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I have a local network in a Windows system where the Admin gives permission to the PCs by their MAC address. But he is on vacations and I have a new PC.

How can I change the MAC address of my new PC to have the same MAC address as the old one?

I know this can be used for spoofing the address, but this is local, so I don't think I will have a problem.

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Ugh. I hate it when people do that. I've been the unlucky person that ended up troublshooting network failures due to multiple identical MAC addresses on the same broadcast domain. MAC address cloning is evil, please don't do that unless people are dying all around you you have absolutely no other option to save them. :-) –  Brian Knoblauch Oct 2 '09 at 12:57
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@Brian, you downvoted b/c his Admin is on vacation? –  hyperslug Oct 2 '09 at 13:07
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Clone the old PC's but add 1. or 2. or whatever. MACs are pretty random, it's not likely you'll have 2 sequential on the same network. –  quack quixote Oct 2 '09 at 17:55
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@Artur, you could also swap the MAC addresses of two PC's to prevent collision, if someone inadvertently plugged the old one back in. –  hyperslug Oct 2 '09 at 21:49
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one example where hyperslug's suggestion will fail (causing the problem Brian is concerned about) is if the old hardware is given a fresh install of new OS and then placed back on the network. the new OS will by default use the old hardware's original MAC. –  quack quixote Oct 5 '09 at 23:27

7 Answers 7

up vote 4 down vote accepted

I have used these instructions in the past and they work great

There’s a C++ command-line utility called Macshift that allows Windows XP users to change their MAC address to any other valid address. I’ve written about how to use it and how to create shortcuts to change your MAC address on-the-fly. I’ll first explain how to use Macshift for any MAC change, then I’ll show you how to make Windows shortcuts using the command-line options. I’ve also made a small script to make it easier to use, but the script isn’t necessary. Macshift usage
Macshift is a command-only utility, so you need to learn the options to use it.

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note the Macshift program is listed WinXP ONLY. –  quack quixote Oct 2 '09 at 8:49
    
Whilst this may theoretically answer the question, it would be preferable to include the essential parts of the answer here, and provide the link for reference. –  Tom Wijsman Oct 31 '11 at 19:37

From Here

Method 1:

This is depending on the type of Network Interface Card (NIC) you have. If you have a card that doesn't support Clone MAC address, then you have to go to second method.

a) Go to Start->Settings->Control Panel and double click on Network and Dial-up Connections.

b) Right click on the NIC you want to change the MAC address and click on properties.

c) Under "General" tab, click on the "Configure" button

d) Click on "Advanced" tab

e) Under "Property section", you should see an item called "Network Address" or "Locally Administered Address", click on it.

f) On the right side, under "Value", type in the New MAC address you want to assign to your NIC. Usually this value is entered without the "-" between the MAC address numbers.

g) Goto command prompt and type in "ipconfig /all" or "net config rdr" to verify the changes. If the changes are not materialized, then use the second method.

h) If successful, reboot your system.

Method 2:

This should work on all Windows 2000/XP systems

a) Go to Start -> Run, type "regedt32" to start registry editor. Do not use "Regedit".

b) Go to "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\ Control\Class\{4D36E972-E325-11CE-BFC1-08002BE10318}". Double click on it to expand the tree. The subkeys are 4-digit numbers, which represent particular network adapters. You should see it starts with 0000, then 0001, 0002, 0003 and so on.

c) Find the interface you want by searching for the proper "DriverDesc" key.

d) Edit, or add, the string key "NetworkAddress" (has the data type "REG_SZ") to contain the new MAC address.

e) Disable then re-enable the network interface that you changed (or reboot the system).

Method 3:

Use the program Etherchange

Method 4: ( windows 9x)

Use the same method as Windows 2000/XP except for the registry key location is "HKEY_LOCAL_MACHINE\System\ CurrentControlSet\Services\Class\Net" and you must reboot your system.

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+1 for explaining everything so clearly. –  Brandon Wang Oct 4 '09 at 2:17
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There was no need to delete the answer. –  Diago Nov 6 '09 at 17:35
    
regedt32 is a stub that launches regedit on >=XP. –  Hello71 Sep 20 '10 at 1:55

Go into properties for Network Connection. Click "Configure" next to desired network adapter and on Advanced tab you should have one field for MAC address. Usually it is named "Address", "Locally Administered Address" or something similar. There you have text box in which you can type desired MAC.

Take care that you turn off original PC (or change it's MAC also).

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+1 for not needing to install anything. –  hyperslug Oct 2 '09 at 9:47
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"Network Address" is another common name for the field. –  quack quixote Oct 2 '09 at 9:57

You could use the Technitium MAC Address Changer

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You don't specify your OS, so I'm assuming a Windows flavor. Here's a decent writeup of changing MACs on Windows as well as a wide variety of other systems.

Note that that page and Systech's link both recommend a program called Macshift that's listed as WinXP ONLY.

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Some network adapters allow you to change the MAC address of a network adapter through their configuration dialog:

enter image description here

An example is shown in this screencast. But please keep in mind that this doesn't relate to all network adapters!

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A very important note for Windows 7 users: MAC spoofing only works with windows 7 if the new MAC's second hex digit is one of the following: 2,6,A,E.

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While that may be true, can you provide some documentation to proof your point? –  Oliver Salzburg May 27 '12 at 10:54

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