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Monday, April 04, 2011

How to change a MAC address in Microsoft Windows

CATCH ME IF YOU CAN...!

Although physical MAC (Media Access Control) addresses are permanent by design, several mechanisms allow modification, or "spoofing", of the MAC address that is reported by the operating system. This can be useful for privacy reasons, for instance when connecting to a Wi-Fi hotspot, or to ensure interoperability. Some internet service providers bind their service to a specific MAC address; if the user then changes their network card or intends to install a router, the service won't work anymore. Changing the MAC address of the new interface will solve the problem. Similarly, some software licenses are bound to a specific MAC address. Changing the MAC address in this way is not permanent: after a reboot, it will revert to the MAC address physically stored in the card. A MAC address is 48 bits in length.

As a MAC address can be changed, it can be unwise to rely on this as a single method of authentication. IEEE 802.1x is an emerging standard better suited to authenticating devices at a low level.

Under Windows XP, the MAC address can be changed in the Ethernet adapter's Properties menu, in the Advanced tab, as "MAC Address", "Locally Administered Address", "Ethernet Address" or "Network Address". The exact name depends on the Ethernet driver used; not all drivers support changing the MAC address in this way.
However, a better solution - requiring Administrative User Rights - is to pass over the System Registry Keys under HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4D36E972-E325-11CE-BFC1-08002BE10318}. Here settings for each network interface can be found. The contents of the string value called 'NetworkAddress' will be used to set the MAC address of the adapter when next it is enabled. Resetting the adapter can be accomplished in script with the freely available command line utility devcon from Microsoft, or from the adapters context menu in the Network Connections control panel applet.
There is a nice tool to change the MAC address for all cards (even those that can't be changed through the adapter's Properties menu): SMAC MAC Address Changer

Note: to check your MAC address easily on a Windows XP box, go to Run, type CMD, then type "ipconfig /all" without quotation in the command prompt. The number under physical address is the MAC address. If multiple IP are displayed, you should look under the label "Ethernet adapter x", where x is the name of your connection (which is Local Area Connection by default).


Under Windows, the MAC address is stored in a registry key. To change a MAC address, find that key with `regedit` and change it. Of course, Microsoft keeps moving the location of the key around!
Windows XP adds an option to change the MAC address on some network cards under the Advanced tab in the network adapter's Properties menu.
A much easier and more reliable method to change a MAC address under Windows is to use a software utility program designed to do this for you.
Macshift is a free utility that you can use to spoof your MAC address under Microsoft Windows.

9 comments:

  1. Now I know how to change a mac address!! Thank you and I'm following you now!

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  2. very informative. btw, the background pic makes it a bit hard to read the text. :)

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  3. Very informative post, I never knew changing MAC is even possible. I have to agree with Jay about the background though.

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  4. not sure if i need to know this?

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  5. Well if you want to make your computer more secure and undetectable, you definitely need to know this....

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  6. Thanks for the feedback guys, I'll definitely change the background.... :)

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  7. Nice information.. but i already knew this :P

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