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Bonjour discovery

docs/gateway/bonjour.md

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Bonjour / mDNS discovery

OpenClaw can use Bonjour (mDNS / DNS-SD) to discover an active Gateway (WebSocket endpoint). Multicast local. browsing is a LAN-only convenience. The bundled bonjour plugin owns LAN advertising. It auto-starts on macOS hosts and is opt-in on Linux, Windows, and containerized Gateway deployments. For cross-network discovery, the same beacon can also be published through a configured wide-area DNS-SD domain. Discovery is still best-effort and does not replace SSH or Tailnet-based connectivity.

Wide-area Bonjour (Unicast DNS-SD) over Tailscale

If the node and gateway are on different networks, multicast mDNS won’t cross the boundary. You can keep the same discovery UX by switching to unicast DNS‑SD ("Wide‑Area Bonjour") over Tailscale.

High‑level steps:

  1. Run a DNS server on the gateway host (reachable over Tailnet).
  2. Publish DNS‑SD records for _openclaw-gw._tcp under a dedicated zone (example: openclaw.internal.).
  3. Configure Tailscale split DNS so your chosen domain resolves via that DNS server for clients (including iOS).

OpenClaw supports any discovery domain; openclaw.internal. is just an example. iOS/Android nodes browse both local. and your configured wide‑area domain.

Gateway config (recommended)

json5
{
  gateway: { bind: "tailnet" }, // tailnet-only (recommended)
  discovery: { wideArea: { enabled: true } }, // enables wide-area DNS-SD publishing
}

One-time DNS server setup (gateway host)

bash
openclaw dns setup --apply

This installs CoreDNS and configures it to:

  • listen on port 53 only on the gateway’s Tailscale interfaces
  • serve your chosen domain (example: openclaw.internal.) from ~/.openclaw/dns/<domain>.db

Validate from a tailnet‑connected machine:

bash
dns-sd -B _openclaw-gw._tcp openclaw.internal.
dig @<TAILNET_IPV4> -p 53 _openclaw-gw._tcp.openclaw.internal PTR +short

Tailscale DNS settings

In the Tailscale admin console:

  • Add a nameserver pointing at the gateway’s tailnet IP (UDP/TCP 53).
  • Add split DNS so your discovery domain uses that nameserver.

Once clients accept tailnet DNS, iOS nodes and CLI discovery can browse _openclaw-gw._tcp in your discovery domain without multicast.

Gateway listener security (recommended)

The Gateway WS port (default 18789) binds to loopback by default. For LAN/tailnet access, bind explicitly and keep auth enabled.

For tailnet‑only setups:

  • Set gateway.bind: "tailnet" in ~/.openclaw/openclaw.json.
  • Restart the Gateway (or restart the macOS menubar app).

What advertises

Only the Gateway advertises _openclaw-gw._tcp. LAN multicast advertising is provided by the bundled bonjour plugin when the plugin is enabled; wide-area DNS-SD publishing remains Gateway-owned.

Service types

  • _openclaw-gw._tcp — gateway transport beacon (used by macOS/iOS/Android nodes).

TXT keys (non-secret hints)

The Gateway advertises small non‑secret hints to make UI flows convenient:

  • role=gateway
  • displayName=<friendly name>
  • lanHost=<hostname>.local
  • gatewayPort=<port> (Gateway WS + HTTP)
  • gatewayTls=1 (only when TLS is enabled)
  • gatewayTlsSha256=<sha256> (only when TLS is enabled and fingerprint is available)
  • canvasPort=<port> (only when the canvas host is enabled; currently the same as gatewayPort)
  • transport=gateway
  • tailnetDns=<magicdns> (mDNS full mode only, optional hint when Tailnet is available)
  • sshPort=<port> (mDNS full mode only; wide-area DNS-SD may omit it)
  • cliPath=<path> (mDNS full mode only; wide-area DNS-SD still writes it as a remote-install hint)

Security notes:

  • Bonjour/mDNS TXT records are unauthenticated. Clients must not treat TXT as authoritative routing.
  • Clients should route using the resolved service endpoint (SRV + A/AAAA). Treat lanHost, tailnetDns, gatewayPort, and gatewayTlsSha256 as hints only.
  • SSH auto-targeting should likewise use the resolved service host, not TXT-only hints.
  • TLS pinning must never allow an advertised gatewayTlsSha256 to override a previously stored pin.
  • iOS/Android nodes should treat discovery-based direct connects as TLS-only and require explicit user confirmation before trusting a first-time fingerprint.

Debugging on macOS

Useful built‑in tools:

  • Browse instances:

    bash
    dns-sd -B _openclaw-gw._tcp local.

  • Resolve one instance (replace <instance>):

    bash
    dns-sd -L "<instance>" _openclaw-gw._tcp local.

If browsing works but resolving fails, you’re usually hitting a LAN policy or mDNS resolver issue.

Debugging in Gateway logs

The Gateway writes a rolling log file (printed on startup as gateway log file: ...). Look for bonjour: lines, especially:

  • bonjour: advertise failed ...
  • bonjour: suppressing ciao cancellation ...
  • bonjour: ... name conflict resolved / hostname conflict resolved
  • bonjour: watchdog detected non-announced service ...
  • bonjour: disabling advertiser after ... failed restarts ...

Bonjour uses the system hostname for the advertised .local host when it is a valid DNS label. If the system hostname contains spaces, underscores, or another invalid DNS-label character, OpenClaw falls back to openclaw.local. Set OPENCLAW_MDNS_HOSTNAME=<name> before starting the Gateway when you need an explicit host label.

Debugging on iOS node

The iOS node uses NWBrowser to discover _openclaw-gw._tcp.

To capture logs:

  • Settings → Gateway → Advanced → Discovery Debug Logs
  • Settings → Gateway → Advanced → Discovery Logs → reproduce → Copy

The log includes browser state transitions and result‑set changes.

When to enable Bonjour

Bonjour auto-starts for empty-config Gateway startup on macOS hosts because the local app and nearby iOS/Android nodes commonly rely on same-LAN discovery.

Enable Bonjour explicitly when same-LAN auto-discovery is useful on Linux, Windows, or another non-macOS host:

bash
openclaw plugins enable bonjour

When enabled, Bonjour uses discovery.mdns.mode to decide how much TXT metadata to publish. The default mode is minimal; use full only when local clients need cliPath or sshPort hints, and use off to suppress LAN multicast without changing plugin enablement.

When to disable Bonjour

Leave Bonjour disabled when LAN multicast advertising is unnecessary, unavailable, or harmful. The common cases are non-macOS servers, Docker bridge networking, WSL, or a network policy that drops mDNS multicast. In those environments the Gateway is still reachable through its published URL, SSH, Tailnet, or wide-area DNS-SD, but LAN auto-discovery is not reliable.

Prefer the existing environment override when the problem is deployment-scoped:

bash
OPENCLAW_DISABLE_BONJOUR=1

That disables LAN multicast advertising without changing plugin configuration. It is safe for Docker images, service files, launch scripts, and one-off debugging because the setting disappears when the environment does.

Use plugin configuration when you intentionally want to turn off the bundled LAN discovery plugin for that OpenClaw config:

bash
openclaw plugins disable bonjour

Docker gotchas

The bundled Bonjour plugin auto-disables LAN multicast advertising in detected containers when OPENCLAW_DISABLE_BONJOUR is unset. Docker bridge networks usually do not forward mDNS multicast (224.0.0.251:5353) between the container and the LAN, so advertising from the container rarely makes discovery work.

Important gotchas:

  • Bonjour auto-starts on macOS hosts and is opt-in elsewhere. Leaving it disabled does not stop the Gateway; it only skips LAN multicast advertising.
  • Disabling Bonjour does not change gateway.bind; Docker still defaults to OPENCLAW_GATEWAY_BIND=lan so the published host port can work.
  • Disabling Bonjour does not disable wide-area DNS-SD. Use wide-area discovery or Tailnet when the Gateway and node are not on the same LAN.
  • Reusing the same OPENCLAW_CONFIG_DIR outside Docker does not persist the container auto-disable policy.
  • Set OPENCLAW_DISABLE_BONJOUR=0 only for host networking, macvlan, or another network where mDNS multicast is known to pass; set it to 1 to force-disable.

Troubleshooting disabled Bonjour

If a node no longer auto-discovers the Gateway after Docker setup:

  1. Confirm whether the Gateway is running in auto, forced-on, or forced-off mode:

    bash
    docker compose config | grep OPENCLAW_DISABLE_BONJOUR

  2. Confirm the Gateway itself is reachable through the published port:

    bash
    curl -fsS http://127.0.0.1:18789/healthz

  3. Use a direct target when Bonjour is disabled:

    • Control UI or local tools: http://127.0.0.1:18789
    • LAN clients: http://<gateway-host>:18789
    • Cross-network clients: Tailnet MagicDNS, Tailnet IP, SSH tunnel, or wide-area DNS-SD

  4. If you deliberately enabled the Bonjour plugin in Docker and forced advertising with OPENCLAW_DISABLE_BONJOUR=0, test multicast from the host:

    bash
    dns-sd -B _openclaw-gw._tcp local.

    If browsing is empty or the Gateway logs show repeated ciao watchdog cancellations, restore OPENCLAW_DISABLE_BONJOUR=1 and use a direct or Tailnet route.

Common failure modes

  • Bonjour doesn’t cross networks: use Tailnet or SSH.
  • Multicast blocked: some Wi‑Fi networks disable mDNS.
  • Advertiser stuck in probing/announcing: hosts with blocked multicast, container bridges, WSL, or interface churn can leave the ciao advertiser in a non-announced state. OpenClaw retries a few times and then disables Bonjour for the current Gateway process instead of restarting the advertiser forever.
  • Docker bridge networking: Bonjour auto-disables in detected containers. Set OPENCLAW_DISABLE_BONJOUR=0 only for host, macvlan, or another mDNS-capable network.
  • Sleep / interface churn: macOS may temporarily drop mDNS results; retry.
  • Browse works but resolve fails: keep machine names simple (avoid emojis or punctuation), then restart the Gateway. The service instance name derives from the host name, so overly complex names can confuse some resolvers.

Escaped instance names (\032)

Bonjour/DNS‑SD often escapes bytes in service instance names as decimal \DDD sequences (e.g. spaces become \032).

  • This is normal at the protocol level.
  • UIs should decode for display (iOS uses BonjourEscapes.decode).

Enabling / disabling / configuration

  • macOS hosts auto-start the bundled LAN discovery plugin by default.
  • openclaw plugins enable bonjour enables the bundled LAN discovery plugin on hosts where it is not default-enabled.
  • openclaw plugins disable bonjour disables LAN multicast advertising by disabling the bundled plugin.
  • OPENCLAW_DISABLE_BONJOUR=1 disables LAN multicast advertising without changing plugin config; accepted truthy values are 1, true, yes, and on (legacy: OPENCLAW_DISABLE_BONJOUR).
  • OPENCLAW_DISABLE_BONJOUR=0 forces LAN multicast advertising on, including inside detected containers; accepted falsy values are 0, false, no, and off.
  • When the Bonjour plugin is enabled and OPENCLAW_DISABLE_BONJOUR is unset, Bonjour advertises on normal hosts and auto-disables inside detected containers.
  • gateway.bind in ~/.openclaw/openclaw.json controls the Gateway bind mode.
  • OPENCLAW_SSH_PORT overrides the SSH port when sshPort is advertised (legacy: OPENCLAW_SSH_PORT).
  • OPENCLAW_TAILNET_DNS publishes a MagicDNS hint in TXT when mDNS full mode is enabled (legacy: OPENCLAW_TAILNET_DNS).
  • OPENCLAW_CLI_PATH overrides the advertised CLI path (legacy: OPENCLAW_CLI_PATH).