In Mac OS X, how can I find the MAC address of my Ethernet or wireless interface?

In Mac OS X, your MAC address, distinct from the IP address assigned to your Mac, is defined by the hardware of each Ethernet or AirPort interface. The MAC address, or Media Access Control address, is frequently known as the Ethernet Hardware Address (EHA) address; see What is the MAC address (aka the hardware or physical address) of my network adapter?

To find your MAC address, from the Apple menu, select System Preferences... . From the View menu in System Preferences, select Network.

• In Mac OS X 10.5, in the left column of the Network preference window that opens, click the name of your connection (e.g., AirPort, Ethernet, Built-in Ethernet). Click the Advanced... button, and in the sheet that drops down, click either the Ethernet or AirPort tab. The string of letters and numbers next to "Ethernet ID:" or "AirPort ID:" is your MAC address.
  
  
• In Mac OS X 10.3 or 10.4, in the Network preference window that opens, make sure the pull-down menu next to "Show:" lists your connection (e.g., AirPort, Built-in Ethernet). Under the Ethernet or AirPort tab, the string of letters and numbers next to "Ethernet ID:" or "AirPort ID" is your MAC address.

Also see:

• In IUB or IUPUI campus housing, how do I get connected to the network?