ifconfig help

ifconfig eth0

View the network settings on the first Ethernet adapter installed in the computer.

ifconfig -a

Display info on all network interfaces on server, active or inactive.

ifconfig eth0 down

If eth0 exists would take it down causing it cannot send or receive any information.

ifconfig eth0 up

If eth0 exists and in the down state would return it back to the up state allowing to to send and receive information.

ifconfig eth0 192.168.1.102 netmask 255.255.255.0 broadcast 192.168.1.255

Assign eth0 with the above values for IP, netmask and broadcast address.