It is possible to create a private directory?

Hi,
I would like to know if it is possible to create a private directory, where only approved users can have access to view and search the database?

Here is what I have in mind. I belong to a large real estate company and we have large number of exclusive internal home for sale listings every month in all the different offices. Currently we send out a spreadsheet with the properties info. I would be great to create a searchable listing directory with the properties info, but only the real estate agents in this company would have access to search this listing directory. Is this possible with geodirectory?

In other words, the users would have to log in before they can view any properties.
and maybe they have to log in too before posting any properties.

Let me know.
Thank you.