How can I allow people outside the company to have access to a folder, but nothing else in our network so they can drop of files they are working on or download new files, etc. Basically a simple FTP setup for people who will be working together on a project.

I would like some security though as I don't want other people from in our company or outside it that don't have permission to manipulate or remove/add files since they are not part of this project. Just a select few would be good...or is it better to use our VPN and set up a limited access for them to a folder(s)?

As always thanks for the help in advance.