Created attachment 153907 [details]
The screenshot shows the New Firewall Rule dialog.

SUMMARY

In System Settings -> Firewall tab, the dialog that opens by pressing the Add Rule... button is not very usable. The two fields for source and destination addresses are too narrow and are not able to display a full IPv4 address, let alone IPv6. They also don't allow to enter a network mask. The port fields are also too narrow to fit port numbers beyond two digits and do not allow entering service names (e.g. ssh, http).

See the attached screenshot.

STEPS TO REPRODUCE

1. Open System Settings -> Firewall tab. Enable the firewall, if not enabled already.
2. Press Add Rule... button in the lower right.
3. Try entering a network mask 192.168.10.0/24 in the Source field.
4. Try entering a service name in the Destination port field, e.g. http.

OBSERVED RESULT

The address doesn't fit in the field. Pressing / does nothing, the field does not allow this character. The port fields do not accept non-numeric characters.

EXPECTED RESULT

The Source and Destination fields should be properly sized, at least to be able to show a full IPv4 address such as 255.255.255.255/32. The port fields next to addresses should also be wider to be able to fit all port numbers (i.e 65535).

The address fields should allow to enter an address mask in the address/width notation.

The port fields should allow service names.

SOFTWARE/OS VERSIONS

Operating System: Kubuntu 22.04
KDE Plasma Version: 5.24.6
KDE Frameworks Version: 5.92.0
Qt Version: 5.15.3
Kernel Version: 5.15.0-53-lowlatency (64-bit)
Graphics Platform: X11
Processors: 16 × 12th Gen Intel® Core™ i7-12700K
Memory: 31.1 GiB of RAM
Graphics Processor: NVIDIA GeForce RTX 2080 Ti/PCIe/SSE2