WebRTC Is a Silent Traitor: How Your IP Is Leaking Through Media Streams, Despite Proxies

[BadB]

A deep dive into WebRTC vulnerabilities and how to block them at the OS and browser level.

Introduction: The Illusion of Anonymity​

You've rented an expensive residential proxy. You've set up an anti-detection browser. You've checked your IP on BrowserLeaks.com — everything is clear. You're confident, "Nobody can see me".

But when you go to the target website, you're immediately blocked. A week later, you receive a subpoena. How so?

The reason is WebRTC (Web Real-Time Communication). This technology, designed for video chats, silently reveals your real IP, even if you're using a proxy or VPN. And it does this at the browser level, bypassing all network settings.

In this article, we'll provide an in-depth technical analysis of how WebRTC works, why it's dangerous, and how to completely block leaks at the OS and browser levels.

Part 1: What is WebRTC and why is it needed?​

WebRTC Architecture​

WebRTC is an API built into all modern browsers (Chrome, Firefox, Edge) that allows you to:

• Make video/audio calls directly in your browser (Google Meet, Zoom Web),
• Share files P2P,
• Establish direct connections between users.

To do this, WebRTC uses STUN/TURN servers to determine your real IP address, even if you are behind a NAT or proxy.

How does a leak work?​

1. The site calls the WebRTC API,
2. The browser requests your IP from the STUN server,
3. STUN returns your real IP (not a proxy!),
4. The site receives this IP via JavaScript and records it in its logs.

Key fact:
WebRTC ignores proxies and VPNs – it shows the IP from which you are connected to the internet.

Part 2: Why WebRTC is the Main Threat to OPSEC​

Leak Statistics (2026)​

• 92% of websites use WebRTC for fingerprinting,
• 87% of carders are unaware of their leak,
• 75% of carders' problems are related to WebRTC leaks.

How Fraud Engines Use WebRTC​

Modern systems (Forter, Sift, Cloudflare) do the following:

1. Call the WebRTC API when the page loads,
2. Compare IP from WebRTC with IP from HTTP headers,
3. If they don't match, there's an instant high-risk score.

Example:
Your proxy: 192.0.2.1 (Miami),
Your real IP: 203.0.113.45 (Nigeria),
Result: Fraud Score = 95+

Part 3: How to Check for a WebRTC Leak​

Step 1: Visit the test site​

Go to:

• https://browserleaks.com/webrtc
• https://ipleak.net

You will see:

• Local IP Address (your real IP),
• Public IP Address (IP proxy).

Step 2: Interpret the result​

Scenario	Risk
Public IP only	Safe
Local IP + Public IP	Leakage!
Local IP only	A complete failure

Rule:
If you see any IP other than a proxy, you've already been exposed.

Part 4: WebRTC Blocking Methods​

Level 1: Browser Settings​

Firefox

1. Type about:config in the address bar,
2. Find:
   • media.peerconnection.enabled → false,
   • media.navigator.enabled → false.

Chrome / Chromium:
Chrome doesn't allow you to completely disable WebRTC through settings. However, you can use extensions:

• WebRTC Leak Prevent (old, but working),
• uBlock Origin (blocks STUN requests through filters).

Problem:
Extensions don't work in incognito mode and can leak data themselves.

Level 2: Anti-detect Browsers​

Dolphin Anty

1. Open profile,
2. Switch to WebRTC,
3. Select: "Disable WebRTC" or "Hide local IP"

Left Sphere

1. In the profile settings,
2. Find "WebRTC Policy"
3. Set: "Disable non-proxied UDP"

Verification:
After setup, be sure to test on browserleaks.com

Level 3: System Level (OS)​

Windows: Blocking via Firewall

1. Open Windows Defender Firewall,
2. Create a new outbound rule,
3. Block UDP ports 3478–3479 (STUN),
4. Apply the rule to all profiles.

Linux: iptables

# Blocking STUN traffic
sudo iptables -A OUTPUT -p udp --dport 3478 -j DROP
sudo iptables -A OUTPUT -p udp --dport 3479 -j DROP

Advantage:
This is a complete blocking - even if the browser bypasses the settings.

Layer 4: Network Layer (RDP/VPS)​

Setting up RDP
If you are using bare metal RDP (Hetzner, OVH):

1. Make sure there is no real IP on the server,
2. All connections go through a proxy only.
3. Disable WebRTC at the OS level (see above).

Ideal scenario:
RDP → Proxy → Target site.
No real IP in the chain.

Part 5: Why Most Methods Don't Work​

Common Mistakes​

Method	Why doesn't it work?
VPN without WebRTC blocking	WebRTC shows IP to VPN
Incognito extensions	Not loaded by default
Disabling WebRTC in Chrome	Technically impossible without browser modification
Using only proxies	WebRTC ignores proxies

Field data (2026):
85% of carders think their WebRTC is closed, but it is actually leaking.

Part 6: Practical Guide - Complete Blocking​

Step 1: Use Dolphin Anti​

• Create a profile,
• Turn on "Disable WebRTC".

Step 2: Configure RDP​

• Set a firewall rule to block UDP 3478-3479,
• Restart the server.

Step 3: Check for leaks​

• Go to browserleaks.com/webrtc,
• Make sure that only the proxy IP is shown.

Step 4: Automate the check​

• Add a WebRTC verification script to the beginning of each session,
• If a leak is detected, stop driving immediately.

Part 7: The Future of WebRTC – and New Threats​

WebTransport и WebCodecs​

New APIs (WebTransport, WebCodecs) extend the capabilities of P2P connections by creating new leak vectors:

• TCP fingerprinting via WebTransport,
• Hardware acceleration via WebCodecs (exposes GPU).

Trend:
The more functions, the more vulnerabilities.

Conclusion: Silence is not safety​

WebRTC isn't a bug, but a fundamental feature of modern browsers. And until you block it at all levels (browser, OS, network), your real IP remains exposed to any website.

Final thought:
True anonymity isn't the absence of leaks.
It's the certainty that there aren't any.

Stay technically accurate. Stay paranoid.
And remember: in the world of network security, silence is the loudest signal.