Today’s modern society greatly depends on computer systems. Security is a basic need for any computer system. This is more than acceptable if we consider that any disruption of the normal function of the computer and networks may lead to catastrophic consequences. The most frequently attacks conducting malicious activities against the networks and systems are the Distributed Denial of Service (DDoS) attacks. The paper concerns the TCP (Transmission Control Protocol) vulnerability that gives space for a type of DoS (Denial of Service) attack called TCP-SYN Flood DDoS attack which is well-known to the community for several years. It explains in more detail the TCP SYN Flood DDoS attacks and methods for preventing and mitigating the effects of these attacks. Furthermore, the paper proposes a novel method consisting of five modules which can be used for mitigation and protection against the considered TCP SYN Flood attack, as well as against other similar flooding based attacks
