[Ubuntu 14.04] My Plex server does not require authentication for remote access ! How to fix that ?

Hi,

I'm running a Plex server on Ubuntu 14.04, and I've allowed remote access. I've got a domain name that points to this plex server.

When I use this domain name from outside my local network, I can access my medias without being authenticated. Worst, I can even edit the server settings ! What can I do to fix this authentication issue ?