If it tells you it wants port 8000, you don't need to open anything else. Giving java all ports == not a great idea. Make it ask for what it wants.
Lot of lazy developers out there, taking a "throw your legs wide open" approach. (We get packages all the time that say "set the protection on this directory to allow ANYBODY IN THE WORLD TO WRITE TO IT." Yeah, I'm really gonna do that for some lazy, fuggin', mommy-mating Pakistani freeware writer.)