Setting a NAS up to collect the invoice archive meant three machines and a
dozen commands: generate a keypair there, carry the public half to the server,
write it into authorized_keys with a restriction, install rsync, and get every
path right on the first try. Every one of those steps was a place to be told
"permission denied" with no clue which of the three was wrong. It was, and
several times over.
One button now. The panel asks, the host does it — because the host is where
all of it lives: the home directory, ssh-keygen, rrsync, and the archive itself.
The panel is www-data in a container and owns none of that, so it uses the
mailbox it already uses for updates. The private half is shown exactly once,
alongside the finished rsync command, and is never written to the database: it
exists to be copied into a NAS, and storing it "for convenience" would put a
working credential in every backup of that database.
rrsync does the restricting, not a pinned rsync option string. That string
differs between rsync versions and fails silently — a refusal with no reason
given, which is the shape of the afternoon this replaces. If rrsync is missing
the agent refuses rather than issuing an unrestricted key while the panel says
it is restricted.
rsync now comes with install-agent.sh, which already runs as root once per
machine. It has to be on the HOST: a NAS connects by ssh and sshd starts
`rsync --server` here, so without it the pull fails with "command not found"
from a NAS whose own setup is perfectly correct.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
nexxo