Ransomware-safe backup of your Windows Client without any Backup Software

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Windows Setup

  • Add a new user like "unraid" through Computer Management > Local Users and Groups, use a strong password, disable password change
  • Right click on a folder like "Documents" and click on "Advanced Share" to enable sharing this folder, delete "Everyone", add "unraid" with "read-only" permissions (this enables sharing the "Documents" folder)
  • Now click on "Share" and again add the user "unraid" with the "read-only" permission (this enables sharing all content and subfolders, ask Microsoft why you need both steps ;)  )
  • Repeat this step for each folder you need to backup


Unraid Setup

  • Add Windows SMB Share through Unassigned Devices, skip "Domain"
  • Repeat this step for each shared folder
  • Disable "Share" and enable "Auto-Mount". "Mount" all Shares


rsync Setup

  • Add the rsync script through CA User Scripts and set the paths accordingly
  • Set schedule like "Hourly"






  • As long the backup path is not a writable share, this is safe against ransomware as our server has only read permissions on the client and the client has no permission on the server at all.
  • It seems to be easier, but do not share your full user path (C:\Users\USERNAME) as this path contains the hidden "AppData" directory which contains a massive amount of temporary files and thousands of useless files. If you want to backup a specific app, then add a share to its folder like "C:\Users\USERNAME\AppData\Roaming\Thunderbird\Profiles".
Edited by mgutt
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"chattr +i" does not allow incremental rsync backups as it disallows new links to already existing files. This is only something which could be used before an after creating a backup to guard it in the meantime. But I do not really see a benefit as the backup folder is not reachable by usual users and if the attacker gets root access the immutable bit could be easily removed.

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