WebRTC leak test

WebRTC is the browser technology behind in-page video calls and peer-to-peer connections. To connect two people directly it has to discover the network addresses each device can be reached on, and it does this using a mechanism called ICE candidates gathered from STUN servers. The side effect is that a web page can ask the browser for those candidates — which can include your real IP address — even while you are connected to a VPN, because WebRTC operates below the level a VPN normally controls.

This test runs entirely in your browser. It triggers the same ICE-gathering process a video-call site would and lists the candidates your browser produces, separating local (private network) addresses from public, server-reflexive ones. If a public address appears here that matches your real IP rather than your VPN’s, that is a WebRTC leak: sites using this technique could identify your true address despite the tunnel.

A leak does not mean your VPN is broken — it means the browser is exposing information around it. The usual fixes are to disable WebRTC or restrict it with a browser setting or extension, to use a VPN client or firewall rule that blocks non-tunnel traffic, or to use a browser that confines WebRTC to the VPN interface. Re-run this test after any change to confirm the public address no longer appears.