Date Added: Jan 2013
In today's world means of communications has changed rapidly and the main focus is on wireless communications. Communication in wireless mode has many threats. This paper discusses a brief overview of various threats to wireless networks at various layers and also presents a survey of the defense mechanisms. The main aim is to discuss attacks on MANET and their defense mechanisms. Communication in wireless mode is more challenging as compared to wired mode because of dynamically changing network topology. Wireless networks are mostly used in military applications and commercial applications. This paper also discusses internal threats and external threats. It also gives an overview of routing protocols being used in wireless networks and various attacks that take place against these routing protocols and their counter measures.