What Is a VPN Leak?
A VPN ‘leak’ occurs when personal information is exposed that could be traced back to your true identity. This typically refers to your IP address, DNS information, or geographic location.
VPN leaks allow your ISP, government, and any other third party monitoring your connection to determine your identity and activity. For this reason, a leaking VPN is fundamentally useless.
You undoubtedly want to keep this information private, so VPN providers market themselves accordingly. The truth is, however, that most VPN connection protocols were not actually designed with privacy in mind.
By default, most protocols send DNS requests to default servers. They leak IPv4 traffic when forced to reconnect, and they are usually completely oblivious to IPv6 traffic. Only the VPNs specifically developed to offset these problems will offer you protection.
Here is a summary of the four main types of VPN leak:
- IP Address leaks: IP leaks occur when your VPN fails to mask your personal IP address with one of its own. This is a significant privacy risk as your ISP and any websites you visit will be able to link your activity to your identity.
- DNS leaks: A VPN is supposed to route your DNS requests to its own DNS servers. If your VPN routes these requests to your ISP’s DNS servers instead, it’s called a DNS leak. This exposes your browsing activity and any websites you visit to any other eavesdroppers.
- WebRTC leaks: WebRTC is a browser-based technology that allows audio and video communications to work inside web pages. WebRTC has clever ways of discovering your true IP address even if a VPN is on. The best VPNs block WebRTC requests. Alternatively, you can disable WebRTC completely at the browser level.
- IPv6 leaks: IPv6 is a new form of IP address that is not currently supported by most VPNs. Unless a VPN supports or actively blocks IPv6, your personal IPv6 address can be exposed if you’re on an IPv6-enabled network.
To find out if your VPN is working as it should, you can conduct a basic manual test for IP leaks using our IP checker tool, or another IP testing website like browserleaks.com. Simply check your IP address before and after connecting to a VPN server – if your IP doesn’t change, your VPN isn’t working.
There are also more advanced VPN leak tests you can run at home. While these tests will help you take a closer look at your VPN traffic, they will require significantly more technical knowledge.
You can use a testing suite to collect and inspect your VPN traffic. Building a testing suite can be quite complex and will depend on the operating system you’re using. You can find free, open-source testing tools online on websites like GitHub.
ExpressVPN also has an advanced testing suite used to check its apps for leaks. You can find this testing suite available for free here, as well as this helpful quick-start guide.
ExpressVPN’s open-source VPN leak testing tools.
If you’re seriously concerned about your online privacy and security, it’s wise to run some advanced tests with your VPN rather than relying solely on basic tests to detect any problems.
If you don’t feel technically confident enough to follow advanced instructions, it’s sensible to choose a VPN provider that has been independently reviewed and verified by a trusted third party.
If your VPN has tested positive for leaks and you’d like to fix or prevent them, it might be time to choose a new VPN provider.