1. Issues

The concepts of AAA (Authentication, Authorization, Accounting) emerged in the early 1990s, when ISPs wanted to offer their customers on the move the possibility of connecting to the Internet via the switched telephone network (PSTN). The need arose to offer reliable user authentication, as this could no longer be based on knowledge of the user's geographical location (e.g. telephone number). This authentication service is all the more crucial as the billing system or access to certain services, such as VPN (Virtual Private Network), rely on proper authentication. To prevent fraud, network equipment must be able to implement AAA functions, i.e. :

• authenticate and identify each other ;

• manage mobile user rights ;

• collect and store information on user connections.

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