Every network device has its MAC address, a kind of birth identifier of the network card. Usually you do not need to deal with it, but sometimes it is useful to change or clone it, for example when replacing a router. Let us explain what a MAC address is, how it is changed and why it is done.

What a MAC address is

A MAC address is a unique identifier of a network card, assigned by the manufacturer. Unlike an IP address, which changes by network, a MAC address is tied directly to the device. It serves to identify the device on the local network.

Simply put, an IP address is like a flat’s address (it changes by where you live), a MAC address is more like the device’s identity number.

Why change or clone a MAC address

Replacing a router at the operator

The most common reason. Some operators tie your connection to the MAC address of the device they had registered. When you replace the router with your own, the new one has a different MAC address and the internet may not work until the operator allows it. The solution is to clone the old MAC address into the new router, so the operator sees the same device as before. This relates to the article on an operator’s router versus your own.

Privacy

A random or changed MAC address makes tracking the device harder across networks (for example on public WiFi). Modern phones and computers therefore today often use a random MAC address for each network.

Troubleshooting and testing

Occasionally the MAC address is changed when diagnosing network problems or restoring access.

How to change a MAC address in Windows

In Windows you can change the network card’s MAC address in its settings:

  1. Open Device Manager.
  2. Find your network card and open its properties.
  3. On the Advanced tab, look for the Network Address or Locally Administered Address item.
  4. Enter the new MAC address and confirm. After the network card restarts, the new one is used.

Not every network card allows this, and some drivers hide this option.

How MAC cloning works in a router

Routers have this feature built in, usually under the name MAC Clone, MAC Address Clone or Clone MAC. In the internet (WAN) connection settings you find the option to either copy the MAC address of the computer you are logged in from, or manually enter a specific MAC address (for example from the old router). This makes the router “pretend” to be the original device and the operator allows the connection.

What to watch for

  • Do it only on your own devices and networks. Unauthorized imitation of someone else’s device on a network is a problem.
  • Note the original MAC address, so you can return to it.
  • A MAC address is not protection. Filtering by MAC addresses in a router can be bypassed, so do not rely on it as the only security, more in the article on who is connected to my WiFi.

Conclusion

A MAC address is the birth identifier of a network card, and sometimes it is useful to change or clone it, most often when replacing a router, when the operator ties the connection to a specific device. In Windows it is changed in the network card settings, in a router via the MAC Clone feature. But do it only on your own devices.

Replaced a router and the internet does not work, or dealing with a network problem? Get in touch, we will set it up correctly, including a possible MAC address cloning.

This article is part of our Computer networks overview.