The
ethers file maps Ethernet MAC addresses to host names. Lines consist of an address and a host name, separated by any number of blanks and/or tab characters. A ‘#' character indicates the beginning of a comment; characters up to the end of the line are not interpreted by routines which search the file.
Each line in
ethers has the format:
ethernet-MAC-address hostname-or-IP
Ethernet MAC addresses are expressed as six hexadecimal numbers separated by colons, e.g. "08:00:20:00:5a:bc". The functions described in
ethers(3) and
ether_aton(3) can read and produce this format.
The traditional use of
ethers involved using hostnames for the second argument. This may not be suitable for machines that don't have a common MAC address for all interfaces (i.e., just about every non Sun machine). There should be no problem in using an IP address as the second field if you wish to differentiate between different interfaces on a system.