XServe FTP – stopping access to main folders?

Hi

Can someone please advise me on how i can stop a user accessing other folders outsdide there designated home directory when using FTP on a MAC xserve?

At the moment if a user uses Firefox, and the standard FTP address settings, they get dircected to the appropriate home directory. however, they can then click “up a level” and access all the other folders on the system. As far as i can see i have set all the settings on the server correctly, but i’m guessing i’ve missed something simple.

any help would be great

running a xserve and xraid combo

thanks

jimzippy