Researches On Access Control Technology In Public Wireless Local Area Network (Pwlan) Security Architecture

With the rapid development of wireless broad-banded IP access technology, Public Wireless LAN (PWLAN) has becoming one of research hotpots recently. In the secure architecture of PWLAN, access controller (AC), which acts as the Internet gateway between the wireless access network and the fixed IP backbone, connects the LANs with the Internet. Access controller contains all necessary elements including user authentication, access control, billing information collection, network management and so on. Based on one part of the research work of the "Research and Development on the Secure Architecture of the PWLAN" supported by The Project of Hi-tech Research and Development Program of China (Grant No. 2002AA143010), this thesis discusses the design and the implementation of the Access Controller in great details. First of all, this thesis introduces the development of WLAN standards, describes the topological architecture of WLAN and analyzes its secure architecture as well. Then we present the overall design, module design and the system implementation scheme through analyzing the functions of the AC. What's more, we build the kernel function module of the AC by applying the related technology such as socket programming and multi-thread programming. For example, we create four kinds of Access Control List (ACL) by extending the technology of ACL, realize the functions of Network Address Translation (NAT), Dynamic Host Configuration Protocol (DHCP) and fulfill the goal of billing information collection together with its the transmission through Remote Authentication Dial-In User Service (Radius) Protocol. Our work can roughly satisfy the specification of the operators including China Mobile and China Unicom. The conclusion of this thesis is included in the final part.