WebRTC Leak

A WebRTC leak exposes your true IP address through the browser's WebRTC feature, which powers in-page voice and video. To connect peers directly, WebRTC can enumerate your local and public IP addresses and share them with a page via JavaScript — and it may reveal the real address behind a VPN or proxy, because it operates independently of your usual proxy settings. So a site could show your genuine IP even when your other traffic is safely tunnelled, which is why it is a favourite check in anti-fraud and de-anonymisation tools.

Unlike a DNS leak, a WebRTC leak is a browser-layer problem, so the fix lives in the browser: disable WebRTC where you do not need it, use an extension that blocks the address enumeration, or rely on an anti-detect browser that controls these APIs. A device-wide VPN tunnel helps because even WebRTC's traffic then leaves through the tunnel, but you should still verify. Test with a WebRTC-leak checker while connected; if it shows your real IP, close the hole before doing anything where your origin must stay hidden.

Because this is a browser-layer issue, fix it in the browser: disable WebRTC where you do not need it, block the address enumeration with an extension, or use an anti-detect browser that governs these APIs. A device-wide s4m VPN helps, since WebRTC's own traffic then leaves through the tunnel, but always verify with a WebRTC-leak test while connected. Pair the browser fix with the tunnel rather than assuming either alone hides your real address in every case.