How to block traffic country-wise?

[Dirk]

Hello,
I want to write a firewall that can block traffic from specific
countries using GeoIP.dat.

I downloaded libnetfilter_queue because I think it can do what I want.

1) Get IP of connection
2) Check local GeoIP database
3) Refuse or Allow connection

But the included examples don't work. Maybe I'm completely wrong by
starting with libnetfilter_queue or the included example?

Can someone give me a hint, example, snippet or link?

Thanks,
Dirk