'\"macro stdmacro
.if n .pH g1a.rarpd @(#)rarpd	40.6 of 10/10/89
.\" Copyright 1989 AT&T
.nr X
.if \nX=0 .ds x} rarpd 1M "TCP/IP" "\&"
.if \nX=1 .ds x} rarpd 1M "TCP/IP"
.if \nX=2 .ds x} rarpd 1M "" "\&"
.if \nX=3 .ds x} rarpd "" "" "\&"
.TH \*(x}
.SH NAME
\f4rarpd\f1 \- \s-1DARPA\s0 Reverse Address Resolution Protocol server
.SH SYNOPSIS
\f4rarpd\f1
.I interface
[
.I hostname
]
.LP
\f4/usr/sbin/rarpd -a\f1
.SH DESCRIPTION
\f4rarpd\f1
starts a daemon that responds to Reverse Address Resolution Protocol
(\s-1RARP\s0) requests.
The daemon forks a copy of itself that runs in background.
It must be run as root.
.LP
\s-1RARP\s0 is used by machines at boot time to discover their
Internet Protocol (\s-1IP\s0) address.
The booting machine provides its Ethernet Address in 
a
.SM RARP 
request message.
Using the \f4ethers\f1 and \f4hosts\f1 databases,
\f4rarpd\f1
maps this Ethernet Address into the corresponding IP address
which it returns to the booting machine in an RARP reply message.
The booting machine must be listed in both databases for
\f4rarpd\f1
to locate its IP address.
\f4rarpd\f1
issues no reply when it fails to locate an IP address.
.LP
In the first synopsis, the
.I interface 
parameter names the network interface upon which 
\f4rarpd\f1
is to listen for requests.
The
.I interface
parameter takes the ``name unit'' form used by
\f4ifconfig\f1(1M).
The second argument,
.IR hostname ,
is used to obtain the IP address of that interface.
An IP address in ``decimal dot'' notation may be used for
.IR hostname .
If
.I hostname
is omitted, the address of the interface will be obtained from the kernel.
When the first form of the command is used,
\f4rarpd\f1
must be run separately for each interface
on which \s-1RARP\s0 service is to be supported.
A machine that is a router may invoke
\f4rarpd\f1
multiple times, for example:
.LP
.RS
\f4/usr/sbin/rarpd emd1 host\f1
.br
\f4/usr/sbin/rarpd emd2 host-backbone\f1
.RE
.LP
In the second synopsis,
\f4rarpd\f1
locates all of the network interfaces present on the system
and starts a daemon process for each one that supports \s-1RARP\s0.
.SH "FILES"
.PD 0
.TP 20
\f4/etc/ethers\f1
.\" .TP 
.\" .BI /var/yp/ domainname /ethers.byaddr.*
.\" .TP
.\" .BI /var/yp/ domainname /ethers.byname.*
.TP
\f4/etc/hosts\f1
.\" .TP
.\" .BI /var/yp/ domainname /hosts.byname.*
.PD
.SH "SEE ALSO"
\f4ifconfig\f1(1M),
\f4ethers\f1(4),
\f4hosts\f1(4),
\f4netconfig\f1(4),
\f4boot\f1(8).
.LP
Finlayson, Ross, Timothy Mann, Jeffrey Mogul, and Marvin Theimer,
.IR "A Reverse Address Resolution Protocol" ,
.SM RFC
903,
Network Information Center,
.SM SRI
International, Menlo Park, Calif.,
June 1984.
