MAC filtering is a security measure used in wireless networks to deny or allow access to the network based on the MAC address of the devices attempting to connect to it. The MAC address is a unique identifier assigned to network interfaces for communications at the data link layer of a network segment. By filtering these addresses, a network administrator can provide an additional layer of control over which devices can connect to the wireless network. While MAC addresses can sometimes be spoofed, MAC filtering can still be a useful component of a layered security approach.