Per-machine host identity on /data: SSH host keys and machine-id never ship baked - #917
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Both were baked into the appliance image at build time (openssh-server's and systemd's own postinst), making them extractable from a published release and identical across every machine flashed from one — and silently rotating on any image rebuild (#894, #895). The image now ships neither: no ssh_host_* files, and a 0-byte machine-id so systemd runs its own documented first-boot semantics. Both are then generated once, at boot, into /data — the single persistence root Tor's onion identity already lives on: - SSH: a baked ssh.service drop-in (RequiresMountsFor=/data) generates a host key into /data/ssh before sshd starts, and sshd_config.d points HostKey there. The debug variant's baked authorized_keys stays untouched (user auth, out of scope). - machine-id: a new early oneshot unit (pithead-machine-id.service, ordered before systemd-networkd and systemd-journal-flush) restores the persisted id from /data, or adopts and persists this boot's id on a genuinely first boot. The installer's reinstall tiers and the appliance's own factory-reset both already destroy or preserve /data/pithead wholesale, so host identity follows the same keep/wipe classification as everything else there with one small addition (pithead-install now also clears /data/ssh, which sits outside the pithead/ tree the existing wipe already rm -rf's). tests/os/verify-image.sh asserts the built image ships neither identity concrete; tests/os/run.sh asserts host identity survives an A/B update and machine-id stays stable across a plain reboot. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
An empty /etc/machine-id on a volatile /etc upper makes EVERY boot a first boot to systemd, and PID 1 applies preset-all (enable-only) on first boot. Debian ships no preset files and systemd's no-preset fallback is enable — a release image would quietly re-enable the deliberately-disabled ssh.service each power cycle. Bake a blanket disable-* preset so the pass is a no-op, and mask systemd-firstboot (would re-run per boot and can prompt on console for unset basics). Also harden the machine-id restore for both PID-1 shapes (direct write into the writable overlay upper vs read-only bind mount from /run): drop a bind mount if one exists before writing, and correct the comment that described only the read-only shape. verify-image.sh now pins the preset file and the firstboot mask alongside the identity assertions. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
…iew) Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
This was referenced Aug 13, 2026
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Closes #894, closes #895.
Both identities were generated by their packages' postinst inside the Docker build: extractable from any published release, identical across every machine flashed from it, silently rotated whenever the apt layer rebuilt. One mechanism now carries both, per the issues' option 1:
os/rootfs/Dockerfile):ssh_host_*deleted,/etc/machine-idshipped empty; sshd pointed at/data/sshviasshd_config.d(Debian trixie's stock config Includes it, and one explicit HostKey disables the compiled-in default paths).ssh.servicedrop-in (RequiresMountsFor=/data) runs a generate-if-missing ExecStartPre — ed25519 into/data/ssh, tight modes, idempotent, stale-partial-safe. Identity survives A/B swaps and rebuilds; the debug variant's baked authorized_keys is user auth and untouched.DefaultDependencies=no,Before=systemd-networkd.service systemd-journal-flush.service) restores the persisted id from/data/pithead/machine-id— before the DHCP DUID and the journal directory key observe it — or adopts+persists this boot's id on a true first boot. Handles both PID-1 shapes (direct overlay write and ro bind mount).ssh.serviceon release images. A bakeddisable *preset neutralizes that pass andsystemd-firstbootis masked. verify-image pins both./data/ssh(machine-id already goes with the pithead tree);all/factory-reset destroy everything as before — a handed-over machine keeps nothing.make lint+ full suite green (stack 2171/0, dashboard 1760, verify-image and run.sh additions shellchecked). The KVM battery run right after merge is the live proof for the new asserts. Verifier + security review passed; ponytail cut two env knobs nothing set.🤖 Generated with Claude Code