How to detect a VPN
5 min read
If you suddenly hit a wall and can’t access a website while browsing the web, your VPN might be the reason. Some sites, ISPs, and networks block VPN users to prevent fraud, protect copyrighted content, and enforce geo-restrictions. Want to know how they spot VPN users? Keep reading.
Table of Contents
Table of Contents
What is VPN detection?
VPN detection is the process that websites, online services, and internet service providers (ISPs) use to identify when you are connecting through a virtual private network (VPN). Even though VPNs encrypt your online activity to give you more privacy, tricks like traffic analysis can still expose that you’re using a VPN.
Why do websites use VPN detectors and block VPNs?
Some businesses and websites track IP addresses simply to see when users return, while others, like streaming platforms, use IP tracking to enforce location-based restrictions. VPNs help you get around these restrictions by giving you an IP address from another region. But since websites know people use VPNs to bypass these geo-blocks (and sometimes for fraud), they’ve developed ways to detect and block them.
Stop fraud
When people use VPNs, it’s hard for websites to tell where the user is really from, which might raise the stakes for fraud. So, to keep the online environment safe, websites block VPNs to prevent people from creating multiple accounts, fake profiles, and using false identities.
VPNs are great – they conceal your IP address and online activity, keeping your online browsing safe. However, they create a security layer that websites cannot fully control or monitor, which is very convenient for bad actors. With a VPN shielding their online activity, criminals can take over accounts, commit credit card fraud, and carry out cyberattacks.
Services that use VPN detection to stop fraud include e-commerce websites, online gaming platforms, cryptocurrency exchanges, and financial institutions. Banks are especially cautious about VPN use. If someone logs into their bank account through a VPN server, it might seem like they’re logging in from a new or unusual location, which could signal fraud or hacking. This triggers security alerts and blocks access to the online banking platform.
Enforce location restrictions
Some online services, like streaming services, only let in users from specific locations. They typically do it for legal reasons. For example, some movies are only licensed in certain countries or are appropriate for viewers from a certain age. So, websites block VPNs to stop people from bypassing these local restrictions.
Comply with government censorship
In some countries, governments strictly control what citizens can access online and block websites that go against their agenda. North Korea and China are the most extreme examples in terms of online surveillance. While China bans VPNs, social media, and streaming services, North Korea has an allowlist of only a few websites that its citizens can access.
Governments obligate ISPs and online businesses to block VPN traffic to enforce these regulations. This way, governments can better control people’s online activity and restrict them from content that conflicts with the official religion and leaks information about government activities or secrets.
Protect copyright
Websites also try to protect copyrighted content by blocking VPNs. Since the late 1990s, media and entertainment companies have worked hard to stop music, movies, TV shows, e-books, software, and games piracy. And it’s understandable. Every time someone pirates their content, businesses and authors lose money.
On top of that, there are people who use VPNs to get around regional restrictions on streaming services. These platforms have different deals for various regions, so what’s available in one country might not be in another. When someone uses a VPN to sneak into the content that’s unavailable in their region, it forces websites to step in. They start using VPN detection methods and block access for users trying to work around the system.
Disclaimer: Using a VPN to bypass copyright restrictions undermines content creators’ rights and can lead to legal trouble. It’s smarter to stick to what you can access legally.
How do websites detect VPNs?
Websites use IP monitoring, WebRTC leaks, and packet analysis to track where visitors are coming from and if they’re using a VPN.
- IP address monitoring. Websites often block VPNs by tracking your IP addresses. When you connect through a VPN, it routes your traffic through a server that assigns you an IP. However, VPN IP addresses are often used by dozens, if not hundreds, of people. So, if multiple users try to access a service with the same IP, it’s a dead giveaway that a VPN provider is involved. The site then blocks that IP and shuts down its access.
- Geo-location matching. Your device or browser can give away your real location to websites even when connected to a VPN. If this geo-location data doesn’t match the location your VPN is showing, it can raise suspicion for the site. The service might then compare your geo-location with your account details or previous login locations, detect that you’re using a VPN, and block your access.
- WebRTC leaks. When you connect to a VPN, it routes your traffic through a server and shields your actual IP address. However, if a website uses WebRTC, it can bypass the VPN and reveal your actual location. If the website notices a mismatch between your real IP and the one you’re using to connect – you’re caught red-handed. This alerts the website that you’re hiding behind a VPN.
- Packet analysis. When you use a VPN, it slightly changes the structure of your data packets. Some websites dig into these packets, using techniques like traffic fingerprinting and protocol or port analysis to spot the signs of a VPN. They look at the ports you’re using, your traffic structure, and the specific flow of your data. By doing this, the websites can figure out if you’re connected through a VPN.
How do ISPs and local networks detect VPNs?
ISPs and local networks also have a few tricks up their sleeve to detect if you’re using a VPN.
- Traffic analysis. ISPs can spot when you’re connected to a VPN by analyzing your traffic patterns, which stand out from regular traffic because it’s encrypted. Unlike websites that flag unusual behavior, ISPs have the tools and knowledge to monitor how your traffic flows. For example, they can see if your traffic continuously sends data to a specific server. Such patterns make it easy for ISPs to recognize VPN usage.
- Deep packet inspection (DPI). DPI is the most advanced method that ISPs and local networks use for VPN detection. This complex software uses programmed pattern recognition rules to analyze the content of data packets. It is mainly used in restrictive regime countries like Russia and China that force ISPs to use DPI to detect VPN users and prevent access to certain sites.
- Port analysis. Many VPNs use specific ports to provide a smooth connection. System administrators can monitor these ports and set up rules to filter and block incoming VPN traffic through them.
- Connection frequency. When you browse the web without a VPN, you jump between multiple servers, while with a VPN, you stay connected to one server for a long time. This steady VPN connection can alert ISPs that you might be using a VPN service, which could lead them to block your access to certain services.
How to avoid VPN detection
If you want to keep your online traffic even more private, try using obfuscated VPN servers, especially in locations with strict internet rules. These servers hide the fact that you’re using a VPN, so you can browse without anyone watching.
ISPs don’t need to see the exact websites or services you’re using to tell if you have a VPN on — the way your traffic looks gives it away. But if you connect through an obfuscated server, it scrambles those patterns, so the tools meant to block VPN traffic can’t detect it as easily. ISPs would have to check your traffic manually to determine that you’re using a VPN.