How to test your VPN connection for leaks and security

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If you're not using one of the best VPNs, you may be at risk of a data leak. If a leak happens, your data will no longer be hidden by the VPN tunnel, and can be accessed by external users quite easily.

The repercussions of a VPN leak could range from absolutely nothing to your bank and social media accounts being hacked – after all, cybercriminals can easily carry out identity theft or financial fraud by stealing your sensitive information and tracking your online activities.

This is why leak tests are so important; you might not be aware that your data is even at risk. It's like cruising on the highway with no idea that your car's gas tank is leaking. If there's a glitch in your VPN provider's app, there's a high chance that the software might show that you're using a secure VPN connection when, in reality, your data will be leaking.

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Understanding VPN leaks

A VPN (Virtual Private Network) keeps you anonymous on the internet by establishing an encrypted connection between your device and the network. The best can stop snoopers, like hackers, ISPs, and even governments, from following your online activity by sending data through this secure tunnel to servers that are far away from your physical location.

Unfortunately, weak VPNs can cause a number of security issues – like exposing your IP address, browsing activity, and DNS requests to an online predator. Most VPNs have tools to help combat these threats, however, like a kill switch and built-in leak protection, which can protect your data and IP address in the unlikely scenario of your VPN connection dropping.

Let's take a look at the different types of leaks: 

IP leaks

An IP address is a unique string of numbers assigned to each device when it's connected to the internet. These addresses are linked to your searches, clicks, visits, and even your geographical location. 

One of the most popular uses of VPNs is masking your IP address, and when a VPN fails to do that – usually due to a technical flaw – it results in access to default servers instead of the anonymous VPN servers. This makes your data vulnerable to tracking and snooping, which defeats the purpose of using a VPN in the first place.

DNS leaks

In layman's terms, DNS (Domain Name System) is the internet's phonebook. When you access a website, a DNS is sent to that site, and you'll be able to see it when the request is accepted. When you use a VPN, all DNS requests are routed through your VPN to protect them from third-party access. 

Because DNS leaks imply that these requests can be accessed by anyone with the know-how, the sites you visit could be revealed. It's worth noting that DNS leaks are fundamentally a subset of IP leaks, and these, too, typically occur due to poor configuration of your VPN app.

WebRTC leaks

WebRTC, or Web Real-Time Communication, is a browser-based technology that enables audio and video sharing inside web pages. It eliminates the need for any plugins or software by connecting directly to the browser. 

Sketchy websites can use the WebRTC functionality to discover your true IP address, however, even when you're using a VPN. These leaks are known as WebRTC leaks, and they're a newer but increasingly popular leak mechanism.

Glowing neon VPN tunnel

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How to check if your VPN is leaking

Some VPN providers, like ExpressVPN and Astrill VPN, offer a leak tester on their website that'll help you figure out if your VPN is leaking. However, if you'd rather test a VPN manually, here's how you can do it yourself:

  • Step 1: Disconnect your VPN, go to Google, and search for: "What is my IP address?" Jot down the IP address displayed on the top of the page.
  • Step 2: Turn on your VPN and connect to any server.
  • Step 3: Head to Google again and search for "What is my IP address?" Make a note of the IP address displayed.
  • Step 4: If the IP address displayed in Step 3 is the same as that in Step 1, your VPN is leaking.
  • Step 5: To simultaneously perform a WebRTC test, go to Browserleaks, and if your VPN is connected, your public address will show "n/a," whereas if it's not, it'll show your real IP address.

How to fix a VPN leak

The most straightforward way to fix a leaking VPN is to replace it with a reliable and simple alternative – especially if the leaks are consistent. If you're not ready to ditch your current provider, however, there are a few tweaks you can try to solve the situation.

Fixing IP leaks

If your VPN uses IPv4 too, I'd recommend trying the good old "disconnect and reconnect" method. If your real VPN address is still showing after this reboot, it's time to put your foot down and break up with your VPN in favor of a top-notch service like NordVPN.

With the newer IPv6 protocol becoming the norm now, it's important to check whether your service provider offers IPv6 protection – and both ExpressVPN and NordVPN do. If it doesn't, all your IPv6 traffic will go through an unsecured and unencrypted route. 

To prevent IPv6 leaks, you can go to Settings and disable IPv6 on your operating system. Once you have, your device will start using the VPN-supported IPv4, and your privacy will remain intact. 

Fixing DNS leaks

A leaking DNS can divulge your entire browsing history, so it's important that you make sure your VPN provider has built-in DNS leak protection. Look out for companies that provide custom and private DNS and ensure that you use them at all times. 

If your VPN doesn’t automatically connect to a private DNS server, you'll need to go to DNS settings and manually connect to a third-party DNS server, preferably Google Public DNS or OpenDNS. 

Fixing WebRTC leaks

Since WebRTC leaks are typically a browser issue, fixing it isn't as simple as just switching to a different VPN. If you detect a WebRTC leak, one way to get around the issue is to disable WebRTC in your browser settings. 

If you can't find the 'Disable WebRTC' feature in your desktop application, have a look in the VPN's web extension - it's usually hidden there.

Close-up of a hand touching an illuminated digital screen displaying a padlock

(Image credit: Oscar Wong via Getty Images)

Bottom line

We put a lot of trust in VPNs to keep our browsing habits and sensitive information private – and our digital security ultimately depends on which provider we pick. A functioning VPN will fully encrypt your information, mask your location, and allow you to enjoy awesome speed and performance. 

Selecting a tried and tested VPN reduces your chances of falling foul to a cyber hazard, like leaks, although it's never zero. So, it's vital to run period checks on your VPN to ensure that it's working the way it should – and that your data isn't falling into the wrong hands.

Krishi Chowdhary

Krishi is a VPN writer covering buying guides, how-to's, and other cybersecurity content here at Tom's Guide. His expertise lies in reviewing products and software, from VPNs, online browsers, and antivirus solutions to smartphones and laptops. As a tech fanatic, Krishi also loves writing about the latest happenings in the world of cybersecurity, AI, and software.