Research And Implementation Of Key Techniques For The Client Layer Of The Progressively Weakened DDoS Attack Defensive System

In recent years, Distributed Denial of service (DDoS) attacks caused greater and greater damage. The research on defense technology of DDoS attacks has become of the hotspots in network security area. We proposed a bed-by-bed defensive system that can weaken the DDoS attacks, including client layer, verify scheduling layer, and link scheduling layer and service layer. This major work focuses on the design and implementation of the system of client layer, including the following four parts:(1) Analyzing several mainstream DDoS defense technologies and summarizing the disadvantages of them. Introducing the key technologies such as security identifiers, DLL injection, API Hook technology, IE intercepted technology and software online updating technology;(2) Based on the framework design and implementation principles of progressively weakened DDoS attacks defensive system, the detailed design of the client layer is presented, including design of the whole framework, four key modules and their relationships, running procedure;(3) Analyzing and implementing of the key techniques of the client layer, the main contributions include: based on the DLL injection through the remote thread and network data interception using API Hook, the thesis implemented the dynamic URL redirection; based on the introduction of user's ID, plug-in identification and the connection identification, the thesis describe the mapping relationships among the three kinds of identification and implement the creation algorithm for user's ID and self-security-checking for client plug-in; the design and implementation of online updating of client plug-in is also presented;(4) Implementing the client layer prototype system, and verifying the algorithms and techniques metioned above preliminarily.The main contributions are important parts of the state 863 High-tech project named"the research of hologram mechanism based network survivability system model and key technologies implementation", and they have played a solid fundation for the further research and design of DDoS defense system.