Remote Authentication Dial-In User Service (RADIUS) could be a networking protocols, in operation on ports 1812 and 1813, that gives centralized Authentication, Authorization, and Accounting (AAA or Triple A) management for users who connect and use a network service. RADIUS was developed by American Revolutionary leader Enterprises, Inc. in 1991 as an access server authentication and accounting protocol and later brought into the net Engineering Task Force (IETF) standards.
RADIUS could be a client/server protocol that runs within the application layer, and might use either protocol or UDP as transport. Network access servers, the gateways that management access to a network, sometimes contain a RADIUS consumer element that communicates with the RADIUS server . RADIUS is commonly the back-end of alternative for 802.1X authentication moreover.
The RADIUS server is sometimes a background method running on a UNIX system or Microsoft Windows server.