Nix Firewall Manager

Nix Firewall Manager is a graphical application for managing firewall rules on GLF-OS without using the terminal. It automatically generates the NixOS configuration and rebuilds the system.

Launch the application

Application icon:

The application is accessible from:

• the Applications > System > Nix Firewall Manager menu
• or via the terminal: nix-firewall-mngt

The following window will open:

Enable the firewall

On first launch, the firewall should already be enabled by default on GLF-OS.

1. From the application's main screen, you can enable/disable it using the main switch at the top of the window
2. Click Save and Rebuild

A window asking for your user account password to start the rebuild will appear:

Then the rebuild, once completed, will ask you to close the window:

Note: The NixOS firewall uses iptables / nftables in the background. Enabling it blocks all unsolicited incoming traffic by default.

Add rules

Manual rule

Click Add a rule and fill in:

Field	Description	Example
Name	A name to identify the rule	My web server
Protocol	TCP, UDP or both	TCP
Port(s)	Single port, range or list	8080, 27015-27030, 80, 443

Built-in presets

Preconfigured rules are available via the Presets button for common use cases:

Common services

Preset	Protocol	Port(s)
SSH	TCP	22
HTTP / HTTPS	TCP	80, 443
DNS	UDP	53

Gaming

Preset	Protocol	Port(s)
Steam	TCP + UDP	27015 - 27030
Sunshine / Moonlight	TCP + UDP	47984 - 47990
Minecraft Server	TCP	25565

Connectivity

Preset	Protocol	Port(s)
KDE Connect	TCP + UDP	1714 - 1764
Syncthing	TCP	22000, 21027
Samba (TCP)	TCP	139, 445
Samba (UDP)	UDP	137, 138

Info: Presets add the corresponding rules to your list. You can modify or delete them after adding.

Trusted interfaces

Some software (Docker, QEMU/libvirt) creates virtual network interfaces that need to be declared as "trusted" to work properly with the firewall enabled.

Click Trusted interfaces to add:

Interface	Usage
docker0	Docker
virbr0	Libvirt / QEMU (virtual machines)
br0	Network bridge

Warning

Be careful when designating an interface as "trusted": All traffic from this interface will no longer be protected! Think carefully about your needs before using this feature.

Save and apply

Once your rules are configured:

1. Click Save and Rebuild.
2. A terminal opens.
3. Enter your password if prompted.
4. Validate your password to start the operation which will automatically run sudo nixos-rebuild switch
5. Wait for the rebuild to complete.
6. Close the terminal when prompted.

Warning: Do not close the terminal before the rebuild finishes. If the rebuild fails, your old rules remain active.

How it works

The application generates a file /etc/nixos/customConfig/firewall.nix containing your firewall configuration in NixOS syntax, then automatically imports it into your configuration.

Example of a generated file:

{
  networking.firewall = {
    enable = true;
    allowedTCPPorts = [ 22 80 443 ]; # nfm:SSH # nfm:HTTP / HTTPS
    allowedUDPPorts = [ 53 ]; # nfm:DNS
    allowedTCPPortRanges = [
      { from = 27015; to = 27030; } # nfm:Steam
    ];
    allowedUDPPortRanges = [
      { from = 27015; to = 27030; } # nfm:Steam
    ];
    trustedInterfaces = [ "docker0" ];
  };
}

Info: The # nfm: comments allow the application to retrieve the names of your rules when next opened. Never edit this file manually — it is entirely managed by the application.

Theme

The application adapts to your system theme (light or dark). You can force a theme from the application preferences.

Available languages

Nix Firewall Manager is translated into 9 languages: French, English, Breton, German, Spanish, Italian, Dutch, Portuguese and Walloon.

---

\\\\---

© 2026 GLF