What is a MAC Address?

A MAC (Media Access Control) address is your computer's unique hardware number on a local area network (LAN) or other network. Each interface card (ethernet, 802.11b, etc.) used by your computer will have a different hardware number associated with it. The format is a string of 6 pairs of hexadecimal digits delimited by colons: XX:XX:XX:XX:XX:XX.

Why do I need to register my MAC address?

With the many issues surrounding networking at an academic institution - security, file sharing in violation of copyright law, etc. - many of the networks on campus are moving towards closed access. On the closed networks only 'trusted' machines that have had their appropriate MAC address registered will be assigned an IP address. Two networks that may be of interest to workshop attendees will require registration of either the ethernet adapter MAC address or the wireless card MAC address.

How do I find my MAC address?

• Windows:
  You can find both your ethernet and wireless MAC addresses by opening a command (or DOS) window and typing the command

  
  IPCONFIG /ALL
  
  

  Both your wireless and ethernet cards will appear listed as separate "ethernet" interfaces. For each card, the hardware ethernet address is displayed on the line that starts with the phrase "Physical Address". To distinguish the ethernet and wireless MAC addresses, you will need to refer to the information in the "Description" field. If you are not sure which is which, email the full output of the command to us (the name of your wireless card would be helpful as well).

• Linux:
  you can find the hardware ethernet and the wireless MAC address by opening a terminal window and typing the command

  
  /sbin/ifconfig
  
  

  In both cases, the MAC address is displayed on the line starting with "HWaddr". To distinguish between the ethernet and wireless interfaces, type the command

  /sbin/iwconfig
  

  Any interface (eg., "eth1") corresponding to a wireless adapter will have detailed information about the wireless connection. The interface corresponding to tour hardware ethernet adapter will say only "no wireless extensions".

• MacOS v8 or v9:
  1. Open the Apple Talk control panel.
  2. Make sure that "Ethernet" or "Airport" is selected in the "Connect Via" drop-down menu for the ethernet MAC address or the 802.11b MAC address, respectively. (on newer Macs without a modem or airport card installed, Ethernet may be the only option and there will be no drop-down menu).
  3. While the Apple Talk control panel is opened go the File menu and select Get Info.
  4. An Apple Talk info window will appear and the hardware address will be listed there.

• MacOS X:
  1. In the Finder navigate to the Utilities folder in the Applications folder.
  2. Double click "Network Utility" from "System Preferences".
  3. Select the "Ethernet" or "Airport" interface from the pop-up menu on the Info tab:
     Click on the "Show" tab. Choose "Built-in Ethernet" or "Airport".
  4. In both cases you will see a colon separated 12 digit alphanumeric code. It will be labeled "Hardware Address" or "Ethernet Address" is your for your ethernet MAC address, and "Airport ID" for your 802.11b MAC address. Those are the addresses that we need.

     Your current "IP Address", so labeled, will also be reported (eg, 192.168.1.101). That is NOT the address we need.