Specs:
Operating System: KDE neon 5.25
KDE Plasma Version: 5.25.3
KDE Frameworks Version: 5.96.0
Qt Version: 5.15.5
Kernel Version: 5.15.0-41-generic (64-bit)
Graphics Platform: X11
Processors: 16 × 12th Gen Intel® Core™ i7-1260P
Memory: 15.2 GiB of RAM
Graphics Processor: Mesa Intel® Graphics
Manufacturer: Dell Inc.
Product Name: XPS 9320


Basic Steps:
1. Ensure your device is supported https://fprint.freedesktop.org/supported-devices.html
2. Ensure your device is listed on your machine: run

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lsusb

A. Example return:

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27c6:63bc Shenzhen Goodix Technology Co.,Ltd. Goodix USB2.0 MISC

B. It's also a good idea to see how linux runs with your specific sensor. https://linux-hardware.org/?view=search Vendor ID = first 4 chars from ID listed in lsusb. Device ID = last 4 chars from ID listed in lsusb.

3.

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sudo apt install fprintd

4.

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sudo apt install libpam-fprintd

5. Add your fingerprints via KDE User settings


6. Check the fingerprint box in the opened GUI(nav using arrows and spacebar), saved by pressing enter.

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sudo pam-auth-update

7. Add these strings to both the sudo and sddm(kde for some users) files located in /etc/pam.d/

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auth    sufficient      pam_unix.so try_first_pass likeauth nullok

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auth    sufficient      pam_fprintd.so

8. You are done.
A. When logging in, press enter with an empty password field, or press the arrow key, and scan your registered print(s).
B. When running sudo in the terminal, press enter instead of a password then scan your registered print(s).
C. When running privileged GUI windows, it should prompt you for either your password or registered print(s). NOTE: I have noticed a few windows still require a password and do not even prompt for alternative auth methods.


If you have previously used the fingerprint sensor, or it's just still not working, try this:
1. Remove fingerprints on sensor using whichever method works for you(AppImage worked for me)
A. Python3 https://community.frame.work/t/reset-fingerprint-scanner/8699
B. AppImage https://community.frame.work/t/fingerprint-scanner-compatibility-with-linux-ubuntu-fedora-etc/1501/214
C.

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sudo fprintd-delete "$USER"

2. Try to add your print(s) now.


fprintd terminal debugging:
1.

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sudo fprintd-enroll

2. If the device keeps disconnecting, or you get an unknown error, you probably need to update your sensor.
A. Example errors:

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An unknown error has occured

|

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Impossible to enroll: GDBus.Error:net.reactivated.Fprint.Error.NoSuchDevice: No devices available

|

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Verify Stop failed: GDBus.Error:org.freedesktop.DBus.Error.UnknownMethod: No such interface “net.reactivated.Fprint.Device” on object at path /net/reactivated/Fprint/Device/0

3.

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sudo apt install fwupd

4. See if your system can see the device using: (NOTE: Mine couldn't using fwupd but this still worked for me)

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fwupdmgr get-devices

5.

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fwupdmgr refresh --force

6.

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fwupdmgr update

7. Reboot immediately.

8. fprintd-enroll should work now. Use the KDE User fingerprint GUI to add your print(s).

9. If you still have the error device already claimed, run

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sudo service fprintd stop

Summary of events:
-Switched from Windows 11 (previously had fingerprints on Hello and forgot to delete them). I wiped my drive and installed KDE Neon (User Edition as of 25JUL2022), but after installing fprintd every attempt to add/configure prints resulted in an unknown error. Looked up different error records and figured I needed to delete my old prints - I did and it still didn't work. Next I updated my sensor and it still was shooting errors out. So i installed libpam-fprintd and added them to the Auth with pam.d - boom, I can add prints now... but they still wouldn't do anything. So, after adding the lines to the sudo and sddm files in the /etc/pam.d dir, now I can use prints for sudo, privileged windows (mostly), and the login screen.
-I am new to Linux, I have distro hopped for the last couple weeks(from Ubuntu to Arch and all the top 20s/30s/etc lists I could find) and decided on KDE Neon for now, I like it.
-Sorry for the bad formatting, I don't like it either.


Listed below are all the links I used to get this working:
https://fprint.freedesktop.org/
https://community.frame.work/t/reset-fi ... anner/8699
https://community.frame.work/t/fingerpr ... c/1501/214
https://unix.stackexchange.com/question ... the-device
https://askubuntu.com/questions/878072/ ... dy-claimed
viewtopic.php?f=309&t=174078
https://forum.endeavouros.com/t/how-to- ... 24/24401/6
https://linux-hardware.org/?view=search

Hi there,
Thanks a lot for taking the time to write this post down to help others.
I'm trying to set up the fingerprint reader to work on Kubuntu 22.04 and Plasma 5.24.4, while I could get the fingerprint adding dialogue in the system settings to work, I couldn't actually get it to authenticate by following this tutorial. The problem is, where exactly do the lines in the /etc/pam.d/sudo and sddm should be placed? I added these lines to both and afterwards, I could no longer log in to the system anymore, probably because I broke the authentication system by adding lines incorrectly to those two files. So had to restore to an earlier snapshot using Timeshift.
Since I could not figure it out by myself, is it possible for you to post the contents of the “sudo” and “sddm” files inside /etc/pam.d/ from your laptop? — or parts of it that will make clear where these lines should be added – since I could not figure it out by myself? It would be a really massive help if you could do this!

Any idea how to properly undo this? (because for me this solution is very unstable and i now need 4-5 Times to get logged in)
In am attempt to undo the steps I undid the changes to the both files. I couldn't login anymore 😭
Any ideas?
Should I uninstall fprintd or libpam-fprintd first? Do i need to pam-auth-update again?