The main objective is to discuss the security features and weakness of IEEE 802.15, IEEE802.11 and IEEE802.16 i.e. wireless PAN, wireless LAN and wireless WAN networks. Bluetooth, Wi-Fi and WiMax are the three most widely used wireless networking technologies. These networks are exposed to many types of risks and have various flaws in their respective protocol structure. Bluetooth belongs to a category of short-range wireless technologies, wireless LAN or Wi-Fi is the LAN network the people use in their home, offices or buildings etc to provide user the network availability.