On a simple NT4 network lives a Sonic Wall Firewall. The logs indicate a IP Spoof detected and dropped. The source IP address is a private address and the MAC address is listed.

IP spoof detected - Source:192.168.81.1, 137, LAN - Destination:192.168.80.2, 137, WAN - MAC address: 00.0D.56.34.64.8B -

Here's my dilemma: The private range is not on my network, I'm using 10. So I assume that someone (Probably a MCSE - Sorry about that) has configured a device incorrectly and plugged into the LAN.

I have scanned the network for the MAC address with no luck. Address not found!

I'm not too worried about this but I would like to find out what's going on - any suggestions?

Thanks,