iirc you could use phex and try a private ip storing server, which only you and your friends know about.

After some time you wouldn't need it anymore (in fact after one run), because phex still uses a host-catcher. If noone connects outside the network you have a private network.

You can have that bit easier, if you have a few friends with static ips. Then you put them into auto-connect of phex and let the program do the rest.

Voila, your own private network.

jJst make sure you and all your friends delete the other auto-connect hosts before, or you'll become part of the whole network, as the host-catcher gets other ips.

I wish you good sharing and "Hail To Phex"! :-)

(URL of Phex: http://phex.sourceforge.net/)