DoS and DDoS Attacks at OSI Layers

Among different online attacks obstructing IT security, Denial of Service (DoS) and Distributed Denial of Service (DDoS) are the most devastating attack. It also put the security experts under enormous pressure recently in finding efficient defiance methods. DoS attack can be performed variously with diverse codes and tools and can be launched form different OSI model layers. This paper describes in details DoS and DDoS attack, and explains how different types of attacks can be implemented and launched from different OSI model layers. It provides a better understanding of these increasing occurrences in order to improve efficient countermeasure