Move standalone repository docs from the root into docs/ and add a documentation index that links the moved docs and the code-local runbooks.
Update Markdown links, source comments, and the root entry points to the new locations. Keep README.md and AGENTS.md at the root as required entry points.
Assisted-by: DeepSeek Harness (deepseek-flash)
The homelab hosts accept root SSH with long-lived file keys, run several
exposed services with almost no systemd sandboxing, and keep no audit trail of
privileged actions. Close those three gaps, weighing each measure against its
cost instead of adopting a policy wholesale.
SSH
- Turn off KbdInteractiveAuthentication: nixpkgs defaults it to true and PAM
then still accepts the Unix password despite PasswordAuthentication = false.
- authorizedKeysInHomedir = false: only keys declared in Nix take effect;
youko keeps Gitea's forced-command file through `Match User gitea`.
- Pin aquamarine's passphrase-free remote-builder keys to
`restrict,command="nix-daemon --stdio --store daemon"`, so builds run in the
system daemon instead of an audited root login session.
systemd sandboxing
- Add the mylib.systemdHardening preset and apply it to the exposed, weakly
sandboxed services: caddy 7.8 -> 1.5, vmalert 8.2 -> 1.4, rustfs 6.6 -> 1.4,
whisper-asr 7.7 -> 1.6. An eval test pins the key restrictions.
- Rejected: a global all-keys policy (<=0.2 score gains on services nixpkgs
already sandboxes) and per-service confinement (bind paths to maintain).
auditd on all four hosts, reusing nixpkgs' loader and unit
- Audit login sessions only: a first `-a never,task -F auid=unset` rule keeps
services out of the per-syscall audit path. A compromised service is
therefore unrecorded until it opens a session.
- Record root commands, credential and host-key access, writes to SSH, account,
PAM, Nix-trust and audit configuration, module loads and session denials.
- Rejected: global denial logging, service-UID watches and
--loginuid-immutable (the kernel already records loginuid changes).
Verified on all four hosts after deployment: zero failed units, k3s 6/6 Ready,
and the exposed services healthy.
Assisted-by: Claude Code (claude-opus-5-5)
Ryan Yin