[Cerowrt-devel] Recording RF management info _and_ associated traffic?

David Lang david at lang.hm
Wed Jan 21 18:58:01 EST 2015

On Wed, 21 Jan 2015, Richard Smith wrote:

> On 01/20/2015 11:59 AM, Rich Brown wrote:
>> One of the first things I would do is a Wifi site survey, to look for
>> conflicts between access points/channels, etc. Two recommendations
>> for tools:
>> MacOSX: WiFi Explorer from Adrian Granados - US$4.99 from the Mac App
>> Store. http://www.adriangranados.com/apps/wifi-explorer Android: WiFi
>> Analyzer from farproc - Donationware from the Android store.
>> https://sites.google.com/site/farproc/wifi-analyzer
> Thanks for the suggestion. I've done that.
> I'll offer up a 3rd choice which I have been using.  Horst.
> Runs on OpenWrt perfectly and free.  I've not tried it on CeroWrt yet but I 
> don't see why it would not work.
> http://br1.einfach.org/tech/horst/
> With horst I've verified that the 3 AP's we are running are all on 5Ghz 
> channels that don't have another AP on them.  We are up on the 10th floor of 
> a tower type building and 3 of our walls have large windows with clear views 
> of surrounding buildings.  We are higher than most of the stuff around us.

Ok, this would suggest that you are unlikely to have interference causing your 
problems. I don't have the earlier part of this thread still in my mailbox, what 
is the problem that you are trying to solve again?

When you do a wifi survey, you are not just looking at one spot, or near the APs 
for what you see. You should also be going to all the areas your users are going 
to be trying to access your network and see if you have a strong enough signal 
from at least one AP everywhere. Also note that if you have high-power APs, you 
may hear a signal from them, but they may not be able to hear the signal from 
the mobile device very well. Mobile devices tend to have lousy antennas, and try 
to operate a lower power levels to save battery power. So you may need to look 
at the stats on the AP showing the signal it sees from the client.

Assuming that you have enough signal, the next question is how many people are 
going to be trying to use the network at one time. You may be better off with 
more APs operating at lower power levels so that you have fewer people talking 
to each one.

David Lang

> So when I scan I do see a lot of intermittent probes or wifi traffic
> from other things but nothing cronic.  I haven't been able to run a scan when 
> it all goes to hell though.
> With horst it shows me the DATA or QDATA packet among the radiotap info and 
> that the contents are encrypted  but I've not figured out how to capture 
> decrypted traffic at the same time as radiotap info.  This would let me see 
> exactly what sort of dynamic was happening from our network.
> As an aside if any of the gurus here are near the Boston, MA area and
> want to do small business Wi-Fi consulting let me know.  We will gladly
> pay someone to fix our wireless.
> --
> Richard A. Smith
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