The Raspberry Pi 3 is equipped with an in-built wifi interface which is handy if you want to connect to your local router.
If you want to use your Pi 3 to monitor network data on your local network using applications such as aircrack-ng or Wireshark, the problem is that the in-built wifi adapter is not able to go into monitor mode – or at least I have not been able to make it do that.
Monitor mode is needed if you want to monitor other network data other than the one that you are connected to.
The solution is to get a USB wifi adapter which has a chip set compatible with monitor mode.
The one that I use is an adapter with the RT5370 chipset which works fine.
Assuming that you have the aircrack-ng suite of applications installed on your Pi:
To set to monitor mode first do:
which will display the list of wireless interfaces.
#sudo airmon-ng start wlan1
In my case I want the second interface wlan1 to be in monitor mode, (not the in-built wifi adapter wlan0).
The problem is that this stops communications and my SSH connection hangs, hence I have to exit and log back in again then:
This should display wlan1mon as the interface in monitor mode – it has created a new version of wlan1 and called it wlan1mon.
To check connections on the interface:
#sudo airodump-ng wlan1mon