IPv4 vs IPv6
The internet is shifting from IPv4 (addresses like 192.168.1.1) to IPv6 (addresses like 2001:db8::1). Many connections now support both, known as "dual-stack." Your device may have both an IPv4 and an IPv6 address, and it can use either one to reach websites.
The IPv6 Leak Problem
Many VPN services only tunnel IPv4 traffic. When your device connects to a website that supports IPv6, that connection may bypass the VPN tunnel entirely and go straight through your ISP. The result:
- Your real IPv6 address is visible to the website
- Your real location is exposed
- Your ISP can see the IPv6 traffic
- You think you're protected, but you're not
This is one of the most common and least understood VPN vulnerabilities. Research has consistently found that many commercial VPN services fail to properly handle IPv6 traffic.
How to Detect IPv6 Leaks
Node On? tests for IPv6 leaks by checking whether your device has an active IPv6 connection and, if so, whether that IPv6 address belongs to your VPN provider or your ISP. If your IPv6 address is from your ISP while your IPv4 is from the VPN, you have an IPv6 leak.
How VPNs Handle IPv6
VPN providers generally take one of three approaches:
- Block IPv6. The simplest approach. The VPN disables IPv6 on your device while connected, forcing all traffic through IPv4 and the VPN tunnel. Most VPNs do this, including NodeVPN.
- Tunnel IPv6. The VPN assigns its own IPv6 address and tunnels both IPv4 and IPv6 traffic. More complex, but it gives you full IPv6 connectivity through the VPN.
- Ignore IPv6. The worst option. The VPN does nothing about IPv6, leaving it completely exposed. Unfortunately common among smaller providers.
How to Fix IPv6 Leaks
- Use a VPN with IPv6 leak protection. NodeVPN blocks IPv6 traffic by default, preventing leaks.
- Disable IPv6 manually. On Windows: Network adapter settings > IPv6 > uncheck. On macOS: System Preferences > Network > Advanced > TCP/IP > Configure IPv6 > Off.
- Check your router. Some routers enable IPv6 by default. You can disable it in your router's admin panel if you don't need it.