PSA: "Free Public Wi-Fi" is NOT a Free Wireless Internet Hotspot

Public Service Announcement

I often get asked why our hotspots aren’t providing internet access, only to learn that someone is trying to connect to the network named “Free Public Wi-Fi”. When I explain that the network named “Free Public Wi-Fi” is not only never going to provide free internet, but is also a Microsoft Windows “virus” (in a loose sense), they are astonished.

But its true! As a result of the way Microsoft Windows XP “Preferred Network Lists” function, Windows will try to connect to each of the preferred networks in the order they appear in the Wi-Fi card’s Network Properties panel. Usually, people have a few preferred networks, and when they are at home or at work, one of them is available and Windows will connect to that Wi-Fi network.

However, in a public space, most likely there will be no network named after one of the preferred networks. As Windows tries to connect to each network name (or SSID) in turn, it eventually gets to one called “Free Public Wi-Fi”, which is likely in the list from a user’s prior attempt to get free Wi-Fi (that’s the viral part). When Windows tries the network named “Free Public Wi-Fi”, since its an “ad-hoc” network, it will start broadcasting over Wi-Fi for other computers that are also looking to join the “Free Public Wi-Fi” network.

At some point, as its broadcasting for “Free Public Wi-Fi”, someone at another computer thinks “Oh, what good luck! Someone is offering free Wi-Fi for the public,” and that person then connects to the Free Public Wi-Fi ad-hoc network, and then their computer becomes a “carrier” for the Free Public Wi-Fi virus.

Its quite unfortunate that Microsoft’s attempt to be helpful in reconnecting to a known Wi-Fi network has caused this terrible virus to propogate. While most of the time, accidentally connecting to this rogue network won’t cause your Windows computer any harm, it is possible to catch a computer virus from the computer broadcasting the rogue network. To make sure your laptop isn’t in harm’s way, make sure you have the latest Windows updates, have your firewall enabled and properly configured, and have up-to-date virus protection. And most important: check your Wi-Fi card’s Preferred Network List to make sure that the Free Public Wi-Fi network isn’t listed. If it is, be sure to delete it from the list!

And of course, if you have a Mac, since your computer won’t attempt to reconnect to the network in the same way as a Windows laptop, nor will it propogate the Free Public Wi-Fi (nor is it susceptible to Windows viruses, for that matter), you are most likely safe.