I've been trying to accomplish this very thing. After years of having a home NAS of some description I decided for a number of different reasons to rent and setup a remote server to download and steam my content from. I know there are quite of few of Seedbox companies out there that provide this service but they are restrictive and can be costly. I now rent a OVH/Kimsurf server and have installed Ubuntu 12.04 server, rTorrent, and run Apache2 server for web content. I have very basic Linux skills so this was a little tricky but there are some resources out there to do such a thing.
I thought it would simply be a matter of pointing XBMC to the same network path which I'm able to view content in my browser (with login info). XBMC does support http and https streaming so it didn't seem unreasonable. I'm able to view my download folder in any browser but for whatever reason I can't get XBMC to connect.
https://www.digitalocean.com/community/t...untu-12-04
I haven't attempted to use FTP, I'm sure it work work but I've read it's not the protocol you want to use for streaming media on the WAN. I may try SFTP (which is not related to FTP) and see how that goes.
If anyone else wants to recommend a good protocol to try that is easy to setup on a linux server and works well with XBMC I'd be happy to try it. I hear Upnp works so-so with XBMC but developers are working on it.
Edit: I've tried SFTP with no luck. I can easily connect with WinSCP on the same computer but not though Kodi.
Be prepared for headache and heartbreak....