> How might one go about determining the MAC address of the Ethernet NIC
> which is physically attached to an Ethernet NIC within a computer
> running Linux?
> Other Important Facts
> The connection is a physically direct connection via a CAT5 crossover
> cable with no other network hardware in between.
> The other, physically connected, computer does not have an IP address
> assigned; it s NIC is running in promiscuous mode.
Now this is strange. I was but asked a month ago to help someone with the
same 'problem', they wanted it for auditing purposes.
I told them to either send packets with a destination MAC address of
FF:FF:FF:FF:FF:FF (broadcast address) and you should get replies.....you
really should read the Ethernet document standards document on this
If the other machine did have an IP address then you could broadcast ping the
subnet (255.255.255.255 destination IP).
You might find the ethernet bridging websites are useful with this as the
spanning tree protocol creates a list of MAC addresses for the ethernet
bridge to know whom is where (Ethernet MAC address wise).
 according to RFC894 it is:
"The Ethernet - A Local Area Network", Version 1.0, Digital
Equipment Corporation, Intel Corporation, Xerox Corporation,