The ethers database is built from information that is entered into the /etc/ethers file. This database associates host names to their Ethernet addresses. You need to create an ethers database only if you are running the RARP daemon. That is, you need to create this database if you are configuring network clients.
RARP uses the file to map Ethernet addresses to IP addresses. If you are running the RARP daemon in.rarpd, you need to set up the ethers file and maintain this file on all hosts that are running the daemon to reflect changes to the network.
The ethers(4) man page contains complete syntax information for this database. The man page's basic format follows:
Ethernet-address hostname #comment
Ethernet-address is the Ethernet address of the host.
hostname is the official name of the host.
#comment is any note that you want to append to an entry in the file.
The equipment manufacturer provides the Ethernet address. If a machine does not display the Ethernet address when you power up, see your hardware manuals for assistance.
When adding entries to the ethers database, ensure that host names correspond to the primary names in the hosts and ipnodes databases, not to the nicknames, as follows.
8:0:20:1:40:16 fayoum 8:0:20:1:40:15 nubian 8:0:20:1:40:7 sahara # This is a comment 8:0:20:1:40:14 tenere