`write_nftables_ruleset` emitted a forward chain with `policy drop` and no
rules at all. That chain runs at the same netfilter hook as Docker's own
DOCKER-USER/DOCKER-FORWARD chains, so it vetoed them: every bridged
container lost outbound networking while the host itself stayed online, so
nothing looked broken.
It cost the Signal bot three silent hours today. signal-cli lost its
connection to Signal at 15:32:50 and looped on reconnect for 2.5h, while
the bot kept answering /healthz with 200 -- `/v1/groups` still served from
local state, so every surface said healthy.
`flush ruleset` also deletes Docker's own tables, and dockerd only rebuilds
them on its next network event, so restore_docker_rules() now restarts
docker right after a successful apply.
Verified in vmbox (Arch guest, docker installed, alpine probe):
BASELINE=reachable -> OLD=blocked -> NEW=reachable, sshd active throughout.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KbjfWdAyHbCubac7wJKJZW
