ifconfig

Ifconfig is a command -line tool on Unix, which is used to configure and control of IP network interfaces. The name stands for "interface configurator". Originally, the tool appeared in 4.2BSD as part of the BSD TCP / IP suite. It thus became the standard tool and is used to this day.

Typically, the program is used to set up a network interface in order to set the IP address and the network mask to enable or disable the interface.

During the boot process used by many Unix systems, shell scripts that invoke ifconfig in order to configure the network adapter.

The program can also be used as a virtual air gap, in order to separate systems connected by network, such as the Internet. An air gap is more secure than a firewall, because in the first case, no active network connection (more) exists.