The Digital Tripwire: How a Home Network Can Warn of a Stalker's Presence

Yesterday, we received an alert at 2:13 PM that a known iPhone had connected to one of our client's home Wi-Fi networks. Normally, this wouldn't be unusual. However, in this case, the phone belonged to our client's ex-partner, who has been harassing her.

We immediately contacted our client to let her know that her ex-partner was likely nearby, as his phone had automatically connected to her network. Just two minutes later, we saw his phone disconnect, and we were able to inform her that he had probably left the immediate area.

So, how did we know it was him? Once the harassment began, we set up a bespoke system for her. First, we created a new Wi-Fi network at her home, giving it the exact same name and password that the stalker's phone would have remembered from before. Then, we changed the name and password of her original Wi-Fi network to make it much more secure. We also moved all her devices to this new, secure network.

This gave us two networks:

The Secure Network: This is her new main network, with a new name (e.g. changed from "WIFIOne" to "WIFITwo"), a new password, and all her devices connected to it. It's also hidden.

The "Bait" Network: This network has the original name and password ("WIFIOne"). It' allows the stalker's devices to connect automatically, and we actively monitor it from a distance.

Because the stalker's phone (and even his car, if he parked nearby) are configured to automatically connect to known historic networks (i.e. WIFIOne), it would connect to our "bait" network as soon as it came within range. Our monitoring device then immediately alerted us to this connection in real-time.

This system provides a valuable early warning for victims of stalking, essentially using the stalker's own technology (phone, car, smartwatch) against them.

Currently, we use this for known stalkers. If a stalker is unknown but has previously had access to the network (e.g. neighbour, friend of a friend, or hacker), this system would still generate an alert, helping to build a profile for further investigation. This is similar to alerting systems used in large businesses, but specifically tailored to those concerned with known threats at home.

While this is excellent for monitoring known stalkers, we can go even further by adding more wireless access points to the property. This allows us to detect the stalker even earlier, giving the victim crucial extra time. The network monitoring also makes it easier to spot any hidden cameras or other surveillance devices that might be added to the network and, if necessary, disable them remotely.

Although this solution was originally designed for stalking victims, it's also perfect for anyone who values their privacy or is in the public eye and concerned about technically skilled individuals or groups that may access their networks. Small businesses can also use a similar system to monitor for ex-employees attempting to connect to their old company network (even with someone else's login details) or to ensure that second homes are not being accessed by unauthorised individuals. Finally, senior executives wishing to have independent monitoring at home, can choose either a single analysis of their network, making sure there are no unexpected devices, or a longer term monitoring option.

When should this not be used? If you are moving to a new property specifically because of active harassment, it's vital to change your router and never use the same Wi-Fi network name you used before. There are services that allow people to search for Wi-Fi network names geographically, which could inadvertently reveal your new location. In such a situation, we would only recommend adding network monitoring to your new network, and not installing a second network (other than a genuine guest one).

For many years, we've aimed to turn a stalker's own technology against them, not just for identification, but also to gather intelligence and determine their routines. These initial steps in counter-surveillance can be incredibly empowering, giving control back to those experiencing harassment. Our final stages of testing should complete soon, and we will make the service available to a small number clients in the coming months.