In the terminal
Step 1: Familiarize yourself with arp. Type "arp" in the command prompt. ...
Step 2: List all MAC addresses. Type "arp -a" in the command prompt. ...
You get something like this:
zed_pc (192.168.0.1) at 01-a3-56-b5-ff-22 on en0 ifscope [ethernet]
