AAA, a network security mechanism, is the abbreviation of Authentication,
Authorization and Accounting. Through testifying the user ID, AAA authorizes the
user with corresponding access right and account the charge of the user according
to his using of the network. AAA aims to control the user’s access right and ensure
the network security.

AAA can implement the following services:

■

Authentication: to authenticate whether the user has the right of access. The
RADIUS protocol can be used here.

■

Authorization: to authorize the user with certain types of services.

■

Accounting: to record the information about network resources usage by users

AAA usually adopts the structure of client/server. The client operates on the
managed resources and the server mainly manages the information of users. This
structure possesses good scalability and facilitates the management of users’
information.

RADIUS Protocol

Introduction to Radius

RADIUS (Remote Authentication Dial-In User Service) was developed by Livingston
Enterprise. As a distributed client/server system, RADIUS provides AAA function
and protects networks from being intruded by unauthorized visitors, so it is mainly
applied in the network environments that require high security and support
remote login. (For example, it can be used to manage enormous scattered dial-up
users using serial interfaces and modems.)