OpenVPN setup and telemetry transmission via MAVProxy on Raspberry Pi

1. Task

Create a reliable VPN network using OpenVPN for remote connection to Raspberry Pi, which uses a dynamic IP address. Ensure telemetry transmission via MAVProxy.

2. Requirements

Hardware:

• Raspberry Pi with Raspberry Pi OS (or similar) installed.
• Server with a static IP address for setting up OpenVPN.
• Access to the server via SSH.

Software:

• OpenVPN (server and client).
• Utility ddclient for dynamic DNS (if necessary).
• MAVProxy for telemetry transmission.
• Python (for working with MAVProxy and drone-related utilities).

3. Setup Steps

3.1. Installing OpenVPN on the Server

1. Install OpenVPN on the server:

      ```bash

      sudo apt update

      sudo apt install openvpn easy-rsa

      ```

2. Configure PKI (Public Key Infrastructure) for creating certificates:

      ```bash

      make-cadir ~/openvpn-ca

      cd ~/openvpn-ca

      source ./vars

      ./clean-all

      ./build-ca

      ```

3. Create keys for the server and clients:

      ```bash

      ./build-key-server server

      ./build-dh

      openvpn --genkey --secret keys/ta.key

      ./build-key client1  # Repeat for each client

      ```

4. Configure the OpenVPN server. Example configuration (/etc/openvpn/server.conf):

   (`/etc/openvpn/server.conf`):

      ```

      port 1194

      proto udp

      dev tun

      ca ca.crt

      cert server.crt

      key server.key

      dh dh2048.pem

      tls-auth ta.key 0

      keepalive 10 120

      cipher AES-256-CBC

      persist-key

      persist-tun

      user nobody

      group nogroup

      status openvpn-status.log

      log /var/log/openvpn.log

      verb 3

      ```

5. Start the OpenVPN server:

      ```bash

      sudo systemctl start openvpn@server

      sudo systemctl enable openvpn@server

      ```

3.2. Configuring OpenVPN on Raspberry Pi (Client)

1. Install OpenVPN on Raspberry Pi:

      ```bash

      sudo apt update

      sudo apt install openvpn

      ```

2. Obtain the client configuration file and keys from the server:

   • For example, copy them using scp.

3. Configure the client configuration file

   (`/etc/openvpn/client.conf`):

      ```

      client

      dev tun

      proto udp

      remote YOUR_SERVER_IP 1194

      resolv-retry infinite

      nobind

      persist-key

      persist-tun

      ca ca.crt

      cert client1.crt

      key client1.key

      remote-cert-tls server

      cipher AES-256-CBC

      verb 3

      ```

   


4. Start OpenVPN on Raspberry Pi:

      ```bash

      sudo systemctl start openvpn@client

      sudo systemctl enable openvpn@client

      ```

3.3. Configuring Dynamic DNS (if necessary)

If Raspberry Pi uses a dynamic IP address, you can set up dynamic DNS using ddclient:

1. Install ddclient:

   ```bash

      sudo apt install ddclient

      ```

2. Configure ddclient to update DNS records (for example, via No-IP or DynDNS service).

3.4. Configuring MAVProxy for Telemetry Transmission

1. Install MAVProxy on Raspberry Pi:

     ```bash

      sudo apt install python3-mavproxy

      ```

2. Configure MAVProxy for telemetry transmission over the VPN tunnel. Example command for data transmission:

      ```bash

      mavproxy.py --master=/dev/serial0 --baudrate 57600 --out udp:YOUR_VPN_IP:14550

      ```

3. On the client side (on your computer or another device), you can connect to the telemetry using the IP address provided by OpenVPN.

3.5. Testing

1. Connect to Raspberry Pi via VPN from the client.

2. Check telemetry transmission via MAVProxy:

   • Open Mission Planner or QGroundControl on the client device.
   • Check the connection to MAVProxy via UDP.

4. Documentation

• Detailed description of all setup steps, including installation, configuration, and testing.
• Troubleshooting section and common issues (for example, OpenVPN connection problems, lack of telemetry via MAVProxy).

5. Acceptance Criteria

• Remote connection to Raspberry Pi via OpenVPN works correctly.
• Telemetry is transmitted correctly via MAVProxy, and data is available on the client device.