Peter got an idea to turn his Raspberry Pi into an WIFI access point in order to sniff out the traffic for research purposes. So after following some tutorials on Adafruit to get his Pi in AP mode he started dumping traffic.
He’s using hostapd for authentication, and started out just using good ol’ tcpdump to dump the traffic. After noticing the traffic was a little hard to follow from tcpdump he moved into running a man in the middle proxy script which allows him to see the traffic in a little more sane manor.
In his example he is spying on the traffic an app on his phone generates, but this method could be useful similar applications.
He has a bash script with his firewall rules up on his site, as well as some explanation of his test app on his site.