boinc-manager software package provides GUI to control and monitor the BOINC core client, 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-manager
boinc-manager is installed in your system.
Make ensure the boinc-manager package were installed using the commands given below,
$ sudo dpkg-query -l | grep boinc-manager *
You will get with boinc-manager package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | X Window System software |
| Package | boinc-manager |
| Version | 7.6.33+dfsg-4 |
| Description | GUI to control and monitor the BOINC core client |
| Sub Section | x11 |