This is work in progress, there's some content now and expect more in 2018 :-)Memory Game
Here you can find the source code.
Executables binaries for MS Windows as well as other operating systems (gnu/linux, MacOS) will follow soon!
My Linux Server is a virtual one and I'm not allowed to build kernel modules.
So iptables with module geoblocking won't work.
Therefore I wrote a small c++ program which downloads 2 files with German networks (IPv4 and IPv6).
My aim is to allow incoming traffic for http, https and smtp, but restrict access for management traffic from foreign countries.
You can download my programm here