Commonly in some distros there is no Firewall installed by default, in the Minimal versions of Manjaro it is the case.
As most will think having a Firewalld is of some importance to protect your network from attacks and unauthorized entry into your network.
I have made this short and simple How To to install Firewalld, a Firewall that is easy to manipulate and that works based on security zones that you can configure for each of your network interfaces.
First is to install the package:
sudo pacman -Syu firewalld, or with pamac install firewalld
Once the package is installed, it will be integrated into the system, but it is not working as an active process, so it must be activated.
sudo systemctl enable firewalld
(“systemctl” is the process manager on systemd Manjaro systems and many modern distros use it, “enable” is for starting the process and letting it run at boot time).
Once up and running in DE as KDE Plasma, an “Icon” will be created in your bar if you use one with your Firewalld Started.
If you right click on it it will open a submenu and you can open its settings.
(Also from the menu you can run it probably has the name of Firewall).
You will notice a lot of information but you can focus on the zones, by default you should use “public”.
With that you can see that your system is working with a Firewall protection.
There are ways to also adjust the zones and configure it from the terminal with: firewalld-cmd.
(To see its user guide you can use firewalld-cmd --help)
“Note that some extra things will need to clear gates in your firewalld to work in case of KDE Plasma, KDE Connect has a registered service since enabling it to work.”
I hope this somewhat textual guide has been useful to you.