Change MAC Address In BackTrack

For changing the MAC Address of your network adapter , first you need to choose the adapter.
1. run the terminal, type ifconfig.
2. In my case i want to change the Ethernet MAC address so eth0.

3. now we have to disable the network adapter, so run ifconfig eth0 down.
4. run  macchanger --mac 00:11:22:33:44:55 eth0 . it will change your mac address to the new mac that marked in red. you can
5.  ifcofig eth0 up   will enable your adapter.

Now your mac address changed successfully.

more details about this command:
-r switch will generate a random mac address
-l  will show the list of all known vendors.