Hello Flood Attack and its Countermeasures in Wireless Sensor Networks

Wireless sensor network have emerged as an important application of the ad-hoc networks paradigm, such as for monitoring physical environment. These sensor networks have limitations of system resources like battery power, communication range and processing capability. Low processing power and wireless connectivity make such networks vulnerable to various types of network attacks. One of them is hello flood attack, in which an adversary, which is not a legal node in the network, can flood hello request to any legitimate node and break the security of WSN. The current solutions for these types of attacks are mainly cryptographic, which suffer from heavy computational complexity. Hence they are less suitable for wireless sensor networks. In this paper a method based on signal strength has been proposed to detect and prevent hello flood attack. Nodes have been classified as friend and stranger based on the signal strength. Short client puzzles that require less computational power and battery power have been used to check the validity of suspicious nodes.