ZeroScale

High-performance, swapless Tailscale manager & live monitor for Asuswrt-Merlin routers.

Note

Attribution & Origin: ZeroScale is based on and inspired by TAILMON originally created by Viktor Jaep (licensed under GPLv3). ZeroScale is an independently developed, standalone evolution engineered specifically for swapless, zero-overhead Tailscale monitoring and management on Asuswrt-Merlin routers.

---

100% Swapless Tailscale Management & Monitoring

Running modern Go-based services like Tailscale on embedded, memory-constrained Asus routers has traditionally required dedicated USB swap partitions to prevent memory exhaustion, out-of-memory (OOM) kernel kills, and fork failures.

ZeroScale completely eliminates the need for USB swap partitions:

• 🛡️ Zero Swap Dependency: Operates smoothly on bare router RAM without requiring an external USB flash drive or swap file.
• 💾 Ultra-Low Memory Footprint: Consumes less than 800 KB of RAM (compared to 10–25 MB with heavy multi-process shell loops).
• ⚡ Zero Fork Overhead: Native C99 execution avoids spawning hundreds of background awk, sed, grep, and subshell processes every polling cycle.
• 🔒 Flash Wear Protection: Event-driven architecture eliminates disk thrashing, significantly extending the lifespan of router NAND flash and attached storage.
• ⏱️ 0.0% Idle CPU Usage: Sleeps on an event-driven terminal loop, reserving 100% of router CPU power for NAT routing, QoS, and WireGuard cryptography.

---

📊 Technical Comparison

Metric / Capability	Traditional Shell Monitors	ZeroScale (C99)
Swap Requirement	USB swap partition recommended	100% Swapless (No USB swap needed)
RAM Footprint	~5–15 MB (spawning subshells)	< 800 KB resident memory
CPU Usage (Idle/Poll)	2–5% spikes on subshell forks	0.0% CPU (event-driven tick)
Binary Size	Multiple scripts / disk files	~149 KB single static musl binary
Rendering Engine	ANSI escapes (flickers on refresh)	Double-buffered differential matrix (0% flicker)
Input Navigation	Number-key menus	Full Keyboard (Arrows/Tab) + SGR Mouse Navigation
Dependencies	Requires coreutils, awk, sed, screen	Zero external dependencies (pure static C99)

---

✨ Features

1. 🖥️ Live Monitor Dashboard (VIEW_DASHBOARD)

• Real-time Status Cards: Live indicators for Daemon status, Tailnet connectivity, Operating Mode (Userspace / Kernel), Watchdog Keepalive state, Exit Node advertisement, and advertised Subnet Routes.
• Interactive Action Bar: Dynamic action buttons with instant keyboard shortcuts (u, d, r, s, t, l, c, q) and arrow navigation (←/→).
• Color-Coded Peer Topology:
  • 🟣 Self (Router): Bold Magenta (router - self)
  • 🟡 Exit Nodes: Vivid Gold / Yellow (offers exit node)
  • 🟢 Active (Direct WireGuard): Bright Green (active; direct ...)
  • 🔵 Idle (Online): Soft Cyan (idle; ...)
  • ⚫ Offline Nodes: Dim Gray (offline, last seen ...)
• Smooth Scrolling: Scroll through large peer lists with the mouse wheel or arrow keys.

2. 🔍 Modal Peer Inspector (VIEW_PEER_DETAIL)

• Select any peer with mouse click or Enter to open a floating, bordered modal inspector.
• Inspect Node Name, Tailscale IP, OS Platform, Account Owner, Connection Endpoint (Direct vs. DERP Relay), and real-time Tailnet status.
• Interactive actions directly inside modal:
  • Press p: Instant ICMP ping test.
  • Press t: Real Tailscale WireGuard latency ping.
  • Press c / Esc: Close inspector.

3. ⚙️ Unified Configuration & Service Management (VIEW_CONFIG)

Consolidated, interactive settings management with instant persistence to /jffs/addons/zeroscale.d/zeroscale.cfg:

• Section 1: Daemon & Health Monitor — Toggle Watchdog Keepalive, Persistent Settings, and Boot Autostart (/jffs/scripts/post-mount).
• Section 2: Tailscale Routing & Mode — Toggle Userspace ⟷ Kernel mode, Exit Node advertisement, Subnet Routes advertisement, and interactive Subnet CIDR editor.
• Section 3: Interface & Logging — Cycle status check intervals (10s ➔ 300s) and edit Event Log row retention limits.
• Section 4: Notifications & Automation — Configure amtm email alerts and scheduled daily autoupdates.
• Section 5: Binary & Maintenance — Check & update Tailscale binaries, reset daemon state, and run safe install/reinstall/uninstall workflows.

4. 📜 Full-Screen Event Log Viewer (VIEW_LOGS)

• Real-time logging of all configuration changes and daemon events directly to /jffs/addons/zeroscale.d/zeroscale.log.
• Syntax highlighting for log levels (INFO, WARN, FAIL, ONLINE).
• Opens directly to the most recent log entries filling the entire screen.
• Supports ↑/↓, PgUp/PgDn, g (top), G (bottom), and r (live reload).

---

🛠️ Universal Installation on Asuswrt-Merlin

Run the following one-line installer on your router over SSH. It automatically detects your router's architecture (ARMv7 vs ARM64) and migrates any existing Tailmon settings:

curl -fsSL https://raw.githubusercontent.com/underd0se/ZeroScale/main/install.sh | sh

Tip

Existing Tailmon Users: The installer automatically detects /jffs/addons/tailmon.d/tailmon.cfg, migrates your routing and exit-node settings to zeroscale.cfg, cleans up old boot hooks, and creates a /opt/bin/tailmon compatibility alias.

# Launch ZeroScale
zeroscale

---

💻 Building from Source (macOS / Linux)

Cross-compiling requires Zig:

# 1. Install Zig via Homebrew (macOS)
brew install zig

# 2. Clone repository
git clone https://github.com/underd0se/ZeroScale.git
cd ZeroScale

# 3. Build release binaries for Asus routers (ARMv7 & ARM64)
./build-all.sh

---

🎮 Navigation & Keyboard Controls

Context	Key / Action	Description
Anywhere	Mouse Left-Click	Activate buttons, select peers, toggle settings
Anywhere	Shift + Drag (or Fn + Drag)	Native terminal text selection and copying across all terminal emulators
Dashboard	↑ / ↓	Navigate between Header Action Bar and Peer Node Table
Dashboard	← / →	Cycle through Header Action Bar buttons when focused
Dashboard	Enter	Trigger focused button or open Peer Inspector for selected node
Dashboard	u / d	Quick direct shortcut for Tailscale up / down
Dashboard	r / s / t	Quick direct shortcut for daemon restart / start / stop
Dashboard	c / l / q	Open Configuration / Logs / Quit
Config Menu	↑ / ↓ / ← / →	Navigate through all 17 configuration items in 2-column layout
Config Menu	Enter / Space	Toggle setting / Open Subnet CIDR editor / Edit Log retention / Edit Auto-Update Time
Config Menu	1–9, t, z, u, x, i	Direct jump and toggle hotkeys (z: Update ZScale, u: Update TS)
Config Menu	Esc / e / q	Return to Dashboard
Modals & Dialogs	← / → / Tab	Switch between Action and Cancel buttons
Modals & Dialogs	Enter / Space	Execute focused modal action
Modals & Dialogs	Esc / e / c / q	Cancel modal and return cleanly
Input Modals	Tab / ↓ / ↑	Move focus between Text Input field and Save/Cancel buttons
Peer Inspector	p / t / c / e	Live ICMP Ping / Tailscale WireGuard Ping / Close modal
Log Viewer	↑ / ↓ / PgUp / PgDn	Scroll log viewer
Log Viewer	/ / n / N	Real-time substring search through event logs
Log Viewer	g / G / r / e	Jump to Top / Bottom / Refresh logs / Exit

---

🙏 Acknowledgments & Credits

• Viktor Jaep — Creator of TAILMON, whose original Asuswrt-Merlin addon laid the foundation and inspired this project.
• Eric Sauvageau (RMerl) — Developer of Asuswrt-Merlin firmware.
• Tailscale — Zero-config WireGuard mesh VPN.

---

📄 License

GPL-3.0 License. See LICENSE for details.