| With the rapid development and wide application of network technology, it is important that we need guarantee network and information security, and reduce or avoid information disclosure and damage caused by the network access clients.This thesis introduces the current popular network access control technology, summarizes several systems used in this field, and discusses the advantages and disadvatages of these systems. It describes the main implementing processes of the network access control system and the relationships of these processes.This research studies the rules and the methods of the network access control system, and implements the combination of its strategy, technology and management. This research proposes the designing model of the network access control system. It has developed the main modules successfully on the basis of the designing model. These modules include the certification client, topology discovery, RADIUS services and the access control based on 802.1X. |