RADIUS Network

Remote Authentication Dial-In User Service (RADIUS) is an access server authentication, authorization, and accounting protocol developed by Livingston Enterprises, Inc., now a division of Lucent Technologies. RADIUS is a system of distributed security that secures remote access to networks and network services against unauthorized access.

RADIUS is a fully open protocol, distributed in source code format that can be modified to work with any security system currently available on the market. Numerous implementations of RADIUS server code are commercially and freely available. Cisco’s servers include CiscoSecure ACS for Windows, CiscoSecure UNIX, and Cisco Access Registrar. Several IETF RFCs define the RADIUS protocol, but currently it’s still a proposed standard.

A RADIUS implementation is made of the three following components:

• Protocol using UDP/IP communication.

• RADIUS server—a service running on a central Windows or UNIX server, typically at the customer’s site.

• RADIUS client—a service residing in the dial-up access servers that can be distributed throughout the network. Cisco added RADIUS client support beginning with IOS v11.1.