iMac mac address changes by itself.

[parisv]

Our network only allows computers who's mac address have been added to the system. We have a strange problem where a 2010 iMac with fresh install of osx 10.6 keeps changing it's mac address from it's original.

I'm guessing it's a NIC fault, was just wondering if anyone has seen this before?

 

[GenieonWork]

Same problem here; non-persistent MAC-address changes

I've kinda the same problem here.

I've 10 iMAC's here, which I want to give specific IP-addresses by adding DCHP-reservations to the server.
However, sometimes they provide a weird MAC-address to the DHCP-server (like '494d414335', or even some 28/30-character MAC-addresses).
When I check the Airport-settings on the MAC, they list their normal addresses.
When I check from a Terminal-window (using the ifconfig-command), they list their normal MAC-addresses.

Haven't been able to find anything on the internet yet (except for this post of course 😉 ), let alone find a solution.

Shutdown - startup doesn't help, reboot doesn't help, turning off - turning on the wireless NIC on the MAC doesn't help.
The fun thing is thought, sometimes it's working as it should, but other times the MAC-addresses are all mixed-up.

Edit: On the Airport Extreme (wireless AP in bridged mode) it is showing the correct MAC-addresses; restarting the Airport Extreme doesn't help either.