Please add an explanations what hosts it might connect to through open ports

[yurivict]

I opened ports 12555 and forban still shows nothing. My router connects up to the provider.
What hosts might it find through this port? Does it use the global DHT and is supposed to find others globally? Or, otherwise, what are the other hosts? How can they

I think, you should explain this in details here http://www.foo.be/forban/ to prevent such questions from being asked.

Also, my router doesn't have such choices source any, destination any. In such case, you should explain that users should set 0.0.0.0.

[adulau]

Forban is only designed for link-local networks. He will find other forban in same local-area network (via broadcast and multicast). There is no global DHT.