Radius is a protocol that supports each of the three modules of AAA. Radius is an IP-based protocol that uses UDP as its transport. Radius is a protocol for carrying information related to authentication, authorization, and configuration between a Network Access Server (NAS) that desires to authenticate its links and a shared Authentication Server.
It is also a client/server model. This means the AAA client sends user information to the RADIUS server, and the RADIUS server responds with all the information that is needed for the AAA client to provide connectivity and service to the end user.
- Radius Supports multiple authentication method via Point-to-Point Protocol Challenge Handshake Authentication Protocol (PPP CHAP) and PPP Password Authentication Protocol (PAP), as well as others.
- Radius operates under the UDP protocol and ports used by RADIUS-
1645 & 1812 for Authentication
1646 & 1813 for Accounting
- Radius is considered as connection-less service.
- Radius encrypts only the password and rest is sent in the clear text.