TUXEDO OS: Plasma Firewall explained - TUXEDO Computers

Ubuntu comes with the firewall UFW, which is a frontend for the Netfilter framework of the Linux kernel. The abbreviation stands for Uncomplicated Firewall. For many users, however, it only becomes uncomplicated with an added graphical user interface. 

For Ubuntu and other GNOME-based distributions, GUFW is the recommended interface. However, since TUXEDO OS uses KDE Plasma as its desktop environment, we have preinstalled the Plasma Firewall application introduced with Plasma 5.21.1 as a graphical interface for controlling UFW. It is integrated in Plasmas systemsettings as a module and can be found in the sidebar under Network → Firewall.

Alternative: FirewallD

In addition to UFW, the Plasma Firewall module also works with the somewhat more professionally oriented firewall management tool FirewallD, if this is more suited to your needs. It is important that you have not installed any other GUIs to control a firewall, when using Plasma-Firewall. If you have manually installed such an application, please remove it before using Plasma Firewall. If you are using another distribution with the plasma desktop, you can install the Plasma Firewall via the package management under the package name plasma-firewall.

Application

When you call up the module in systemsettings for the first time, set a check mark at the very top of Firewall Status to activate the module. Then restart the firewall with the command
 
sudo systemctl restart ufw.service
or in case of firewalld

sudo systemctl restart firewalld.service

Set rules

In the graphical module, below the activation, you will see the two basic rules that are usually preset, which determine that incoming network traffic is blocked, while outgoing traffic is allowed. To make the firewall more permeable for desired incoming traffic, you can now define exceptions via the Add rule button at the bottom right of the window.



The operation is largely self-explanatory. You select an application from the list, whose incoming communication is to be allowed, switch the control to Allow and the direction to Incoming. Finally, confirm with Create.



If you tick Advanced, the input mask changes and you can manually enter the source, destination and the respective port as well as the protocol and interface if required. Clicking on Show Connections shows the current connections and allows you to blacklist a selected connection. 

Who needs a firewall?

Perhaps you have already read the widespread view on the Internet that you require neither virus protection nor a firewall when using Linux. But is that true? When it comes to firewalls, the answer is a resounding yes and no. Many routers, such as the popular FritzBox, already come with a firewall that protects the entire network at home. However, if you hook a notebook or other mobile device into this network that has caught a malware outside, it can still spread in the network and infect other computers. For this reason, devices that dial into foreign networks outside the home should for good measure use a firewall.