MAC spoofing

MAC Spoofing is a technique of changing an assigned Media Access Control (MAC) address of a networked device to a different one. The changing of the assigned MAC address may allow the bypassing of access control lists on servers or routers, either hiding a computer on a network or allowing it to impersonate another computer.

MAC spoofing is the activity of altering the MAC address of a network card.

Programs

MAC spoofing may be done with the following programs:

• Technitium Mac Address Changer (Windows)
• SMAC (Windows)
• iproute2

*ifconfig

iproute2

Assuming that wlan0 is the location of the NIC to be used, the following set of commands will change the MAC address of the card to 11:11:11:11:11:ab under Linux:

• ip link set wlan0 down (turns off card — parameter may not be changed while it is up)
• ip link set wlan0 addr 11:11:11:11:11:ab
• ip link set wlan0 up (turns card back on)

ifconfig

For FreeBSD and Mac OS X:

• ifconfig wlan0 down (turns off card)
• ifconfig wlan0 ether 11:11:11:11:11:ab
• ifconfig wlan0 up (turns card back on)

For Linux:

• ifconfig eth0 down (turns off card)
• ifconfig eth0 hw ether 11:11:11:11:11:ab
• ifconfig eth0 up (turns card back on)

Windows manual altering

In Windows, no built-in commands exist. Instead manual altering may be done through editing the Windows Registry or via "My Network Places" by altering the Properties-tab of the NIC. To alter the MAC via the registry, one must open the Windows Registry Editor and change the appropriate values.

The value " NetworkAddress" is located in a subkey under HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4D36E972-E325-11CE-BFC1-08002BE10318}.

Under Windows 7, the possible range of spoofed addresses that can be set is limited for wireless and wired network adapters. To be used by Windows 7, a spoofed MAC address should have 0 as a least significant bit (unicast) and 1 as a second least significant bit (locally administered) in the second nibble. Thus possible values for the second nibble are limited to 2, 6, A and E.