October 2, 2022

What Is A MAC Address?

What is a MAC address

The Mac Address or Mac address is a unique 48-bit identifier to identify all network devices such as Ethernet network cards, Wi-Fi or wireless network cards, network switches, routers, printers, etc.

MAC addresses are globally unique identifiers for each device and therefore it is impossible to find 2 network cards or 2 network devices that have the same Address.

All manufacturers at the time of manufacturing the hardware, such as a Wi-Fi network card, record the Mac Address in binary format in a ROM memory of the device they are manufacturing. As the ROM memory is read-only, it is totally impossible to modify it, and therefore this implies that the Mac address or identifier of a device can never be modified.

However, in future posts, we will see that it is possible to make other people or members of the network believe that our +Address is different from the real one (A term known as MAC spoofing).

It is possible to modify the MAC of the network card of our computer is simple. When our computer starts up, the network card copies the address to our RAM. Once the Mac Address has been copied to RAM all the times the Mac Address is required, the Mac Address stored in RAM will be used. Therefore, if we want to change our address, we only have to modify the Address stored in our RAM memory, which is possible.

What uses does the Mac Address have?

Once we know what the Address is, we will now mention some of the utilities that the MAC Address of a network card or any other device can have, for example in 00-B0-D0-63-C2-26.

We can use the Address of a network card so that our Router assigns a static IP to our computer. In other words, we can configure our Router so that when it detects the presence of a certain Address, it assigns the IP that we have previously defined.

The Address can be useful for restricting access to a computer network. Thus, we can enter the configuration of our Router and configure it so that only computers with a specific Address can connect to the network. As a security mechanism, this point is not very effective since in future articles we will be able to see how easy it is to clone and change a Mac Address of a network device.


As we have said before, the address can be used to identify a computer or user within a computer network. Using Nmap or other programs, we can easily obtain the IP and Mac Addresses of the computers connected to the network.

IP geopositioning

The Address of a router or a mobile device can be used to geoposition people and to spy on our movements and habits with much higher precision than IP geopositioning.

For those who doubt that this is possible here, I leave this link where you can read that in London litter bins were installed capable of recording the Address of the mobile devices of the people who were around them. In addition, when the Google car passes through the streets taking pictures to generate its excellent Street View, they are also tracking all the BSSID (Mac Address of the routers).

That they find in their path, and as if that were not enough every time we approach a Router. We have the Wi-Fi of the mobile phone turned on, we will be leaving the record of our Address in the router that we have approached. If we also have the location services of the phone activated, we will send the BSSID (Mac Address of the access point) to Google, Microsoft, Apple, etc. Faced with this situation and to solve some of the aforementioned problems.

Internet providers

It seems that the iOS 8 operating system will include a system that will generate false Mac addresses randomly, but this does not mean that Apple is better than the rest, since even if they do this all the companies at the time of activating the location services of our phone have more than controlled us.

There are Internet providers that require MAC Authentication to provide internet to their customers. Therefore, the MAC Address in this case also serves as a filter tool to provide a service to a company’s customers.

Final Thoughts on What is A MAC address

Unique MAC addresses provide a device-level bit of protection and identification. However, they can be spoofed. In the Internet of Things (IoT), this element will be critical in smart homes moving forward. Learning to understand what they are and how to use them programmatic should be part of every IT person’s learning.