A VPN is only as secure as its configuration. Even premium VPNs can leak your data if not set up correctly. This guide shows you exactly what to check and how to fix common issues.
VPN Security Risks Overview
VPNs are powerful privacy tools, but they're not foolproof. Understanding potential vulnerabilities helps you make informed decisions and properly configure your VPN for maximum protection.
| Risk | What Happens | Impact | Fix |
|---|---|---|---|
| DNS Leak | DNS queries bypass VPN tunnel | ISP sees websites you visit | Enable DNS leak protection |
| IPv6 Leak | IPv6 traffic not routed through VPN | Real IP exposed to websites | Disable IPv6 or use VPN with IPv6 support |
| WebRTC Leak | Browser reveals local/public IP | Real IP visible to websites | Disable WebRTC in browser |
| Kill Switch Failure | Traffic flows when VPN disconnects | Brief exposure of real IP | Enable and test kill switch |
| Weak Protocol | Outdated encryption can be cracked | Traffic potentially decryptable | Use WireGuard or OpenVPN |
| VPN Logging | Provider stores activity data | Privacy compromised if subpoenaed | Choose audited no-logs provider |
DNS Leaks
What Is a DNS Leak?
When you visit a website, your device sends a DNS query to translate the domain name (like google.com) into an IP address. Normally, a VPN routes these queries through its encrypted tunnel to its own DNS servers.
A DNS leak occurs when these queries bypass the VPN and go directly to your ISP's DNS servers, revealing every website you visit-even while "protected" by a VPN.
Common Causes:
- Misconfigured VPN client
- Windows "Smart Multi-Homed Name Resolution"
- IPv6 DNS queries on IPv4-only VPN
- Transparent DNS proxies by ISP
- Manual DNS settings overriding VPN
Want to check if your VPN has a DNS leak right now?
How to Fix DNS Leaks
Enable VPN's DNS Leak Protection
Most VPN apps have this setting. It forces all DNS queries through the VPN tunnel.
Use VPN's DNS Servers
Configure your device to use the VPN provider's DNS servers, not your ISP's or public DNS.
Disable IPv6
If your VPN doesn't support IPv6, disable it in your OS network settings to prevent IPv6 DNS leaks.
Test Regularly
Use DNS leak test tools after setup and after any system updates to verify protection.
IP Address Leaks
An IP leak occurs when your real IP address is exposed despite being connected to a VPN. This can happen through several mechanisms:
IPv6 Leaks
Many VPNs only tunnel IPv4 traffic. If your ISP supports IPv6 and a website requests it, your real IPv6 address may be exposed. This is one of the most common types of IP leaks.
Kill Switch Failures
When your VPN connection drops (which happens more often than you'd think), your device may revert to your regular internet connection, exposing your real IP. A kill switch prevents this by blocking all traffic when the VPN disconnects.
Pro Tip
Test your kill switch by manually disconnecting from the VPN while running a continuous ping. If packets still go through, your kill switch isn't working properly.
WebRTC Leaks
WebRTC (Web Real-Time Communication) is a browser technology that enables video calls, voice chat, and file sharing directly between browsers. Unfortunately, it can also leak your real IP address.
How WebRTC Leaks Work
WebRTC uses STUN servers to discover your IP address for peer-to-peer connections. This happens at the browser level and can bypass your VPN tunnel entirely, revealing both your local and public IP addresses to websites.
How to Prevent WebRTC Leaks
- Firefox: Go to
about:configand setmedia.peerconnection.enabledtofalse - Chrome: Install a WebRTC blocking extension like "WebRTC Leak Prevent"
- Brave: Settings → Privacy → Disable "WebRTC IP Handling Policy"
- VPN Apps: Some VPNs include built-in WebRTC leak protection
Check if your browser is leaking your IP via WebRTC:
Weak Protocols & Encryption
Not all VPN protocols are created equal. Using outdated protocols can leave your traffic vulnerable to interception and decryption.
| Protocol | Security | Speed | Recommendation |
|---|---|---|---|
| WireGuard | Excellent | Fastest | ✅ Recommended |
| OpenVPN | Excellent | Good | ✅ Recommended |
| IKEv2/IPSec | Good | Fast | ⚠️ Acceptable |
| L2TP/IPSec | Moderate | Moderate | ⚠️ Use if no alternative |
| PPTP | Broken | Fast | ❌ Never use |
Warning: Avoid PPTP
PPTP's encryption has been broken since 2012. It can be cracked in under a day. If your VPN only offers PPTP, switch providers immediately.
Logging & Privacy Policies
Your VPN provider can potentially see all your traffic. This makes their logging policy crucial to your privacy.
Types of Logs
- Connection logs: Timestamps, IP addresses, bandwidth used
- Activity logs: Websites visited, files downloaded, searches made
- No logs: Provider claims to store nothing identifiable
How to Verify No-Logs Claims
- Look for independent audits by firms like Deloitte, PwC, or Cure53
- Check if the provider has been tested in court (subpoenas that yielded no data)
- Review the jurisdiction-some countries require data retention
- Look for warrant canaries and transparency reports
Free VPN Dangers
The saying "if you're not paying, you're the product" applies strongly to free VPNs. Research has found alarming issues with many free VPN services:
Data Selling
Many free VPNs log and sell your browsing data to advertisers and data brokers.
Malware
Studies found that 38% of free Android VPN apps contain malware.
Ad Injection
Some free VPNs inject ads into your browsing sessions or redirect your searches.
Weak Security
Many use outdated protocols, weak encryption, or have DNS/IP leaks.
Safe Free Alternatives
A few reputable providers offer limited free tiers funded by their paid subscribers:
- ProtonVPN Free: No data limits, but limited to 3 countries
- Windscribe Free: 10GB/month, 10 countries
How to Test Your VPN
Regular testing ensures your VPN is actually protecting you. Here's what to check:
When to Test
- After initial VPN setup
- After VPN app updates
- After operating system updates
- When switching VPN servers or protocols
- Monthly as routine maintenance
Security Best Practices Checklist
Follow this checklist to maximize your VPN security: