broadcom-sta-dkms software package provides dkms source for the Broadcom STA Wireless driver, 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 broadcom-sta-dkms
broadcom-sta-dkms is installed in your system.
Make ensure the broadcom-sta-dkms package were installed using the commands given below,
$ sudo dpkg-query -l | grep broadcom-sta-dkms *
You will get with broadcom-sta-dkms package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Kernels |
| Package | broadcom-sta-dkms |
| Version | 6.30.223.271-4 |
| Description | dkms source for the Broadcom STA Wireless driver |
| Sub Section | Kernels |