WebRTC Leak Guide

WebRTC leaks are a browser-level privacy vulnerability that can expose your real IP address even when using a VPN. Unlike IP leaks or DNS leaks that occur at the network level, WebRTC leaks happen because of how web browsers implement real-time communication features. This comprehensive guide explains what WebRTC is, how WebRTC leaks work, why they're dangerous, and how to block WebRTC in Chrome, Firefox, Safari, Edge, and other browsers.

What Is WebRTC?

WebRTC (Web Real-Time Communication) is a technology built into web browsers that enables real-time audio, video, and data communication directly between browsers without requiring plugins or third-party software.

What WebRTC Powers

WebRTC is the technology behind many modern web applications:

• Video conferencing: Google Meet, Discord web, Microsoft Teams web, Zoom web
• Voice calls: WhatsApp Web calls, Facebook Messenger video
• Screen sharing: Collaborative tools like Miro, Figma
• Peer-to-peer file transfers: Browser-based file sharing
• Live streaming: Twitch, YouTube live streams (some implementations)
• Gaming: Browser-based multiplayer games with real-time communication

How WebRTC Works

WebRTC enables direct "peer-to-peer" connections between browsers:

1. Browser A wants to connect to Browser B for a video call
2. To establish a direct connection, both browsers need to discover each other's IP addresses
3. WebRTC uses STUN (Session Traversal Utilities for NAT) servers to discover external IP addresses
4. Browsers exchange IP addresses and establish a direct connection
5. Audio/video data flows directly between browsers (not through a server)

The privacy problem: To discover your IP address for peer-to-peer connections, WebRTC makes special network requests that can bypass your VPN tunnel entirely.

What Is a WebRTC Leak?

A WebRTC leak occurs when a website uses WebRTC to discover your real IP addresses (both local and public) despite you being connected to a VPN. The website can then correlate your VPN IP with your real IP, potentially de-anonymizing you.

What WebRTC Leaks Expose

WebRTC leaks can reveal multiple IP addresses:

1. Local IP address: Your device's IP on your local network (e.g., 192.168.1.105, 10.0.0.23)
   • Reveals your local network configuration
   • Can help identify you across sessions
   • Less dangerous but still privacy-compromising
2. Public IP address: Your ISP-assigned IP (e.g., 73.158.241.92)
   • Reveals your real location (city/region)
   • Reveals your ISP
   • Can be linked to your identity
   • Completely defeats VPN purpose
3. IPv6 address: If your ISP provides IPv6
   • Often more identifying than IPv4
   • Can be unique to your device

How WebRTC Leaks Differ from IP Leaks

Aspect	IP Leak	WebRTC Leak
Where it happens	Network level (VPN tunnel failure)	Browser level (WebRTC API)
What's exposed	Your real public IP	Local IP + real public IP
VPN can prevent	Yes (if properly configured)	No (browser-level, not network-level)
Fix location	VPN settings, OS configuration	Browser settings or extensions
Prevalence	Less common (with quality VPNs)	Very common (all browsers)

Real-World Example

Scenario: You're using a VPN to hide your location and access geo-restricted content.

Without WebRTC leak:

• Website sees your VPN IP: 185.220.101.5 (Amsterdam, Netherlands)
• Website grants access to content restricted to Netherlands
• Your real location remains hidden

With WebRTC leak:

• Website sees your VPN IP: 185.220.101.5 (Amsterdam, Netherlands)
• Website also runs WebRTC detection script
• WebRTC reveals:
  • Local IP: 192.168.1.105
  • Real public IP: 73.158.241.92 (New York, USA)
• Website knows you're actually in New York using a VPN
• Website blocks access or flags your account

Why WebRTC Leaks Are Dangerous

1. Defeats VPN Anonymity

The primary danger of WebRTC leaks is that they allow websites to correlate your VPN IP with your real IP, breaking anonymity:

• Website tracks both your VPN IP and real IP
• Even if you switch VPN servers, your real IP stays the same
• Website can link all your sessions together using your real IP
• Your VPN provides no anonymity benefit

2. Bypasses Geo-Restrictions

Streaming services and websites actively use WebRTC to detect VPN users:

• Netflix, Hulu, BBC iPlayer: Use WebRTC leak detection to identify VPN users
• If they detect your real IP is in a different country than your VPN IP, they block access
• Anti-fraud systems use WebRTC to verify your claimed location

3. Persistent Tracking Across Sessions

Your local IP address is relatively stable and can be used for tracking:

• Even if you clear cookies, your local IP remains the same
• Advertisers use WebRTC to create persistent identifiers
• Tracking works across incognito/private browsing modes

4. Corporate/Government Surveillance

If you're trying to hide your VPN usage from your employer, school, or government:

• WebRTC leaks your real IP to websites
• Websites can log and report your real IP
• Your VPN usage becomes detectable

5. Security Vulnerability

Knowing your local IP can help attackers:

• Understand your network topology
• Target you with network-specific attacks
• Correlate you across different networks

How WebRTC Leaks Happen

1. STUN Server Requests

STUN (Session Traversal Utilities for NAT) servers are the primary cause of WebRTC leaks:

1. A website loads WebRTC code (JavaScript)
2. The browser makes a request to a STUN server (e.g., stun.l.google.com:19302)
3. The STUN server's job is to tell the browser its public IP address
4. This STUN request can bypass the VPN tunnel
5. The STUN server responds with your real public IP
6. The website's JavaScript receives your real IP

2. ICE (Interactive Connectivity Establishment)

WebRTC uses ICE to gather all possible IP addresses for establishing connections:

• Local IP addresses: All network interfaces on your device
• Server reflexive addresses: Your public IP discovered via STUN
• Relay addresses: TURN server addresses (if used)

All of these addresses are collected by JavaScript and can be sent to websites.

3. Malicious Website Scripts

Websites can easily detect WebRTC leaks using simple JavaScript:

// Simplified WebRTC leak detection code
const pc = new RTCPeerConnection({iceServers: [{urls: "stun:stun.l.google.com:19302"}]});
pc.createDataChannel("");
pc.createOffer().then(offer => pc.setLocalDescription(offer));
pc.onicecandidate = (ice) => {
  if (ice && ice.candidate && ice.candidate.candidate) {
    // Extract IP addresses from ICE candidates
    console.log(ice.candidate.candidate);
  }
};

This code runs silently in the background whenever you visit a website that implements it.

4. Browser Defaults Favor Connectivity Over Privacy

Browsers enable WebRTC by default because:

• WebRTC improves user experience (video calls, real-time features)
• Disabling it breaks legitimate functionality
• Most users don't understand or care about WebRTC leaks
• Browser vendors prioritize convenience over privacy

How to Detect WebRTC Leaks

Step 1: Connect to Your VPN

1. Connect to your VPN
2. Choose a server in a different country
3. Verify connection is active

Step 2: Run WebRTC Leak Test

1. Visit dovpn.com/ip-leak-test
2. Check the WebRTC section
3. Review all IP addresses detected

Step 3: Interpret Results

✅ No WebRTC leak (Protected):

• Only your VPN IP is shown
• Or "WebRTC blocked" message appears
• No local IP addresses visible
• No real public IP visible

❌ WebRTC leak detected:

• Local IP addresses shown (192.168.x.x, 10.x.x.x, 172.16.x.x)
• Real public IP shown (different from VPN IP)
• IPv6 address shown (if your ISP provides it)

Blocking WebRTC in Chrome

Google Chrome doesn't allow you to completely disable WebRTC through settings, but you can use extensions:

Method 1: WebRTC Leak Prevent Extension (Recommended)

1. Open Chrome Web Store - WebRTC Leak Prevent
2. Click "Add to Chrome"
3. Click "Add extension"
4. The extension icon appears in your toolbar
5. Click the icon → Settings
6. Choose "Disable non-proxied UDP" (recommended for VPN users)
7. Restart Chrome
8. Test for WebRTC leaks

Method 2: uBlock Origin (Advanced)

uBlock Origin (content blocker) also blocks WebRTC:

1. Install uBlock Origin
2. Click uBlock Origin icon → Settings
3. Go to "Privacy" tab
4. Check "Prevent WebRTC from leaking local IP addresses"
5. Close settings
6. Test for leaks

Verify Protection

1. After installing extension, restart Chrome
2. Connect to VPN
3. Visit dovpn.com/ip-leak-test
4. Verify WebRTC section shows "No leak" or "Blocked"

Blocking WebRTC in Firefox

Firefox allows you to disable WebRTC completely through built-in settings:

Method 1: Disable WebRTC Completely (Most Secure)

1. Type about:config in the address bar
2. Click "Accept the Risk and Continue"
3. In the search box, type: media.peerconnection.enabled
4. Toggle the value to false (double-click or click toggle icon)
5. Restart Firefox
6. Test for WebRTC leaks

Note: This completely disables WebRTC. Video calls and peer-to-peer features won't work.

Method 2: Hide Local IP Only (Moderate Protection)

1. Type about:config in the address bar
2. Search: media.peerconnection.ice.default_address_only
3. Toggle to true
4. Search: media.peerconnection.ice.no_host
5. Toggle to true
6. Restart Firefox
7. Test for leaks

This approach: Allows WebRTC to work but prevents local IP exposure. Public IP may still leak.

Method 3: Use uBlock Origin Extension

1. Install uBlock Origin
2. Settings → Privacy tab
3. Enable "Prevent WebRTC from leaking local IP addresses"
4. Test for leaks

Blocking WebRTC in Safari

Safari has built-in options to limit WebRTC functionality:

Method 1: Disable Legacy WebRTC API (macOS)

1. Open Safari → Settings (or Preferences)
2. Go to Advanced tab
3. Check "Show Develop menu in menu bar"
4. Close Settings
5. In the menu bar, click Develop → WebRTC
6. Select Disable Legacy WebRTC API
7. Test for leaks

Note: This may break some WebRTC applications but provides good protection.

Method 2: Remove Access to WebRTC APIs (macOS)

1. Develop menu → WebRTC → Remove Access to Legacy WebRTC APIs
2. This completely disables WebRTC in Safari
3. Restart Safari and test

iOS Safari

iOS Safari doesn't provide built-in WebRTC controls. Options:

• Use alternative browsers with WebRTC protection (Brave, Firefox Focus)
• Use VPN with built-in WebRTC blocking
• Accept limited WebRTC protection on iOS Safari

Blocking WebRTC in Edge

Microsoft Edge (Chromium-based) doesn't allow disabling WebRTC natively, but supports Chrome extensions:

Method 1: WebRTC Leak Prevent Extension

1. Open Edge Add-ons - WebRTC Leak Prevent
2. Click "Get"
3. Confirm installation
4. Click extension icon → Settings
5. Choose "Disable non-proxied UDP"
6. Restart Edge
7. Test for leaks

Method 2: uBlock Origin

1. Install uBlock Origin for Edge
2. Settings → Privacy tab
3. Enable WebRTC leak prevention
4. Test for leaks

Advanced WebRTC Protection

1. Use Browsers with Built-in Protection

Brave Browser:

• Built-in WebRTC leak protection (enabled by default)
• Settings → Privacy and security → WebRTC IP handling policy
• Choose "Disable non-proxied UDP"

Tor Browser:

• WebRTC completely disabled by default
• Maximum privacy protection

2. VPN with WebRTC Leak Protection

Some VPNs include WebRTC protection features:

• NordVPN: CyberSec feature includes WebRTC protection
• ExpressVPN: Browser extension with WebRTC blocking
• Surfshark: CleanWeb includes WebRTC protection

3. Firewall Rules (Advanced)

Block STUN server access at firewall level:

• Block outbound UDP on ports commonly used by STUN (3478, 19302)
• Block access to known STUN servers (stun.l.google.com, etc.)
• This breaks WebRTC functionality but provides complete protection

4. Regular Testing

WebRTC protection can break after:

• Browser updates (settings may reset)
• Extension updates (behavior may change)
• VPN software updates

Best practice: Test for WebRTC leaks weekly or after any software updates.

Frequently Asked Questions

What is a WebRTC leak?

A WebRTC leak occurs when your web browser exposes your real IP address through WebRTC (Web Real-Time Communication) technology, even when you're connected to a VPN. WebRTC uses special protocols (STUN/TURN) that can bypass your VPN tunnel and reveal your local and public IP addresses to websites.

How do I know if I have a WebRTC leak?

Connect to your VPN, then visit dovpn.com/ip-leak-test and check the WebRTC section. If it shows your local IP address or real public IP (instead of only your VPN's IP), you have a WebRTC leak.

Which browsers are vulnerable to WebRTC leaks?

Chrome, Edge, Firefox, and Safari all have WebRTC enabled by default and are vulnerable to leaks. Brave browser and Tor Browser have built-in WebRTC protection. You can disable or block WebRTC in most browsers through settings or extensions.

Can I disable WebRTC without breaking websites?

Disabling WebRTC may break websites that rely on it for video calls (Google Meet, Discord, Zoom web version) or peer-to-peer features. However, most websites work fine without WebRTC. You can enable it temporarily when needed or use browser extensions that allow selective blocking.

Do VPNs protect against WebRTC leaks?

Not automatically. WebRTC operates at the browser level and can bypass VPN tunnels. You need to either disable WebRTC in your browser, use a browser extension to block it, or use a VPN that includes WebRTC leak protection features.

Is it safe to disable WebRTC completely?

Yes, it's safe to disable WebRTC if you don't use browser-based video calling or peer-to-peer features. Most websites work perfectly without WebRTC. You can always re-enable it temporarily if you need to use a WebRTC-dependent service.

Can WebRTC leaks happen on mobile devices?

Yes, mobile browsers (Chrome, Firefox, Safari on iOS/Android) also support WebRTC and can leak your IP. Mobile Safari provides limited WebRTC controls. Use browsers with built-in protection (Brave, Firefox Focus) or VPNs with WebRTC blocking on mobile.

Conclusion: Protect Against WebRTC Leaks

WebRTC leaks are a browser-level privacy vulnerability that can completely undermine your VPN protection. Because WebRTC operates independently of your VPN tunnel, you must implement browser-level protections to prevent leaks.

Key takeaways:

• WebRTC leaks happen at browser level, not network level
• All major browsers (Chrome, Firefox, Safari, Edge) are vulnerable by default
• VPNs cannot automatically prevent WebRTC leaks
• Use browser extensions (WebRTC Leak Prevent, uBlock Origin) or disable WebRTC in Firefox
• Test regularly using dovpn.com/ip-leak-test
• Retest after browser updates as settings can reset

Need a VPN with WebRTC Protection?

Choose a VPN with built-in WebRTC leak protection: