Design of an extended TCP for preventing DOS attacks

Denial of Service (DoS) attacks have become, in today´s Internet, one of the most difficult issues to address. In the DoS attacks, the attackers consume all of the computing or communication resources that are needed for providing the services. TCP has drawbacks in its connection establishment for possible DoS attacks. TCP maintains the state of each partly established connection in its fixed size queue until it is fully established and accepted by the application. The attackers can make the queue full by sending connection requests very much and not completing the connection establishment steps for those requests. In this paper, we have designed and implemented an extended TCP for preventing the DoS attacks. In the extended TCP, the state of each partly established connection is not maintained in the queue. We have modified the 3-way handshake procedure of TCP, and implemented the extended TCP in Xinu operating system.