In this paper, the authors present how the security can be given to the wireless network with the help of intrusion detection system and firewalls. With the rapid growth of application of Internet in various walks of life, the study of security has become inevitable. Wireless networks are providing tremendous benefit for a number of industries. This paper focuses different kinds of wireless network i.e. mobile ad hoc network, Wi-Fi and Bluetooth. Although wireless networks have appealing features, due to the lack of a physical line of defense, the security of such networks is a big concern.