MAC address

The obvious way to track users across heterogeneous WLANs is to use the MAC address as unique identifier. Trackers can use this information to correlate any other behavioral information to a MAC address to easily create profiles. Fortunately, although MAC addresses are permanent by design, there exist a number of mechanisms that allow users to change the identifier. Gruteser et al  [32] introduce the idea of short-lived disposable MAC addresses as a technique for the reduction of the effectiveness of location tracking. However, randomizing MAC addresses often leads to problems. For example, several ISPs use MAC addresses to map IP addresses. Also, some software licenses are bound to a specific MAC address. Furthermore, even in the presence of such techniques, user profiling can still effectively track users in dense urban environments. In our system, we use MAC addresses as temporary identifiers for correlating information that will be used to create user profiles as described below.