You probably already know that each network interface card (NIC) on a network must have a media access control (MAC) address. Each address must be unique to the network, and should be globally unique.
You might have changed the MAC address on a system using the method I wrote about in a previous article. If the new address is problematic or no longer required, you should use the default MAC address. The method is similar to setting a new MAC address but with one critical difference.
Steps to Change the MAC Address
The steps assume that you’re using an Intel Ethernet NIC and you’ve already installed the Intel PROSet drivers. If you’ve not yet done that, you can get the driver installer package from Intel® Download Center.
Open Control Panel, then click on Network and Sharing Center.
In the Network and Sharing Center windows, click on Change Adapter Settings in the left pane. This displays the Network Connections list as shown in Figure 1.
Figure 1. The list of physical and virtual network adapters.
Right-click on the connection that you want to change and then click Properties to bring up the network connection properties as shown in Figure 2.
Figure 2. The network connection properties.
You want to manage the properties of the NIC itself, not protocol properties like TCP/IP or NetBIOS. To manage NIC properties, click the Configure… button directly under the adapter name. This will bring up the NIC properties as shown in Figure 3.
Figure 3. The network adapter properties.
Did you notice that there are more tabs along the top of this dialog box than other network adapters? That’s the Intel PROSet drivers in action. They expose many more configuration options than the typical drivers.
To revert the MAC address to the original, first click the Advanced tab, and under Settings click Locally Administered Address. This option allows you to configure the MAC address. The adapter currently has an administrator-defined MAC address as shown in Figure 4.
Figure 4. The current MAC address.
In this example, the current MAC address for this NIC is DE:AD:BE:EF:CA:FE. To revert to the built-in unique MAC address, I click Use Default. Then I click OK to apply the change. The network connection will be down for a moment while it restarts with the new MAC address.
Finally, to verify the change was made I’ll use getmac.exe as shown in Figure 5. I’ve run getmac.exe both before and after this procedure to show the difference.
Figure 5. Success! The MAC address has indeed changed.
There you go. The first time getmac ran, the MAC address was DE-AD-BE-EF-CA-FE. After clicking Use Default, the MAC address is the Intel-provided default of 10-BF-48-4D-5A-31.
Mike Danseglio teaches Security classes at Interface Technical Training. His classes can be attended in Phoenix, Arizona or online from anywhere in the world with RemoteLive.