/-a/, i.e. install only router with the best 82preference value. It is default behaviour. 83 </para></listitem> 84 </varlistentry> 85 <varlistentry> 86 <term><option/-d/</term> 87 <listitem><para> 88Send debugging messages to syslog. 89 </para></listitem> 90 </varlistentry> 91 <varlistentry> 92 <term><option/-f/</term> 93 <listitem><para> 94Run <command/rdisc/ forever even if no routers are found. 95Normally <command/rdisc/ gives up if it has not received any 96<emphasis/advertise/ message after after soliciting three times, 97in which case it exits with a non-zero exit code. 98If <option/-f/ is not specified in the first form then 99<option/-s/ must be specified. 100 </para></listitem> 101 </varlistentry> 102 103 <varlistentry> 104 <term><option/-s/</term> 105 <listitem><para> 106Send three <emphasis/solicitation/ messages initially to quickly discover 107the routers when the system is booted. 108When <option/-s/ is specified <command/rdisc/ 109exits with a non-zero exit code if it can not find any routers. 110This can be overridden with the <option/-f/ option. 111 </para></listitem> 112 </varlistentry> 113 114 <varlistentry> 115 <term><option/-t/</term> 116 <listitem><para> 117Test mode. Do not go to background. 118 </para></listitem> 119 </varlistentry> 120 121 122 <varlistentry> 123 <term><option/-v/</term> 124 <listitem><para> 125Be verbose i.e. send lots of debugging messages to syslog. 126 </para></listitem> 127 </varlistentry> 128 129 <varlistentry> 130 <term><option/-V/</term> 131 <listitem><para> 132Print version and exit. 133 </para></listitem> 134 </varlistentry> 135</variablelist> 136</refsect1> 137 138<refsect1><title>HISTORY</title> 139<para> 140This program was developed by Sun Microsystems (see copyright 141notice 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</para> 145</refsect1> 146 147 148<refsect1><title>SEE ALSO</title> 149<para> 150<citerefentry><refentrytitle/icmp/<manvolnum/7/</citerefentry>, 151<citerefentry><refentrytitle/inet/<manvolnum/7/</citerefentry>, 152<link linkend="ping"> 153<citerefentry><refentrytitle/ping/<manvolnum/8/</citerefentry></link>. 154</para> 155</refsect1> 156 157<refsect1><title>REFERENCES</title> 158<para> 159Deering, S.E.,ed "ICMP Router Discovery Messages", 160<ulink url="ftp://ftp.isi.edu/in-notes/rfc1256.txt"> 161RFC1256</ulink>, Network Information Center, SRI International, 162Menlo Park, Calif., September 1991. 163</para> 164</refsect1> 165 166<refsect1><title>SECURITY</title> 167<para> 168<command/rdisc/ requires <constant/CAP_NET_RAWIO/ to listen 169and send ICMP messages and capability <constant/CAP_NET_ADMIN/ 170to update routing tables. 171</para> 172</refsect1> 173 174<refsect1><title>AVAILABILITY</title> 175<para> 176<command/rdisc/ is part of <filename/iputils/ package 177and the latest versions are available in source form for anonymous ftp 178<ulink url="ftp://ftp.inr.ac.ru/ip-routing/iputils-current.tar.gz"> 179ftp://ftp.inr.ac.ru/ip-routing/iputils-current.tar.gz</ulink>. 180</para> 181</refsect1> 182 183<![IGNORE[ 184<refsect1><title>COPYING</title> 185<para> 186<literallayout> 187Rdisc (this program) was developed by Sun Microsystems, Inc. and is 188provided for unrestricted use provided that this legend is included on 189all tape media and as a part of the software program in whole or part. 190Users may copy or modify Rdisc without charge, and they may freely 191distribute it. 192 193RDISC IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING THE 194WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR 195PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE. 196 197Rdisc is provided with no support and without any obligation on the 198part of Sun Microsystems, Inc. to assist in its use, correction, 199modification or enhancement. 200 201SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE 202INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY RDISC 203OR ANY PART THEREOF. 204 205In no event will Sun Microsystems, Inc. be liable for any lost revenue 206or profits or other special, indirect and consequential damages, even if 207Sun has been advised of the possibility of such damages. 208 209Sun Microsystems, Inc. 2102550 Garcia Avenue 211Mountain View, California 94043 212</literallayout> 213</para> 214</refsect1> 215]]> 216 217 218</refentry> 219