the DOCKER-USER chain is the only thing gating docker-published ports from
the internet — docker writes its own DNAT/FORWARD rules and bypasses ufw, so
`ufw allow <port>` has no effect on a published container port. the allowlist
permitted only 80 and 443, so a machine provisioned from this template dropped
gitea ssh silently.
the failure is hard to spot: the port looks open locally and docker ps shows it
published, but external clients hang at TCP connect with no refusal. local tests
pass because they arrive via lo and match the loopback RETURN before reaching the
DROP. comments added so the next person recognises it faster.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
pastilhasandClaude Opus 5
e36c6bb431