MAC address changing on laptop

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Huderon | 09:46 Wed 17th Oct 2012 | Computers
6 Answers
Now, I have no details of the make, model and OS of the laptop, it belongs to a friend of my daughter and she is the one who asked me.

The problem, I am told, is that every time the machine is turned on, the MAC address changes, and as the uni uses the MAC address to verify that someone is entitled to connect to their network, daughter's friend is having a few difficulties getting to stuff he needs. The uni's tech support people have no idea what could be causing the problem

The only things I could think of were some kind of malware spoofing the MAC address or a problem with the wireless hardware itself. Has anyone any idea what else might be causing this ?


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Is it a cheapo USB wireless adaptor by any chance? the MAC address should be hardware encoded into the wireless adaptor and it should be a globally unique number (network card manufacturers buy MAC address numbers and use one for each card).... but there are cards made by unauthorised manufacturers that don't follow the rules for MAC addresses so if it's a USB cheap USB adaptor I'd suggest getting a proper branded adaptor from a reliable source. (even if it is a branded adaptor it could be a fake if it was from ebay or the like)

It could possibly be malware overriding the MAC address, but to be honest I can't really think of any reason to do this, as a MAC address isn't routed so once the packets get past the first hop the NIC MAC would become irrelevant to anything as it's stripped out.

I guess you could boot the computer from a bootable linux CD to see if it's a hardware issue or a software issue.
OH... it's also not unheard of for even large manufacturers of computers to be caught out and end up installing "fake" parts into machines... so even if it's a built in card it's possible that it's not a genuine card from an approved place.
Question Author
Thanks Chuck. I'll point my lass at this and let her pass it on.

The laptop is using the internal wireless adaptor.

I did suggest that the lad do a full scan with the Kapersky or Avira rescue disk and run a check with something like Malwarebytes, just in case it was a malware problem. I also suggested that he get a USB wireless adaptor and use that instead of the internal one.

I hadn't thought of booting from a Linux disk to see if it was hardware or software which was behind the problem, and I never realised that you could get adaptors which were fake or unauthorised. You learn something new every day !
Are you sure its MAC address and not IP address? A while ago I was in a situation where to get access to a remote server I needed a fixed (static) IP address which would be stored on the remote server. At the time my ISP, Orange wouldn't (or couldn't) supply this. When I needed access I had to phone the server people and tell them what my IP address had changed too - along with a pre-agreed verbal id check. Not ideal but it worked.
Question Author
Yes, sidkid, it is the MAC address. The uni ties the MAC address of each student's computer to their login id.

When students arrive at the uni, they have to register their computer in order to get access to the uni's network and if a student replaces their computer (or switches to using a wireless dongle instead of the internal wireless connection), they won't have access to the network until they register the new machine's/dongle's MAC address.

I don't know the details, but my guess would be that as part of their login, the uni's network verifies that the MAC address of the computer matches the one they have registered for the login, and will refuse access if they don't match. That would allow students to keep their normal network access no matter where they are, and stop people who get hold of student logins and passwords from getting access unless they have the right computer.
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