Abstract: A system and method for authenticating and authorizing user access to a computer network. An AAA server comprises a plurality of Authentication transport protocol modules that interface with one or more clients using a native authentication transport protocol. The AAA server is coupled with a DBMS system that stores user authentication, authorization and accounting information in a standard format. Authentication and authorization are performed using a five phase process comprising the phases: Augmentation; Selection; Authentication; Authorization and Confirmation. During the Augmentation phase, client requests are translated into a standard internal format. The requests are parsed into a set of attribute/value pairs according to a parse rules table. In the Selection phase, the AAA server determines the details of the access request and identifies the permit required to authorize access.