netbird-reconnectd (macOS)

A tiny macOS daemon that listens for system wake events and forces a clean NetBird VPN reconnect.

wake → netbird down → short delay → netbird up --enable-lazy-connection → status

• Uses IOKit power notifications (sleep/wake callback).
• Spawns NetBird commands with posix_spawnp (no shell; resolves via $PATH).
• Logs to stderr; when run via Homebrew services, logs are written to Homebrew's log files.

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How it works

• Registers a power notification callback with IORegisterForSystemPower.

• On wake (kIOMessageSystemHasPoweredOn), runs:

  1. netbird down
  2. wait a few seconds (default: SLEEP_BEFORE_UP_SEC = 5)
  3. netbird up --enable-lazy-connection with NB_ENABLE_EXPERIMENTAL_LAZY_CONN=true (set internally)
  4. netbird status

• posix_spawnp("netbird", ...) looks up netbird in $PATH.

• On startup, the daemon sets a sane default PATH for launchd contexts if needed: /opt/homebrew/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin.

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Requirements

• macOS 11+ (Intel or Apple Silicon)
• NetBird CLI installed (e.g., brew install netbird)
• Xcode Command Line Tools or a recent clang/cmake

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Install via Homebrew (recommended)

brew tap dmitriimaksimovdevelop/tap
brew install dmitriimaksimovdevelop/tap/macos-netbird-reconnect
brew services start macos-netbird-reconnect

Status & Logs

brew services list | grep -i netbird
# Logs (captured from stderr):
tail -f "$(brew --prefix)/var/log/netbird-reconnectd.log"

Stop / Uninstall

brew services stop macos-netbird-reconnect
brew uninstall macos-netbird-reconnect

The Homebrew service definition includes a proper PATH so posix_spawnp can find netbird without hardcoded paths.

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Build from source

Option A — clang one-liner

clang -O2 -Wall -Wextra netbird-reconnectd.c -o netbird-reconnectd \
  -framework IOKit -framework CoreFoundation

Option B — CMake (e.g., CLion)

cmake -S . -B build
cmake --build build --config Release
# Result: build/netbird-reconnectd

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Configuration

Edit in netbird-reconnectd.c if desired:

• SLEEP_BEFORE_UP_SEC: seconds to wait after wake before up (default 5).

You do not need to set the NetBird path. The daemon uses posix_spawnp("netbird", ...) and relies on $PATH.

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Running manually (without Homebrew)

./netbird-reconnectd

• Logs are written to stderr; you'll see them in your terminal.
• Stop with Ctrl+C.

Optional: install as a LaunchAgent (manual)

Save as ~/Library/LaunchAgents/com.netbird.reconnectd.plist (adjust the absolute path to your binary):

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN"
 "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
  <dict>
    <key>Label</key>
    <string>com.netbird.reconnectd</string>

    <key>ProgramArguments</key>
    <array>
      <string>/Users/USERNAME/bin/netbird-reconnectd</string>
    </array>

    <key>EnvironmentVariables</key>
    <dict>
      <key>PATH</key>
      <string>/opt/homebrew/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin</string>
    </dict>

    <key>RunAtLoad</key>
    <true/>

    <key>KeepAlive</key>
    <false/>

    <!-- Optional: route launchd's own stdout/stderr (daemon already logs to stderr) -->
    <key>StandardOutPath</key>
    <string>/tmp/netbird-reconnectd.launchd.out.log</string>
    <key>StandardErrorPath</key>
    <string>/tmp/netbird-reconnectd.launchd.err.log</string>

    <key>ProcessType</key>
    <string>Background</string>
  </dict>
</plist>

Load / reload:

launchctl bootout gui/$(id -u)/com.netbird.reconnectd 2>/dev/null || true
launchctl bootstrap gui/$(id -u) ~/Library/LaunchAgents/com.netbird.reconnectd.plist

Check status and live logs:

launchctl print gui/$(id -u)/com.netbird.reconnectd | head -n 80
log stream --predicate 'process == "netbird-reconnectd"' --style syslog --info

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Troubleshooting

• posix_spawn failed: rc=2 (No such file or directory) for netbird

  • NetBird CLI not installed or not on the service $PATH.
  • Fix: brew install netbird. With Homebrew services, PATH is set automatically; for manual LaunchAgents, add EnvironmentVariables.PATH in the plist as shown above.

• Service not started / disappears

  • Check: brew services list | grep -i netbird
  • Foreground run for debugging: brew services run macos-netbird-reconnect

• Bootstrap failed: 5: Input/output error (manual plist)

  • Usually an invalid plist or wrong ProgramArguments path. Validate: plutil -lint ~/Library/LaunchAgents/com.netbird.reconnectd.plist.

• Exec format error on Apple Silicon

  • Ensure you built an ARM64 binary (Apple clang does this by default on Apple Silicon). Avoid running Intel-only binaries without Rosetta.

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Security notes

• No shell is invoked; arguments/env are passed directly to posix_spawnp.
• Consider code signing if you distribute the binary.

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License

MIT — see LICENSE.