I've got my LinkStation Live 320 (HSDH320GL) configured as follows:
/web - Web access enabled. FTP enabled.
/usbdisk1 - FTP enabled.
Access restrictions are enabled for both of those shares. I have /web set up to allow guest read access (so that the webaccess feature can be accessible). There's also a user set up with r/w access to /web (for ftp purposes).
For /usbdisk1, there is no 'guest' access, but there is a user set up with r/w access.
/share is open access to my lan, but ftp and web features are disabled for that folder.
My firewall is configured to forward port 21 to the linkstation, and configured to support webaccess.
So... what have I missed? Aside from the potential of someone guessing or sniffing my ftp account password, am I reasonably secured?
You want to forward ports 20 and 21 (both are used for FTP).
These default users and groups that come preloaded on the unit are really only meant for access to the web interface, so I would highly recommend creating your own users and groups for data access (local, ftp, and http).
Aside from that, yes with using all of those features, that is about as secure as you can make it.