AAA Security in Computer Network

Network resources such as servers, routers, and switches contain sensitive information. Network administrators implement various security options to protect sensitive information stored on network resources.

AAA is a security framework. It protects network resources from unauthorized access. It stands for Authentication, Authorization, and Accounting. It controls who is allowed to access network resources (through authentication) and what they are authorized to access (through authorization). It also captures the actions performed while accessing the network resource (through accounting).


Authentication is the process that identifies users who are allowed to access specific network resources. Administrators have many options for authentication. The most widely used method of authentication is password-based authentication. This authentication method assigns a unique username and password to each user. Users authenticate themselves by typing their usernames and passwords.

Devices that support authentication have a local database to save usernames and passwords. Administrators can configure the device to use its local database for authentication or send authentication requests to an external authentication server like the ADS server.

The authentication server compares the user's authentication credentials with other user credentials stored in a database. If the user's login credentials match, it allows the user to access the requested resource. If credentials do not match, it blocks the user from accessing the requested resource.

Apart from password-based authentication, based on network requirements, administrators can also use other authentication methods, such as biometrics or a smart card.


After the successful authentication, authorization determines the resources the user is allowed to access and the actions the user can perform on the resources. It enforces security policies on network resources after the user has gained access to the network resources through authentication. For example, a user can execute commands after logging. The authorization process determines the commands the user can run.

Authorization occurs within the context of authentication. It works only after the authentication. It limits the actions the authorized users can perform on the allowed resources.


Accounting monitors and captures the user actions while accessing the network resources. For example, it captures the duration the user used a resource or logs the amount of data the user accessed. It monitors the user session's statistics and usage information that the administrator can use for authorization control, billing, trend analysis, resource utilization and capacity planning activities.

Advantages of the AAA framework

The AAA framework provides the following benefits.

Network security

The AAA framework enhances network security. Users are required to undergo credential-based authentication before accessing network resources. It also enforces the rule of least privilege. The least privilege principle prevents malicious or negligent-based user behavior that could cause data deletion, compromise, or theft.

Protocol management

It helps administrators manage and standardize protocols by providing a single source of trust. The protocol standardizes access controls across the network.


It allows administrators to deploy a security policy based on the network requirements. The policy defines the user roles and functions. Users can perform only allowed actions on resources.

Information-based decision making

It provides the information administrators need to make user-resource authorization, capacity planning, resource allocation, and capacity planning.

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