System MAC address

Each network interface on your computer is identified by a series of letters and numbers down as a MAC address. This string is useful for identifying a computer:

Windows system

Open the Windows Run dialog by holding down the Windows Key and pressing ‘r’.
Type cmd in the Run dialog box and press Enter.
Type getmac at the command prompt. Your MAC address will be displayed.

Linux system

Open a terminal window.
Type ifconfig at the command prompt. Your MAC address will be displayed beside the label HWaddr.

 Mac System

Open the Terminal application.
Type ifconfig at the command prompt. Your MAC address will be displayed beside the label ether.