What is the use of MAC filtering in WLANs?

MAC filtering in WLANs is used to control network access based on the MAC address of the device.

MAC filtering, or Media Access Control filtering, is a security measure used in wireless networks (WLANs) to control which devices can connect to the network. This is done by either allowing or denying network access based on the MAC address of the device. A MAC address is a unique identifier assigned to network interfaces for communications on the physical network segment.

In a WLAN, the network administrator can set up a list of MAC addresses that are allowed to connect to the network. This is known as a 'white list'. Any device not on this list will be unable to connect to the network, even if they have the correct network name (SSID) and password. This adds an extra layer of security, as it prevents unauthorised devices from connecting to the network, even if they have somehow obtained the password.

Conversely, the network administrator can also set up a 'black list' of MAC addresses. Any device on this list will be denied access to the network, regardless of whether they have the correct SSID and password. This can be useful for blocking devices that are known to be problematic or malicious.

However, it's important to note that MAC filtering is not a foolproof security measure. MAC addresses can be spoofed, or faked, by someone with the right knowledge and tools. This means that a determined attacker could potentially bypass the MAC filter by pretending to be a device that is allowed on the network. Therefore, while MAC filtering can be a useful part of a WLAN's security, it should not be relied upon as the sole security measure. It is best used in conjunction with other security measures, such as strong network encryption and regular changing of the network password.