CryptBackup is an encrypted backup application for Linux desktop users. It allows even a layperson to backup their home directory (including the desktop) on an encrypted external device with just a few clicks. Even the setup is only to choose the external device (such as an external hard drive) and to set a password.
Arkeia Network Backup Enterprise Edition for Ubuntu LTS is a completely free version of the Arkeia Network Backup software specifically for Ubuntu servers. It is available in the Ubuntu LTS (Long-Term Support) software repository. It allows an administrator to backup and restore files via a Web UI. This edition has the option to backup up to 2 machines to a 250 GB VTL or tape drive. It allows you to backup Linux machines, Windows desktops, Mac desktops, FreeBSD servers, and more.