.TH RARPD 8
.SH NAME
rarpd \- reverse address resolution protocol daemon
.SH SYNOPSIS
.B rarpd
.RB [ \-d [\fIlevel\fR]]
.I network-name
\&...
.SH DESCRIPTION
.de SP
.if t .sp 0.4
.if n .sp
..
.B Rarpd
listens on the given networks for broadcast packets asking for reverse address
resolution.  These packets are sent by hosts at boot time to find out their
IP address.
.B Rarpd
looks up the six octet ethernet number in the
.B /etc/ethers
file finding a host name.  This name is translated to the IP address of the
host by a DNS lookup.  The IP address is then sent to the host.
.PP
Under Minix the program forks as needed to give each network its own server.
Under Minix-vmd all networks are handled in the same program using async I/O.
.SS "Private Ethernet Addresses"
For VU practical work, where students have to create their own IP stack
starting at the bottom with RARP, this implementation recognizes Ethernet
addresses starting with octet 0x76 as special.  The next octet is used as a
additional host number and the next and last four octets as an IP address
that this Ethernet address is additional for.  The IP address is translated
back to a name, and the first component of that name gets a dash and the
additional host number added to it.  That hostname is then looked up and its
IP address returned in a RARP reply.  Example:
.PP
.RS
.ta +\w'flotsam-3.example.commmm'u
76:3:c0:a8:e7:fa	Additional 3, IP 192.168.231.250
.SP
flotsam.example.com	Reverse lookup on 192.168.231.250
.SP
flotsam-3.example.com	Splicing in additional number
.SP
192.168.231.42		Forward lookup
.RE
.PP
In this example a RARP query for 76:3:c0:a8:e7:fa gets 192.168.231.42 as reply.
.SH OPTIONS
.TP
.BR \-d [\fIlevel\fP]
Turns on debugging messages at the given level, by default 1.  At level 1 you
will be shown what answers are sent, and at level 2 or higher you will be told
about queries from unknown hosts or host on the wrong network.
The debug level can also be increased by 1 at runtime by sending signal
.B SIGUSR1
or turned off (set to 0) with
.BR SIGUSR2 .
.SH "SEE ALSO"
.BR ifconfig (8),
.BR ethers (5),
.BR hosts (5),
.BR inet (8),
.BR boot (8),
.BR dhcpd (8),
.BR irdpd (8),
.BR inetd (8),
.BR nonamed (8).
.SH NOTES
A "network name" is the device name of the IP device of a network, i.e.
.BR ip0 ,
.BR ip1 ", ..."
.PP
The RARP protocol has gone out of fashion in favour of DHCP.
.SH AUTHOR
Kees J. Bot (kjb@cs.vu.nl)