An IP leak happens when a site can discover your real address even while you use a VPN or proxy. The most common path is WebRTC.
Why WebRTC exposes addresses
To connect two people directly, WebRTC collects network candidates: local addresses, public addresses obtained via STUN and relayed addresses via TURN. Those candidates are exchanged during negotiation — and a script on the page can read them.
What may appear
- Private addresses from your local network, such as
192.168.x.x. - The public IP your browser uses to reach the internet.
- STUN server addresses, which do not identify you.
How to test
The WebRTC Leak Test runs candidate gathering in your browser and lists what it found, sending nothing externally. If the listed public address differs from your VPN IP, there is a leak.
How to reduce the risk
Disable WebRTC when you do not need it, use a VPN that blocks STUN traffic outside the tunnel and keep your browser updated.