Sniffer captures and collects limited information from mobile devices, for later analysis. On the base of the collected data, the attendance of events, the traffic of passenger traffic can be presented. Areas of use: identification of people at events with subsequent identification of individuals by external data bank; counting people (in buses, on ships, at places of congestion, in corridors, tunnels) device coverage is a 50 meters radius; construction of a correspondence matrix throughout the city or at various events (mass meeting, concerts, etc.), identifying an audience; analysis of the Wi-Fi frequency channels congestion.