The ifconfig command without any options will display information about all of the active interfaces being used.

[root@server1 ~]$ ifconfig
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
    inet 192.168.0.101 netmask 255.255.255.0 broadcast 192.168.0.255
    inet6 fe80::20c:29ff:fe03:2e90 prefixlen 64 scopeid 0x20<link>
    ether 00:12:13:1a:b4:c2 txqueuelen 1000 (Ethernet)
    RX packets 7858997 bytes 654953014 (624.6 MiB)
    RX errors 0 dropped 248 overruns 0 frame 0
    TX packets 10466 bytes 126679 (1.2 MiB)
    TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
    inet 127.0.0.1 netmask 255.255.255.0
    inet6 ::1 prefixlen 128 scopeid 0x10<host>
    loop txqueuelen 0 (Local Loopback)
    RX packets 1544 bytes 275726 (269.2 MiB)
    RX errors 0 dropped 0 overruns 0 frame 0
    TX packets 1544 bytes 275726 (269.2 KiB)
    TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

Show all

The -a (all) option can be used to display information about active and inactive interfaces.

[root@server1 ~]$ ifconfig -a

Specific interface

Appending the interface name can be used to only show information for a certain interface.

[root@server1 ~]$ ifconfig eth0
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
    inet 192.168.0.101 netmask 255.255.255.0 broadcast 192.168.0.255
    inet6 fe80::20c:29ff:fe03:2e90 prefixlen 64 scopeid 0x20<link>
    ether 00:12:13:1a:b4:c2 txqueuelen 1000 (Ethernet)
    RX packets 7858997 bytes 654953014 (624.6 MiB)
    RX errors 0 dropped 248 overruns 0 frame 0
    TX packets 10466 bytes 126679 (1.2 MiB)
    TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

Bring interface up or down

The up or down option can  be used to bring an interface up or down.

[root@server1 ~]$ ifconfig eth0 up
[root@server1 ~]$ ifconfig eth0 down

Change IP address, subnet mask, broadcast

The IP address, subnet mask, or broadcast address of an interface can temporarily be changed. This is not permanent.

[root@server1 ~]$ ifconfig eth0 192.168.0.10
[root@server1 ~]$ ifconfig eth0 netmask 255.255.255.0
[root@server1 ~]$ ifconfig eth0 broadcast 192.168.0.255