MAC Authentication Bypass (MAB) is a technique that allows non-802.1X-capable devices to bypass the 802.1X authentication process and gain network access based on their MAC addresses. However, MAB has some security drawbacks, such as the possibility of MAC address spoofing or unauthorized devices being added to the network. Therefore, it is recommended to use a custom MAC-Auth authentication method that adds an additional layer of security to MAB.

A custom MAC-Auth authentication method is a method that uses a combination of the MAC address and another attribute, such as a username, password, or certificate, to authenticate the device. This way, the device needs to provide both the MAC address and the additional attribute to gain access, making it harder for an attacker to spoof or impersonate the device. A custom MAC-Auth authentication method can be created and configured in ClearPass Policy Manager (CPPM) by following the steps in the Customizing MAC Authentication - Aruba page.