Hi there.
Airodump-ng seems to be working perfectly with my atheros internal card set as monitor. But in an environment with a very high traffic level (more than 70 APs and more than 300 devices), something strange happened.
Airodump-ng was executed from my laptop as always. My iPad wast together and connected to an SSID called "A" for instance. That SSID has a lot of APs spreading that SSID name. I sent a deauthentication to my iPad using MDK3 and specifying the channel, and it was deauthenticated properly. A few seconds later, mi iPad reconnected to another AP in another channel, what is OK, but it was being saw in the airodump-ng command as "not associated", even I could navigate without problem. Time later, I didn't see my iPad anymore, and even the AP where it was connected.
From that point on, I could never saw the AP or my iPad anymore with airodump-ng, (I don't know if the AP was seen at the beginning, but I don't think so) even rebooting and using different USB network cards that works perfectly. Another strange thing is that I could see many others APs that are exactly the same as the "invisible" one, and configured in the exactly same way.
In a nutshell: There was an AP broadcasting an SSID that seemed not to be visible for airodump-ng. I don't know if it has something to do with the very high number of APs and clients that were in the network, but after rebooting and testing with different network cards, that AP was invisible for me even the iPad was connected to it (maybe there are more APs I was not seeying, I don't know).
Any ideas? Your help would be very appreciated...
Kind regards.