How to detect the presence of mobile devices in an area using WiFi router

Question

I have a requirement to detect the presence of mobile devices inside an area using my WiFi router,without connecting to them , So I did some research on it and found some interesting things like WiFi sniffing, but for testing purpose I want to use my Mac machine (Yosemite) as a WiFi router in monitor mode my problem is how I will get the list of all the devices Mac address inside my region, and how I will use my Mac machine for this purpose... Thanks for any kind of help.

Answer 1

Thanks to wireshark its awesome tool for listing all the WiFi devices in monitor mode