Dedicated server software

I'm looking at creating a dedicated server for several games (mainly BF 1942, CS:S & DM:S )

my problem is i want this to be a secure server so only certain people can access this. my problem is i need a program which will do indivdual passwords, rather than one server log on password this needs to be for the user it's self

EG:

Clan has 10 people - one person tells his friend how good this server is and give them the password - this means that one member is getting free server time when the rest are all chipping in for the server.

Hence my question - is it possible to create and run a server that unless the people on the clan list (ie to payers) can not join?

any idea?

If its for CS, the easiest way to do it is install something like mani's admin mod, which can restrict based on steam ticket (unique to player), IIRC theres a HL2:DM version, and theres prob something similar for BF2 knowcking around.

do you have a URL for this?

http://www.mani-admin-plugin.com/forums/portal.php

sorry, i wrote main the first time, meant mani