May I suggest an easier (and quicker) solution?
We could add a psw entry in netpanzer-dedicated.ini. The server admin can choose to add a password (or a list of user:passwords) which is then requested to all players who want to join (at connection time).
The password is given to all registered players (netpanzer.org and .info communities or other) - via control panel on the website or email etc
This is very useful also for tournament management, when you need to invite certain players only. In the future we could have a "spectator" psw and a "player" psw
Banning is a bit more problematic since one can transmit the new password to a friend
banned player... (though multiple passwords could help identify the spy, hehe)
I know this is a easy-to-circumvent protection, but probably enough for our purposes and not so complicated to reallize.
Btw, another useful entry in netpanzer-dedicated.ini could be a "all-allied" flag to prevent automatic shooting as one spawns in.