A high-performance, event-driven Terminal UI (TUI) network monitor that tracks ICMP ping latency, jitter, and packet loss across multiple targets simultaneously — all from a single, zero-dependency executable.

go-deadman is a real-time network health monitor built for network engineers and system administrators. It continuously pings a configurable list of devices — from global Tier-1 ISPs and cloud Anycast endpoints to local LAN hosts — and renders a live, color-coded dashboard directly in your terminal.

Key design goals:

• Zero external dependencies at runtime — the config YAML is compiled directly into the binary via Go's //go:embed
• Event-driven, socket-reuse architecture — avoids the overhead of spawning a new process or socket per ping cycle
• Graceful degradation — automatically falls back to the OS native ping command when raw socket privileges are unavailable
• Single-file simplicity — the entire application logic lives in main.go

Inspired by https://github.com/upa/deadman

go-deadman/
├── main.go              # Entire application: config, ping engine, TUI, entry point
├── internet.yaml        # Preset: Global ISPs, CDNs, IXPs, and Taiwan ISPs
├── tasks.yaml           # Preset: Local LAN targets (192.168.x.x)
├── config.yaml          # ⚠️ Required at build time — copy from internet.yaml or tasks.yaml
├── screenshot.jpg       # Dashboard screenshot for README
├── winres/
│   ├── icon.png         # App icon (256×256)
│   ├── icon16.png       # App icon (16×16)
│   └── winres.json      # Windows resource manifest (version, icon, UAC level)
└── .github/
    ├── workflows/
    │   └── build.yml    # CI: lint → build → release pipeline
    └── dependabot.yml   # Automated dependency update config

• Go 1.21+ — Download
• config.yaml must exist in the project root before building (see below)

git clone https://github.com/<your-org>/go-deadman.git
cd go-deadman

The binary embeds config.yaml at compile time using //go:embed. Choose one of the two presets and copy it:

# Option A: Monitor global internet infrastructure (ISPs, CDNs, IXPs)
cp internet.yaml config.yaml

# Option B: Monitor a local LAN subnet (192.168.77.x)
cp tasks.yaml config.yaml

⚠️ Build will fail if config.yaml does not exist — it is a required embed source.

go mod tidy
go mod download

# Standard build
go build -ldflags="-s -w" -trimpath -o go-deadman .

# Windows (cross-compile from Linux/macOS)
GOOS=windows GOARCH=amd64 go build -ldflags="-s -w" -trimpath -o go-deadman.exe .

# Linux / macOS
./go-deadman

# Windows
.\go-deadman.exe

Press q or Ctrl+C to exit.

go-deadman uses native Go ICMP sockets by default for maximum performance. This requires elevated privileges:

If privileges are not available, the app automatically falls back to parsing the OS native ping command. Targets using the fallback will not show the * indicator.

Both internet.yaml and tasks.yaml follow the same schema:

interval: 1s       # Base ping interval (e.g., "1s", "500ms", "2s")
jitter: 0.1        # ±10% random timing variation applied in fallback mode
devices:
  - name: "Cloudflare-Anycast"
    ip: "1.1.1.1"
  - name: "Google-DNS"
    ip: "8.8.8.8"
  - name: "---"          # Renders as a visual separator line
  - name: "My-Router"
    ip: "192.168.1.1"

💡 You can provide only name (hostname) or only ip — the app resolves the missing field automatically via DNS.

                              go-deadman
       From: myhost  Version: v1.11.0  loss+rtt+avg+jitter+history

  HOSTNAME              ADDRESS          LOSS  RTT(ms)  AVG(ms)  JIT(ms)   SNT  HISTORY
  ─────────────────────────────────────────────────────────────────────────────────────────
  Cloudflare-Anycast    1.1.1.1           0%    2.341    2.298    0.103   142*  ▄▄▃▃▄▃▄▄▅▃
  Google-DNS            8.8.8.8           0%    4.102    4.011    0.214   142*  ▃▃▃▄▃▃▄▃▃▃
  ─────────────────────────────────────────────────────────────────────────────────────────
  My-Router             192.168.1.1       2%    0.812    0.799    0.031   142*  ▁▁▁·▁▁▁▁▁▁

  Interval: 1s  App Jitter: 10%  *: Native  Window: 50

//go:embed config.yaml
var embeddedYaml []byte

The YAML configuration is compiled directly into the binary at build time. At runtime, main() unmarshals this byte slice — no external files required. 1

Each device entry launches a goroutine that:

1. Resolves missing hostname ↔ IP pairs via net.LookupIP / net.LookupAddr
2. Sets IsDNSFail = true and skips pinging if resolution fails
3. Hands off to deviceWorker (native) or fallbackWorker (OS command) 1

This is the performance-critical path, implementing a socket-reuse, event-callback architecture:

┌─────────────────────────────────────────────────────────┐
│  probing.NewPinger  →  Count = -1 (infinite send mode)  │
│                                                         │
│  OnRecv callback → recvCh (buffered channel, cap 100)   │
│                                                         │
│  Main select loop:                                      │
│   ├─ recvCh:   packet received → fill gap losses →      │
│   │            UpdateStats(rtt, true)                   │
│   ├─ timer.C:  timeout → UpdateStats(0, false)          │
│   └─ errCh:    pinger error → fallback                  │
└─────────────────────────────────────────────────────────┘

Sequence gap filling: If pkt.Seq skips ahead (consecutive drops), the worker immediately back-fills UpdateStats(0, false) for each missing sequence number before recording the received packet. This guarantees history graph accuracy even during burst loss events. 1

When native ICMP sockets are unavailable, the worker:

1. Spawns ping -n 1 (Windows) or ping -c 1 (Linux/macOS) per interval
2. Parses RTT from stdout via parseRTT() — supports both English (time=) and Chinese (時間=) system locales
3. Applies configurable jitter to the sleep interval to prevent thundering-herd effects across many devices 1

func (d *Device) UpdateStats(rtt float64, success bool) {
    d.mu.Lock()
    defer d.mu.Unlock()
    // Updates: Snt, Loss, LossRate, Window (sliding), AvgRTT, Jitter, History ring buffer
}

• Uses a sync.RWMutex — write-locked during stats update, read-locked during UI rendering
• Sliding window (WINDOW_SIZE = 50): RTT history for avg and jitter calculation
• Ring buffer (HIST_SIZE = 100): Fixed-size circular history for the sparkline 1

idx := int(math.Log(math.Max(1, rtt)) / math.Log(2.4))
scales := []string{"▁", "▂", "▃", "▄", "▅", "▆", "▇", "█"}

RTT is mapped to a block character using base-2.4 logarithm, so:

• ~1ms → ▁, ~6ms → ▃, ~35ms → ▆, >200ms → █
• · is shown for dropped packets (success == false) 1

The UI re-renders at 20 FPS (RENDER_FPS = 20) driven by tea.Tick. All device data is read under d.mu.RLock() to prevent data races with background goroutines. 1

Each build automatically:

1. Copies the appropriate preset YAML as config.yaml
2. Embeds Windows resources (icon + version) via go-winres
3. Compiles with -ldflags="-s -w" -trimpath for minimal binary size
4. Uploads artifact with 7-day retention; publishes to GitHub Release on tag push 1

This project is licensed under the MIT License.
Copyright © 2026 go-deadman.