Nowadays wireless networks tends to be more and more popular among the population with the millions of users. In a wireless environment everybody is to access the wireless transmitted data. This feature gives the capability to some vicious users to deceive the clients of a wireless network by imitating the characteristics of a Wireless Access Point(AP), thus staling valuable information from them. This kind of attack, where a fake Access Point is set up to deceive the clients from the legitimate one, is known as the Man-in-The-Middle attack(MITM). The main focus of this Thesis is to detect and actively prevent the attacker of performing the MITM attack. In the first part of the Thesis a fake AP will be created mimicking the characteristics of a legitimate one. Then a series of Denial of Service(DoS) attacks will be conducted to the legitimate AP in order to whisk the clients from their AP and force them to connect to the fake AP. Finally, since the attack is successful the traffic of the clients will be intercepted to reveal their private information.

The second part of the Thesis focuses on the detection and the prevention of a MITM attack. A system will be developed that it will be able to store the legitimate APs in a database and to perform scanning operations in the vicinity. Since the MITM attack is based mostly on deception, the system will be able to recognise any fake APs that are meant to be used in a MITM attack. Then system will automatically prevent these APs to provide any service to the deceived clients. The above experiment have been implemented using Backtrack 5R3 and Kali linux distributions and the system was developed using the Python language.. .