IPv6 Leak Test: How to Detect and Fix IPv6 Leaks in Your VPN

What Is an IPv6 Leak?

An IPv6 leak occurs when your device sends internet traffic over IPv6 (Internet Protocol version 6) while your VPN only protects IPv4 traffic. This means your real IP address and location are exposed through the unprotected IPv6 connection, completely bypassing the VPN tunnel.

IPv6 is the newer internet protocol designed to replace IPv4, which is running out of available addresses. While IPv4 uses 32-bit addresses (like 192.168.1.1), IPv6 uses 128-bit addresses (like 2001:0db8:85a3::8a2e:0370:7334), providing virtually unlimited IP addresses.

IPv4 vs IPv6: Key Differences

Why IPv6 Leaks Happen

IPv6 leaks occur due to a fundamental mismatch between modern internet infrastructure and VPN technology:

1. Limited VPN IPv6 Support

Most VPN protocols (OpenVPN, WireGuard, IKEv2) support IPv6 tunneling, but many VPN providers haven't implemented it. Budget VPNs often skip IPv6 support entirely to save on infrastructure costs, as IPv6 requires separate server configurations and routing tables.

2. Dual-Stack Networking

Modern devices and ISPs use "dual-stack" networking, supporting both IPv4 and IPv6 simultaneously. When you connect to a website that supports IPv6, your device prefers IPv6 over IPv4. If your VPN doesn't route IPv6, the traffic bypasses the tunnel completely.

3. ISP IPv6 Deployment

Major ISPs (Comcast, Verizon, T-Mobile, etc.) have deployed IPv6 to address IPv4 exhaustion. As of 2024, approximately 35-40% of internet users have IPv6 connectivity, creating a large attack surface for leaks.

4. Operating System Behavior

Windows, macOS, iOS, and Android all enable IPv6 by default and prefer it when available. They don't automatically disable IPv6 when connecting to a VPN that doesn't support it, creating an invisible leak.

How to Test for IPv6 Leaks

Testing for IPv6 leaks is straightforward but requires checking both with and without your VPN connected:

Step-by-Step Testing Process

1. Disconnect from your VPN and visit dovpn.com/ip-leak-test
   • Note your real IPv4 address
   • Note your real IPv6 address (if displayed)
   • Note your ISP and location
2. Connect to your VPN and refresh the leak test page
   • IPv4 should show your VPN server's address
   • IPv6 should show VPN server's address OR be hidden completely
   • Location should match your VPN server location
3. Analyze the results:
   • ✅ No leak: Only VPN server IPs shown, or no IPv6 at all
   • ❌ IPv6 leak: Your real IPv6 address is visible
   • ❌ Dual leak: Both real IPv4 and IPv6 addresses shown

IPv6 Leak Detection Methods

Beyond web-based tests, you can use command-line tools to verify IPv6 leak protection:

Command-Line Detection

Windows (PowerShell)

Get-NetIPAddress | Where-Object {$_.AddressFamily -eq "IPv6" -and $_.InterfaceAlias -notlike "*Loopback*"}
Test-NetConnection -ComputerName ipv6.google.com -InformationLevel Detailed

macOS/Linux (Terminal)

ifconfig | grep inet6
curl -6 https://api64.ipify.org
dig AAAA google.com +short

Android (Termux)

ip -6 addr show
curl -6 ifconfig.co

Browser Developer Tools Method

You can also check for IPv6 leaks using browser developer tools:

1. Open Chrome/Firefox Developer Tools (F12)
2. Go to the Network tab
3. Visit a dual-stack website like ipv6.google.com
4. Check the Remote Address column for IPv6 format (colons instead of dots)
5. If you see an IPv6 address, your traffic is using IPv6

How to Fix IPv6 Leaks

There are three main approaches to fixing IPv6 leaks, listed from most effective to least:

Solution 1: Use a VPN with IPv6 Support (Recommended)

The best solution is switching to a VPN that properly handles IPv6 through native tunneling:

• NordVPN: Routes IPv6 through the VPN tunnel on all servers
• Surfshark: Full IPv6 leak protection with dual-stack tunneling
• Mullvad: Native IPv6 support on WireGuard protocol
• IVPN: IPv6 routing available on all server locations

Solution 2: Disable IPv6 at System Level

If your VPN doesn't support IPv6, disabling it completely prevents leaks. This is the most reliable fix for VPNs without IPv6 support.

Solution 3: Configure VPN-Level IPv6 Blocking

Some VPNs offer IPv6 blocking features in their settings:

• ExpressVPN: "Block IPv6" option in settings (app version 12+)
• Private Internet Access: IPv6 leak protection toggle
• ProtonVPN: IPv6 blocking in advanced settings

Platform-Specific IPv6 Fixes

Windows 10/11

Method 1: Network Adapter Settings (GUI)

1. Press Win + R, type ncpa.cpl, press Enter
2. Right-click your network adapter → Properties
3. Uncheck "Internet Protocol Version 6 (TCP/IPv6)"
4. Click OK and restart your network adapter

Method 2: Registry Edit (Permanent)

1. Press Win + R, type regedit, press Enter
2. Navigate to: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip6\Parameters
3. Right-click → New → DWORD (32-bit) Value
4. Name: DisabledComponents
5. Set value to: 0xFF (hexadecimal) or 255 (decimal)
6. Restart computer for changes to take effect

Method 3: PowerShell (One Command)

Disable-NetAdapterBinding -Name "*" -ComponentID ms_tcpip6

macOS (Ventura, Sonoma, Sequoia)

For Wi-Fi Connections

networksetup -setv6off Wi-Fi

For Ethernet Connections

networksetup -setv6off Ethernet

Verify IPv6 is Disabled

networksetup -getinfo Wi-Fi | grep IPv6

Re-enable IPv6 (if needed)

networksetup -setv6automatic Wi-Fi

iOS (iPhone/iPad)

iOS doesn't allow direct IPv6 disabling, but you can prevent leaks through VPN configuration:

Option 1: Use VPN Apps with IPv6 Blocking

• NordVPN iOS app (auto-blocks IPv6)
• Surfshark iOS app (IPv6 leak protection)
• ExpressVPN iOS app (blocks IPv6 when connected)

Option 2: Manual VPN Configuration (Advanced)

1. Settings → General → VPN & Device Management
2. Add VPN Configuration → IKEv2 or IPSec
3. In advanced settings, ensure "Send All Traffic" is enabled
4. This forces IPv6 through the tunnel or blocks it

Android

Method 1: Developer Options

1. Settings → About Phone → Tap Build Number 7 times
2. Settings → System → Developer Options
3. Scroll to "Networking" section
4. Disable "Enable IPv6"

Method 2: ADB Command (Root/Developer)

adb shell settings put global ipv6_enabled 0

Method 3: VPN Apps (Easiest)

Use VPN apps with built-in IPv6 blocking (NordVPN, Surfshark, Mullvad). These apps automatically prevent IPv6 leaks without system-level changes.

Linux (Ubuntu/Debian)

Temporary Disable

sudo sysctl -w net.ipv6.conf.all.disable_ipv6=1
sudo sysctl -w net.ipv6.conf.default.disable_ipv6=1

Permanent Disable

echo "net.ipv6.conf.all.disable_ipv6 = 1" | sudo tee -a /etc/sysctl.conf
echo "net.ipv6.conf.default.disable_ipv6 = 1" | sudo tee -a /etc/sysctl.conf
sudo sysctl -p

VPN Solutions for IPv6 Protection

If disabling IPv6 isn't ideal for your use case, these VPNs offer robust IPv6 leak protection:

Top VPNs with IPv6 Support

VPNs to Avoid for IPv6

These popular VPNs have known IPv6 leak issues:

• HideMyAss (HMA): No IPv6 support, leaks on dual-stack networks
• TunnelBear: IPv6 not routed, requires manual disabling
• Hotspot Shield: Free version doesn't block IPv6
• Betternet: No IPv6 leak protection

Frequently Asked Questions

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