Beacon

Beacon is a native macOS menu bar app that re-broadcasts Bonjour/mDNS services on your local network, so other devices can see services that Docker/OrbStack on macOS will not relay, such as HomeKit bridges, Home Assistant, and more.

It is a GUI successor to the homekit-mdns-broadcaster script, rebuilt in pure Swift on top of the system dns_sd API (the same daemon the dns-sd command talks to). There is no Python and no spawning of dns-sd subprocesses, and you get true per-service control.

The problem it solves

Docker and OrbStack on macOS do not relay container mDNS advertisements to the local network. Your Mac can see the services (for example with dns-sd -B), but other devices on the LAN cannot. This breaks setups like Home Assistant running in a container, where HomeKit and other devices need to discover the bridge over mDNS.

Beacon resolves each service you whitelist on the host, then re-advertises it through the host's own mDNSResponder so the whole network can see it. Background on the underlying issue: orbstack/orbstack#342

Features

• Menu bar Status screen: see every whitelisted service with its live state, and start or stop each one individually or all at once.
• Discovery: browse the local network for services, resolve any of them to inspect host, port and TXT records, and add them to your whitelist with one click.
• Whitelist: add services manually or from Discovery, pause and resume them, reorder them, and delete them.
• Settings: choose which service groups and custom service types to scan, enable launch at login, set a start delay, and turn on periodic auto-refresh.
• Auto-refresh and network awareness: Beacon can periodically re-resolve running services and also reacts to network changes, so a container restart or a new IP address is picked up automatically.
• Pure native Swift, launch at login via SMAppService, and a design that keeps the door open to a future Mac App Store build.

Requirements

• macOS 14 (Sonoma) or later.

Installation

1. Download Beacon-x.y.z.dmg from the Releases page.
2. Open the DMG and drag Beacon into your Applications folder.
3. Launch Beacon. Its icon appears in the menu bar.
4. The first time Beacon uses the network, macOS asks for Local Network access. Allow it, otherwise discovery and broadcasting will not work.

Usage

1. Open the menu bar icon and choose Discover, or open the main window and select the Discovery tab.
2. Find the service you want to re-broadcast (for example your HomeKit bridge) and click the plus button to add it to the whitelist. Selecting a service shows its resolved host, port and TXT records.
3. On the Status screen, press play next to a service to start broadcasting it, or press Start All. You can also enable "Start broadcasting on launch" in Settings.
4. Other devices on your LAN can now see the service.

The instance name must match exactly what is on the network, as shown in Discovery or by dns-sd -B. You can pause a service to keep it in the list without broadcasting, or delete it entirely.

Service groups

Beacon ships with the same service groups as the original script. The HomeKit group is selected by default. You can toggle groups and add your own literal service types in Settings.

Group	Description	Example types
homekit	HomeKit and Matter	_hap._tcp, _matter._tcp
web	Web and remote access	_http._tcp, _ssh._tcp, _rfb._tcp
files	File sharing	_smb._tcp, _afpovertcp._tcp
printing	Printing and scanning	_ipp._tcp, _printer._tcp
apple	Apple devices	_airplay._tcp, _companion-link._tcp
google	Google and Cast	_googlecast._tcp
iot	Smart home / IoT	_shelly._tcp, _philipshue._tcp
media	Media and streaming	_spotify-connect._tcp, _sonos._tcp
dev	Developer tools	_jenkins._tcp, _distcc._tcp
p2p	Peer-to-peer	_bp2p._tcp
enumeration	Service enumeration	_services._dns-sd._udp

How it works

• Discovery uses DNSServiceBrowse for each selected service type.
• Resolving a service uses DNSServiceResolve, which returns the host, port and raw TXT record.
• Re-broadcasting uses DNSServiceRegister with the host set to NULL, so the SRV target points at the local machine. This is the key detail that makes the container reachable at the host's address, and it mirrors what dns-sd -R does.
• TXT records are round-tripped byte for byte, so the re-broadcast carries the same metadata as the original service.
• Registrations are withdrawn automatically when Beacon quits.

Settings and the whitelist are stored as JSON in ~/Library/Application Support/Beacon/ (settings.json and whitelist.json).

Diagnostics

Beacon logs to macOS Unified Logging with subsystem com.lplaboratories.beacon. Open Console.app and filter for Beacon or the subsystem, or stream logs in Terminal:

log stream --predicate 'subsystem == "com.lplaboratories.beacon"'

The Settings screen includes "Verbose diagnostics in Console.app". When it is off, Beacon logs app startup, persistence failures, DNS-SD failures and important state changes. When it is on, Beacon also logs discovery, resolve, registration, auto-refresh and network-change details. TXT values are not dumped into logs.

Importing from the original script

If you used homekit-mdns-broadcaster and have a service_whitelist.txt, open Settings and choose "Import service_whitelist.txt". One name per line, and lines starting with # are ignored, just like the script.

Building from source

The Xcode project is generated from project.yml with XcodeGen, so the .xcodeproj is not committed. Generate it first:

brew install xcodegen
xcodegen generate
open Beacon.xcodeproj
# or build from the command line:
xcodebuild -project Beacon.xcodeproj -scheme Beacon -configuration Debug build

Self-test CLI

SelfTest/ builds a small command line tool, beacon-selftest, that exercises the dns_sd engine directly. It is useful for debugging and for comparing against the system dns-sd:

beacon-selftest browse   _hap._tcp
beacon-selftest resolve  "My Service" _hap._tcp
beacon-selftest register "Test Service" _http._tcp 8080
beacon-selftest mirror   "My Service" _hap._tcp

Releasing

# One-time notarization setup (stores credentials in the keychain):
xcrun notarytool store-credentials "beacon-notary" \
    --apple-id "you@example.com" \
    --team-id "<your-team-id>"

# Build, sign with Developer ID, package a DMG, then notarize and staple:
scripts/release.sh 1.0.0

Omit --password so notarytool prompts securely. Do not store app-specific passwords in .env or shell history.

If the notary profile is not present, the script still produces a signed DMG and skips notarization.

Project structure

Beacon/
  BeaconApp.swift          App entry, menu bar and main window scenes
  LoginItem.swift          Launch at login via SMAppService
  Engine/                  dns_sd wrappers and the BroadcastEngine orchestrator
  Model/                   Service catalog, whitelist, settings, persistence
  UI/                      Status, Discovery, Whitelist, Settings, About
SelfTest/                  Command line harness for the engine
scripts/release.sh         Sign, package, notarize, staple
project.yml                XcodeGen project definition

Roadmap

• Optional Mac App Store build (add the App Sandbox and network entitlements).

Credit and license

Based on the original homekit-mdns-broadcaster script. Released under the MIT License. See the LICENSE file.

Anything else?

Beacon is not bacon, though there may be an extra-crispy surprise hidden in the app.