What Is a VPN Tunnel?

VPN tunneling uses a process called encapsulation: your original data packets are wrapped inside new packets with encryption applied.

Here's the step-by-step process:

1. You send data — Your browser requests a webpage, your email app checks for new messages, or any app sends network traffic
2. Encryption — The VPN client on your device encrypts the original data packet using a cipher like AES-256 or ChaCha20
3. Encapsulation — The encrypted packet is wrapped inside a new packet with a new header. The outer header is addressed to the VPN server, hiding the original destination
4. Transmission — The encapsulated packet travels through the internet to the VPN server. Anyone intercepting it sees only the outer header (your device → VPN server) and encrypted content
5. Decapsulation — The VPN server removes the outer header and decrypts the original packet
6. Forwarding — The VPN server forwards your original request to its destination (the website, service, etc.)
7. Response — The destination responds to the VPN server, which encrypts and tunnels the response back to you

This entire process happens for every packet and completes in milliseconds. Modern VPN protocols like WireGuard are so efficient that many everyday connections remain usable for browsing, calls, and streaming.

Different tunneling protocols create tunnels in different ways, each with tradeoffs:

Full Tunnel — All your internet traffic routes through the VPN. This is the default mode for most consumer VPNs. Provides complete protection but routes even local traffic (like accessing your printer) through the VPN server.

Split Tunnel — You choose which traffic goes through the VPN tunnel and which connects directly. For example, route browsers through the VPN while keeping video calls on a direct connection. More efficient but requires manual configuration. See our split tunneling guide for setup instructions.

Site-to-Site Tunnel — Connects two entire networks (e.g., a company's offices in two cities). All traffic between the networks is encrypted. Used in enterprise environments, not consumer VPNs.

Point-to-Site Tunnel — Connects an individual device to a network. This is what happens when a remote worker connects to their corporate VPN. The concentrator manages these connections on the enterprise side.

Consumer VPNs typically use full tunnel by default with an option for split tunneling. This gives you the best balance of security and flexibility.

The tunneling protocol determines how the tunnel is created, how data is encrypted, and how fast the connection performs:

WireGuard - Encryption: ChaCha20-Poly1305 - Speed: Often strong in public reports - Codebase: ~4,000 lines (easy to reported) - Best for: Most users, all use cases - Used by: NordVPN (as NordLynx), Surfshark, Mullvad, Private Internet Access

OpenVPN - Encryption: AES-256-GCM (configurable) - Speed: Moderate (moderate to strong reported performance) - Codebase: ~100,000 lines - Best for: Maximum compatibility, restrictive networks - Used by: All major VPN providers

IKEv2/IPSec - Encryption: AES-256 - Speed: Often strong in public reports - Codebase: Built into most operating systems - Best for: Mobile devices (handles network switching well) - Used by: Most VPN providers on mobile

Lightway (ExpressVPN) - Encryption: ChaCha20 or AES-256 (via wolfSSL) - Speed: Often strong in public reports - Codebase: ~2,000 lines - Best for: ExpressVPN users seeking maximum speed - Documented by: public provider materials

For most users, WireGuard is the strong choice. It's the modern, efficient, and has the smallest attack surface due to its lean codebase.

A secure VPN tunnel requires several components working together:

Strong Encryption — The cipher (AES-256 or ChaCha20) must be strong enough that intercepted data is unreadable. Both ciphers are considered unbreakable with current technology.

Perfect Forward Secrecy (PFS) — Each session uses unique, temporary encryption keys. If a key is somehow compromised, only that one session's data is at risk — past and future sessions remain protected.

Authentication — The tunnel must verify the identity of both endpoints (your device and the VPN server) to prevent man-in-the-middle attacks. This is done through digital certificates or pre-shared keys.

Integrity Checking — Every packet includes an authentication tag (HMAC or Poly1305) that verifies the data hasn't been tampered with during transit.

DNS Leak Protection — DNS queries must travel through the tunnel, not directly to your ISP. A DNS leak defeats the purpose of the tunnel by revealing which websites you visit.

All VPNs we recommend at StatesVPN implement all of these security measures. We verify them through independent testing — see our research methodology.

VPN tunnels can occasionally experience issues. Here are the most common problems and how to fix them:

Slow speeds through the tunnel: - Switch from OpenVPN to WireGuard (2–3x faster) - Connect to a closer VPN server - Check if your ISP is throttling VPN traffic (try port 443)

Tunnel keeps disconnecting: - Enable the VPN's kill switch to maintain protection during reconnection - Switch protocols — some networks handle OpenVPN TCP better than UDP - Check if your router's VPN passthrough is enabled

DNS leaks despite the tunnel: - Enable the VPN app's DNS leak protection setting - Use the VPN provider's DNS servers (not your ISP's) - Test for leaks at dnsleaktest.com

Can't connect to the tunnel at all: - Your network may block VPN protocols. Try obfuscated servers (NordVPN, ExpressVPN) - Switch to OpenVPN on TCP port 443 (looks like HTTPS traffic) - Check firewall settings on your device and router

For persistent issues, contact your VPN provider's support team with details about your network environment and the error messages you're seeing.