Wireless 802.11 networks are becoming more and more popular as a means to augment traditional wire-based LANs within companies. The pervasive nature of wireless communications forces a security perimeter designer to reexamine some of the underlying principles of traditional network architectures. In a wireless world, we can no longer assume that physical infrastructure (walls, doors, guards, and so on) will reliably protect the network against unauthorized external access on Layer 2 (media access) and Layer 1 (physical). To access wireless resources, the attacker only has to be in the proximity of the wireless network, often without even having to enter the building of the potential victim. In this chapter we will briefly examine the fundamental 802.11 wireless technologies, go over popular wireless network encryption protocols and important techniques used to secure wireless networks from attack, look at tools and methods used to audit our secure wireless infrastructure, and then finally review an example of a secure wireless deployment.