but who could be so stupid to do bad things using its own name and its own registered domain?
How do I know you're you, that it's your domain, etc. :-)
Also it might not be you. EvilHacker may spend foolishly large amounts of time cracking your box.
Anyway, I hope that my quick fix can solve that problem
Yes it does. Although I still think that asking before making a network connection that the user didn't ask for is the only polite thing to do.