Distributed  Denial  of Service Mitigation<br/>

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Distributed Denial of Service Mitigation

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Type of Document: M.Sc. Thesis
Language: Farsi
Document No: 45582 (19)
University: Sharif University of Technology
Department: Computer Engineering
Advisor(s): Kharrazi, Mehdi
Abstract:
Denial of service (DoS) attacks is the main challenges of service providers due to their purpose to makes their service unavaillable. Nowadays this attacks are changed from centralized to distributed (DDoS) by means of botnets. In addition botnets allow attackers to launch attack on higher layers of network, such as application layer. In new application layer DDoS attacks, attacker send HTTP requests to waste victims resources. In addition, attacker can start attack during flash crowd event which makes attack more undetectable. In this research, in order to migigating such attacks, we introduced a method based on user’s history.
This history consist of user’s request rate for each predefined interval. Each interval has its own weight which used for mapping history to a number, called score. In attack period users are prioritized based on their score, In a way that requests with higher score have more chance to be served. The scoring scheme uses the website visit statistics to obtain weight of each interval so attacker can not treat like a legitimate user. Simulation results show that our proposed method in average can dedicate 87
Keywords:
Distributed Denial of Service (DDOS)Attack ; Hypertext Transfer Protocol (HTTP)Flooding ; History ; Cookie