Linux on Learning Journey of Alexander Allgäuer

YubiKey: SSH with FIDO2

Wed, 15 Apr 2026 00:00:00 +0000

The YubiKey supports four methods to enable hardware-backed SSH authentication.

FIDO2
PIV
PGP
OTP

FIDO2 provides the highest security and comes with low complexity. The private key is non-exportable.

Limitations

OpenSSH v 8.2.p1 is a requirement better 8.3 for the verify-required option, shouldn’t be an issue since both versions were released in 2020.
Windows SSH at the time of writing not supported.
The Mac OS bundled openssh version doesn’t support it but this can be fixed.

YubiKey: Autolockscreen via udev (Hyprland)

Tue, 14 Apr 2026 00:00:00 +0000

Automatically lock your Hyprland session the moment you pull your YubiKey out of the USB port. A udev rule triggers a screen lock script.

Read hyprlock doc first!

⚠️ : If you are using hyprland the default application to lock the screen is Hyprlock. Hyprlock does not automatically create a config, and without one, hyprlock will not render anything. But even without a config, your session will get locked and thus Hyprland will cover your session with a black screen.
https://wiki.hypr.land/Hypr-Ecosystem/hyprlock/

YubiKey: Passwordless Sudo

Tue, 14 Apr 2026 00:00:00 +0000

Use a YubiKey touch to replace your password for sudo .

Install pam-u2f

sudo pacman -S pam-u2f
mkdir -p ~/.config/Yubico

Register the keys

pamu2fcfg > ~/.config/Yubico/u2f_keys # primary key
pamu2fcfg -n >> ~/.config/Yubico/u2f_keys # append backup key

Edit PAM

⚠️ Warning: Keep a root session open in another terminal in case something goes wrong.

sudo nano /etc/pam.d/sudo

Add at the top:

auth sufficient pam_u2f.so cue

sufficient → the YubiKey alone is enough to authenticate.
Change to required if you want 2FA (YubiKey and password).
cue prints a hint when a touch is needed.

Test it

sudo -s
Please touch the FIDO authenticator.

Filesystem Comparison, ext4, btrfs, xfs

Mon, 13 Apr 2026 00:00:00 +0000

A good comparison between the ext4, btrfs and xfs.

https://www.linuxteck.com/linux-file-system-comparison-ext4-xfs-btrfs/