WebRTC IP Leaks: Why Your VPN Might Not Be Protecting You

What is WebRTC and Why Does It Leak Your IP?

WebRTC (Web Real-Time Communication) is a powerful technology built into your browser. It's what makes video calls, voice chat, and peer-to-peer file sharing work directly in your browser without plugins. Google Hangouts, Discord web, Zoom's browser client - they all use WebRTC.

Here's the problem: for two computers to connect directly (peer-to-peer), they need to know each other's IP addresses. WebRTC was designed to find this information automatically, and it does this REALLY well. Too well, actually.

The technology queries something called STUN servers (Session Traversal Utilities for NAT) to discover all your IP addresses - including your real one, your local network IP, and any VPN IPs. And here's the kicker: any website with JavaScript can access this information.

How WebRTC Leaks Work: Technical Deep Dive

Let me break down exactly what happens when a website exploits WebRTC to find your real IP:

Step 1: Create a Peer Connection

A website creates a WebRTC peer connection object. This is legitimate browser API that's supposed to enable video calls, but it can be used for tracking:

// This is all it takes to start discovering your IPs
const pc = new RTCPeerConnection({
  iceServers: [
    { urls: 'stun:stun.l.google.com:19302' },
    { urls: 'stun:stun1.l.google.com:19302' }
  ]
});

Step 2: Request ICE Candidates

The browser automatically starts gathering ICE candidates - essentially, all the different ways another computer could connect to you:

// Create a fake data channel to trigger ICE gathering
pc.createDataChannel('');

// Create an offer to force candidate gathering
pc.createOffer().then(offer => pc.setLocalDescription(offer));

// Listen for candidates (your IP addresses)
pc.onicecandidate = (event) => {
  if (event.candidate) {
    // This contains your IP address!
    console.log(event.candidate.candidate);
  }
};

Step 3: Extract IP Addresses

The ICE candidates contain IP addresses in a specific format. The website parses these to extract all your IPs:

// Example ICE candidate string:
// "candidate:842163049 1 udp 1677729535 192.168.1.105 54321 typ srflx raddr 0.0.0.0 rport 0 generation 0"
//                                       ^^^^^^^^^^^^^^
//                                       Your real local IP!

// "candidate:842163049 1 udp 1677729535 98.76.54.32 54321 typ srflx raddr 0.0.0.0 rport 0 generation 0"
//                                       ^^^^^^^^^^^
//                                       Your real PUBLIC IP (bypassed VPN!)

What Gets Exposed

Why VPNs Don't Always Protect You

This is the part that makes most people angry when they learn about it. You're paying for a VPN. You see that green "Connected" icon. But WebRTC can still expose your real IP. Here's why:

The VPN Tunnel Problem

VPNs work by routing your internet traffic through an encrypted tunnel. But WebRTC uses STUN servers to discover your IP OUTSIDE of the browser's normal network stack. It's essentially asking your network interface directly: "Hey, what's my IP?"

UDP vs TCP

WebRTC prefers UDP connections (faster for real-time communication). Some VPNs only tunnel TCP traffic, leaving UDP requests to go through your real connection.

IPv6 Leaks

Many VPNs only handle IPv4 traffic. If your ISP provides IPv6, WebRTC can discover and expose your IPv6 address - which is often more identifying than IPv4 since it's frequently static and unique to your connection.

VPNs That DO Protect Against WebRTC

Not all VPNs are equal. Here's which ones handle WebRTC properly:

• ✓ExpressVPN - Built-in WebRTC leak protection
• ✓NordVPN - Browser extensions block WebRTC
• ✓Mullvad - Disables WebRTC by default in their browser
• ~Most others - Require manual browser configuration

How to Test for WebRTC Leaks

Testing is simple. Here's exactly what to do:

Step 1: Note Your Real IP

Before connecting to your VPN, note your real IP address. You can find it at any "what is my ip" site.

Step 2: Connect to VPN

Connect to your VPN and verify it's working. Your IP should now show the VPN server's IP.

Step 3: Run a WebRTC Test

Use a WebRTC leak test tool (like ours!) to check if your real IP is exposed:

What to Look For

• ❌LEAK: Your real public IP appears alongside VPN IP
• ⚠️PARTIAL: Local IP visible (192.168.x.x) - less critical but still trackable
• ✓SAFE: Only VPN IP shown, or WebRTC disabled

How to Prevent WebRTC Leaks

Here are your options, from easiest to most thorough:

Option 1: Browser Extensions

The quickest fix is a browser extension that blocks WebRTC:

• •WebRTC Leak Prevent (Chrome) - Simple toggle to disable WebRTC
• •uBlock Origin (All browsers) - Has WebRTC blocking option in settings
• •VPN browser extensions - Most include WebRTC protection

Option 2: Browser Settings

Each browser has different ways to disable WebRTC natively. See the browser-specific guide below for details.

Option 3: Use WebRTC-Safe Browsers

Some browsers handle WebRTC more safely by default:

• •Tor Browser - WebRTC completely disabled
• •Brave - Has WebRTC leak protection built-in (Settings → Privacy)
• •Mullvad Browser - Privacy-focused Firefox fork, WebRTC disabled

Option 4: Anti-Detect Browsers

For maximum protection, anti-detect browsers let you control WebRTC per profile:

• •Completely disable WebRTC
• •Spoof WebRTC IP to match VPN location
• •Enable WebRTC for specific sites that need it (like video calls)

Browser-by-Browser Protection Guide

Google Chrome

Chrome doesn't let you fully disable WebRTC through settings. You need an extension:

1. 1.Install "WebRTC Leak Prevent" from Chrome Web Store
2. 2.Set to "Disable non-proxied UDP"
3. 3.Test with our WebRTC tool to verify

Firefox

Firefox lets you disable WebRTC completely through about:config:

1. 1.Type about:config in address bar
2. 2.Search for media.peerconnection.enabled
3. 3.Set to false

Note: This will break video calling in the browser.

Safari

Safari has limited WebRTC support and is less vulnerable by default. To disable:

1. 1.Safari → Preferences → Advanced
2. 2.Enable "Show Develop menu"
3. 3.Develop → Experimental Features → Disable "WebRTC mDNS ICE candidates"

Microsoft Edge

Edge (Chromium-based) requires an extension similar to Chrome, or you can use the flags:

1. 1.Go to edge://flags
2. 2.Search "WebRTC"
3. 3.Disable "Anonymize local IPs exposed by WebRTC"

Brave Browser

Brave has built-in protection - just make sure it's enabled:

1. 1.Settings → Privacy and Security
2. 2.Find "WebRTC IP Handling Policy"
3. 3.Set to "Disable non-proxied UDP"

WebRTC Leak Statistics