From TorontoMathWiki

How to determine the hardware (MAC=Media Access Control) address

In order to connect your laptop to the Mathematics Department's network via dhcp it is necessary for you to provide us with your hardware address. This is a number of the form 00:04:25:0a:1d:2f which is in principle unique to each network card.

Under Linux or Mac OS X open a terminal window and type:

   ifconfig -a

• and then look for the number after HWaddr or ether, respectively for the appropriate interface (usually eth0, the non-wireless ethernet interface on your machine). Under Windows you can open an MS-DOS window and run:

   ipconfig /all

• The hardware address is listed after Physical Address and the number pairs are separated by hyphens, not colons.

Under Mac OS X one can also open System Preferences>Networking

Finding the Hardware Address for DHCP

For more detailed information on how to obtain the hardware address you can consult the following excellent references from the University of Minnesota computing services:

• Network Setup Guides for wired Ethernet Connections
• Wireless Network Setup Guides
• Virtual Private Network (VPN)