MAC Addresses

A MAC or Media Access Control address is a unique identifier that is used in networking. It is sometimes called the "Physical Address." Currently, the Ethernet specification uses a MAC convention scheme called "MAC-48" which has 248 possible unique identifiers for each device on a network. IEEE expects MAC-48 space to be exhausted around the year 2100, at which time a newer specification such as EUI-64 will have to be used. Every network interface card (NIC) has a MAC address "burned in" from the manufacturer. This can be overwritten by software using a "locally administered address." MAC addresses are formatted as a sequence of 6 hexadecimal pairs, e.g. 00:AA:22:33:44:FF 

How are MAC addresses useful?

Besides their purpose in networking, MAC addresses can also be used to control DHCP access. For the Keller Hall laptop network, we require you to register the "burned in" MAC address that came with your network card in order to control the devices that are added to the network.

Help me find my MAC address

Windows

  1. Go to the Start Menu
  2. Click on Run
  3. Type in "cmd" and hit enter
  4. In the command window that comes up type "ipconfig /all"
  5. Your MAC/Physical address should be printed for all of your network cards. Look for the one under something like "Wireless Network Adapter 1" or "Broadcom Wireless NIC" etc.

Macintosh

  1. Go to Applications -> Utilities.
  2. Open Network Utility.
  3. Select the "Info" tab.
  4. Select the "Ethernet Interface (en1)" from the pull down menu to get to your wireless info. (you could select "en0" for your wired info or "fw0" for the info about your firewire connection)
  5. Your MAC address is the string labeled "Hardware Address".

Linux/UNIX

You can use the "ifconfig" or "ifconfig -a" command to find your hardware address. In Linux this is printed by default for each real interface and is called "HWaddr". The output of ifconfig varies from distribution to distribution. Consult the man pages for ifconfig to find out how to locate the MAC address.