分布式拒絕服務（DDoS）攻擊是當前影響因特網正常工作的一個嚴重的問題，出現的攻擊將會阻止合法的用戶使用其所需要的資源。本研究將借助于SSFNet(Scalable Simulation Framework)模擬軟件構建相應的網絡環境，并模擬了TCP SYN 溢出攻擊的全過程。通過調整相關的實驗參數設置，給出了在不同攻擊強度下被攻擊子網的通訊流量圖。通過實驗可以看出， DDoS 攻擊的目的在于耗費被攻擊目標機器的資源而使其拒絕提供正常服務，而不是消耗大量的網絡帶寬。論文還進一步說明了從攻擊開始到目標機器癱瘓的時間取決于攻擊的強度，即攻擊者所控制的發起攻擊的機器數量以及發送攻擊包的數量。
關鍵詞: 分布式拒絕服務（DDoS）；SSFNet；TCP SYN
Abstract: The Distributed Denial of Services (DDoS) Attack is a serious issue on current Internet, and frustrates legal users to use some resources they needed. This paper uses SSFNet tools to build network environments, and simulates attack process of TCP SYN. The different network flow graphs are given according to different attack intensity by changing parameter settings in the paper. The target attached by DDoS will consume its resources and provide no services. The period from starting attack to crash of the computer is based on the intensity of attacks which are related to the number of attackers and the number of attack packets.
Key Words: DDoS, SSFNet, TCP SYN