It can't be said often enough: Backups are important. This is something you painfully realize at the moment when you need to restore something and don't have a backup. This magazine regularly presents backup applications and strategies to help readers avoid this kind of situation. Restoring the data in case of an emergency is equally as important as creating a backup, and something you definitely need to test up front.

The more valuable the data, the more important it is to have a well thought out backup strategy. For example, you could store backups locally for ease of access, but at the same time keep another backup in a secure location outside your home. This can be accomplished with a wide variety of tools for a wide variety of requirements. Duplicati [1] lets you do both with ease.

Duplicati Lab

Continuously evolving since 2009, Duplicati promises to securely store encrypted, incremental, and compressed backups on your home network, in the cloud, and on remote file servers. The open source backup client is licensed under the LGPL, and available for Linux, macOS, and Windows. On Linux it can be controlled using the GUI or at the command line.

Duplicati works with a large number of network protocols and services [2]. They include Amazon S3, Box, Dropbox, Google Cloud and Google Drive, Microsoft Azure and OneDrive, OpenStack Storage (Swift), SSH (SFTP), FTP, and WebDAV. The software also works with USB sticks or other external data carriers. You can also store backups on a NAS or on another computer on the same network.

This means that you don't have to trust the interfaces and the encryption techniques offered by proprietary services such as Dropbox, OneDrive, and others, but can ensure that your data is AES-256 encrypted prior to transmission. Alternatively, you can choose GNU Privacy Guard (GPG) for this purpose. Each backup includes a local SQLite-based database that stores information about the remote backup.

Installation

Duplicati is not available in the repositories of most Linux distributions; only Arch Linux provides it in the AUR. The website gives you the source code and packages for macOS, Windows, Synology NAS, Debian, Fedora, and other DEB and RPM-based distributions. A ZIP archive supports portable use without installing or command line-only operation. The current version for all platforms is 2.0.7.1. You install the Linux packages in the usual way with apt install or with dfn install on Fedora. Alternatively, you can set up Duplicati via software stores such as Discover on the Plasma Desktop or Gnome Software.

Mono or Not?

One more note before installing: Duplicati works with Mono, an open-source implementation of Microsoft's .NET framework, which is somewhat frowned upon by purist Linux users. The installation occupies up to 400MB on the hard disk due to Mono. Before the first startup, you need to create Duplicati as a systemd service. To do this, open the /etc/system/system/duplicati.service file and enter the contents from Listing 1. Then, enable the service using the commands from Listing 2.

[Unit]
Description=Duplicati web-server
After=network.target
[Service]
Nice=19
IOSchedulingClass=idle
EnvironmentFile=-/etc/default/duplicati
ExecStart=/usr/bin/duplicati-server $DAEMON_OPTS
Restart=always
[Install]
WantedBy=multi-user.target

$ sudo systemctl enable duplicati.service
$ sudo systemctl daemon-reload
$ sudo systemctl start duplicati.service
$ sudo systemctl status duplicati.service

After this preliminary work, the software will ask you at first start if more than one user is using the installation; if yes, it will tell you to assign a password. After doing so, a clear-cut interface appears. It launches automatically after you press the button in your browser's taskbar, thanks to a small web server running on port 8200. The advantage of this is that Duplicati also runs on devices such as a NAS without a display.

Your first task is to check the settings. Among other things, you can set the password here, if needed, and grant access on your home network by checking the box. You can also specify how long you want the system to wait after start-up or wake-up before starting a backup it missed previously.

If necessary, you can choose a different language for the user interface or switch to dark mode. It is best to leave the default, Beta, as the update channel setting. In the case of anonymous usage statistics, you can decide if and what you want developers to know about your usage of Duplicati. Last but not least, there are many advanced settings available in Settings; I will not be going into these settings here.

Besides the settings, the sidebar provides options for adding backup and restore tasks. A click on Home shows the current status with backups you already created and the next scheduled task. To the right, you can pause the backup process or limit the connection bandwidth.