Protecting TCP services from denial of service attacks

Abstract

In this paper, we present a scheme that protects legitimate traffic from the large volume of attackers packets during a DDoS attack. Legitimate packets can be recognized by the tokens they carry in the IP header. Obtaining a token does not require protocol additions or changes, rather it is automatically obtained when a TCP connection is established. We believe that the Implicit Token Scheme (ITS) has numerous advantages: (1) It is totally transparent to clients. (2) No new protocols or modification of existing ones is needed to implement ITS. (3) Operations required by intermediate routers are computationally not more intensive than a couple of addition operations which could be easily done at wire-speed. (4) Does not lead to false positives. (5) Can sustain server availability even during attacks involving hundreds of thousands of attackers. Copyright 2006 ACM.