Can you track someone by their cell phone

As of , smartphone manufacturers have started to recognize that this kind of tracking is problematic, but it may not be fixed in every device for years—if ever. In comparison to GSM monitoring, these forms of tracking are not necessarily as useful for government surveillance.

This is because they work best at short distances and require prior knowledge or observation to determine what MAC address is built into a particular person's device. However, these forms of tracking can be a highly accurate way to tell when a person enters and leaves a building. Turning off Wi-Fi and Bluetooth on a smartphone can prevent this type of tracking, although this can be inconvenient for users who want to use these technologies frequently. Wi-Fi network operators can also see the MAC address of every device that joins their network, which means that they can recognize particular devices over time, and tell whether you are the same person who joined the network in the past even if you don't type your name or e-mail address anywhere or sign in to any services.

On a few devices, it is physically possible to change the MAC address so that other people can't recognize your Wi-Fi device as easily over time; on these devices, with the right software and configuration, it would be possible to choose a new and different MAC address every day, for example. On smartphones, this commonly requires special software such as a MAC address-changing app.

Currently, this option is not available for the majority of smartphone models. Apps can ask the phone for this location information and use it to provide services that are based on location, such as maps that show you your position on the map. Some of these apps will then transmit your location over the network to a service provider, which, in turn, provides a way for other people to track you.

The app developers might not have been motivated by the desire to track users, but they might still end up with the ability to do that, and they might end up revealing location information about their users to governments or hackers. Some smartphones will give you some kind of control over whether apps can find out your physical location; a good privacy practice is to try to restrict which apps can see this information, and at a minimum to make sure that your location is only shared with apps that you trust and that have a good reason to know where you are.

In each case, location tracking is not only about finding where someone is right now, like in an exciting movie chase scene where agents are pursuing someone through the streets. It can also be about answering questions about people's historical activities and also about their beliefs, participation in events, and personal relationships. For example, location tracking could be used to try to find out whether certain people are in a romantic relationship, to find out who attended a particular meeting or who was at a particular protest, or to try and identify a journalist's confidential source.

A tool called CO-TRAVELER uses this data to find relationships between different people's movements to figure out which people's devices seem to be traveling together, as well as whether one person appears to be following another.