VPN Test Environment with Docker Compose

This project sets up a VPN test environment using Docker Compose, allowing two remote clients to securely access an internal Ubuntu server and a simple web server on a simulated enterprise LAN.

Project Structure

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vpn-test/
├── docker-compose.yml
├── openvpn-data/
│   └── conf/
├── webserver/
│   └── html/
│       └── index.html
└── ubuntu-server/
└── client1.ovpn
└── client2.ovpn

docker-compose.yml: Defines the services (OpenVPN server, web server, Ubuntu server) and their configurations.
openvpn-data/conf/: Stores OpenVPN server configuration files, certificates, and keys.
webserver/html/: Contains the index.html file served by the internal web server.
ubuntu-server/: (Optional) You can place scripts or configuration files for the Ubuntu server here.
client1.ovpn: OpenVPN configuration file for client 1.
client2.ovpn: OpenVPN configuration file for client 2.

Prerequisites

Docker Engine and Docker Compose installed on your server machine.
Basic understanding of networking concepts (IP addresses, subnets, ports).
At least one another machine for testing.

Setup Steps

1. Project Directory

Create a directory for this project:
SH
```
mkdir vpn-test
cd vpn-test
```

Create subdirectories:

mkdir -p openvpn-data/conf webserver/html ubuntu-server

2. Docker Compose File

Create a file named docker-compose.yml with the following content:

YAML

services:
  openvpn:
    image: kylemanna/openvpn:latest
    container_name: openvpn-server
    cap_add:
      - NET_ADMIN
    volumes:
      - ./openvpn-data/conf:/etc/openvpn
    ports:
      - "40000:1194/udp" # Expose a non-standard port (>= 32768 for my Freebox)
    networks:
      - vpn_network
    restart: always

  webserver:
    image: nginx:latest
    container_name: internal-webserver
    volumes:
      - ./webserver/html:/usr/share/nginx/html:ro
    networks:
      - vpn_network
    restart: always

  ubuntu-server:
    image: ubuntu:latest
    container_name: internal-ubuntu
    command: tail -f /dev/null # Keep it running
    networks:
      - vpn_network
    restart: always

networks:
  vpn_network:
    driver: bridge
    ipam:
      config:
        - subnet: 172.20.0.0/16

3. Web Server Content

Create a simple index.html file in ./webserver/html:

HTML

<!DOCTYPE html>
<html>
<head>
    <title>Internal Webserver</title>
</head>
<body>
    <h1>Hello from Big local company Webserver!</h1>
</body>

4. Generate OpenVPN Configuration

Initialize OpenVPN and Generate Server Config:
SH
```
docker-compose run --rm openvpn ovpn_genconfig -u udp://YOUR_PUBLIC_IP:40000 -n 8.8.8.8 -n 8.8.4.4
```
- Replace YOUR_PUBLIC_IP with the actual public IP address of your server. (use curl ifconfig.me to get the public IP or check on google)
- Adjust the port (40000 here) if you chose a different one.
- -n option allows you to set DNS, here we use google's one, but you can use the one you prefer
Initialize the PKI (Public Key Infrastructure):
SH
```
docker-compose run --rm openvpn ovpn_initpki
```
- You'll be prompted to set a passphrase for the CA (Certificate Authority). Choose a strong one and remember it.

Generate Client Certificates:

docker-compose run --rm openvpn easyrsa build-client-full client1 nopass
docker-compose run --rm openvpn easyrsa build-client-full client2 nopass
...

Retrieve Client Configuration Files:

docker-compose run --rm openvpn ovpn_getclient client1 > client1.ovpn
docker-compose run --rm openvpn ovpn_getclient client2 > client2.ovpn
...

This will create client1.ovpn and client2.ovpn in your project directory.

The .ovpn file contains all the necessary parameters to connect to the server such as:

Server's address (IP or hostname) and port.
Protocol (UDP or TCP).
Certificates and keys.
Cipher and authentication settings.
Other options like compression, persistence, etc.

5. Configure Router (Port Forwarding)

If your server is behind a router (like Freebox), you need to configure port forwarding:
- Log in to your router's administration interface (e.g., 192.168.1.254 for Freebox).
- Find the "Port Forwarding" or "Redirection de Ports" settings.
- Create a rule to forward UDP port 40000 (or the port you chose) from the internet to the internal IP address of your server machine on port 40000.

alt text

6. Configure Firewall (Server)

If you have a firewall enabled on your server (e.g., ufw), allow incoming traffic on the OpenVPN port:
SH
```
sudo ufw allow 40000/udp
```

7. Start the Environment

Start the Docker Compose services:
SH
```
docker-compose up -d
```

8. Client Setup (Ubuntu Example for Client 1, my other Ubuntu laptop)

Install OpenVPN:
SH
```
sudo apt update
sudo apt install openvpn
```
Transfer client1.ovpn:
- Transfer the client1.ovpn file to your Ubuntu client machine (using scp, a USB drive, or other methods). I've used gmail mhahaha!!!
Connect (Command Line):
SH
```
sudo openvpn --config client1.ovpn
```
- Keep the terminal open while connected.
Connect (Network Manager - Optional):
- Import client1.ovpn into Network Manager.
- Connect through the Network Manager interface.

9. Testing the Connection

Verify IP and Interface:
- On the client, use ip addr show to check for a tun0 or tap0 interface with an IP in the 172.20.0.0/16 subnet.
Ping Tests:
- Ping the web server: ping 172.20.0.3
- Ping the Ubuntu server: ping 172.20.0.4
Access Web Server:
- Open a browser on the client and go to http://172.20.0.3.
SSH to Ubuntu Server (Optional):
- ssh username@172.20.0.4 (replace with the correct username and IP).

Look at openvpn in detail.pdf file to learn more about the core key exchange and tls.

Troubleshooting

TLS Key Negotiation Failed:
- Verify your server's public IP address in client1.ovpn.
- Check firewall rules on the server and router.
- Ensure port forwarding is configured correctly.
- Double-check for typos in commands.
netcat Test:
- On the server, inside the openvpn container: nc -u -l -p 5555
- On the client: nc -u YOUR_SERVER_PUBLIC_IP 1194
- Type messages to see if they are received on the other end. This tests basic UDP connectivity.
Cipher Issue (Warning):
- Add data-ciphers-fallback BF-CBC to both server.conf and client1.ovpn if needed (less likely to be the cause of major problems).
Other Issues:
- Examine OpenVPN server logs: docker-compose logs openvpn
- Check client-side logs.
- Consult OpenVPN documentation and forums.

Security Considerations (for Production)

Stronger Authentication: Use certificate-based authentication with strong ciphers.
Firewall: Implement a robust firewall on your server.
Intrusion Detection: Set up an IDS to monitor for suspicious activity.
Regular Updates: Keep all software up to date.
Principle of Least Privilege: Grant users only the necessary access.

This guide is for educational and testing purposes. It provides a basic setup and may not cover all security aspects required for a production environment. Adapt and enhance the configuration based on your specific security needs and best practices.

Setting up OpenVPN