How does an IPv6 dual-stack leak occur?

Many standard proxy configurations and legacy VPN tunnels only route IPv4 traffic. If your ISP has enabled native IPv6 on your router, modern browsers will attempt IPv6 connections directly. When visiting dual-stack websites, your browser bypasses the IPv4 tunnel and exposes your authentic IPv6 residential address.

What is a DNS leak and how does this test check for it?

A DNS leak happens when DNS resolution requests are directed to your default local ISP recursive resolvers instead of going through the encrypted proxy or VPN gateway. Our DNS leak test verifies whether your DNS queries originate from your proxy provider or directly identify your ISP and physical country.

What is TCP/IP passive OS fingerprinting (JA4T & MTU)?

When your operating system establishes a TCP connection, its TCP SYN packet contains unique initial TTL values, window sizes, MTU options, and TCP option orders. Web application firewalls (WAFs) and anti-bot systems use this signature (JA4T) to detect if you claim to be a Windows Chrome user while running on a Linux headless server.

How do ProxyCrown residential proxies prevent IP leaks?

ProxyCrown provides clean, genuine residential peer IP addresses across 195+ countries. When combined with DNS resolution on the remote proxy node and our free Chrome extension with built-in WebRTC leak shields, all outbound traffic (HTTP, DNS, and WebRTC) is completely masked.

BrowserLeaks Privacy & IP Leak Suite

What Is My IP & Leak Test

Audits your IP privacy in real time: reverse DNS hostname, WebRTC leak detection, IPv6 dual-stack exposure, DNS leaks, TCP/IP OS passive fingerprinting, TLS JA3/JA4, and live HTTP request headers.

Quick Tests:

My IP Address & Hostname

IP Address

Detecting...

Hostname (Reverse DNS)

Resolving PTR record...

Tor Relay Details

This IP is not identified as a Tor Relay

IP Address Location & Autonomous System

Country

—

State / Region & City

—, —

ISP & Organization

—

Network (ASN)

—

Timezone & Local Time

UTC(+00:00)—

Coordinates

IPv6 Leak Test

Testing...

IPv6 Address

Probing IPv6 stack...

Dual-Stack Exposure Risk

✓ Clean: No IPv6 packets bypass your network interface. All traffic is bound to the primary IPv4 gateway.

WebRTC Leak Test

Interactive RTCPeerConnection STUN candidate reflection test

Local IP Address(es)

None leaked (mDNS / Policy protected)

Public IP Address (STUN srflx)

Shielded (No public candidate returned via STUN)

DNS Leak Test

Discovers recursive DNS servers resolving your web requests. If your detected DNS servers belong to your local residential ISP instead of your proxy network, your DNS is leaking.

IP Address	Resolver Organization / ISP	Country	Status

TCP/IP & OS Passive Fingerprint (JA4T)

Estimated Operating System

MTU (Max Transmission Unit)

bytes

Link Type

Distance (Network Hops)

~ Hops

JA4T (TCP SYN Signature)

TLS Client & HTTP/2 Fingerprints

JA4 TLS Fingerprint

JA3 Hash

Akamai HTTP/2 Hash

HTTP Request Headers

Request Line

GET /api/tools/ip-leak HTTP/2

Where is My IP (Interactive Map)

City, Country • Lat: 0, Lon: 0

Localhost / Private Network

The detected address is a private, loopback, or non-routable IP subnet (RFC 1918). Physical GPS coordinates are not broadcast on public satellite grids.

IP Address Whois & RDAP Lookup

CIDR Route

—

NetName & Handle

()

NetRange

Developer API & Automated Testing

Automate IP and browser leak audits with JSON payloads in your scrapers & proxies.

# 1. Deep IP & Leak Inspection via API
curl -s https://www.proxycrown.com/api/tools/ip-leak

# 2. Check specific IP or domain
curl -s "https://www.proxycrown.com/api/tools/ip-leak?ip=8.8.8.8"

Privacy Engineering Guide

Frequently Asked Questions

WebRTC (Web Real-Time Communication) is an HTML5 browser standard used for real-time voice, video, and P2P connections. Because WebRTC STUN requests bypass standard HTTP proxy configurations, it can silently transmit STUN packets that reflect and reveal your actual public ISP IP address, completely nullifying your proxy or VPN anonymity.