Detection & trust · glossary

WebRTC leak

A WebRTC leak occurs when a browser configured to use a proxy for web traffic still discloses the device's real public or local IP addresses through WebRTC, the real-time communication API, because WebRTC gathers connection candidates directly rather than through the proxy. Any page can trigger it with JavaScript, so a browser session through a proxy is only as private as its WebRTC settings.

1 min read Updated

Protocols All terms

How to prevent it#

BrowserSetting
Firefoxmedia.peerconnection.enabled = false in about:config, or the network.proxy policy to force proxied candidates only
Chrome / ChromiumWebRTC IP handling policy "disable non-proxied UDP" (extension or enterprise policy); anti-detect browsers expose it as a toggle
Headless automationLaunch flags that disable WebRTC, or block STUN servers at the network level

Testing#

Load a WebRTC leak test page through the proxy: the only address listed must be the exit. Scripts and non-browser clients are not affected; the leak is a browser feature.

How it works at Proxy Cyber#

Because Proxy Cyber is TCP-only and never touches the browser, WebRTC candidates cannot travel through it; the fix is on the browser side, and the guides list the settings per browser.

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