Grab your Board! We’re going Channel Surfing!

Jim Thor, WildPackets Professional Services

Sorry, no pictures in this tip, just great information!

Historically, for WLAN capture, the only way to capture was to surf – surf each channel, one at a time! Each adapter only has one tuner, and therefore can only be tuned into and listen on one channel at a time. We can scan channels, but we miss packets while we are scanning and listening on other channels. Often we want to capture on more than one channel simultaneously to capture roaming performance or to see the entire spectrum in a particular area. Another historical hurtle with capturing on multiple channels simultaneously is that laptops do not generally have multiple Cardbus slots. Even if you have two, Windows will only allow both of them to be used if Windows thinks they are both using different drivers. So you either need to run two different chipset devices with different drivers, or tweak the .inf and .sys files of the driver so Windows ‘thinks’ it is a different driver. Either way, this was a big pain.

NEWS FLASH! We NOW have the capability to use USB adapters. Yes, they do have to be models that are supported, but they can be found from companies like Linksys and DLink, and many others. The base ingredients are that they must be USB and have a chipset by a company called Ralink.

The adapters I use are the Linksys WUSB600N. This is a USB dual band adapter, both 2.4 and 5 GHz, and supports all current technologies, 802.11b/g/a/n. It is the complete solution for WLAN analysis when teamed with OmniPeek! So now you can have one laptop, with a series of USB wireless capture adapters, and capture on multiple channels simultaneously on a single laptop.

So there you have it. The complete WLAN analysis solution! Now grab your board (sorry, laptop) and let’s go surfing on multiple waves at once!