Part two of a two-part article titled Network Authentication, Authorization, and Accounting was just published in the Internet Protocol Journal. I wrote the article to be a survey of the entire AAA space and so it covers a lot of ground without spending too much time in one place. If you are new to AAA or are looking for a conceptual model of AAA to help others grasp its concepts, please take a look. Here’s a snippet:
Network Authentication, Authorization, and Accounting has been used since before the days of the Internet as we know it today. Authentication asks the question, “Who or what are you?” Authorization asks, “What are you allowed to do?” And finally, accounting wants to know, “What did you do?” These fundamental security building blocks are being used in expanded ways today. The first part of this two-part series focused on the overall concepts of AAA, the elements involved in AAA communications, and high-level approaches to achieving specific AAA goals. It was published in IPJ Volume 10, No. 1. This second part of the series discusses the protocols involved, specific applications of AAA, and considerations for the future of AAA.
Although AAA is often thought of as the exclusive province of the Remote Authentication Dial-In User Service (RADIUS) protocol, in reality a range of protocols is involved at various stages of the AAA conversation. This section introduces these AAA protocols, organized according to the parties involved in the communication. We divide AAA communications into the following categories: Client to Policy Enforcement Point (PEP), PEP to Policy Decision Point (PDP), Client to PDP, and PDP to Policy Information Point (PIP).