MAC (Media Access Control)

It is an element that normally goes unnoticed, but that uniquely identifies any network card connected to any network in the world and that works under any computer system, operating system, software and network protocols.

The MAC (Media Access Control) consists of an alphanumeric code in hexadecimal format, comprising six blocks of two digits each.

Thus, a direction MAC would have the form XX-XX-XX-XX-XX-XX, where each X can be a number from 0 to 9, or a lyrics from A to F (following the order marked by the Alphabet), according to the hexadecimal numbering system.

The MAC address is unique for each network card, in the sense that it is not unique in the local network, like an IPv4 address, but is unique throughout the world, like IPv6 addresses.

This is possible thanks to the high number of combinations allowed by the numbering of the MAC addresses, which makes them virtually endless.

Thanks to this, it is possible to refer univocally and without the possibility of error to a specific network card within the entire planet. If we have two, three or more network cards in a computer system, each of them will have its own MAC address, different from all the others.

Among the utilities that are given to the MAC address we have the security one, filtering in routers and access points, what devices can connect to the network, so that those whose network card does not contain one of the allowed MACs, it will not be possible to connect.

In this way, we increase the safety of the network, shielding it even more, since by expelling computers that do not meet the requirement of having an accepted MAC, we save ourselves from having to protect ourselves against extraction of information that are used when there is a possibility to connect to the network.

We could also take advantage of its exclusivity to work in reverse, that is, with a list of MAC addresses that we do not allow to connect to a specific network.

In the MAC address we can distinguish two parts: the first 24 bits, whose encoding belongs to the manufacturer, and the last 24, which are assigned by the IEEE (Institute of Electrical and Electronics Engineers).

The address is physically "stamped" on the card so that the hardware is related to that address. Theoretically it is not possible to change it, although there are techniques that can use both hackers as cybercriminals to bypass the protection explained above (although this is not so easy because it requires knowing an authorized MAC address, which will be impersonated).

To know the MAC address, each system operative incorporates a series of mechanisms and, in addition, in many cases the address is usually written on a label on the computer set by the manufacturer.

If you're wondering, yes, even the Wi-Fi network cards of smartphones Y tablets They have a MAC address. When I say that ALL network cards have it, they are all.

Photo: Fotolia - Kseniiavladimir