MAC Address all zeros

Question

Our network is flapping a scan on the network revealed A MAC address of all zeros. What could be the problem? Its certainly not a valid MAC address and if it was changed for what good reason?

Answer 1

MAC addresses are changeable and easily so. In windows this is done in

the registry or if the NIC is a clonable (rare) you can just right

click it. In Linux it can be done from command prompt. It's called MAC

spoofing and is very common and very easy.

 

On to Ur problem there are several reasons why U would get a MAC zero.

A misconfigured router is one. Then there is a faulty NIC and IBM load

balancers (doubt U have these). Of worry though would be certain

traffic generators (software)...which some user may have installed on

the network. But since U mention a flipping network...it could be a

misconfigured router!

Comments

Thanks for the response apparently I do not have a router on the
network I only have a Linux box for my internet and e-mail which has a
MAC address of all zeros.

After switching off a hub in the network the LAN started performing
normally, switching it back on did not deteriorate the LAN performance.

Now it leads to another question

DOES A HUB GENERATE AND RANDOM DATA IF IT IS FAULTY?

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I get U correctly. U running a Linux box and the Mac on the box is all zeros? (That in itself is of course not a problem). Then U have a hub in the network? And sometime today you had some performance issues in your LAN? These issues went away with Ur reloading the hub? Is this the case?

If it is the case then I am sure U have Ur answer.

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Got my Answer and you also managed to get me in stitches, but I still dispute the fact that a Hub can generate random data I stand to corrected.

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Sounds to like mac address flooding problem!

Answer 2

Just a guess. Not sure what you mean by ‘change’ but MAC addresses don’t change coz they are hardcoded on the NIC. I suspect it could be a device that couldn’t report it’s MAC correctly to your scanner.

Maybe a phone or some wireless gadget.