<refentry id="rdisc"> <refmeta> <refentrytitle>rdisc</refentrytitle> <manvolnum>8</manvolnum> <refmiscinfo>iputils-&snapshot;</refmiscinfo> </refmeta> <refnamediv> <refname>rdisc</refname> <refpurpose>network router discovery daemon</refpurpose> </refnamediv> <refsynopsisdiv> <cmdsynopsis> <command>rdisc</command> <arg choice="opt"><option>-abdfrstvV</option></arg> <arg choice="opt">-p <replaceable/preference/</arg> <arg choice="opt">-T <replaceable/max_interval/</arg> <arg choice="opt"><replaceable/send_address/</arg> <arg choice="opt"><replaceable/receive_address/</arg> </cmdsynopsis> </refsynopsisdiv> <refsect1><title>DESCRIPTION</title> <para> <command/rdisc/ implements client side of the ICMP router discover protocol. <command/rdisc/ is invoked at boot time to populate the network routing tables with default routes. </para> <para> <command/rdisc/ listens on the ALL_HOSTS (224.0.0.1) multicast address (or <replaceable/receive_address/ provided it is given) for ROUTER_ADVERTISE messages from routers. The received messages are handled by first ignoring those listed router addresses with which the host does not share a network. Among the remaining addresses the ones with the highest preference are selected as default routers and a default route is entered in the kernel routing table for each one of them. </para> <para> Optionally, <command/rdisc/ can avoid waiting for routers to announce themselves by sending out a few ROUTER_SOLICITATION messages to the ALL_ROUTERS (224.0.0.2) multicast address (or <replaceable/send_address/ provided it is given) when it is started. </para> <para> A timer is associated with each router address and the address will no longer be considered for inclusion in the the routing tables if the timer expires before a new <emphasis/advertise/ message is received from the router. The address will also be excluded from consideration if the host receives an <emphasis/advertise/ message with the preference being maximally negative. </para> <para> Server side of router discovery protocol is supported by Cisco IOS and by any more or less complete UNIX routing daemon, f.e <command/gated/. Or, <command/rdisc/ can act as responder, if compiled with -DRDISC_SERVER. </para> </refsect1> <refsect1><title>OPTIONS</title> <variablelist> <varlistentry> <term><option/-a/</term> <listitem><para> Accept all routers independently of the preference they have in their <emphasis/advertise/ messages. Normally <command/rdisc/ only accepts (and enters in the kernel routing tables) the router or routers with the highest preference. </para></listitem> </varlistentry> <varlistentry> <term><option/-b/</term> <listitem><para> Opposite to <option/-a/, i.e. install only router with the best preference value. It is default behaviour. </para></listitem> </varlistentry> <varlistentry> <term><option/-d/</term> <listitem><para> Send debugging messages to syslog. </para></listitem> </varlistentry> <varlistentry> <term><option/-f/</term> <listitem><para> Run <command/rdisc/ forever even if no routers are found. Normally <command/rdisc/ gives up if it has not received any <emphasis/advertise/ message after after soliciting three times, in which case it exits with a non-zero exit code. If <option/-f/ is not specified in the first form then <option/-s/ must be specified. </para></listitem> </varlistentry> <varlistentry> <term><option/-r/</term> <listitem><para> Responder mode, available only if compiled with -DRDISC_SERVER. </para></listitem> </varlistentry> <varlistentry> <term><option/-s/</term> <listitem><para> Send three <emphasis/solicitation/ messages initially to quickly discover the routers when the system is booted. When <option/-s/ is specified <command/rdisc/ exits with a non-zero exit code if it can not find any routers. This can be overridden with the <option/-f/ option. </para></listitem> </varlistentry> <varlistentry> <term><option>-p <replaceable/preference/</option></term> <listitem><para> Set preference in advertisement. Available only with -r option. </para></listitem> </varlistentry> <varlistentry> <term><option>-T <replaceable/max_interval/</option></term> <listitem><para> Set maximum advertisement interval in seconds. Default is 600 secs. Available only with -r option. </para></listitem> </varlistentry> <varlistentry> <term><option/-t/</term> <listitem><para> Test mode. Do not go to background. </para></listitem> </varlistentry> <varlistentry> <term><option/-v/</term> <listitem><para> Be verbose i.e. send lots of debugging messages to syslog. </para></listitem> </varlistentry> <varlistentry> <term><option/-V/</term> <listitem><para> Print version and exit. </para></listitem> </varlistentry> </variablelist> </refsect1> <refsect1><title>HISTORY</title> <para> This program was developed by Sun Microsystems (see copyright notice in source file). It was ported to Linux by <ulink url="mailto:kuznet@ms2.inr.ac.ru">Alexey Kuznetsov <kuznet@ms2.inr.ac.ru></ulink>. It is now maintained by <ulink url="mailto:yoshfuji@skbuff.net">YOSHIFUJI Hideaki <yoshfuji@skbuff.net></ulink>. </para> </refsect1> <refsect1><title>SEE ALSO</title> <para> <citerefentry><refentrytitle/icmp/<manvolnum/7/</citerefentry>, <citerefentry><refentrytitle/inet/<manvolnum/7/</citerefentry>, <link linkend="ping"> <citerefentry><refentrytitle/ping/<manvolnum/8/</citerefentry></link>. </para> </refsect1> <refsect1><title>REFERENCES</title> <para> Deering, S.E.,ed "ICMP Router Discovery Messages", <ulink url="http://tools.ietf.org/rfc/rfc1256.txt"> RFC1256</ulink>, Network Information Center, SRI International, Menlo Park, Calif., September 1991. </para> </refsect1> <refsect1><title>SECURITY</title> <para> <command/rdisc/ requires <constant/CAP_NET_RAW/ to listen and send ICMP messages and capability <constant/CAP_NET_ADMIN/ to update routing tables. </para> </refsect1> <refsect1><title>AVAILABILITY</title> <para> <command/rdisc/ is part of <filename/iputils/ package and the latest versions are available in source form at <ulink url="http://www.skbuff.net/iputils/iputils-current.tar.bz2"> http://www.skbuff.net/iputils/iputils-current.tar.bz2</ulink>. </para> </refsect1> <![IGNORE[ <refsect1><title>COPYING</title> <para> <literallayout> Rdisc (this program) was developed by Sun Microsystems, Inc. and is provided for unrestricted use provided that this legend is included on all tape media and as a part of the software program in whole or part. Users may copy or modify Rdisc without charge, and they may freely distribute it. RDISC IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING THE WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE. Rdisc is provided with no support and without any obligation on the part of Sun Microsystems, Inc. to assist in its use, correction, modification or enhancement. SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY RDISC OR ANY PART THEREOF. In no event will Sun Microsystems, Inc. be liable for any lost revenue or profits or other special, indirect and consequential damages, even if Sun has been advised of the possibility of such damages. Sun Microsystems, Inc. 2550 Garcia Avenue Mountain View, California 94043 </literallayout> </para> </refsect1> ]]> </refentry>