Genesis Docs

Bonjour / mDNS discovery

Genesis uses 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 and is enabled by default. 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 _genesis-gw._tcp under a dedicated zone (example: genesis.internal.).
  3. Configure Tailscale split DNS so your chosen domain resolves via that DNS server for clients (including iOS).

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

Gateway config (recommended)

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

One-time DNS server setup (gateway host)

genesis 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: genesis.internal.) from ~/.genesis/dns/<domain>.db

Validate from a tailnet‑connected machine:

dns-sd -B _genesis-gw._tcp genesis.internal.
dig @<TAILNET_IPV4> -p 53 _genesis-gw._tcp.genesis.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 _genesis-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 ~/.genesis/genesis.json.
  • Restart the Gateway (or restart the macOS menubar app).

What advertises

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

Service types

  • _genesis-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:

    dns-sd -B _genesis-gw._tcp local.

  • Resolve one instance (replace <instance>):

    dns-sd -L "<instance>" _genesis-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: ... name conflict resolved / hostname conflict resolved
  • bonjour: watchdog detected non-announced service ...

Debugging on iOS node

The iOS node uses NWBrowser to discover _genesis-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.

Common failure modes

  • Bonjour doesn’t cross networks: use Tailnet or SSH.
  • Multicast blocked: some Wi‑Fi networks disable mDNS.
  • 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).

Disabling / configuration

  • genesis plugins disable bonjour disables LAN multicast advertising by disabling the bundled plugin.
  • genesis plugins enable bonjour restores the default LAN discovery plugin.
  • GENESIS_DISABLE_BONJOUR=1 disables LAN multicast advertising without changing plugin config; accepted truthy values are 1, true, yes, and on (legacy: GENESIS_DISABLE_BONJOUR).
  • gateway.bind in ~/.genesis/genesis.json controls the Gateway bind mode.
  • GENESIS_SSH_PORT overrides the SSH port when sshPort is advertised (legacy: GENESIS_SSH_PORT).
  • GENESIS_TAILNET_DNS publishes a MagicDNS hint in TXT when mDNS full mode is enabled (legacy: GENESIS_TAILNET_DNS).
  • GENESIS_CLI_PATH overrides the advertised CLI path (legacy: GENESIS_CLI_PATH).

Related docs