Maybe I can't use Google, maybe it was not answered anywhere.
Is there a way for a "passive" DFS radar scan? I.e. I'd like to run second AP in listen-only mode for a longer period (let's say a month) to determine if there are any "safe" channels where I live.
I live relatively close (let's say ~6-8km) to a commercial airport and in multi story building so the non-DFS channels are really congested. I want to avoid "switch channel and use it until it dies, then test another" scenario if possible.
I've never heard of this...perhaps running tcpdump or Wireshark maybe?
You could simply set the AP to the desired channel and monitor the log for DFS events.
They're likely not "safe".
This is indication.
You can add multiple channels via
option channels '36 116'
option channel '116'
If it ever lands on 36 it got radar event.
airodump-ng wlan0 --band a
IMO just confirm channel switch event works properly by triggering it manually. And select a clear channel. At least for me all my devices behave properly on channel switch event and doesn't really cause any issues?
I'd just log for DFS events and deploy. Then play with adding and removing different DFS channel options. i.e. a more restrictive list per:
Anyway to answer the question, although i've not done this whilst trying to look for DFS events nor trigger etc.....
Use devices in monitor mode. (Horst + log output for example?) Hold on a channel for a certain period of time. Monitor debug or normal driver DFS output.... profit?
Or use SDR , downconverter and a spectrum analyser? =P