EDIT

I looked into it further, and the mac address from the System Information is not the mac address that is used by the ethernet dongle.

1. MacHD > Applications > Utilities > Terminal.app
2. ifconfig -a
3. look for bridge0, that is the mac address of your dongle.

PREVIOUS WRONG ANSWER

You can also access by going to

1. apple menu (top left) > About This Mac
2. Click on "More Info..."
3. Click on "System Information"
4. Under Hardware look for Ethernet Cards

I looked into it further, and the MAC address from the System Information is not the MAC address that is used by the Ethernet dongle.

1. MacHD > Applications > Utilities > Terminal.app
2. ifconfig -a
3. look for bridge0, that is the mac address of your dongle.

previous wrong answer:

You can also access by going to

1. apple menu (top left) > About This Mac
2. Click on "More Info..."
3. Click on "System Information"
4. Under Hardware look for Ethernet Cards

You can also access by going to

1. apple menu (top left) > About This Mac
2. Click on "More Info..."
3. Click on "System Information"
4. Under Hardware look for Ethernet Cards

EDIT

I looked into it further, and the mac address from the System Information is not the mac address that is used by the ethernet dongle.

1. MacHD > Applications > Utilities > Terminal.app
2. ifconfig -a
3. look for bridge0, that is the mac address of your dongle.

PREVIOUS WRONG ANSWER

You can also access by going to

1. apple menu (top left) > About This Mac
2. Click on "More Info..."
3. Click on "System Information"
4. Under Hardware look for Ethernet Cards