Detecting DoS attacks using packet size distribution

Enabling early detection of Denial of service (DoS) attacks in network traffic is an important and challenging task because DoS attacks have become one of the most serious threats to the Internet. In this paper, we develop an IP packet size entropy (IPSE)-based DoS detection scheme in which the entropy is markedly changed when traffic is affected by an attack. Through our analysis, we find that the IPSE-based scheme is capable of detecting not only long-term attacks but also short-term attacks that are beyond the volume-based schemespsila ability to detect.