How VPNs Work: A Technical Guide to Virtual Private Networks

Classification: PUBLIC
Category: Privacy & Encryption
Reading Time: 4 min

What Is a VPN?

A Virtual Private Network (VPN) creates an encrypted tunnel between your device and a remote server, routing all your internet traffic through that tunnel. This provides two key benefits: encrypting your data in transit and masking your real IP address.

VPNs were originally designed for businesses to allow remote employees to securely access corporate networks. Today, they are widely used by individuals for privacy, security, and bypassing geographic restrictions.

How VPN Tunneling Works

When you connect to a VPN, the following process occurs:

Connection Initiation — Your VPN client establishes a connection to the VPN server using a tunneling protocol
Authentication — The client and server verify each other's identity using certificates or pre-shared keys
Encryption Negotiation — Both parties agree on encryption algorithms and exchange keys
Tunnel Establishment — A secure, encrypted tunnel is created between your device and the VPN server
Traffic Routing — All your internet traffic is encrypted, sent through the tunnel, and forwarded by the VPN server to its destination

To the outside world, your traffic appears to originate from the VPN server's IP address, not your actual IP.

VPN Protocols Compared

WireGuard

The newest and increasingly popular protocol, WireGuard uses state-of-the-art cryptography (ChaCha20, Curve25519, BLAKE2) with a minimal codebase of roughly 4,000 lines. It offers excellent performance and strong security.

OpenVPN

An open-source protocol using OpenSSL for encryption. It supports both TCP and UDP, is highly configurable, and has been extensively audited. However, it can be slower than WireGuard due to its larger codebase and overhead.

IPSec/IKEv2

A protocol suite that provides strong security and is natively supported on most operating systems. IKEv2 is particularly good at handling network changes (switching from Wi-Fi to cellular), making it ideal for mobile devices.

Deprecated Protocols

PPTP (Point-to-Point Tunneling Protocol) has known vulnerabilities and should never be used. L2TP/IPSec is considered adequate but has been largely superseded by more modern alternatives.

What VPNs Do and Don't Protect Against

VPNs Protect Against:

ISP monitoring — Your ISP can see that you're connected to a VPN but cannot inspect your traffic
Man-in-the-middle attacks on public Wi-Fi networks
IP-based tracking — Websites see the VPN server's IP, not yours
Geographic restrictions — Access content from different regions

VPNs Do NOT Protect Against:

Malware and viruses — A VPN encrypts traffic but doesn't scan for threats
Phishing attacks — VPNs don't prevent you from visiting malicious websites
Browser fingerprinting — Techniques that identify you based on browser configuration
Account-level tracking — If you log into a service, the VPN won't hide your identity

Curious about your current IP address and its geolocation data? Try Aegis Core's IP Intelligence tool to see what information your IP reveals about you.