ifconfig

The above command will show all active interface of the machine and also give the information of

1. IP address assign to interface
2. MAC address of the interface
3. Broadcast address
4. Transmit and Receive bytes

Some example

ifconfig -a

The above command also show the disable interface

ifconfig eth0

The above command will only show the eth0 interface

ifconfig eth0 192.168.1.100 netmask 255.255.255.0

The above command will assign the static IP to eth0 interface

ifup eth0

The above command will enable the eth0 interface

ifdown eth0

The below command will disable the eth0 interface

ping

The above command (Packet Internet Grouper) is to test the connectivity between the two nodes

ping -c2 8.8.8.8