I don't want to say anything in case I jinx it, but if it's a closed network, I think it should be much, much harder--[She won't say impossible, that's just inviting trouble.]--someone would have to know it existed in the first place. Surmising out of common sense wouldn't be enough. I think the only, or rather, easiest way to get into it is if someone had the right compass, so you might want to work from there.