Some kind of site should supply kids with FREE minecraft servers with Whitelisting. Even just vanilla with whitelisting is good because there would be a whitelist. Config would probably look like this.
The X,* and numbers are just to hide the peoples usernames
CraftBukkit could be enabled but required a donation to the providers. On the other hand I think kids having their own servers for free for friends to play on is a good idea.
A minecraft server is their own world for them and their own group of friends. They only reveal the ip address and port address to their friends it allows them to play a great game of survival and creativity with their friends. Sure someone may find their server by accident but minecraft has ban as a default server handling verb when players are operators.
It can teach your child how to manage their money (you must pay to run a server) so in the future they can pay taxes and bills on time, because if you don't pay for the server monthly, it will close down. It will generally just help them in the future!
Minecraft servers makes up a very big part of the Minecraft community. By having their own Minecraft server, they can train up their social and coo-operation skills with other people. They can have the chance to interact more with other people and this can also teach them about how to act in public, etc. Plus, you can do more with teamwork in Minecraft. Things can be accomplished faster and overall, the kid is having more fun than ever. At the same time, he/she is also learning skills that you will never get from playing Singleplayer. Overall, it is a good idea.
I think, that if keeps need mine craft servers, than the game is more child-based now, i know the entire world is made of blocks and it is a very childish game, but it is more reasonable that kids do not own mine craft server because we do not need anymore mine craft servers that have a pathetic setup.
And only share the ip with close friends. This can lead to a lot of frustration if they open a server without setting some scripts (or whatever they are called) to avoid people logging in and destroying their creations, or if they share the ip on forums and someone with bad intentions enters.
They could be deceived into meeting adults pretending to be children. I get that it can be prevented if their parents teach them, but opening a minecraft server is so simple that they could be doing it on their own.