IP Leak Protection: How to Prevent Your Real IP From Being Exposed

Introduction

Using a VPN is one of the most straightforward ways to hide your IP address from websites, ISPs, and trackers. You connect, your traffic gets encrypted, and your real IP is replaced with one from the VPN server. But what if that protection has a hole in it?

IP leaks are a class of vulnerabilities that can expose your real IP address even while your VPN connection appears active. They happen through DNS resolution, WebRTC, IPv6, or browser misconfigurations. For anyone relying on a VPN for genuine privacy — journalists, researchers, security professionals, or just privacy-conscious users — understanding and preventing IP leaks is essential.

This guide explains the main leak types, how to test for them, and how to close the gaps.

What Is an IP Leak?

An IP leak occurs when your true IP address is exposed to a third party despite being connected to a VPN. The VPN tunnel itself is working, but traffic is bypassing it in some way — either through DNS requests, WebRTC connections, or IPv6 traffic.

The result is that websites, advertisers, or network observers can determine your real IP address, defeating the purpose of using a VPN in the first place.

Leaks are not always deliberate. They can be caused by software bugs, misconfigured apps, network routing quirks, or simply using a VPN that lacks proper leak protection built in.

The Four Main Leak Types

1. DNS Leaks

A DNS leak is the most common IP leak. When you visit a website, your device needs to resolve a domain name into an IP address. This happens via a DNS request.

If your VPN is not intercepting and routing your DNS queries through its own servers, those requests go to your ISP’s DNS servers — typically over the regular internet, outside the VPN tunnel. Your ISP can see every domain you visit, even if your web traffic itself is encrypted.

DNS leaks are especially common with older VPN protocols, split-tunneling configurations, or when the VPN app crashes and traffic falls back to the default network route.

How to test: Use a DNS leak test tool and check whether the DNS servers shown belong to your ISP or to your VPN provider.

2. WebRTC Leaks

WebRTC (Web Real-Time Communication) is a browser feature that enables direct peer-to-peer connections — used by video chat apps, screen sharing, and some real-time collaboration tools. WebRTC uses STUN/TURN protocols to discover your public IP address, including the IP assigned to your real network interface.

Even if you are behind a VPN, browsers with WebRTC enabled can discover and expose your real IP address through the ICE (Interactive Connectivity Establishment) candidate gathering process. This happens silently, without any prompt, and websites can access it via JavaScript.

WebRTC leaks affect all browsers (Chrome, Firefox, Safari, Edge) unless the feature is disabled or routed through the VPN.

How to test: Visit a WebRTC leak test page and compare the displayed IP with your VPN IP. Your real IP should not appear.

3. IPv6 Leaks

If your ISP assigns you an IPv6 address and your VPN only handles IPv4 traffic, any IPv6 request will bypass the VPN tunnel entirely. Your IPv6 address — which is directly tied to your device and identity — will be visible to websites.

This is particularly common because many VPN apps still do not block or tunnel IPv6 traffic by default. The VPN encrypts your IPv4 traffic while your IPv6 traffic sails through unencrypted, directly to the internet.

How to test: Disable IPv4 and see if your browser can still connect. If it does, your IPv6 is leaking. Alternatively, use an IPv6 leak test tool.

4. Teredo Leaks

Teredo is a tunneling protocol that allows IPv6 traffic to pass through IPv4-only networks. Windows has built-in Teredo support. If Teredo is active and your VPN does not properly intercept it, IPv6 packets can escape the VPN tunnel through the Teredo interface.

Teredo leaks are less common on modern systems but still appear on Windows machines where VPN clients do not fully disable the Teredo adapter.

How to fix: Disable Teredo in Windows via a registry setting or via the VPN client’s own Teredo blocking feature.

How to Check for IP Leaks

Before fixing leaks, you need to know they exist. Here is a practical testing workflow:

Note your real IP. Disconnect from your VPN and note your public IP address from a site like WhatIsMyIP.com or your VPN provider’s IP check page.
Connect your VPN. Verify the connection is active. Note the new IP address shown.
Run a DNS leak test. Use your VPN provider’s leak test tool or a third-party service like dnsleaktest.com. The results should show DNS servers belonging to your VPN provider, not your ISP.
Run a WebRTC leak test. Visit a WebRTC test page. The detected IP should match your VPN IP, not your real IP.
Test IPv6. Check whether your browser can load sites over IPv6 while connected. If it can, your VPN is not blocking IPv6.
Check for Torrenting leaks. Some VPN apps have a kill switch that should prevent all traffic if the VPN drops. Test this by disconnecting the VPN while a download is in progress and verifying that the download stops.

How to Prevent IP Leaks

Use a VPN With Built-In Leak Protection

Not all VPN providers take leak protection seriously. Choose a provider that implements:

DNS leak protection: All DNS queries routed through the VPN’s encrypted tunnel, never to the ISP’s servers.
WebRTC leak blocking: Browser-side WebRTC disable option or VPN-level IP routing that prevents WebRTC from exposing your real IP.
IPv6 leak blocking: Complete IPv6 blocking or tunneling when the VPN is active.
Kill switch: Prevents all internet traffic if the VPN connection drops unexpectedly.

Most reputable paid VPNs include these features. Free VPN services frequently do not, and many free providers have been found to suffer from chronic DNS leaks.

Configure Your Browser

Even with a leak-protected VPN, hardening your browser adds a layer of defense.

Disable WebRTC in your browser settings or via extensions. In Firefox: set media.peerconnection.enabled to false in about:config. In Chrome: use an extension like WebRTC Leak Prevent.
Use a privacy-focused browser like Firefox with ETP (Enhanced Tracking Protection) or Brave, which have WebRTC leak mitigation enabled by default.
Disable IPv6 at the browser level if not needed.

Set Up a VPN Kill Switch

A kill switch blocks all network traffic if the VPN disconnects unexpectedly. Without one, your traffic reverts to your regular ISP connection the moment the VPN drops — and you may not notice.

Most VPN apps include a kill switch toggle. Enable it. For advanced users, you can configure a firewall-based kill switch using iptables rules on Linux or a third-party app on Windows/macOS.

Use Split Tunneling Carefully

Split tunneling lets you route some apps through the VPN while others use your regular connection. This is useful for performance or accessing local network devices. But it can also cause accidental leaks if traffic you expected to go through the VPN routes outside it instead.

Audit split-tunneling rules regularly. When in doubt, send all traffic through the VPN.

Test After Every Update

VPN apps update frequently. Sometimes an update changes network routing behavior, inadvertently enabling a leak. Run a leak test after any VPN client update to confirm everything is still working as expected.

The Difference Between a Leak and a DNS Leak Test Failure

It is worth clarifying: not every DNS leak test failure indicates a privacy compromise. Some VPN providers use shared DNS infrastructure, so the DNS server IP may not exactly match your VPN server IP but still belong to the provider.

What matters is that the DNS server does not belong to your ISP and is not traceable to you as an individual. A leak test that shows a third-party DNS server not associated with your ISP is generally fine.

On the other hand, if you see your ISP’s DNS servers in the results, your DNS is leaking — your ISP can see every domain you visit.

Signs Your VPN May Be Leaking

Watch for these signals:

Your ISP IP appears in a leak test after connecting to a VPN.
Websites showing your real location despite being connected to a VPN in a different country.
Your real IP visible in a WebRTC test on a site like BrowserLeaks.
Downloads continue after intentionally disconnecting the VPN (indicates no active kill switch).
Slow speeds on IPv6 or complete inability to reach IPv6 sites while the VPN is active — may indicate IPv6 is being blocked rather than tunneled, which is fine but worth confirming.

Conclusion

A VPN is only as good as its leak protection. DNS leaks, WebRTC leaks, IPv6 leaks, and Teredo leaks can silently undermine your privacy even when the VPN itself appears to be working. The good news is that all four are preventable with the right combination of a reputable VPN provider, proper browser configuration, and a working kill switch.

Regular leak testing takes under five minutes and gives you confidence that your IP address is genuinely hidden. Make it part of your routine — especially after updating your VPN client or changing network configurations.

For more privacy guides and IP tools, explore the ippriv.com blog.