First install nmap
sudo apt-get install nmap
Then run IP addr show and look for something like ‘inet 10.1.1.68/24 brd 10.1.1.255’
ip addr show eth0
Now based on the inet IP CIDR type
sudo nmap -sn 10.1.1.68/24
You should see something like this
Nmap scan report for 10.1.1.54
Host is up (0.00088s latency).
MAC Address: B8:27:EB:18:E0:B3 (Raspberry Pi Foundation)
Referenced from: http://trevorappleton.blogspot.com/2013/03/remotely-find-raspberry-pi-ip-address.html