How to determine the operating system using?

Question

bash

Hello! There is a task to check the user's OS by IP.
It is necessary that each time a client connects to the server, the server checks the user's OS by IP. It is desirable that it collects all the data that is possible, and if the OS is blacklisted, then block this IP through the firewall.
How can such a scheme be implemented with minimal delays and resource costs.

Answer 1

Start here

Answer 2

Hello! There is a task to check the user's OS by IP.
Monsieur, get some sleep.