Ever get the Netflix proxy error and wonder, "how do websites even know I'm using a VPN?" Well, wonder no further. Here are five different ways websites can detect your VPN usage. Naturally, we've also included some reliable ways to counteract these detection methods and hide the fact that you're using a VPN.
#1 The VPN Server's IP Address Is Blacklisted
VPNs hide your true IP address and replace it with a different one based on the server you connect. Of course, these VPN IP addresses are publicly available. As such, they can easily be collected by companies like MaxMind and other VPN detection services and sold off to websites for blacklisting purposes.
Oftentimes, IPs that are owned by the same host or datacenter are also blocked. Yes, even if they weren't previously associated with any VPNs in a detection service's database. Just this August, Netflix mistakenly blocked the residential IP addresses of users who weren't even using a VPN. All because some VPN providers started using residential IPs to hide their presence.
Websites may also know you're using a VPN if they detect too many requests coming from the same IP address. A thousand different accounts all using the same IP will seem suspicious to any network admin.
Of course, that won't always lead to that IP address being blacklisted. How so? Well, businesses like airports, hotels, universities, and others may have a shared IP address among hundreds or even thousands of users. So blocking IPs solely based on these criteria would lead to many false positives.
What to do about it
Simply switch to a different VPN server in the region and try to access the website again. The best VPN services out there have huge server networks and regularly refresh their IP tables to get around geo-blocks.
#2 Websites Know You're Using a VPN Due to DNS Location Mismatch
VPNs often use their own Domain Name System (DNS) servers. This is so your ISP doesn't see what you do online by looking through your DNS requests, thus preserving your privacy. It also helps prevent mismatches between your IP and DNS regions in case of a VPN leak.
Assuming your VPN doesn't leak, however, DNS location mismatches can happen when you use the app version of an online service. For instance, the Netflix iOS and Android apps completely override your VPN's DNS settings, thus exposing your true location.
What to do about it
Always use the browser version of any online service to prevent the app from overriding your VPN's DNS settings. Alternatively, you can install a VPN on a compatible router to prevent such issues. This will also allow you to use a VPN connection on game consoles, smart TVs, and other devices that don't natively support VPN.
#3 They Check Your System Time Settings
Websites can easily verify your system time settings through a process called browser fingerprinting. What happens is your browser sends out various details about your device, which often includes your timezone. As such, websites may know you're using a VPN if your system time settings and your VPN server's timezone are mismatched.
While browser fingerprinting is pretty privacy-invasive overall, it's not all bad. For example, security emails often contain details about any devices that have accessed your account recently. Here's how it might be worded:
"New login detected from [IP address/ location, browser X, Operating System Y] – is this you?"
What to do about it
Always ensure that your system clock settings coincide with the timezone your VPN server is located in. For example, if you connect to a server in Montreal, you should set your system time to GMT-4 (adjusted for daylight savings). It might be worth restarting your system or using a different browser after adjusting your clock settings.
#4 Websites Can Detect VPN Use Through GPS Data
Pretty straightforward. Allowing online services to use your location data for any reason pretty much voids the location-hiding capabilities of a VPN. Of course, in some cases, websites or apps don't even ask for consent when tracking your GPS data. Alternatively, they bury the option to disable GPS tracking deep in the app's settings to dissuade users from turning it off.
Fortunately, it's pretty easy to avoid this issue. Aside from being careful about which apps you use and what websites you visit, you can also use a VPN that spoofs GPS data, like Surfshark. Otherwise, just use a different device without built-in GPS capabilities.
#5 Deep Packet Inspection (DPI)
Without getting too technical, DPI is basically putting network data under a (metaphorical) microscope and analyzing its origin, destination, content, and other valuable info.
DPI is only really used by enterprises, ISPs, and governments to detect and prevent cyberattacks, optimize servers, or analyze and control user behavior. See the Great Firewall of China or Russia's Sovereign Internet project for the most extreme examples. If you're using a VPN in an area with known Internet censorship issues, websites may simply not work.
When using DPI to analyze for VPN traffic, the company or government body typically looks for signatures specific to protocols like OpenVPN. Think of it as identifying a pattern in the encryption that distinguishes it from the everyday encryption used by websites or HTTPS. They still can't tell what your data consists of - just that you're using a VPN and possibly which protocol as well.
What to do about it
All this can be avoided by using a VPN with obfuscation technology. Follow the link to learn more about how this hides your VPN activity from websites, ISPs, and restrictive governments. We've also included several different providers that offer obfuscation in their apps, though we recommend ExpressVPN for the best results.