How to find your Ethernet Hardware Address

What is an Ethernet Hardware Address?

The Ethernet hardware address (HW Address) is your Ethernet card's unique identity.

It is a 6-byte hexadecimal number represented by 12 digits (12 digits in hex = 48 bits = 6 bytes). Each digit must be a number between 0 and 9 or a letter between A and F ( Example: 0040051c0e9f ). It was permanently assigned and "burnt in" to the card's electronics when it was manufactured and cannot be altered.

An Ethernet card transmits its address with each packet of data, so it acts as a signature or fingerprint of your computer.

It may be referred to as either a hardware address, Ethernet address, NODE ID, adapter address, or MAC (medium access control) address, and might appear as:

  • Digits separated by a colon: 00:40:05:1c:0e:9f
  • Digits separated by a dash: 00-40-05-1c-0e-9f
  • Digits separated by spaces: 00 40 05 1C 0E 9F
  • Digits separated by a period: 0040.051c.0e9f
  • Digits run together: 0040051C0E9F
  • With leading zeros dropped: 0:40:5:1c:e:9f (Note that when dropping leading zeroes, '00' is represented by '0'.)

How do I Find the Ethernet HW Address on Various Operating Systems?

External network adapters and some Ethernet cards will have the HW Address imprinted on them, have a sticker on them with the information, or it will be included in the manual. NOTE: These strings may omit 0's at the beginning - make sure your HW Address is 12 characters long. If it is not, you need to pad the beginning with 0's. (e.g. Your adapter has 94560e45 printed on it. Your HW address actually is 000094560e45.)

If your card does not have the HW Address on it, or it is already installed in the computer, use the instructions below to determine the HW Address.

Apple Macintosh

Instructions for Mac OS X 10.3 and later:

  1. You can find the ethernet hardware address of your network card in System Preferences' Network preference pane. You can get to System Preferences from the Apple menu, or in the Applications folder. Open System Preferences and click the Network button.
  2. Click the "Show" drop down menu and select "Built-in Ethernet."
  3. Click the "Ethernet" tab
  4. Your Ethernet hardware ID is displayed on that screen.

Instructions for Mac OS X 10.2

  1. You can find the ethernet hardware address of your network card in System Preferences' Network preference pane. You can get to System Preferences from the Apple menu, or in the Applications folder. Open System Preferences and click the Network button.
  2. Click the "Show" drop down menu and select "Built-in Ethernet."
  3. Make sure the "TCP/IP" tab is selected.
  4. Your Ethernet Hardware ID should be displayed.

Microsoft Windows

  1. Go to the Start Menu and click on Run....
  2. Type cmd in the Open box and press ENTER.
  3. At the prompt, type: ipconfig /all
  4. In the output, there will be a heading that begins with Ethernet adapter. Under that heading will be an entry entitled Physical Address. This string is your HW Address.

Linux/UNIX

  1. From the command prompt type: /sbin/ifconfig
  2. In the output, there will be a heading that begins with HWaddr. After that heading will be an entry entitled Physical Address. This string is your HW Address.