This Anti-Tracking Tool Checks If You’re Being Followed

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In recent years there’s been an explosion in the number of ways people can be tracked by domestic abusers, stalkers, or those in the murky world of government-backed espionage. Tracking can either be software- or hardware-based. Stalkerware and spyware that can be installed directly on people’s phones can give attackers access to all your location data, messages, photos, videos, and more, while physical trackers—such as Apple’s AirTags—have been used to track where people are in real time. (In response to criticism, Apple has added some anti-tracking tools to AirTags.)

A quick search online reveals plenty of tracking tools, which are easy to buy. “There’s so much out there to spy on people, and so little to help people who are wondering whether they’re being spied on,” Edmondson says.

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The homemade system works by scanning for wireless devices around it and then checking its logs to see whether they also were present within the past 20 minutes. It was designed to be used while people are on the move rather than sitting in, say, a coffee shop, where it would pick up too many false readings.

The anti-tracking tool, which can sit inside a shoebox-sized case, is made up of a few components. A Raspberry Pi 3 runs its software, a Wi-Fi card looks for nearby devices, a small waterproof case protects it, and a portable charger powers the system. A touchscreen shows the alerts the device produces. Each alert may be a sign that you are being tailed.

The device runs Kismet, which is a wireless network detector, and is able to detect smartphones and tablets around it that are looking for Wi-Fi or Bluetooth connections. The phones we use are constantly looking for

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wireless networks around them, including networks they’ve connected to before as well as new networks.

Edmondson says Kismet makes a record of the first time it sees a device and then the most recent time it was detected. But to make the anti-tracking system work, he had to write code in Python to create lists of what Kismet detects over time. There are lists for devices spotted in the past five to 10 minutes, 10 to 15 minutes, and 15 to 20 minutes. If a device appears twice, an alert flashes up on the screen. The system can show a phone’s MAC address, although this is not much use if it’s been randomized. It can also record the names of Wi-Fi networks that devices around it are looking for—a phone that’s trying to connect to a Wi-Fi network called Langley may give some clues about its owner. “If you have a device on you, I should see it,” he says. In an example, he showed WIRED that a device was looking for a network called SAMSUNGSMART.

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