What is a VPN Tunnel & How Does It Work?

Key takeaways:

• A VPN tunnel is a secure, encrypted connection between a user's device and a VPN server, typically consisting of encapsulation, encryption, and authentication.
• Types and implementation of VPN tunnels depend on the protocol used, with the two most common modern protocols being OpenVPN and WireGuard tunneling.
• VPN split tunneling is a feature that routes only a part of your traffic through the encrypted connection, but it increases the potential for vulnerabilities.

What Is a VPN Tunnel?

A Virtual Private Network (VPN) tunnel is the encrypted connection established between a VPN client and a VPN server. The term "tunnel" here shouldn't be taken literally. Your data still travels through a public network operated by Internet Service Providers (ISPs).

Instead, VPN tunneling refers to the underlying VPN technology used to create a secure connection for remote access. Different VPN protocols might be used, but VPN tunnels generally consist of three parts.

• Encapsulation is about taking your original data packets and hiding their contents, origin, or other information in new packets. Data is traveling inside of data, which is the meaning of the VPN tunnel metaphor.
• Encryption converts your data from a machine or human-readable format into an unintelligible ciphertext that can only be read with a decryption key. Even if the data were intercepted after encapsulation, encryption doesn't allow it to be read.
• Authentication allows the user's device (VPN client) and the endpoint (VPN server) to verify that both are what they claim to be. Authentication reduces the chances of data interception or the loss of encryption keys.

These three processes constitute the secure tunnel of VPNs, governed differently by various VPN tunneling protocols. It is the cornerstone of all VPN services and creates many of the differences between VPNs and proxies, residential proxies, or other similar tools.

How Does a VPN Tunnel Work?

1. Connecting to the VPN server. The VPN software on your device initiates a handshake with the VPN gateway, verifying identity on both sides. A session key is established for the current VPN tunnel.
2. The device encrypts traffic. All data is encrypted and encapsulated before leaving your device. The packet's true origin, intent, and contents are hidden. Only the server of your VPN provider (endpoint) can decipher it.
3. Data travels through a secure tunnel. Encrypted data travels across public networks to the VPN server. Since data packets are secured, they can bypass firewalls and other restrictions.
4. VPN server decrypts and forwards traffic. When data has reached the endpoint, it strips the data packets, decrypts the data, and forwards the original request to its destinations. Websites and services only see the VPN server's IP address.

Once the VPN server gets a response, it follows the same path in reverse. All data is encrypted and hidden from your ISP or anyone else snooping around. Some aspects of how it's realized differ depending on the VPN tunneling protocols used.

Types of VPN Tunnels

PPTP tunneling

Point-to-Point Tunneling Protocol (PPTP) is a legacy VPN tunneling protocol developed by Microsoft back in the 1990s. PPTP is supported by almost any machine and operating system, but the encryption used is outdated by current network security standards. Besides legacy support, PPTP is not recommended.

L2TP/IPSec tunneling

Layer 2 Tunneling Protocol (L2TP) and Internet Protocol Security (IPSec) protocols are paired to create a tunnel and provide data encryption. The L2TP/IPSec double encapsulation is widely supported and more secure than PPTP, but noticeably slower. Yet, compared to modern VPN tunneling protocols, L2TP/IPSec is easy to detect for firewalls and requires lots of resources.

OpenVPN tunneling

Due to its open source nature and focus on simplicity, OpenVPN is the VPN industry standard for tunneling protocols. The OpenSSL library is used to create the AES-256 encrypted tunnel over either TCP or UDP while mimicking regular internet traffic. The OpenVPN codebase has been extensively audited and improved by security specialists.

WireGuard tunneling

WireGuard is a more lightweight alternative to OpenVPN that's faster with a similar level of protection. WireGuard operates exclusively over UDP, which is the source of its speed, especially on mobile devices. Most VPN providers use both OpenVPN and WireGuard to some extent, as for different use cases, one or the other is better.

VPN Tunnel vs Regular Internet Connection

What Is Split Tunneling?

Normally, all of your device traffic goes through the VPN tunnel. With VPN split tunneling enabled, outbound internet traffic is divided into two separate routing paths. Part of the data is sent via the VPN tunnel, and the rest is left as is.

In practice, VPN split tunneling means you can choose which apps or websites use the VPN tunnel and which don't. One of the most common use cases is routing your browser traffic through a VPN while keeping more demanding apps, like games or downloads, through your ISP.

As such, VPN split tunneling might preserve your connection speed while providing privacy where it matters. In remote access use cases, it also helps for quickly accessing the needed infrastructure, such as corporate servers, without disrupting other connections.

VPN services are reluctant to implement split tunneling, as potential bugs, human mistakes, or hacker exploits might create vulnerabilities due to it. For example, one provider allowed a bug in their split tunneling to reveal visited websites to attackers who might be tracking VPNs.

Experts at CometVPN have worked hard to secure our split tunneling feature for Android devices. More device coverage is to arrive when we can ensure you all the split tunneling benefits with no risks.

Pros of VPN Tunneling

• Encrypted connection. Scrambled data transfers can only be read by someone with a decryption key, even if intercepted.
• Secure remote access. In business settings, remote employees can access internal systems without risking network security.
• Improved privacy. Online services only see your VPN server's IP address, masking your real identity.
• Bypassing geo-restrictions. A VPN tunnel reroutes your requests to appear as if you're connecting from a different location.

Cons of VPN Tunneling

• Possible connection drops. If the VPN service is interrupted or malfunctions, the connection might briefly revert to being unprotected. Test your VPN regularly to avoid such issues.
• Reduced performance. The encryption process and routing of your internet traffic via the VPN tunnel might result in slower connection speeds.
• Higher latency. If the VPN server isn't fast enough or in a favorable location, it might increase latency.

Frequently Asked Questions

Is VPN tunneling secure?

Yes, VPN tunneling is widely considered a secure method for protecting your internet traffic. Depending on the VPN tunneling protocol used, your data in a VPN tunnel is protected with encapsulation and advanced encryption techniques, like AES-256. Any third party trying to spy on your data will need to decipher it.

Can a VPN tunnel hide your IP address?

Yes, a VPN tunnel hides your original IP address, making only the VPN server IP visible online. With a VPN tunnel, all of your data is wrapped in packets, encrypted, and routed through VPN servers, which changes your visible IP address as a result.

Can VPN tunnels be blocked?

Yes. VPN tunnels can be detected and blocked with a couple of methods. Firewalls might block IP ranges and ports belonging to VPN providers, DNS leaks may expose your activity, and deep packet inspection might analyze traffic patterns to detect VPN use. Obfuscated residential IP VPNs can counter these methods.

What is the difference between VPN tunneling and encryption?

VPN tunneling creates a private and encrypted connection for data to travel from a user's device to a secure server using public networks. Encryption renders data unreadable without an encryption key. Encryption alone would still reveal your IP address and traffic patterns, while only VPN tunneling leaves data contents accessible.