I'm really afraid of crypto trojans stealing saved credentials for my NAS and encrypting all my backups.
I know I could turn off the NAS while not backing up but I want some convenience.
The backups are done using dejá-dup (Ubuntu's built-in backup solution).
As far as I know, dejá-dup only creates new files and does not modify existing archives.
The easiest solution I can think of is creating a share that only allows adding new files but not delete or modify existing ones. I did not find such an option on my QNAP TS 2-bay NAS - and on FreeNAS I cannot even find the place to set up FTP.
Which software would you recommend for my use case? Or is there a better solution?