Remote Authentication Dial-in User Service (RADIUS) is a networking protocol that is a convenient way to centrally manage connection authentication, authorization, and accounting (AAA) management that connect and use a network service.

Port-based authentication network switches typically have a RADIUS client component that communicates with the RADIUS server. The switch sends the device username, password, and other identifying information to the RADIUS server, which then authenticates the device and allows it access to the network.