Using nmap to find network devices (IP, MAC) in your LAN
If someday you plug a device which does not have a display (something like a monitor) into your LAN network and don't know where it is on the network (IP address), E.g my Beaglebone Black, you can use nmap. Nmap is a free network scanner utility.
$ sudo nmap -sn 172.18.0.0/16
(scan the 172.18.0.0 network, my LAN network, to find the device)
The results are something like:
I can see one Texas Instruments device which is my Beaglebone Black's network chip manufacturer. So, that is my board.