I considered this when setting up my imageboard.

It's hosted locally on my server, using typical cable ISP bandwidth. It's a board for a PvPGN server, and I just decided to stop being such a pussy and allow image replies/threads.

I'm genuinely worried that people will attempt to post illegal materials to my imageboard. I'm not sure how to prevent it, since basically anyone can do it at any time without my knowledge, and I'm not sure what exactly I do (what can I do?) when it does happen. Not just to avoid attracting any unwanted law enforcement attention, or to cover my ass, but to make sure that it doesn't happen again and that the people responsible are reported to the appropriate authorities.