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Posted by:greaneyr
Subject:Channel details detects activity on unused channels
Date:07:39:49 12/06/2011

Hi all

I'm trying to understand the channel details screen a little better and thought I'd ask in here as I can't seem to find much explanation in the docs. When I go to the channel details screen (with channel hopping enabled) initially I see signals only on the channels I know have active access points on them. However, over time I gradually see activity on all 11 channels. I'm trying to understand why this is. I live in a sparsely populated area, and I know what the RF environment is like here. If kismet is picking up other access points on other channels, 1) the signals from them would be very weak and 2) there would not be enough to fill all 11 channels. None of the channels are 40MHz bonded channels either.

I know how wireless channels work, how an AP transmitting on channel 1 will overlap with channels 2-5 etc, and that an AP broadcasting on channel 1 will obviously take up some of the spectrum used by higher channels, but that's not what I'm seeing is it? I understood kismet just used the wireless NIC in a way that the driver supported it, which would mean you only saw activity from the AP. If the AP was set to channel 1, I'd expect to only see data coming from channel 1. If kismet was capable of doing more than this, then it could in theory start to form the basis of a crude spectrum analyser.

What I actually want is a device that can hop from channels 1 through to 11 and report the RSSI of whatever it hears, not just the strength of a valid 802.11 frame. This isn't what I'm seeing with kismet, is it? If it is, then there is potential to extend on this.

Can anyone shed some light on this?

Thanks
Richard


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