Research On Network Security Mechanism Of Defending Against Denial Of Service Attacks

With the development of network technology and application, network security becomes increasingly more important. Denial of service attack is becoming one of the hardest network security problems because it is easy to launch, difficult to defend and trace, it is doing great harm to network security. So, researching on defending against denial of service attacks is very important.This paper have a detailed research on denial of service. First, the mechanism, methods and tools of denial of service attacks are discussed, then analyzing the present countermeasures to denial of service, to have a conclusion of their characteristics. After that, for the three typical countermeasures to denial of service: filtering, IP traceback and pushback, corresponding algorithms are put forward:"based on network attacks'traffic characters, an anomaly traffic character aggregation algorithm (AFCAA)","adaptive packet marking scheme","based on pushback of aggregated traffic algorithm", thus we constitute the whole system of defending against denial of service attacks from detection, defense to traceback.Because normal DoS attack traffic has some characters in their packets'head, AFCAA uses the center of gravity theory to process statistic aggregation and aggregation partition based on the special field of the destination IP attack traffic in a fixed Euclid distance, and then it distills the center of attack traffic dynamically as the characters of attacks. Afterwards, through transmitting these characters to Net Filter, AFCAA can filter abnormal packets efficiently.Knowing that in existing packet marking schemes, router marks packets with fixed...