Unregistered users

[thezoo]

How do I change the settings in my server options so that I only allow registered users to join my server? Any help on this would be greatly appreciated as I have been getting a few unwanted guests breaking in on my conversations with my friends.
P.S. Yes I have gone into my sever and unchecked all boxes reguarding unregistered users

[McAfee]

Put a general server password.
Registered users can use their account as normal.
Unregistered users will require the "general server password",
that in your case, no-one should know.

[Bastian]

And next time please use the search function cause especially this question has been answered more then 10 times now.