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AAA configuration
Overview
Introduction to AAA
Authentication, Authorization, and Accounting (AAA) provides a uniform framework for implementing
network access management. It can provide the following security functions:
 Authentication—Identifies users and determines whether a user is valid.
 Authorization—Grants different users different rights and controls their access to resources and
services. For example, a user who has successfully logged in to the device can be granted read and
print permissions to the files on the device.
 Accounting—Records all network service usage information of users, including the service type,
start time, and traffic. The accounting function not only provides the information required for
charging, but also allows for network security surveillance.
AAA usually uses a client/server model. The client runs on the network access server (NAS), which is
also referred to as the access device. The server maintains user information centrally. In an AAA network,
a NAS is a server for users but a client for the AAA servers. See Fi g u r e 315.
Figure 315 Network diagram for AAA
When a user tries to log in to the NAS, use the network resources, or access other networks, the NAS
authenticates the user. The NAS can transparently pass the user’s authentication, authorization, and
accounting information to the servers. The RADIUS protocol define how a NAS and a remote server
exchange user information between them.
In the network shown in Figure 315, there are two RADIUS servers. You can choose different servers for
different security functions. For example, you can use RADIUS server 1 for authentication and
authorization, and RADIUS server 2 for accounting.
You can choose the three security functions provided by AAA as required. For example, if your company
only wants employees to be authenticated before they access specific resources, you only need to
configure an authentication server. If network usage information is needed, you must also configure an
accounting server.
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