Denial of Service: Denial of Service (DoS) attacks occur when attackers use PC or laptops to transmit signals in order to interfere with the radio frequencies being used by the network. In a WSN, this kind of attack can also be visible at the data link layer where, in order to disrupt the communication protocols using IEEE 802.15.4 or ZigBee, attacks are committed by transmitting a continuous stream of messages with a view to generate collisions.