分布式拒絕服務攻擊是因特網安全的頭號威脅。針對DDoS 攻擊，本文介紹了一種基于MPC860 和FPGA 的實時檢測防御系統的體系結構與實現原理，探討了基于非參數累積和（CUSUM）算法檢測新IP 地址到達速率變化的DDoS攻擊檢測方法。實驗結果表明該系統不僅實時檢測準確性高、在線檢測速度快、防御效果好，而且不損失網絡信息
吞吐量，保證了合法用戶的正常訪問。
關鍵詞：DDoS 攻擊；FPGA ；CUSUM 算法；實時檢測；門限
Abstract: Distributed denial-of-service(DDoS) attacks present an immense threat to the Internet.The paper concentrates on the architecture and principles of the system of real-time detecting and defending against DDoS attack，which is based on MPC860 and FPGA.We propose a scheme to detect the DDoS attacks by monitoring the increase of new IP addresses.We use the non-parametric CUSUM algorithm to detect the change of the
rate of the new IP addresses arriving. Experiment results show that our scheme is characterized by high detection accuracy ,short detection time and good defence effect. Finally ,the mechanism guarantees the usual network throughput efficiently and reliably ,and provides good service to the legitimate traffics during the attack.
Keywords: DDoS attack; FPGA; CUSUM algorithm;Real-time Detection; Threshold