Unless of course Poiuyt joins.
This logs chat, bans, status, and dis/connections. Along with the connections are the IPs.08/13/10 11:55:32 D Xalos 11239 10.1.1.126No that's not my actual IP address as anyone with the slightest Internet knowledge will instantly know. It's my LAN address.10.#.#.# is a reserved range for LAN use. Or is it just 10.1.1.#? I forget precisely which.
Everyones IP is public information as DrenDran said. Anyone can get your IP simply by just connecting to your server but they can't hack you or anything. The worse they can do is try to get a slightly inaccurate idea of what city you live in.
As long as your ports are 28000-28000 -28030 there will be no problem.