Finding Your Machine's MAC Address: Windows and Macs

In computer networking, a Media Access Control address, better known as MAC address, is a unique identifier assigned to a network adapter or network interface card (NIC) by the manufacturer for identification. The MAC address can also be called the Ethernet Hardware Address (EHA), hardware address, adapter address or physical address. Your computer may have more than one MAC address. Do you have wireless and an ethernet port? Then you have at least two MAC addresses. Your smart phone probably also has a MAC address -- my iPhone has two; one for wireless and one for bluetooth.

MAC addresses are typically 6 groups of two hexadecimal digits (0-9,A,B,C,D,E,F), separated either by colons (:) or hyphens (-). The Wi-Fi Mac address on my iPhone, for example is: 00:1C:B3:09:85:15. The first three numbers, 00:1C:B3, are an Apple manufacturing code; only Apple products will have MAC address starting with those digits. (Settings General About Wi-Fi Address. :)

Why do you care about MAC addresses? Generally speaking, you don't. But if you are having trouble with connecting to a network or if your computer has been hacked, then the ACCC's security, networking, operations, or repair folks might need you to tell them what it is to help them troubleshoot your problem. So here is how to tell.

Note that you must have TCP/IP installed to be able to query your MAC address.

1. Start Run
2. Enter: cmd
3. Enter: ipconfig /all
   If the output scrolls off your screen, and it will on Vista, use: ipconfig /all | more
   
4. The Physical Address is your MAC address; it will look like 00-15-E9-2B-99-3C. You will have a physical address for each network connection that you have.

Figure 1. The is the ipconfig output on Windows XP. My XP computer has two network connections -- an ethernet connection, labeled Local Area Connection, and a wireless connection, labeled Wireless Network Connection (the wireless connection isn't currently set up). The actual network adaptors present in your computer are all that XP lists. Vista, on the other hand, lists many additional possible network connections, even if they aren't being used. But the Wireless and Local Area Connection sections are the same.

1. Start Run
2. Type: winipcfg and click OK.
3. Select the network adapter you are interested in,
4. The box marked Adapter Address is your MAC address; it will look like 00-15-E9-2B-99-3C.

1. Apple menu System Preferences Network
2. MAC address for wired ethernet connections:
   1. From the Show: menu, select Built-in Ethernet.
   2. On the Ethernet tab (TCP/IP tab for Mac OS X 10.2 and earlier), the Ethernet ID is your MAC address.
3. MAC address for wireless connections:
   1. From the Show: menu, select AirPort.
   2. On the AirPort tab, the AirPort ID is your MAC address. The illustration below is the AirPort tab on Mac OS X Tiger.
      

1. Apple menu System Preferences Network
2. MAC address for wired ethernet connections:
   1. Select Ethernet from the list on the left.
   2. Click the Advanced button.
   3. On the Ethernet tab, the Ethernet ID is your MAC address.
3. MAC address for wireless connections:
   1. Select AirPort from the list on the left.
   2. Click the Advanced button.
   3. On the AirPort tab, the AirPort ID is your MAC address.
      

1. Apple Menu Control Panels TCP/IP Control Panel
2. From the Connect via: menu, select Ethernet.
3. Click the Info button.
4. The Hardware address is your MAC address.

If you have Open Transport, use it. If not, while you are connected to an ethernet network (the Internet, for example), do the following:

1. System Folder Control Panel MacTCP Control Panel
2. Without the Shift or Caps Lock keys depressed, and while holding down the Option key, click the Ethernet built-in icon.
3. The Hardware address is your MAC address.

There are some additional ideas at MacTCP and related Macintosh software, Tricks, hints, and caveats, by Eric Behr at Northern Illinois University.