Date Added: Apr 2013
Wireless sensor network consists of tiny miniaturized motes which gather information about their vicinity and collaborate with each other through wireless link. These motes are mostly deployed in a harsh environment and left unattended for the duration of their lifetime. Hostility of the environment and physical intervention possess various threats to these energy-thirsty sensor motes which results in severe catastrophic affects. In this paper, the authors have provided a brief overview of denial of service attacks at various layers and proposed countermeasures available in literature and their proposed solutions in wireless sensor network. In Denial of Service attack, a sensor node is deprived of resources in one way or another. Also, security is classified into four major classes in this paper.