CrushFTP can be run as the reverse proxy server, or as a back end server with Apache in the front end (Reverse Proxy Apache).

To make CrushFTP be the reverse proxy, you need to have an entire sub-domain that you want proxied. For example, www.crushftp.com goes to one server, but example.crushftp.com could hit the same server, but be reverse proxied to another server behind CrushFTP.