3.1 Hacks #20-42
Perhaps the most difficult task in
wireless networking is trying to visualize what is really going on.
Radio waves are invisible and undetectable to humans without the aid
of sophisticated tools, such as a spectrum analyzer. Such devices
aren't cheap, ranging from several hundreds to tens
of thousands of dollars, depending on its capabilities. Obviously,
such devices are well beyond the reach of the average networking
aficionado. And even if they weren't, a spectrum
only gives you a visualization of what is going on at the physical
radio layer, and doesn't give you any indication of
what is happening with the actual network data.
Fortunately, every radio networking device can not only transmit
data, but can listen as well. Combined with sophisticated (and
generally free) software, this can turn an average laptop or handheld
into a powerful monitoring tool. In this chapter,
I'll show you how to use standard hardware to detect
wireless networks and clients, generate statistics on their usage,
and gather valuable insight into how your network is being used by
sifting through the deluge of available radio information. Using
these tools can help you coordinate networking efforts with people in
your local vicinity to make the most efficient possible use of the
available radio spectrum.
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