ifconfig – CONFIGure a `network’ InterFace
Summary :
ifconfig is used to display/configure the kernel-resident network interfaces. It is used at boot time to set up interfaces.
Example:
$ ifconfig — Show info abt the active network interfaces like IP Address, MAC address, Subnet mask, and status.
$ ifconfig -a — Show the status of active and inactive interfaces.
# ifconfig eth0 down — Deactivate/Shutdown the eth0 interface.
# ifconfig eth0 up — Activate the eth0 interface.
# ifconfig eth0 192.168.1.100 netmask 255.255.255.0 up — Activate an interface with specific IP address.
# ifconfig eth0:0 192.168.1.101 netmask 255.255.255.0 broadcast 192.168.1.255
# ifconfig eth0:1 192.168.1.102 netmask 255.255.255.0 — Creating alias for eth0, ie Assign more than one IP address to eth0.
# ifconfig eth0 arp — Enable the use of the ARP protocol on eth0.
# ifconfig eth0 -arp — Disable the use of the ARP protocol on eth0.
# ifconfig eth0 promisc — Enable the promiscuous mode on eth0.
# ifconfig eth0 hw ether 09:08:07:06:05:04 — Change eth0 MAC address.
# ifconfig eth0 mtu 1412 — Change Max Transfer Unit of eth0.
NOTE:
- Deactivate the interface before changing the IP/MAC.
- Note down the original MAC, Otherwise Reboot needed to get the original MAC Address.
- Some command sequence needs super user permission.
Read : man ifconfig