Anyone who is not shocked by quantum theory has not understood it.
In wireless networks, the word "broadcast" takes on an entirely new meaning. Wireless networks rely on an open medium, and the risk of using them is greatly increased if no cryptographic protection can be applied on the air link. With an open network medium, unprotected traffic can be seen by anybody with the right equipment. In the case of wireless LANs, the "right equipment" is a radio capable of receiving and decoding 802.11, which is hardly an expensive purchase. For extra eavesdropping power, a high-gain external antenna may be used. Antennas are inexpensive enough that you must assume that a determined attacher has purchased one.
Guarding against traffic interception is the domain of cryptographic protocols. As frames fly through the air, they must be protected against harm. Protection takes many forms, but the two most commonly cited informal objectives are maintaining the secrecy of network data and ensuring it has not been tampered with. Initially, the Wired Equivalent Privacy (WEP) standard was the answer for wireless security. In the first four years of 802.11's life, researchers built a strong case for the insecurity of WEP.
If WEP is so bad, why bother with it? In many cases, it is the only security protocol available on a particular device. WEP's design is easy to implement. Though it lacks the sophistication of later cryptographic protocols, it does not require the computational power, either. Older devices, especially handheld application-specific devices, may lack the processing punch necessary to run anything better, and WEP is the best that you can do. It is also important to learn about WEP because the WEP frame-handling operations underlie newer technology such as TKIP.
Introduction to Wireless Networking
Overview of 802.11 Networks
11 MAC Fundamentals
11 Framing in Detail
Wired Equivalent Privacy (WEP)
User Authentication with 802.1X
11i: Robust Security Networks, TKIP, and CCMP
Contention-Free Service with the PCF
Physical Layer Overview
The Frequency-Hopping (FH) PHY
The Direct Sequence PHYs: DSSS and HR/DSSS (802.11b)
11a and 802.11j: 5-GHz OFDM PHY
11g: The Extended-Rate PHY (ERP)
A Peek Ahead at 802.11n: MIMO-OFDM
Using 802.11 on Windows
11 on the Macintosh
Using 802.11 on Linux
Using 802.11 Access Points
Logical Wireless Network Architecture
Site Planning and Project Management
11 Network Analysis
11 Performance Tuning
Conclusions and Predictions