This thesis is based upon the work of Beck and Tews [ 24 ]. It presents and experimentally Validate the Beck and Tews attack on a network with QoS client Associated with a Non- QoS AP.This is done by Slightly extending the source code Provided by Beck and Tews . A detailed study of the wireless security protocols has Also Been done followed by description of how the original Beck and Tews attack works.Martin Beck define a new approach of obtaining keystreams [ 1 ] Which has Been Thoroughly analyzed . A description of how the different packets are exceptional in obtaining more usable keystreams has Been dealer. The experimental validation of how extra keystream bytes are Obtained through the new approach [ 1 ] has Been done . This was done Using one of the network security tools.