How To Use A Digital Ocean VPS And Caddy As A Reverse Proxy For A Self Hosted Raspberry Pi Website (Behind A Firewall) Using An SSH Reverse Tunnel

This tutorial is inspired by a question posted on the Rasberry Pi Stack Exchange site titled “Website behind Firewall: How to SSL through a Reverse SSH Tunnel?”.

A little background. The person posting the question is using a Raspberry Pi to host a website and has opened a reverse SSH tunnel from their Raspberry Pi to a VPS..for the sake of this tutorial, a Digital Ocean VPS. The original poster has pointed DNS for a custom domain to the Digital Ocean VPS and would like to know how to access the Pi’s website from said domain.

In this tutorial we will cover setting up a self hosted website using a Raspberry Pi and Docker. Obtaining and setting up a Digital Ocean VPS. Installing Caddy on our VPS to be used as a proxy server to route traffic to our custom domain back to the Raspberry Pi via an ssh reverse tunnel. An added benefit of using Caddy is that Caddy will obtain a free SSL certificate via Let’s encrypt for us.

So, if this is of interest to you continue reading…

What is a Raspberry Pi?

Raspberry Pi is an ultra affordable computer the size of a credit card and can be had for as little as $35 dollars for a 2GB model capable of running Raspberry Pi OS and Ubuntu. For this tutorial we will also be running Docker on the Raspberry Pi and use an Apache Docker container to host our website.

What is a Digital Ocean VPS?

Digital Ocean is a cloud provider offering services ranging from managed databases and storage to hosted Virtual Private Server (VPS) solutions. A VPS is a virtual computer hosted on managed infrastructure. You don’t have to worry about the underlying hardware, but have to manage the OS on the VPS.

What is SSH?

SSH is a secure shell typically used for server administration. It allows a remote system to access another system using public/private key pairs to secure the connection. In our use case we will be using the SSH session to create a reverse tunnel from our Raspberry Pi to a Digital Ocean VPS. You can SSH into another system with the following command.

ssh user@ip

Where “user” is the username with access credentials on the remote server and “ip” is the FQDN or IP address of the remote system.

What is a Reverse SSH Tunnel?

A reverse ssh tunnel is a tunnel in which the originating system maps a port on the remote system giving the remote system access to services on the originating system. Later in the tutorial we will create a reverse tunnel from the Raspberry Pi with the following command

ssh -R 8081: user@ip

As you can see the SSH command is a bit different for a reverse tunnel. The -R flag is where the magic happens. We are telling our Digital Ocean VPS that any request made to port 8081 should be forwarded over the tunnel to port 8080 on the Raspberry Pi

What is Caddy?

Caddy is an open source web server that automatically takes care of SSL provisioning via Let’s Encrypt. In our use case we will be using Caddy as a Reverse Web Proxy for our self hosted site. This is the piece that will allow our VPS to serve pages from our Raspberry Pi which is being tunneled to our VPS via SSH. That was a bit long winded…but, hopefully it makes sense.

What is a Reverse Proxy?

A reverse proxy is a server that sits in front of an application server, in our case the Raspberry Pi, and will proxy requested made to our VPS via our custom domain name to the Raspberry Pi.

Proxies add a layer of security by limiting public access to the proxy server — allowing our application servers to be hosted in a more isolated network such as our home.

Self Hosting a Website on the Raspberry Pi

For demonstration purposes, and in case you don’t already have a self hosted website, let’s set one up quickly using Docker via the command below (hint…this will work on any server or desktop that has Docker installed…not just a Raspberry Pi).

docker run -dit -p 8080:80 httpd

With this command we are asking Docker to run the Apache httpd container and map it to port 8080 on the Raspberry Pi.

For the sake of brevity I will not go into setting up Docker. If you don’t already have Docker installed you can install Docker Desktop fairly quickly with the Get Started with Docker link found in the reference section below.

Now that we have a website up and running we can navigate to it via our browser. My Raspb