This post quickly introduces encrypted folders and backing them up on a Synology NAS. It focuses on how to restore those backups, as this is not straightforward.
Encrypting shared folders
Creating an encrypted folder on a Synology NAS can be done easily, as described in detail by Synology here. Note: Don’t store you password on the NAS (Mount automatically on startup option), because this will render encryption useless! You don’t write the password to your computer on the display, do you?
Versioned backups – only for unencrypted folders!
Synology offers the Time Machine package that can be used to create different versions of stored file. However, this does still not work with encrypted folders (as of version 1.2-2300). Why Synology, why?
A simple backup solution for encrypted folders
Fortunately, there is an alternative that provides at least rudimentary ways for backing up data: The Backup and Restore package.
Once the encrypted folder is mounted, Backup and Restore can be used to create a local backup for all or some of the folders contained within the encrypted folder. Backups can be create for example on a daily, weekly or monthly basis. Unfortunately, it’s not possible to keep several versions of a backup – that’s what Time Machine would be for 😦
Note: The Maximum number of kept versions only relates to the NAS configuration, not to the data!
Restoring encrypted backups – almost impossible?
By now, our data gets backed up regularly by the NAS. But how to restore a file, in case of emergency? There is the Restore tab within the Backup and Restore package. For encrypted backups, you can only use it to restore all or nothing. You can’t even choose where to restore the data to. That is, if you want to restore a single file, your only option is to overwrite all of your productive data. In other words: This is useless.
Restoring encrypted backups – a comfortable workaround
There is a workaround, however, that will make the backups accessible like any other shared folder:
- On the web interface of your NAS: Create a new shared folder, use the same password as for the encrypted folder that should be backed up. Let’s call it myBackup.
Use the Read only permission within the Privileges setup in order to protected your backups.
- Unmount the new folder
- SSH to your NAS
- Delete the container you just created. For example:
rm -r /volume1/@myBackup@
- Create a link to the backup that is named just like the container. For example:
ln -s /volume1/backup/folder/@folder@ /volume1/@myBackup@
Where backup is the shared folder where the backup was written to by the Backup and Restore package and folder is the name of the folder within backup that was set up in Backup and Restore.
- Go back to the web interface and mount the folder using the password of the encrypted container.
That’s it. You can now access the backup like any other folder (SMB/CIFS, NFS, FTP, …)
Restoring encrypted backups – mount backup on separate system
As an alternative, you could also mount the encrypted folder on any other Linux system.
Synology uses EcrytpFS to encrypt shared folders. Those can be mounted on a separate Linux system, as described here:
- HOWTO Recover Synology encrypted folders in Linu
- How do I decrypt / unencrypt or decipher Synology NAS encrypted drives?
This is useful for remote backups or when your Synology Diskstation should be damaged but the hard disks still work.