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What is a MAC Address?

A MAC or Media Access Control address is a unique identifier that is used in networking. It is also sometimes called the "Physical Address". Currently the Ethernet specification uses a MAC convention scheme called "MAC-48" which has 2^48 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

Why are MAC addresses useful?

Besides their purpose in networking, they can also be used for access control, for both DHCP servers and Wireless Access Points. For the EE/CS Building Wireless network we require you to register your "burned in" MAC address that came with your wireless network card in order to restrict wireless access to only staff, grad students, and undergrads enrolled in IT Labs courses.

How do I register my MAC address?

Simply proceed to the wireless access page.

How do I find my MAC address?

Windows 98/ME

1. Go to the Start Menu
2. Click on Run
3. Type in "command" 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.

Windows 2000/2003/XP

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.