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Logan CusanoandClaude Opus 5 ee633cbe46
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Secure the broker for public exposure: TLS and per-node credentials
Edge nodes are deployed to arbitrary locations by arbitrary people, so the
broker has to be reachable from the internet and secured on its own merits
rather than by a VPN.

Three defects made that impossible. The broker only had a plaintext 1883
listener; every node shared one drb-node password; and the ACL pattern used
%c, the client-supplied client id, so any holder of that shared password
could set client_id to another node and take over its namespace. The comment
claiming this cryptographically prevented cross-node access was wrong and is
gone.

Authentication now uses mosquitto 2.x's built-in dynamic-security plugin on
the stock eclipse-mosquitto image. c2-core administers it over the control
topic, creating each node's client on approval with username=<node_id> and
password=<its node_keys api_key>, attached to a role whose ACL is nodes/%u/#
against the authenticated username. One credential, one revocation point.
An HTTP-callback plugin was implemented first and rejected: that project is
archived upstream, which is not an acceptable dependency on an
internet-facing broker.

Because dynsec state is a second source of truth alongside Firestore,
approve/reissue/delete now write to the broker first and surface a 502
rather than drifting, and c2-core reconciles every approved node into dynsec
on startup.

Adds node self-enrollment (POST /nodes/enroll, GET /nodes/{id}/credentials)
so a new node can obtain its key over HTTPS without an operator handling
secrets by hand. Enrolling an already-approved node_id is refused on the
fleet token alone — otherwise a leaked token plus a guessable id would let
an attacker steal a live node's key before the real node asked for it.
Pickup secrets are stored hashed and returned once, and the endpoint is rate
limited per source IP.

Infrastructure: an 8883 TLS listener fed by Caddy's certificate via a
systemd path unit, a firewall rule for it, and Caddy now 404s /internal/*
so the api vhost cannot proxy internal routes.

Also fixes CORS, which allowed https://app.<domain> while the frontend is
served on the bare domain — every call from the portal would have failed —
and widens the vault gitignore to a glob, since ansible-vault leaves
backup siblings that the exact-name rule left committable.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
2026-08-16 09:34:44 -04:00

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# Top-level docker-compose environment variables
# Copy to .env and fill in values before running `docker compose up`
# -----------------------------------------------------------------------
# MQTT broker credentials
# These are injected into the mosquitto container at startup to build the
# password file. Use different values in production — do NOT reuse defaults.
# -----------------------------------------------------------------------
# C2-core service account (full broker access via the "c2core" dynsec role)
MQTT_C2_USER=drb-c2-core
MQTT_C2_PASS=change-me-c2
# Seeds mosquitto's built-in dynamic-security plugin's one-time "admin"
# bootstrap client on first boot (read directly by mosquitto, no entrypoint
# scripting involved). Must be >=12 chars. c2-core needs this SAME value as
# MQTT_DYNSEC_ADMIN_PASS in drb-c2-core/.env to log in as "admin" and
# administer node credentials — see app/internal/dynsec.py.
MOSQUITTO_DYNSEC_PASSWORD=change-me-dynsec-admin-min-12-chars
# There is no shared node credential anymore. Each node authenticates as
# username=<node_id>, password=<its node_keys.api_key> — checked by
# mosquitto's dynamic-security plugin (not an HTTP backend — that was an
# earlier, since-rejected design using the now-archived mosquitto-go-auth).
# Nodes obtain that key via the enrollment flow — see ENROLLMENT_TOKEN in
# drb-c2-core/.env.example.