How to restrict access to applications through proxy/VPN?

Question

Java

Good afternoon. I have an application with access to a resource on the network. I want to restrict access to users who use proxy/VPN on their devices. I decided to implement it in the application itself. Tell me an example, if any, or links to reading material for review, Ideally, an implementation mechanism.
I know how to get an ip address to use, but I don't know what to do with it and how to check it.
I wanted to block access by geo, let's say only the CIS, or Russia Ukraine (is it possible to implement this in the application). For other countries the resource is useless.

Answer 1

It is necessary to collect a database of VPN IPs and block them, there are a lot of such databases, you need to search in Google.
Of course, this does not give a 100% guarantee, because here you already need to trick it, however, as the simplest solution, it will do just fine.