What Is WebRTC and Why Can It Leak Your IP?
WebRTC (Web Real-Time Communication) is an open standard built into modern browsers that enables peer-to-peer audio, video, and data sharing directly between browsers - Without plugins. It powers video calls, online games, and file sharing. However, it has a well-documented side effect: it can expose your real IP address even when you're connected to a VPN. Test whether you're affected right now with our VPN leak test.
How WebRTC Causes IP Leaks
To establish a peer-to-peer connection, WebRTC uses a protocol called ICE (Interactive Connectivity Establishment) to discover all possible network paths between peers. This process, called STUN (Session Traversal Utilities for NAT), contacts public STUN servers that reflect your IP back. A malicious or curious website can trigger this process via JavaScript and read your real IP address - Including both your local network IP and your public IP - Even if you're routing all traffic through a VPN.
WebRTC Leak Types
| Leak Type | What's Exposed | Risk |
|---|---|---|
| Public IP leak | Your real public IP via STUN server query | High - Defeats VPN anonymity |
| Local IP leak | Your private LAN IP (192.168.x.x or 10.x.x.x) | Low - Not useful to most attackers |
| IPv6 leak | Your real IPv6 address if VPN doesn't tunnel IPv6 | High - Uniquely identifies you |
| mDNS obfuscation bypass | Older browsers may bypass mDNS and reveal LAN IP | Medium |
Browser Support and Default Behavior
| Browser | WebRTC Enabled by Default | How to Disable |
|---|---|---|
| Chrome / Edge | Yes | Extension required (e.g. WebRTC Network Limiter); no built-in toggle |
| Firefox | Yes | Set media.peerconnection.enabled = false in about:config |
| Safari | Yes | Develop menu → WebRTC → disable; or use content blockers |
| Tor Browser | No - Disabled by default | N/A |
| Brave | Yes, but with fingerprinting protection | Settings → Privacy → WebRTC IP handling policy |
How to Prevent WebRTC Leaks
- Use a VPN that includes WebRTC leak protection at the network level (routes all UDP traffic through the tunnel).
- In Firefox, set
media.peerconnection.enabledtofalsein about:config to disable WebRTC entirely. - In Chrome, install a reputable WebRTC control extension and set IP handling to "Disable non-proxied UDP".
- Test for WebRTC leaks regularly using our VPN leak test - It checks WebRTC, DNS, and IPv6 leaks simultaneously.
- If you don't use video calling in your browser, disabling WebRTC has no practical downside. Also check browser fingerprinting as an additional tracking vector.
The Protocol Stack Behind WebRTC
WebRTC is not one protocol but a bundle of standards working together. Understanding the pieces explains both why it works so well and why it leaks.
The components
| Component | Standard | Role |
|---|---|---|
| ICE | RFC 8445 | Gathers every possible connection path (candidate) between two peers and picks the best one |
| STUN | RFC 8489 | Asks an external server "what IP do you see me as?" to discover the public address behind NAT |
| TURN | RFC 8656 | Relays traffic through an intermediary server when no direct path exists |
| DTLS / SRTP | RFC 8827 | Encrypts the media and data channels - WebRTC traffic itself is always encrypted |
Why the leak is a feature, not a bug
For a video call to connect directly between two homes, each browser must enumerate all of its addresses - LAN, public, IPv4, IPv6 - And offer them to the other side. The leak exists because JavaScript on any page can start this candidate-gathering process without ever placing a call, then simply read the addresses out of the API. Browsers have narrowed this over the years (local IPs are now masked with mDNS hostnames in current Chrome, Edge, and Safari), but the public-address discovery that defeats VPNs is inherent to how WebRTC traverses NAT.
How to Test for a WebRTC Leak - Step by Step
- Step 1: Disconnect your VPN and run the leak test - Note your real public IP as the baseline.
- Step 2: Connect your VPN, reload the test, and compare. The WebRTC section should show either no address at all or only the VPN server's address.
- Step 3: If your real IP from step 1 appears anywhere in step 2, you have a confirmed leak - Apply one of the browser or VPN fixes above and retest.
- Step 4: Repeat in every browser you actually use. WebRTC settings are per-browser, so a fix in Firefox does nothing for Chrome.
- Step 5: Retest after browser updates - Major version upgrades have been known to reset privacy-related flags.
What This Means for You
If you never rely on a VPN or proxy for privacy, WebRTC requires no action: the addresses it exposes are the same ones every website already sees. The moment you do use a VPN, WebRTC becomes the most common way your real address slips out, because it bypasses the browser's normal connection path. The robust fix order is: choose a VPN whose client blocks non-tunnelled WebRTC traffic at the system level, harden the browser setting as a second layer, and verify with a leak test rather than trusting either. Remember the scope, too - WebRTC leaks affect browsers, not your whole device, so apps outside the browser are unaffected.
Frequently Asked Questions
Does WebRTC leak my IP even without a VPN?
Technically it exposes your public IP, but without a VPN that address is already visible to every site you visit, so nothing extra is revealed. The leak only matters when you are deliberately masking your IP and WebRTC sidesteps the mask.
Will disabling WebRTC break websites?
Only features that need real-time peer connections: browser-based video meetings, voice chat in web games, some screen-sharing and file-transfer tools. Ordinary browsing, streaming, and shopping are unaffected. If something breaks, re-enable WebRTC for that one trusted site or use its desktop app instead.
Is a WebRTC leak the same as a DNS leak?
No. A WebRTC leak reveals your IP address through the browser's peer-connection API, while a DNS leak reveals your browsing targets by sending name lookups outside the VPN tunnel. They have different fixes, which is why a thorough leak test checks both separately.