Description: This technical article will describe what MAC Filtering is and what it can be used for.

Most, if not all, consumer-grade routers on the market have a feature known as MAC Filtering. This is a control mechanism to ensure that only certain people can or cannot use the network.

To best understand MAC Filtering, it is first necessary to understand what a MAC address is. MAC stands for Media Access Control. The MAC address is a unique identifier indicating which physical interface device is being used. For this reason, a hardwired connection will use a different MAC address than a wireless connection, since the hardware being used for the link is different. As such, MAC address filtering can be a powerful tool, but it can also be circumvented by changing the physical interface adapter being used.

MAC Filtering can be configured in such a way that any listed client machines are either allowed network access or denied network access, depending on the usage. For a home that has a set list of devices that connect, MAC Filtering can be enabled to only allow those devices access to the network while denying access to all others. This is particularly useful if there is a risk of neighbors or strangers connecting to the network.

Should MAC Filtering be configured in the other way, any client listed in the MAC Filtering screen will be denied access to the network. This is useful if there are particular devices that need to be prevented from connecting to the network. For instance, if a parent wants to temporarily lock a computer out of the network, such as that of a child, then the parent can configure MAC Filtering to deny access, and then add the MAC address of the child's computer.

MAC Filtering may also, depending on the router, be configured to deny or allow access only during specified time periods. For example, a home router may be configured to deny access to a particular computer or group of computers only between 7PM and 8AM. This can be useful in situations where a network administrator wants to limit access during these hours, such as in a business setting.

It is highly recommended to be very careful with the MAC Filtering settings on a router, as configuring these incorrectly can cause the router to deny connections to all devices or all but one device. Should this occur, it may be necessary to restore factory default settings to the router and start fresh.