Building Wireless Community Networks, Second Edition

Security Considerations

Although the differences between tethered and untethered are few, they are significant. For example, everyone has heard of the archetypal "black-hat packet sniffer,” a giggling sociopath sitting on your physical Ethernet segment, surreptitiously logging packets for his own nefarious ends. This could be a disgruntled worker, a consultant with a bad attitude, or even (in one legendary case) a competitor with a laptop, time on his hands, and a lot of nerve.^[7] Although switched networks, a reasonable working environment, and conscientious reception staff can go a long way to minimize exposure to the physical wiretapper, the stakes are raised with wireless. Suddenly, one no longer needs physical presence to log data: why bother trying to smuggle equipment onsite when you can crack from your own home or office two blocks away with a high-gain antenna?

Visions of cigarette smoking, pale-skinned über-crackers in darkened rooms aside, there is a point that many admins tend to overlook when designing networks: the whole reason that the network exists is to connect people to each other! Services that are difficult for people to use will simply go unused. You may very well have the most cryptographically sound method on the planet for authenticating a user to the system. You may even have the latest in biometric identification, full winnow and chaff capability, and independently verified and digitally signed content assurance for every individual packet. But if the average ...