WebRTC and DNS Leaks Explained: How to Test and Protect Your True IP

Many internet users believe that turning on a VPN provides 100% invulnerability. However, two insidious browser-level vulnerabilities—WebRTC leaks and DNS leaks—can silently broadcast your true residential IP address to third-party web trackers.

What Is a WebRTC IP Leak?

WebRTC (Web Real-Time Communication) is an open-source standard integrated into Chrome, Firefox, Edge, and Safari that facilitates direct peer-to-peer audio, video calling, and file sharing without browser plugins.

To establish peer-to-peer connections through firewalls, WebRTC uses STUN (Session Traversal Utilities for NAT) requests. JavaScript executing on any web page can silently query your browser's WebRTC API, forcing it to reveal both your internal private LAN IP and your raw public WAN interface—completely bypassing the encrypted VPN tunnel!

What Is a DNS Leak?

When you visit a website (e.g. example.com), your computer must resolve that domain name into an IP address. If your VPN software does not properly enforce secure encrypted DNS queries, your operating system will default back to your ISP's local DNS servers, giving your ISP a complete unencrypted log of every domain you browse.