The ifconfig command is an ancestor of ip. It is still found on many Linux systems but is less powerful (some would call it obsolete). We’ll cover a few simple commands here, but you should be using ip instead.

To display information about the default network interface (usually called eth0):

$ ifconfig eth0
eth0  Link encap:Ethernet  HWaddr 00:50:BA:48:4F:BA
      inet addr:192.168.0.10  Bcast:192.168.0.255 ...
      UP BROADCAST RUNNING MULTICAST  MTU:1500 ...
      RX packets:1955231 errors:0 dropped:0 overruns:0 ...
      TX packets:1314765 errors:0 dropped:0 overruns:0 ...
      collisions:0 txqueuelen:100
      ...

This includes your MAC address (00:50:BA:48:4F:BA), your IP address (192.168.0.21), your netmask (255.255.255.0), and various other information. To view all loaded network interfaces, run:

$ ifconfig -a