boinc-screensaver software package provides screen saver auto-controlling volunteer computing, you can install in your Debian 9 (Stretch) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install boinc-screensaver
boinc-screensaver is installed in your system.
Make ensure the boinc-screensaver package were installed using the commands given below,
$ sudo dpkg-query -l | grep boinc-screensaver *
You will get with boinc-screensaver package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | X Window System software |
| Package | boinc-screensaver |
| Version | 7.6.33+dfsg-4 |
| Description | screen saver auto-controlling volunteer computing |
| Sub Section | x11 |