WebRTC Leaks: The Hidden Fingerprint That Exposes Multi-Account Users

Most people know about IP addresses. Fewer know about WebRTC leaks — and they're often more dangerous for multi-account setups.

What is WebRTC?

WebRTC (Web Real-Time Communication) is a browser API for peer-to-peer connections — used by video calls, gaming, file sharing. The problem: it exposes your local network IP address to any website, even when you're behind a VPN or proxy.

// Any website can run this to get your real local IP
const pc = new RTCPeerConnection({iceServers: []});
pc.createDataChannel('');
pc.createOffer().then(offer => pc.setLocalDescription(offer));
pc.onicecandidate = event => {
  if (event.candidate) {
    const ipMatch = event.candidate.candidate.match(/\d+\.\d+\.\d+\.\d+/);
    if (ipMatch) console.log('Your local IP:', ipMatch[0]); // e.g., 192.168.1.42
  }
};

Why This Breaks Multi-Account Setups

Your local IP (192.168.1.x or 10.0.0.x) is assigned by your router. It:

Stays constant across different browser sessions
Persists through proxy rotation — the proxy hides your public IP, not your local one
Works in incognito mode — it's not a cookie, it's hardware-level

If you're running 5 Amazon seller accounts, all from the same machine, they all share the same local IP via WebRTC. Platform detection systems correlate this within milliseconds.

The Full Fingerprint Attack Surface

WebRTC is one of several vectors:

Signal	What it reveals	Persistence
WebRTC	Local network IP	Very high
Canvas hash	GPU rendering signature	Very high
WebGL	GPU model/driver	High
Font list	Installed fonts	Medium-high
Screen resolution	Monitor setup	Medium
Timezone	Location	Medium

How to Actually Protect Yourself

Block WebRTC entirely per profile (not globally — that breaks video calls for your main browser)
Spoof canvas/WebGL rendering per profile
Match timezone + locale to your proxy's exit location

I use FireKey for this — free open beta, each profile gets WebRTC blocked and a unique fingerprint. The key is profile-level isolation, not browser-level settings.