Virtualmin backup destination SFTP (is it available?)

OS type and version Alma 9.1
Webmin version 2.021
Virtualmin version 7.7.3
Related packages SUGGESTED

Having upgraded a Virtualmin managed server to Alma Linux 9.1, VM backup no longer works fully to my Synology (DSM 7.1.1) backup device.

The problem has several elements:

  1. RH version 9 systems (e.g. Alma 9) no longer support SCP file transfers by default. Instead using SFTP.

  2. Although my Synology has SSH configured on port 22, AND SFTP server on port 22 - it does not seem to accept SCP transfers using SFTP.
    The Synology does accept SFTP transfers using the SFTP command line and provides a sftp> prompt.

  3. I can override SCP to not use SFTP by supplying the -O parameter. VM backups then transfer the files correctly.

  4. However, override parameters (e.g. -O) are apparently applied to both SCP and SSH commands.
    Incremental backup history deletions appear to use SSH to list the directory and SSH does not accept the -O option, and the backup fails (only the history deletion part).

With the coming demise of the SCP protocol, I’d like to transfer the VM backup files using SFTP but I don’t see that option and the docs don’t mention it.

Could we have another “backup destination type” for SFTP?
Or separate command options for SSH and SCP?


I think you’d have to enable SHA-1 on RH9 to connect to legacy Synology, I vaguely remember someone on Reddit talking about a similar issue.

Personally, I wouldn’t do that except as a last resort. I’d rather try something else first. Maybe Rclone? Or maybe Synology has an update for their SSH server to support SFTP?

I really don’t know much about Synology. I’m just throwing an idea out there.


Thanks for the suggestion. It is not the problem (so presumably Synology supports a better cipher hash).
SSH works just fine, and SCP will work if I suppress it using SFTP (with the -O).
So connection is not a problem.

Full backups work with the -O option.
Incremental backups also require the -O for SCP but fail when SSH is given the -O option.

If I could specify -O for SCP and no extra parameter for SSH it would work.

But the better solution for the long term is to move away from SCP to SFTP direclty.
At least that’s the way I read it. I’m open to having my mind changed :slight_smile: