firehol software package provides easy to use but powerful iptables stateful firewall (program), 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 firehol
firehol is installed in your system.
Make ensure the firehol package were installed using the commands given below,
$ sudo dpkg-query -l | grep firehol *
You will get with firehol package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Network |
| Package | firehol |
| Version | 3.0.1+ds-3 |
| Description | easy to use but powerful iptables stateful firewall (program) |
| Sub Section | Net |