Find MAC address of a device on the other end of an Ethernet cable

Before anyone points it out, this is a different question to Check MAC address of a device on the other end of an Ethernet cable.

I'm interested in an automated way (rather than Wireshark, etc) of finding only the MAC address of the device on the other end of an ethernet cable, rather than mapping the entire network. Is this even possible?

Update: The scenario is that my user has several boxes running embedded Linux connected to a network along with other equipment. I can figure out how those boxes are connected to each other by detecting the MAC or IP address each one is connected to.

Assuming you're talking about doing this from a PC, by looking at the ARP table you should be able to find the MAC address you're looking for. Of course, you also need to know the devices IP address so you're looking at the right one.

The command you want to use in cmd is arp -a