We’ve seen a number of projects that exploit probe requests. Newer versions of iOS, Android, and Windows 10 feature MAC address randomization which can limit the ability to track devices in this manner, but it isn’t always activated.

This is nothing new, and is relatively common technique used for gathering information in retail locations, and could be also be used for more nefarious purposes. All the recorded MAC addresses were logged to a server, where the data can be used for traffic analysis in and around the library, or even for tracking and locating specific devices. tested the OpenMAC at a local library (with permission), in combination with a number of his own little Wi-Fi repeaters to expand the reach of the network. An external antenna is required for the module, which can be selected based on the size or gain requirements for a specific deployment. The device consists of an ESP-07S module, a regulator circuit for getting power from a USB-C connector, and a button for power cycling. After experimenting with these probe requests, has created OpenMAC, a tiny ESP8266 based sniffer that could be hidden anywhere. These probe requests contain the device’s MAC address and the SSID of the hotspot it’s looking for, which can potentially be used to identify a specific device and where it’s been.

When a Wi-Fi device is switched on, it starts spewing out probe requests to try and find a familiar access point.

Space sniffer for mac