How to Geek: “As governments and companies around the world seem to be on a bit of an internet censorship binge, many people are turning to VPNs (Virtual Private Networks) to get around these restrictions—only to be caught out! So how, if VPNs are supposed to hide your identity and location, do these systems seem to know you’re using one? It turns out that the way VPNs operate may not be all that clandestine. While VPNs are generally good at obscuring your identity and location, they aren’t good at hiding the fact that you’re using a VPN in the first place. Wait, doesn’t a VPN hide your IP address? Well, yes it does, but the VPN server you’re using still has an IP address of its own. You can’t access the internet without an IP address, and while your real IP address is obscured from the web when you work through a VPN, the VPN’s own IP can tell a server a lot. For one thing, VPNs tend to use shared pools of IP addresses. The server that’s forwarding your traffic to the net is being used by multiple people at the same time. Which means that a long list of people are accessing the web using the same IP address, which is suspicious. Over time, web servers and security companies that sell server security services build up lists of known VPN IP addresses. Which is to say, that if you access a site from one of these banned IPs, you’ll get a “VPN detected” message. Of course, the VPN companies don’t use the same IP addresses forever, and innocent people get caught up in this trap when their dynamic IPs happen to cycle into an old banned one…”