Wireless mesh networks are becoming an attractive solution for providing low-cost Internet access citywide. However, network attack is a critical and destructive behavior in such networks, and is an extensive problem worldwide. This thesis aims to identify the behavior of different network attacks and their defense mechanisms, as well as their effective measurements. It mainly focuses on different protocols and models to figure out how the attacks behave and also evaluates various attacks. By doing so, some sort of advance consolidate can be exert to the existing defense solutions to handle with the network attacks and strengthen the network system to better understand the characteristics of cyber attacks, and the impact of cyber attacks on a wireless network. First, a simple simulation is conducted to study the various network attacks on basic topology structure with varying nodes and links. The purpose of this experiment is to understand the characteristics of the attack itself, and to get some insight into the network topology structure? Besides that, in this thesis, discussion about the real attacks in a wireless mesh network has been reviewed. Further more some simple attack model has been implemented by simulation in the OMNeT++. The purpose of this thesis is not only to do research on network attacks, but our ultimate aim is to have a better understanding of a network?s defense against cyber-attacks by optimizing the network structure so we can increase the security level of the network structure.