ifconfig command : Manage network configuration in linux

The most frequent use of ifconfig command is setting an interface’s IP address and netmask, and disabling or enabling a interface.
To see IP address of the machine, open terminal and type ifconfig
It’ll list all the interfaces connected to the device e.g.

root@ubuntu:~$ ifconfig
eth0    Link encap:Ethernet  HWaddr 00:1c:23:a4:ed:b0
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:160524 errors:0 dropped:0 overruns:0 frame:0
          TX packets:59261 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:40668433 (40.6 MB)  TX bytes:14468340 (14.4 MB)
          Interrupt:17 

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:21240 errors:0 dropped:0 overruns:0 frame:0
          TX packets:21240 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:3990382 (3.9 MB)  TX bytes:3990382 (3.9 MB)

To view a particular interface, provide interface name after ifconfig command.

root@ubuntu:~$ ifconfig eth0
eth0    Link encap:Ethernet  HWaddr 00:1c:23:a4:ed:b0
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:160524 errors:0 dropped:0 overruns:0 frame:0
          TX packets:59261 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:40668433 (40.6 MB)  TX bytes:14468340 (14.4 MB)
          Interrupt:17

here are few more frequent usages of ifconfig
ifconfig eth0 down
This flag causes eth0 interface to be shut down.
ifconfig eth0 up
If interface eth0 is in the down state then by setting this flag will make eth0 interface active.

ifconfig eth0 192.168.1.2 netmask 255.255.255.0 broadcast 192.168.1.20
Assign eth0 with the above values for IP, netmask and broadcast address.

January 21, 2009 | Filed Under Linux