It is a real hassle for cable Internet customers that they are restricted to using a single machine for Internet access. If you want to plug your laptop in your friend's cable Internet connection, you have to call the service provider to refresh the MAC address.

The MAC address is permanent to the hardware and cannot be changed. Since we operate the hardware via the software abstraction layer, it is quite possible to do some software-level cheating for the network card's MAC ID. We can Simply spoof it to some other MAC addresses.

You can obtain the original MAC ID from the ifconfig output. Mine is as follows:
Now, let's change the last part of the MAC ID from 22 to 23:

[root@gnubox slynux]# ifconfig ethO
ethO Link encap:Ethernet HWaddr 00:IC:23:FB:37:23
inet addr:192.168.0.2 Bcast:l92 1680255 Mask 255.255.255.0 BROADCAST MULTICAST MTU:1500 Metric:1

RX packets:O errors:O dropped:O overruns:O lrame:O TX packets:O errors:O dropped:O overruns:O carrieLO collisions:O txqueuelen: I 000
RX bytes:O (0.0 b) TX bytes:O (0.0 b) Interrupt: 17

Easy enough? Well, let's consider the following instance: suppose you are in a Wi-Fi campus and the access to the wireless network is restricted using MAC addressing. You can Simply look at your friend's laptop MAC ID and spoof it. Yes! You are now free to access th network. Have fun!