Basic user management for duplicati backups

In the backup server create a new user without login password. This user should only have access via a SSH key. Generate one with ssh-key, and register the public key under the .ssh/authorized_keys file.

We should have access via SSH using the private key: ssh -i id_rsa user@server. We need to clone this repository under this user, so we can send commands:

ssh -i keys/id_rsa user@server usrmgmt/um -h