VPN Simulator

Visualizing Encrypted Tunnels and Secure Networks
Learning Module: Network Security Basics

1. Choose Scenario

2. VPN Control

VPN Status Disabled (Plaintext)

How to Interact

1. Toggle the VPN Status switch to see the traffic encrypt/decrypt.

2. Hover/Click on any traveling packet in the network visualization map to inspect its packet headers and payload contents.

3. Observe the live Console Log to understand what the ISP and destination servers can see.

Unencrypted IP Packet
Encrypted VPN Tunnel (ESP/IPsec)

Packet Inspector

Hover or click a traveling packet to inspect its layers

ISP & Network Log

The Mechanics of a VPN

A Virtual Private Network (VPN) works by establishing an encrypted connection (often called a "tunnel") between your local device and a remote VPN server. All of your network traffic is routed through this secure tunnel.

1. Encapsulation & Encryption

Before leaving your device, the real IP packet (containing your destination website and data) is encrypted. It is then wrapped inside a new "outer" packet. This process is called encapsulation.

2. The ISP's Perspective

Because the packet is encapsulated, your Internet Service Provider (ISP) can only see the outer header. They know you are sending data to a VPN server, but they cannot read your payload or see your final destination (e.g., Amazon or your company server).

3. Decryption & Delivery

Once the packet reaches the VPN server/gateway, the server strips away the outer header, decrypts the inner packet, and forwards the original request to its destination using the VPN's own IP address.

Remote Access vs. Site-to-Site VPNs

Different network designs require different types of VPN architectures:

Remote Access VPN (Client-to-Gateway)

Allows individual users to securely connect to a private network from a remote location. A software agent is installed on the user's computer.

  • Used by remote employees connecting to corporate servers
  • Used by consumers subscribing to commercial VPN services
  • Protects individual endpoints over untrusted Wi-Fi

Site-to-Site VPN (Gateway-to-Gateway)

Connects entire networks in different physical locations (like a branch office to headquarters) without requiring software on individual host devices.

  • Implemented on edge routers or dedicated firewalls
  • Transparent to the end-users on both sides
  • Allows secure communication over the public internet

Common Tunneling & Security Protocols

VPNs rely on different cryptographic and tunneling protocols to ensure security, speed, and reliability:

WireGuard®

The modern, extremely fast standard. It utilizes state-of-the-art cryptography (ChaCha20, Poly1305) and operates with a small, lightweight codebase.

  • Highest performance and throughput
  • Instant reconnect when switching networks
  • Highly secure but lacks legacy features

OpenVPN

A highly configurable open-source protocol that supports custom certificates and operates over either UDP or TCP on any port.

  • Very hard for firewalls to block (can mimic HTTPS)
  • Robust, reliable, and widely supported
  • Slightly heavier CPU overhead than WireGuard

IPsec (with IKEv2/L2TP)

A suite of protocols (often paired with L2TP) that secures IP communications by authenticating and encrypting each IP packet.

  • Built into most desktop and mobile OS natively
  • Strong security utilizing AES encryption
  • Can be blocked easily by standard firewalls

Why Use a VPN?

Using a VPN mitigates several fundamental network vulnerabilities:

Confidentiality

Protects your browsing activities, credentials, and confidential company files from eavesdropping on public Wi-Fi networks (man-in-the-middle attacks).

IP Spoofing & Anonymity

Websites see the IP address of the VPN server rather than your residential IP. This masks your physical location and thwarts ad trackers.

Circumventing Censorship

Enables users to bypass geographic restrictions or local internet filters by routing traffic through servers in different regions.

Self-Hosting an OpenVPN Server

Instead of paying for commercial VPN service or relying on corporate infrastructure, you can set up a VPN server at home using a spare PC, Raspberry Pi, or home server. This can also be hosted on cloud VPS platforms (such as AWS, DigitalOcean, or Linode), but deploying it locally provides a completely free way to access your home network resources and route your traffic securely when away.

Step-by-Step Configuration Guide

Here is how you set up a home VPN using OpenVPN:

  • 1. Set Up Hardware: Install a Linux OS (Ubuntu Server, Debian, or Raspberry Pi OS) on your dedicated VPN host PC.
  • 2. Run Automatic Installer: Use trusted scripts to streamline deployment: wget https://git.io/vpn -O openvpn-install.sh && sudo bash openvpn-install.sh. The script will guide you through setting up ports, local IP addresses, and DNS servers.
  • 3. Configure Port Forwarding: Access your home router's settings and create a port forwarding rule directing traffic on UDP Port 1194 to the internal private IP address of your VPN PC.
  • 4. Dynamic DNS (DDNS): Since ISPs change residential IPs frequently, sign up for a free DDNS service (e.g., DuckDNS or No-IP) to map a domain (like myhome.duckdns.org) to your home router's public WAN IP.
  • 5. Import Profile & Connect: Copy the generated .ovpn configuration profile to your mobile phone or laptop. Open the OpenVPN Connect app, import the profile, and connect to encrypt all external traffic back through your home internet gateway.