1. Click the Apple menu icon in the top left corner of the screen and select System Preferences.
2. In the Internet & Network section of the System Preferences window, click on the Network icon.
3. In the Network window, double-click AirPort.
4. The 12-character alphanumeric combination listed as AirPort ID is the MAC Address.
Another way:
1. Open your System Preferences and then click on Network.
2. Set Location to Automatic and set Show to AirPort. If you are unable to select AirPort, select Active Network Ports and make sure AirPort is selected.
3. Under the TCP/IP tab, next to Configure select Using DHCP.
4. Under the AirPort tab, in Preferred Network, type NSU as shown below.
