Wireless sensor networks are wide spreading, dominating, and has a far-reaching range of utilizations such as battlefield scrutiny, traffic scrutiny, forest fire detection, flood detection etc. Both industry and academia are targeting their research works for the sake of advancing their functions. The safety of a wireless sensor network is negotiated due to the random distribution of sensor nodes in exposed environment, memory restraints, power restraints and unattended nature. Furthermore, providing confidence between every couple of communicating nodes is a demanding issue and is of prime importance in internet of things. Under these conditions this chapter spotlights variety of attacks and their symptoms thoroughly. The chapter analyzes them based on trusting based protection techniques including classical techniques such as fuzzy, Bayesian, game theory etc. Modern techniques such as clustering, bio-inspired computing, key establishment based techniques are stressed upon to provide maximum protection for each node in the wireless sensor network.