Network security refers to the protection of information and resources from loss, corruption, and improper use. Are wireless networks secure? Among businesses considering the implementation of a wireless system, this is a common and very important question. To answer this question, you must consider the functionality of a wireless network.
A wireless network provides a bit pipe, consisting of a medium, synchronization, and error control that supports the flow of data bits from one point to another. The functionality of a wireless network corresponds to the lowest levels of the network architecture and does not include other functions, such as end-to-end connection establishment or login services that higher layers satisfy. Therefore, the only security issues relevant to wireless networks include those dealing with these lower architectural layers, such as data encryption.
The main security issue with wireless networks, especially radio networks, is that they intentionally propagate data over an area that may exceed the limits of the area that the organization physically controls. For instance, radio waves easily penetrate building walls and are receivable from the facility's parking lot and possibly a few blocks away. Someone can passively retrieve your company's sensitive information from this distance without being noticed by network security personnel. The eavesdropper can utilize a protocol analyzer equipped with a wireless LAN NIC and view data within transmitted packets if the wireless LAN does not implement encryption. This problem also exists with wired Ethernet networks, but to a lesser degree. Current flow through the wires emits electromagnetic waves that someone could receive by using sensitive listening equipment. They must be much closer to the cable, though, to receive the signal. Of course, a way to prevent the disclosure of sensitive information to potential eavesdroppers is to implement encryption that most wireless LAN vendors offer as an option.