Chapter 17. Wireless Security

This chapter gives a brief introduction to some of the security challenges implicit in wireless networks. The IEEE’s certification for “wireless Ethernets” is classified and controlled by the 802.11 standard. 802.11 is further broken down into more specific certifications, such as 802.11a, 802.11b, and 802.11g. Each defines a different method for providing wireless Ethernet access. Each protocol specifies various aspects of data transfer that distinguishes it from the other certifications.

Despite gains by 802.11g, 802.11b is currently the most prevalent standard for wireless LANs worldwide, and support for it is found in almost every wireless device. An 802.11b device operates by sending a wireless signal using direct sequence spread spectrum (DSSS) in the 2.4-GHz range.

This chapter assumes that you have at least a passing familiarity with wireless security threats (e.g., wardriving), that you have set up at least one simple 802.11 network, and that you understand the basics of WEP and computer viruses. We will therefore focus primarily on 802.11b security, how to crack it, and what defenses are theoretically possible. We also introduce the growing threat posed by wireless airborne viruses, and some possible countermeasures.

Reducing Signal Drift

Before we get into cracking Wired Equivalent Privacy (WEP) and discuss possible countermeasures, let us pause to consider how the humble antenna can help control radio frequency signal drift. Antennas can be ...

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