rarpd - reverse address resolution protocol daemon
rarpd [-d[level]] network-name ...
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. Rarpd looks up the six octet ethernet
number in the /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.
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.
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:
76:3:c0:a8:e7:fa Additional 3, IP 192.168.231.250
flotsam.example.com Reverse lookup on 192.168.231.250
flotsam-3.example.com Splicing in additional number
192.168.231.42 Forward lookup
In this example a RARP query for 76:3:c0:a8:e7:fa gets 192.168.231.42 as
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 SIGUSR1 or turned off (set to 0) with
ifconfig(8), ethers(5), hosts(5), inet(8), boot(8), dhcpd(8), irdpd(8),
A "network name" is the device name of the IP device of a network, i.e.
ip0, ip1, ...
The RARP protocol has gone out of fashion in favour of DHCP.
Kees J. Bot (email@example.com)