CHANGING MAC ADDRESS OF THE PC

MAC (Media Access Control) Address of Computer
It is a unique identifier assigned to network interfaces. MAC addresses are also known as hardware addresses or physical addresses. They uniquely identify an adapter on a LAN. Any packet sent to remote system on the network contains MAC address and IP address of your computer. MAC address is fixed and cannot be changed unless network card is replaced. Although we cannot change the MAC address of the network card adaptor, we can certainly change it in the operating system.

Changing MAC Address on Windows

1- You can use SMAC. SMAC is a MAC Address Changer (Spoofer) for Windows 7, XP, Server 2003, and VISTA systems, regardless of whether the manufactures allow this option or not. 

SMAC is a powerful tool and intuitive Windows MAC Address Modifying Utility (MAC Address spoofing) which allows users to change MAC address for almost any Network Interface Cards (NIC) on the Windows VISTA, XP, 2003, and 2000 systems, regardless of whether the manufacturers allow this option or not.

SMAC does not change the hardware burned-in MAC addresses.  SMAC changes the "software based" MAC addresses, and the new MAC addresses you change will sustain from reboots.
                                                                             

  Download :  Eatherchange.exe
                     Smac Tool




2- You can also use a console tool called 'etherchange' to change the MAC address. When you run this tool, it will show you all available network interfaces and then you can select particular interface to change its MAC address. You can just disable and enable that network adapter for changes to take effect. You can run this tool again to restore the MAC address back to original.
See in screenshot.
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3- You can also achieved this through a following registry hack. Open up your registry editor and move to the following location.

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

The above key has many subkeys with names such as 0000, 0001, 0002 etc. Each of these keys have a "DriverDesc" value on the right side which contains the description of the network card. You have to go through each one of these entries until you find out the one with the same description as your current network interface. Once you have found it, just create following string value to set new MAC address (in hexadecimal).

NetworkAddress REG_SZ 111213141516

Once you have changed it, disable & re-enable the network card for changes to take effect. Then use the command 'ipconfig  /all' to verify the change in MAC address. 
To set that network interface back to the original address, just delete the above value from registry.

Changing MAC Address on Linux

On Linux platform use 'ifconfig' command to set the new MAC address as shown below.

ifconfig eth1 down

ifconfig eth1 hw ether 00:80:48:BA:d1:30

ifconfig eth1 up

ifconfig eth0 |grep HWaddr

Note above that I have changed the MAC address to a different number highlighted in blue. 00:80:48:BA:d1:30 is the new MAC address I have provided for my Linux machine. You can choose any 48 bits hexadecimal address as your MAC address.