Changing MAC address of a machine is called spoofing a MAC address or faking a MAC address. In linux, you can change MAC address of your machine pretty easily.

First we have to find the physical MAC address of your machine by running the following command :
$ ifconfig -a | grep HWaddr
eth0 Link encap:Ethernet HWaddr 00:25:64:57:f6:ab

The hexadecimal numbers denote my machine’s MAC address.

Next, we need to login as root in Linux
command su then type in your password and enter the following commands –
# ifconfig eth0 down
# ifconfig eth0 hw ether 00:25:64:57:f6:60
# ifconfig eth0 up
# ifconfig eth0 |grep HWaddr

I have changed the MAC address to a different number 00:25:64:57:f6:60 is the new MAC address I have provided for my Linux machine. You can choose any 48 bits hexadecimal address as your MAC address.

Why you should change MAC address of your Linux machine ?

These are the reasons you should change the MAC address of your machine.
• For privacy – For instance when you are connecting to a Wi-Fi hotspot.
• To ensure interoperability. Some internet service providers bind their service to a specific MAC address; if the user then changes their network card or intends to install a router, the service won’t work anymore. Changing the MAC address of the new interface will solve the problem.

But it’s also important to mention that in Linux, Windows, Mac OS X, or a different operating system, changing MAC address is only temporary. Once you reboot your machine, the operating system reflects the physical MAC address burnt in your network card and not the MAC address you set.