I ahd the same converned so when I installed osticket I put it in a secure portion of the site that requires users to log int before they get to the actual ticket page.
You can do this by including a .htaccess and .htpasswd file in the root directory of osticket
The .htaccess file would look like this
AuthType Basic
AuthName "osTicket"
AuthUserFile user/1302575/htdocs/osticket/.htpasswd
require valid-user
Note that the AuthUserFile is not the URL but the absolute path to your directory.
The .htpasswd file would look like this
user1
user2
user3r
Note that you will have to use a htpasswd generator to get the user name and encrypted password
This is a bare bones generator I use
(http://home.flash.net/cgi-bin/pw.pl)
CONS
You must edit the .htpasswd file everytime you need to add a user. If you do not have to many new users or a static pool of users then is not a big deal.
PROS
Cannot get by it even if they know the link to the ticket page or bookmark it. They only need to log in once unless they close the browser whic hcleares the cache information and they will be required to log in again.
There are some PHP or CGI scripts that will provide a user interface for you to manage the .htpasswd file and they are free. here is one I have looked at but have not used it
(http://www.locked-area.com)
Hope this helps
KRASH