I want to make a website that can only be accessed via OPENVPN, and that OpenVPN can only access that website

I am maintaining an academic site using moodle. As usual cheating using floating apps and messenger is a big problem. I want to secure the device connection without using exam browser or anything but only using OpenVPN. The idea is that because I am hosting it in digitalocean I can somehow force student to use OpenVPN specific configuration, tunnel it into self hosted OpenVPN server, and somehow using that configuration I can block student connection only into my website without student be able to access another website. Does anyone know how to do that?

I have tried using blockconcurrent connection, but it is not enough.

I am sorry to tell you but this is not a way to protect exams of an academic institution. You should use proctoring solutions like smowl, proctorio.

Now as far your actual question it is possible to set up a self-hosted OpenVPN server and force students to use a specific configuration in order to connect to your academic site. In addition to that you can configure your server to allow access to your site and block access to other websites.

Here are some high-level steps you can follow to achieve this:

1. Set up a self-hosted OpenVPN server on DigitalOcean or any other cloud provider.
2. Configure the OpenVPN server to only allow connections from specific IP addresses, such as the IP addresses of your academic site's users.
3. Create an OpenVPN configuration file that students can download and use to connect to your server.

But a student is a student, and he will find a way to cheat if he wants.