Sidebar: Configuring the Network Interface

Unlike most other UNIX entities, subnets are not managed through a configuration file. However, each network interface needs to know about the subnets, and the means for doing this is on most UNIX systems is the ifconfig command. Among the parameters given to ifconfig are the interface IP address and the network subnet mask, or netmask, which is the key to determining which subnet a particular host is on. An example of the usage of ifconfig is

ifconfig le0 198.53.64.9 netmask 255.255.255.240 ...

where ... represents the remainder of the commands needed to configure the interface.