Changing Your MAC Address In Window XP/Vista, Linux And Mac OS X

                       First let me explain a few things about MAC addresses. MAC stands for Media Access Control and in a sense the MAC address is a computer's true name on a LAN. An Ethernet MAC address is a six byte number, usually expressed as a twelve digit hexadecimal number (Example: 1AB4C234AB1F).
Ok i won't let u bore lets come to the concept how to change MAC address in various operating systems.

LINUX

               

To change your MAC address in Linux (and most *nix system) is easy as pie. All it takes is two easy to script commands:

    ifconfig eth0 down hw ether 00:00:00:00:00:01

    ifconfig eth0 up

These two little commands would set your eth0 interface to use the MAC 00:00:00:00:00:01. Just plug in the NIC you want to set and the MAC address you want to use into the commands above and your done. Changing your MAC address is one of those things that is much easier to do in Linux then under Windows.

Mac OS X 

       For versions of OS X before Tiger (OS X 10.4) you will need this patch:

         http://slagheap.net/etherspoof/

       Then you use a command like:

         sudo ifconfig en0 lladdr 00:00:00:00:00:01

And For other versions simply open the terminal and type the below command 

by switching of the network device which ur changing the mac address

     to find the network devices type the command

      

         ifconfig

there u can find the devices select ur device to change the MAC address i.e.,

  

        ifconfig en1 ether 00:00:00:00:00:02

//where en1 is the device we are changing the MAC address and remaining cmd is same for other device also

WINDOWS

1)Hard Way

          In XP you can use the 'regedit' to edit the registry from a GUI or the 'reg' command to edit it from the console, I'll be using regedit. Information on all your compiter can be found the registry key 

  

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\ Class\{4D36E972-E325-11CE-BFC1-08002bE10318}\  . 

            

             Under this key you will find a bunch of sub keys labeled as 

             0000, 

            00001, 

            0002 and so forth. We can assume any MAC address we want by finding the key that controls the System we want to change, putting in a string value called "NetworkAddress" and setting it to the MAC address we want to use formatted as a twelve digit hex number (example: 000000000001). To find out which key is which we can search through them for the value "DriverDesc" until we find the one that matches the System we wish to alter. After you set "NetworkAddress" to the address you want just restart the System by disabling it then enabling it (or in the case of PCMCIA cards, just eject and reinsert). You can confirm the MAC address change by using the "getmac" or "ipconfig /all" commands.

2)Eas Way

         

           Use Mac Makeup ( http://www.gorlani.com/publicprj/macmakeup/macmakeup.asp ), MadMACs (http://www.irongeek.com/i.php?page=security/madmacs-mac-spoofer), Smac ( http://www.klcconsulting.net/smac/ ) or Etherchange (http://ntsecurity.nu/toolbox/etherchange/ ). Mac Makeup is a cool little GUI and Command line tool that's freeware, the creator also offers a Plugin for Bart's PE builder. MadMACs is a tool to randomize your MAC address and host name on every reboot. Smac has a nice GUI and was free but has since gone commercial, there's no reason to bother with it as there are free tools that are just as good. I use MadMACs since I wrote it and it lets me keep my host information randomized.

        Have fun with your MAC addresses switching, but be careful not to cause network problems. My favorite MAC address is DEADBEEFCAFE, for other interesting MACs see:

http://www.binrev.com/forums/index.php?showtopic=15942

Enjoy.