It’s easy to see how this feature could lead to tracking: If you move around a city connecting to different public Wi-Fi access points in coffee shops, airports, and libraries, your device would use the same MAC address to connect to each, enabling an organization operating the Wi-Fi hotspots to track your location movements and network activity over time. You could change your MAC address manually on some devices, but few people did. Every network you connect to received the same MAC address from your device. Traditionally, the MAC address was set at the hardware level and was the same for the lifetime of the device. This identifies the device to the network. When an iPhone, iPad, or any other WI-Fi enabled device connects to a Wi-Fi network, it sends a unique media access control (MAC) address.
