System Administration Guide: IP Services

How to Get Information About a Specific Interface

  1. Become superuser.

  2. On the command line, type the following command.

    # ifconfig interface

For an le0 interface, your output resembles the following:

le0: flags=863<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
 	inet netmask ffffff00 broadcast
ether 8:0:20:8:el:fd

The previous flags section shows that the interface is configured “up,” capable of broadcasting, and not using “trailer” link-level encapsulation. The mtu field tells you that this interface has a maximum transfer size of 1500 octets. Information on the second line includes the IP address of the host you are using, the netmask being currently used, and the IP broadcast address of the interface. The third line gives the machine address (Ethernet, in this instance) of the host.