How easy is it to detect if a VPN is being used?

You may have been unable to access one or more websites through your VPN and wondered if it’s because the service is aware you are using a VPN. This is quite possible. Many website operators can now easily detect (and block) VPN users, however, the best VPN providers are still a step ahead and have developed tools that make their usage harder to detect. Some will even work in places like China and Russia, both of which are notoriously difficult.

By routing encrypted data to servers throughout the world, VPN software hides your true location from websites. Your internet protocol (IP) address appears to be the address of your VPN provider’s server instead of the address for your home or remote location. 

Many businesses that operate websites have legitimate business and legal reasons to know where their traffic originates. They do not want their content stolen or their bandwidth monopolized by freeloaders, and they want to be in compliance with countries that don’t allow their citizens to access their websites. As a result, hardware manufacturers and software developers have created products that detect VPN usage and block site access from VPN users. These products are becoming widely adopted. The software they use may have some false positives, but they are willing to take that risk to protect the integrity of their sites.

In response to the success of VPN-blocking software, other businesses have produced products that overcome VPN blockers. Some VPNs are also developing strategies to prevent VPN detection. Thus, we are in the midst of a technological espionage-style battle that threatens the survival of the burgeoning VPN industry.

If you use a VPN, you may encounter an increasing number of sites you can no longer access. If your VPN is successful at implementing strategies to prevent blocking, your access may return. You may decide to switch VPNs in search of one that will give you more access. 

The winner of the detection/anti-detection battle is unpredictable. In the short run, some VPN users may experience intermittent access to some websites as one party’s technology (possibly temporarily) trumps the other party’s technology. Every VPN business needs to be responsive to its customers’ desires and reasons for using its service. You can expect VPN operators to invest in whatever technology they need to remain in business but have realistic expectations about how quickly your VPN provider can respond to blocks. 

How website operators can detect VPNs

Web hosts and third parties, including Google, offer website operators free analytic data, including the locations of site visitors. That information can be useful in many ways, even for small businesses. For example, a residential roofing contractor in a suburb of Toronto might want to analyze its website traffic to measure the effectiveness of its local advertising. If the site has visitors from Germany and New Zealand, the data becomes meaningless. If a high percentage of traffic comes from far-flung places, the business owner can deduce that most of those visitors are using VPNs.

Blacklisting known VPN IP addresses

Every device with an internet connection has an IP address. That means if your VPN has three servers in Cleveland, Ohio, and four in Nice, France, all seven have unique IP addresses. Because VPNs have lots of customers, a high volume of data flows through their servers. A home IP address will generate much less data. Even a public library or a business with free public wi-fi will generate less data than a VPN server will. Thus, if a business whose customers are mostly or entirely individual consumers, such as a streaming service, sees an extraordinary amount of data coming from a certain IP address, it can assume that the IP address belongs to a VPN. It can then use software to blacklist that IP address. 

Website operators can also tell how many times and how much a given IP address is visiting. If 39 streaming service users are simultaneously using the same IP address, that would be a red flag that indicates a VPN is the source of that traffic. Locations such as sports arenas, hotels, and shopping malls might produce false positives.

If all the data coming from a specific IP address is encrypted, that is another clue that the address belongs to a VPN. Because each detection method can produce false positives, detection software is likely to use several of these methods before blacklisting an IP address.

DNS leaks

The Domain Name System associates numeric IP addresses with more human-readable domain names like “comparitech.com”. DNS requests are, by default, sent to your ISP, which allows it to monitor your website visits. 

Many VPNs use their own Domain Name System (DNS) servers and have built-in protection to prevent requests from being sent outside of the encrypted VPN tunnel. Other VPNs leak DNS requests, something we always check for in our reviews.

Without a VPN, you are using the DNS servers assigned by your ISP or possibly a third party, such as Cloudflare. Some mobile apps can override your VPN’s DNS settings and therefore know where you really are. 

Port blocking

Another tool VPN detectors use is port blocking. If you’ve used any type of file-sharing software (e.g., torrenting programs, Usenet programs, Soulseek, etc.), you’ve set up the programs and your firewall and/or router to allow traffic through specific ports. Many VPNs use specific ports. System administrators can monitor those ports and establish rules for their network security systems that filter or block traffic coming through them.

Browser fingerprinting

Websites use cookies and fingerprinting to identify users for the protection of the user. Fingerprinting in cybersecurity is data collected to identify a specific user. That can include the user’s type of device (phone, computer, tablet), operating system, browser, domain name, time zone, and other data. Financial institutions, for example, use fingerprinting to prevent someone from stealing your username and password and getting unauthorized access to your accounts. If the crooks use different hardware and software to connect to the institution, they will have to answer your security questions, respond to a text message sent to your phone number, or enter a code sent to your email address.

Fingerprinting can also be used for nefarious purposes and, as you’ve probably guessed, to detect VPN users. Detection tools can identify users whose device time does not match the time where the VPN server is located.

Account tracking

Some websites and apps allow you to access them from anywhere; some do not. If you sign into an account of any type (bank, utility, streaming service, social media) and you do so from Mexico, Japan, and England in consecutive days, the website operator will know that you are almost certainly connecting through a VPN.

This is a bit of a side topic, but you can defeat much of the purpose of using a VPN by volunteering to be tracked. If you sign into an account provided by a company or organization that engages in user-tracking, it may still be able to follow your digital footsteps. If you sign into Gmail or any other Google service or sign into Facebook, you can expect Google or Facebook to continue to know more about you than your mother or any government agency does. 

If you are using a VPN, be consistent and use a secure browser instead of Google Chrome or Microsoft Edge. Try Brave, Firefox, or Vivaldi. They’re all free.

Browser geolocation

Another issue with web browsers is that they may be set to allow websites to know your location. If your browser is set for that, you may want to change it in the settings. Brave, for example, offers two options:

1. Sites can ask for your location
2. Don’t allow sites to see your location (features that need your location won’t work)

See also: the best VPNs for Brave

When you set up a new computer, you can prevent Windows from knowing your location. That will prevent you from using certain apps, but is a worthwhile privacy measure. Similar strategies apply to mobile browsers. Even if you use an Android phone, you can use a browser other than Chrome. 

Tor gives you more privacy than any other browser, but with a huge price in speed. The combination of a VPN and Tor only makes sense for people with far more time than money.

If your browser is revealing your actual location, and that is in conflict with the location of your VPN’s server, that is another way of letting website operators know that you are using a VPN. 

The strongest VPN detection tool

Deep Packet Inspection (DPI) is the strongest VPN detection tool, but it mostly only affects internet users in countries with severe censorship restrictions or that ban VPNs. DPI provides more data than fingerprinting does by using programmed rules to examine the contents of data packets. Like other security software, DPI uses pattern recognition as a detection tool.

DPI is used by governments, big businesses, and ISPs to prevent cyberattacks. Countries with harsh internet policies, like China, use DPI to block specific websites, VPNs that would allow citizens to bypass that blockage, and any purveyors of content that is critical of the government. 

Since VPNs harm the income of certain businesses, you can expect more of those businesses to adopt DPI as a detection and blocking tool.

Why websites use VPN detectors

Businesses that sell or stream music, movies, videos, and other copyrighted material have legal restrictions on where they can sell or stream media. Sometimes those restrictions are required by copyright holders, and sometimes they are required by governments. 

Qobuz, a French company, has been legally selling high-resolution music files for years and more recently added a streaming service. Its offerings were excluded from many countries, including the United States, until Qobuz completed legal agreements to make a distribution to those countries possible. In 2017, Qobuz services became available in Germany, Italy, and Spain. With a VPN and the willingness to make repeated attempts, citizens of blocked countries could access Qobuz services. No legitimate business wants to get into trouble with the companies that supply its products or with foreign governments. Therefore, Qobuz is a perfect example of the type of company that needs to block VPN traffic. 

The main reasons why many website operators block VPNs are:

1. Government censorship. Repressive governments and religious dictatorships do not allow their citizens to access a variety of popular websites. North Korea and China are the most extreme. North Korea has a small whitelist of allowed websites, while China bans VPNs along with social media and streaming services.Countries often ban political dissent, violent and pornographic content, content that is in conflict with the official religion, leaks of information about government activities or government secrets, and file-sharing websites. ISPs and private-sector businesses in those countries are required to comply with government mandates. They need to block VPN traffic.Website operators in the freer world might want to be a safe haven for people in internet-restricted countries, but they also want to avoid potentially expensive legal battles with foreign governments. This gives them a compelling reason to block traffic.
2. Copyright restrictions on streaming media services. One of the most popular reasons for using a VPN is to access streaming media sites from countries where the service is not legally allowed to operate. Specific content is often restricted to citizens of specific countries. The BBC’s iPlayer, Hulu, and Netflix are among the streaming media services with geographic limitations due to copyright.
3. Copyright protection. Since the late 1990s, large media and entertainment companies have fought to prevent piracy of music, movies, television programs, e-books, software, and games. These companies believe that they and the content creators lose money every time their media or content is pirated. That is based on the unproven premise that the pirates would buy the same material if they couldn’t get it free. Many certainly would, as was proven when Amazon and Apple started selling downloadable media.The music and movie industries, in particular, have pressured governments and ISPs to help them protect their copyrighted material. Many ISPs now warn their customers that their service will be terminated if they continue to download popular copyrighted material through torrents.The people who are most likely to illegally download copyrighted material are students and others who have free time and little money. Private schools, colleges, and universities do not want to be sued for facilitating illegal file sharing, so they have a reason to prevent students from using VPNs for that purpose.
4. Compliance with their country’s gambling laws. Casino and sports betting websites are highly regulated by federal and local governments. These companies want your business, but not if it’s going to cost them theirs. If they aren’t allowed to take wagers from people in other countries (or possibly other U.S. states, in some cases), they are compelled to block VPN users.
5. Protection of business objectives. Many businesses have sales restrictions imposed on them by their vendors. That includes minimum advertised prices, fixed prices, and geographic sales limitations.Certain e-commerce websites have different prices for different regions. Others want to prevent spam in comments sections or forums. Businesses of various types in various industries have other reasons for needing to know where people who access their websites really are.Businesses that are concerned about credit card and e-commerce fraud need to know where their customers are. When people have their credit cards stolen, businesses that sell products to card thieves can also become victims.Some bars have names like “The Library.” The joke is that patrons can honestly tell their spouses that they are going to the library. Your daughter may call you after school and tell you that she’s going to her friend’s home. That’s true, but she isn’t telling you that she is just stopping there before going to her boyfriend’s house, and his parents are at work. The point is that for everyone who wants to hide their location, someone else probably has a right to know where they really are.

Can you circumvent VPN detectors?

You can employ a slew of tools and strategies that may allow you to gain access to blocked sites through a VPN. These tools are called VPN obfuscations, so the easiest strategy is to choose or switch to a VPN that excels at VPN obfuscation. We particularly recommend NordVPN, and Surfshark is a good budget-friendly option.

In the battle between VPN detection and preventing VPN detection, those major VPNs are in the best position to develop new tools as needed.

How can I check if somebody else is using a VPN?

The most straightforward way of checking if somebody else is using a VPN is looking up their IP address (if you have it). There are plenty of IP address check tools that detail the IP address location. If you know someone to be based in a specific location but the IP address location is different, it’s likely they’re using a VPN.

You can also use IP address checkers to see the ISP. By looking up the ISP in question, you may be able to find out if it’s associated with a particular VPN provider. If a person’s IP address changes regularly, this suggests the use of a VPN.

While there are more sophisticated tools and software designed to detect VPN usage, they’re not really practical for the average person. There’s also some legal and ethical considerations as well.