Backup solution Urbackup?

use rsync via ssh. It is easy to set up iif one of the servers is exposed to the internet port 22 (or whatever you use for ssh)

Yes,

First on source host as root create a ssh connection from source host to target host.

1. Create ssh key file pair using ssh-keygen
2. copy public key to target host using ssh-copy-id
3. try to log in to the other host with a key ssh -i path/to/key root@target and accept the key

In OMV:

1. Import the key
2. set up a rsync push job on source OMV

Yes, it should use the key automatically. What command line are you using to connect to target?

ssh -i <path/to/private/key> root@target

should work

Could you explain, how you are going to use the ssh / rsync?

in my understanding, it has to raun as root (at least on the receiving side), so it is able to chown file to the correct owner / group.

The home for root is /root on both sides (source and target) and the keys should be in /root/.ssh/<name_of_file_default_id_xxx and an authorized_hosts file should be there as well. Very narrow permissions for both. owned by the user (here root).

Show me the exact commands you are using and an ls -l ~/.ssh and ssh -v -i <key_file> root@target ls -la ~/.ssh

Is user1 a user created by OMV having a home dir?

Then it may be necessary to give new permissions to the home.

If you are not running as root at the destination, you will not be able to chown the transfered files tis may or may not matter.

I am using a pull backups (target pulls) and have a special authorized_hosts for this:

root@server05:/home/remote-backup/.ssh# cat authorized_keys
command="/home/remote-backup/bin/validate-backup-cmd.sh" ssh-rsa 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 remote rsync backup

Will only allow to execute a save rsnc command

root@server05:/home/remote-backup# cat bin/validate-backup-cmd.sh
#!/bin/bash
# echo "${SSH_ORIGINAL_COMMAND}" >> ~/remote-backup.log
case "$SSH_ORIGINAL_COMMAND" in
*\&*|*\|*|*\;*|*\>*|*\<*|*\!*)
        echo invalid command
        exit 1
;;
/usr/bin/rsync\ --server\ --sender*)
        sudo ${SSH_ORIGINAL_COMMAND}
;;
rsync\ --server\ --sender*)
        sudo /usr/bin/${SSH_ORIGINAL_COMMAND}
;;
*)
        echo invalid command
        exit 1
;;
esac

as root:

root@server05:~# cat /etc/sudoers.d/remote-backup
# remote backup
# allow user remote-backup to execue rsync as root
remote-backup    ALL= NOPASSWD:/usr/bin/rsync
root@server05:~#

I think something similair can be done with push backups too.

Quote from MarcS

Important:

The OMV setup for the rsync job (in the GUI) allows me to select 'key-authentication' but then it expects a key assigned in that menu. The keys to select from are NOT the SSH keys that are maintained in all the OMV user profiles. The SSH key for rsync has to be setup under OMV GUI-Certificates as a new SSH key pair. Now in order for that to be copied to the SSH destination host, ssh-copy-id must take the right SSH certificate. Interestingly, OMV saves the keys under /etc/ssh as files named [openmediavault...]

That'S what I meant with in OMV import the key. You do not have to create on inside OMV, but you can import an existing one.

ssh os allways encrypted. Use the -v flag to ssh to see log messsges