Blocking MAC from being seen on the Internet.

Question

Is it possible to stop my MAC address from being seen on the web?

Here is an example of my ShieldsUP! test for file sharing,

A Next-Generation PRIVACY THREAT is present!
The Media Access Control (MAC) address of the network interface card in your computer can be easily read by any computer or web server on the Internet. Yours is:

XXXXXXXXXXX

The MAC address is a "guaranteed to be globally unique" 48-bit serial number embedded into every Ethernet network adapter ever made. The problem is you can't change it — it's like your machine's unique indelible fingerprint — and it's being made available to any web site (like this one) that you visit. In many ways it's like a "super web browser cookie on steroids" that cannot be disabled or blocked by normal means.

Many people have become very upset over the unique serial number embedded into every Pentium III processor, fearing the invasion of privacy that such a "globally unique ID tag" would represent. But the exposed network MAC address problem is much worse since it's already here, it's fully deployed and available for the asking from most computers on the Internet! More importantly . . . it's freely available from your computer.

Thanks,

TaiBo

NemesisDB · Answer

eh ...  as usually, shields up is creating fear needlessly.  i don't think you can block it (anymore than you can block your IP address -- which, if your ISP almost never changes it, is also an identifier).  if your IP address isnt changing each time you logon (say dialup) then worrying about MAC addresses seems pointless. a router will let you spoof a mac address -- change it whenever you want.  you can also enter in 'fake' MAC addresses for your card in the windows registry -- which is why MAC filtering is sure a worthless form of wireless security.  lastly, some network cards let you change the MAC at the driver level

jmwills · Answer

MAC Addresses are 'not globally unique'.  There are known cases where MAC addresses were duplicated in China.  MAC addresses can be spoofed to obtain wireless access. There is nothing you can do to hide your MAC address that I am aware of.

tgsmith · Answer

NemesisDB, May I add that the MAC address of a cable modem is what allows instant Internet access without supplying a user logon and password. Forget your e-mail password? Go to the cable ISP's e-mail support web site. Key in your modem's MAC address to reset your password. This 'unique global identifier' is an excellent forensics tool. Serial killer in Missouri snail-mailed a  map to The Saint Louis Post-Dispatch. 'Proved' he was the real killer by marking a victim's burial site precisely on the map. Detective determined Encarta on-line generated the map. He contacted Encarta regarding downloads containing GPS location of the body.  Encarta traced download to cable modem in Saint Louis. Search warrant obtained. Killer's lair uncovered.  Killer apprehended.

jmwills · Answer

We scan out networks by NETBIOS, IP Address, and MAC address so if an offender is found is impossible to deny offending actions. My guess is the Road Runner case, someone spoofed an address over the air, did their dirty work, and let the porr user account holder catch all; the blame.

I'll bet the ranch the account holder had an unsecured wireless network as well.

tgsmith · Answer

Taibo and jmwills,

Exactly. Every firewall and router (wireless or hard-wired) I've ever dealt with allowed cloning of your MAC address. If you can clone it there, then that same technology can be used to clone it remotely as Jmwills pointed out. Just had a case where Road Runner tracked a probe complaint to a totally naive user who had no idea what Road Runner was talking about. Road Runner did not do a very good job of explaining what spoofing an address was all about. Oh, and here's the kicker. They told him they would cut off his service if HE didn't fix the problem.

Tony

Message Edited by tgsmith on 12-18-2005 07:22 AM

NemesisDB · Answer

it of course gets messier if you can get access to your cable modem's real config page and spoof/reflash the address from there.   grab someone elses MAC address on your ISP and then you would effectively be them to the cable company as long as the other user wasn't also online

Windows General

Blocking MAC from being seen on the Internet.

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