I am trying to sniff traffic coming from or going to a smartphone on the local WiFi network (in a legal way). For that purpose I use the command TCPDump on a computer connected to the same wireless network.
My goal is to detect when smartphones connects to the wifi access point. I can detect iPhones because they use mDNS to advertise its presence. I can sniff packets from iPhone 5 et 5S, from a Galaxy phone with Android 5, but not from a Galaxy with Android 4.4.2.
With this device (GS3 Android 4.4.2) I can only sniff ICMP traffic, which is what is used for ping request. Instead of that I have nothing.
How can this be possible ? What can I do to sniff packets as I do with iPhones ? Does not Android use broadcasted messages for establishing a communication with an access point ?