192 lines
5.3 KiB
Groff
192 lines
5.3 KiB
Groff
.\" @(#)in.rdisc.8c 1.4 91/10/21 SMI
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'\"macro stdmacro
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.\" Sun Microsystems, Inc.
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.\" 2550 Garcia Avenue
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.\" Mountain View, California 94043
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.\"
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.nr X
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.TH in.rdisc 8C "2 Oct 1991"
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.SH NAME
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in.rdisc \- network router discovery daemon
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.SH SYNOPSIS
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.B in.rdisc
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[
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.B \-sfa
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]
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.LP
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.B in.rdisc
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.B \-r
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[
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.BI \-p " preference"
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] [
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.BI \-T " interval"
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]
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.SH DESCRIPTION
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.IX "in.rdisc" "" "\fLin.rdisc\fP \(em ICMP router discovery daemon"
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.IX "Internet" "ICMP router discovery daemon" "" "ICMP router discovery daemon \(em \fLin.rdisc\fP"
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.IX "Internet Control Message Protocol" "See ICMP"
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.IX "ICMP" "router discovery daemon" "" "router discovery daemon \(em \fLin.rdisc\fP"
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.LP
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\f4in.rdisc\f1
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implements the
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.SM ICMP
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router discover protocol.
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The first form of the command is used on hosts and the
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second form is used on routers.
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On a host \f4in.rdisc\f1 is invoked at
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boot time to populate the network routing tables with default routes.
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On a router it is also invoked at boot time in order to start
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advertising the router to all the hosts.
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.SS "Host (First Form)"
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.PP
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On a host \f4in.rdisc\f1
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listens on the \f4ALL_HOSTS\f1 (224.0.0.1) multicast address
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for \f4ROUTER_ADVERTISE\f1 messages from routers. The received
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messages are handled by first ignoring
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those listed router addresses with which the host does not share a network.
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Among the remaining addresses the ones with the highest preference are selected
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as default routers and a default route is entered in the kernel routing
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table for each one of them.
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.LP
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Optionally, \f4in.rdisc\f1 can avoid waiting for routers to announce
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themselves by sending out a few \f4ROUTER_SOLICITATION\f1 messages
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to the \f4ALL_ROUTERS\f1 (224.0.0.2) multicast address when it is started.
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.LP
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A timer is associated with each router address and the address will
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no longer be considered for inclusion in the the routing tables if the
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timer expires before a new
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.I advertise
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message is received from the router.
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The address will also be excluded from consideration if the host receives an
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.I advertise
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message with the preference being maximally negative.
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.SS "Router (Second Form)"
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.PP
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When
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\f4in.rdisc\f1
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is started on a router, it uses the
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\f4SIOCGIFCONF\f1
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.BR ioctl (2)
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to find the interfaces configured into the system and it starts
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listening on the \f4ALL_ROUTERS\f1 multicast address on all the interfaces
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that support multicast.
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It sends out
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.I advertise
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messages to the \f4ALL_HOSTS\f1 multicast address advertising all its
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.BM IP
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addresses.
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A few initial
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.I advertise
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messages are sent out during the first 30 seconds and after that it will
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transmit
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.I advertise
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messages approximately every 600 seconds.
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.LP
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When \f4in.rdisc\f1
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receives a
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.I solicitation
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message it sends an
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.I advertise
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message to the host that sent the
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.I solicitation
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message.
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.LP
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When
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.B in.rdisc
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is terminated by a signal it sends out an
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.I advertise
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message with the preference being maximally negative.
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.br
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.ne 1i
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.SH OPTIONS
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.TP 15
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.B \-a
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Accept all routers independently of the preference they have in their
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.I advertise
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messages.
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Normally
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.B in.rdisc
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only accepts (and enters in the kernel routing tables)
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the router or routers with the highest preference.
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.TP
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.B \-f
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Run
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.B in.rdisc
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forever even if no routers are found.
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Normally
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.B in.rdisc
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gives up if it has not received any
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.I advertise
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message after after soliciting three times,
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in which case it exits with a non-zero exit code.
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If
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.B \-f
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is not specified in the first form then
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.B \-s
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must be specified.
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.TP
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.BI \-p " preference"
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Set the preference transmitted in the
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.I solicitation
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messages.
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The default is zero.
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.TP
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.B \-r
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Act as a router as opposed to a host.
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.TP
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.B \-s
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Send three
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.I solicitation
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messages initially to quickly discover the routers
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when the system is booted.
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When
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.B \-s
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is specified
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.B in.rdisc
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exits with a non-zero exit code if it can not find any routers.
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This can be overridden with the
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.B \-f
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option.
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.TP
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.BI \-T " interval"
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Set the interval between transmitting the
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.I advertise
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messages.
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The default time is 600 seconds.
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.SH "SEE ALSO"
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.BR in.routed (8C)
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.BR ioctl (2),
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.BR icmp (7),
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.BR inet (7)
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.LP
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Deering, S.E.,ed
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.RI `` "ICMP Router Discovery Messages" ,''
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.SM RFC
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1256, Network Information Center,
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.SM SRI
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International, Menlo Park, Calif.,
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September 1991.
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