IP Leak Test Complete Guide

You think you're anonymous with a VPN. But IP leaks can expose your real identity, location, and browsing activity—without you knowing. Here's how to test for and fix every type of IP leak.

What Is an IP Leak?

An IP leak occurs when your real IP address bypasses your VPN or privacy protection and becomes visible to websites, services, or your ISP. It's like wearing a mask with your name tag still showing.

The Three Major Leak Types

1. IPv4 Leaks

Your standard IP address escapes the VPN tunnel. The most obvious leak—easy to spot, serious if present.

• Test: Connect VPN, check checkmyip.pro. Should show VPN IP, not your real one.
• Fix: Enable kill switch, check VPN settings for IP leak protection.

2. IPv6 Leaks

Most ISPs now assign IPv6 addresses. VPNs often tunnel IPv4 but ignore IPv6, which bypasses completely.

• Test: In terminal: curl -6 https://checkmyip.pro. If it returns your ISP IPv6 (not VPN), you leak.
• Fix: Disable IPv6 in network settings, or enable IPv6 blocking in VPN.

3. WebRTC Leaks

Browsers expose your IP via WebRTC for peer-to-peer connections. Even with VPN, this API can reveal real IPs.

• Test: Visit browserleaks.com/webrtc with VPN connected.
• Fix: Install WebRTC blocking extension, or use Firefox with media.peerconnection.enabled = false.

Why IP Leaks Matter

Complete Testing Protocol

Baseline Test (No VPN)

1. Visit checkmyip.pro
2. Record IP, city, ISP
3. Check WebRTC at browserleaks.com
4. Run DNS leak test at dnsleaktest.com

VPN Test

1. Connect VPN to distant server (e.g., Japan if you're in US)
2. Hard refresh checkmyip.pro (Ctrl/Cmd+Shift+R)
3. Verify IP/location changed
4. Re-test WebRTC
5. Re-test DNS
6. Check both IPv4 and IPv6

Kill Switch Test

1. Enable VPN kill switch
2. Start continuous ping: ping google.com
3. Disconnect VPN abruptly
4. Ping should stop instantly
5. If ping continues, kill switch failed

How to Fix Each Leak

VPN Leak Protection

Enable in VPN settings:

• IP leak protection/IPv6 blocking
• Kill switch
• Custom DNS servers

OS-Level Fixes

Windows:

• Control Panel → Network → Adapter → IPv6 → Disable
• Or PowerShell: Disable-NetAdapterBinding -Name "*" -ComponentID ms_tcpip6

macOS:

• System Preferences → Network → Advanced → TCP/IP → Configure IPv6: Off

Linux:

• Edit /etc/sysctl.conf
• Add: net.ipv6.conf.all.disable_ipv6=1
• Apply: sudo sysctl -p

Browser Fixes

Chrome:

• Install WebRTC Control or WebRTC Leak Prevent extensions

Firefox:

• Type about:config
• Set media.peerconnection.enabled to false

VPN Quality Comparison

Not all VPNs handle leaks equally:

• NordVPN: Built-in leak protection, passed all tests
• ExpressVPN: Automatic leak blocking, regular audits
• Surfshark: Multi-hop, good for high-risk regions

Free VPNs often lack proper leak protection—test thoroughly if using.

Testing Frequency

• Monthly: Basic IP/DNS check
• Weekly: If you're a journalist, activist, or high-risk user
• After: Every VPN software update
• After: OS or browser updates

Red Flags

• Same IP/location with VPN on and off
• Speeds unchanged despite distant VPN server
• DNS servers still show your ISP
• IPv6 address visible in VPN tests
• WebRTC shows multiple IP addresses

Advanced: Multi-Hop Testing

For high-anonymity needs, use VPN through VPN (Multi-hop). Test each hop separately to ensure leaks don't occur at any layer.

Summary

IP leaks are common, dangerous, and fixable. Test regularly: IPv4, IPv6, WebRTC, and DNS. Enable all protections in VPN settings. Disable IPv6 at OS level. Block WebRTC in browsers.

Start testing now: Check your IP without VPN, then connect VPN and check again. If it matches, you're leaking.