Thanks, I’ll try that.

The issue has happening on an increasing number of websites, though: Ecosia, ScienceDirect, TrainSplit (which thankfully has a fallback to hCaptcha), Indeed, and more.

Thanks. What’s your source for that list? I think you’re right that those measurements are factors in the final “bot score”, but I expect there are many other measurements also factored in.

If you look at my OP, though, you’ll see my browser passed the checks but was still blocked, which Cloudflare said shouldn’t happen.

It pops up on which page?

I can’t see it on either of the pages mentioned in my OP:

• https://developers.cloudflare.com/cloudflare-challenges/troubleshooting/challenge-solve-issues/
• https://browser-compat.turnstile.workers.dev/

I’m getting this issue in Chromium.

Like you, I’ve encountered it especially often in the last 3 weeks or so. Thanks for confirming it’s not just me!

Do you have a link to that feedback form, by any chance?

I eventually managed to find contact details for the webmaster for the site on which I most recently encountered this. Hopefully they’ll fix it in their Cloudflare configuration.

Failing that, I’ll try User-Agent spoofing. Failing that, another ISP, or VPN.

Cloudflare is already wrongly flagging this Linux box as a bot when it connects from an ordinary domestic ISP.

Surely it would be more likely to flag it if it was connecting from a VPN exit node.

No VPN present in this particular case.

Progress report 1

• I’m ruling out HMAC-SHA1, because:
  • Plain vanilla HMAC-SHA1 uses a shared secret. I don’t want the PC/server to have a copy of the credential. May also be susceptible to MITM/relay attacks.
  • Rolling-code HMAC-SHA1 only partially solves those problems.
  • Encrypted rolling code HMAC-SHA1 solves those problems, but I haven’t found a reliable source for using it with LUKS.
• If using systemd, pick FIDO2:
  • Avoids flaws of HMAC-SHA1.
  • Native support in systemd, so “future-proof”.
  • Wider support than OpenPGP. More HST vendors to choose from, including cheaper options than NitroKey or Yubikey: useful if each sysadmin (or colleague, or relative) needs an HST.
  • Compatible with QubesOS.
• Otherwise, OpenPGP:
  • Like FIDO2, solves HMAC-SHA1 flaws.
  • However:
    • smartcard-key-luks seems unmaintained on GitHub and on GitLab.
    • LUKS with OpenPGP isn’t well-documented for non-Debian-based distros.
• TBD: Clevis/Tang:
  • Remote/network-based unlocking.

Thank you for this! That thread is helpful in itself, and also links to other relevant resources - including by Lennart Poettering (controversial guy, but the canonical source on systemd).

I read them before writing my OP. I’m still not sure what you’re getting at.

I would be grateful if you could say what you mean, instead of initiating an oblique guessing game.

Which of the 4 recipes I posted are you referring to as “this”?

Thanks, please post relevant steps if you have specific recommendations.

For plain text & Markdown, you don’t even need Collabora. Since 2019, NextCloud has a built-in collaborative text editor.

it’s the only way!

TBF I was trying to follow the docs, aber ich spreche kein Deutsch.

I overlooked this line from the docs:

Benötigt werden cmake, git, libgd und libusb - bei manchen Distributionen (z.B. Ubuntu) sind die Header-Files in separaten Paketen “libusb-dev” die ggf. noch nachinstalliert werden müssen.

I should have done sudo apt install libgd-dev libusb-1.0-0-dev before attempting compilation.