client2server

client2server

Lightweight event forwarder for OpenWrt routers to central server Version 2.0 - Lua + WebSocket implementation

Overview

Lightweight Lua scripts that listen to OpenWrt events (WiFi, DHCP, network) and forward them to a central server via WebSocket with auto-reconnect and local buffering.

Why Lua + WebSocket?

Feature	Bash (v1)	Lua + WS (v2)
Connection	HTTP polling	WebSocket (persistent)
Auto-reconnect	Manual	Built-in
Offline buffer	File only	In-memory + file
Error handling	Basic	Exception-safe
Size	~20KB	~30KB inc. deps

Architecture

┌─────────────────┐      WebSocket       ┌─────────────────┐
│   OpenWrt       │ ════════════════►  │ Central Server  │
│   Router       │                   │                │
│                 │                   │  - Receive    │
│  - DHCP       │                   │  - Store      │
│  - WiFi      │                   │  - Real-time  │
│  - Network   │                   │  - LuIS UI   │
│                 │                   │               │
│ Buffer [offline]│─► sync when ──►  │              │
└─────────────────┘    online        └─────────────────┘

Installing

On OpenWrt Router

# Install dependencies
opkg update
opkg install lua luasocket

# Copy files
scp -r etc root@router:/etc/
scp -r usr root@router:/usr/

# Make executable
chmod +x /etc/init.d/event-forwarder
chmod +x /usr/sbin/event-forwarder.lua

# Configure
uci set event-forwarder.server.url='wss://your-server.com/ws'
uci set event-forwarder.server.token='your-secret-token'
uci set event-forwarder.general.enabled='1'
uci commit event-forwarder

# Enable and start
/etc/init.d/event-forwarder enable
/etc/init.d/event-forwarder start

# Check logs
logread -f -e client2server

On Central Server

cd server
npm install express ws
node server.js

Files

File	Purpose
usr/sbin/client2server.lua	Main Lua forwarder
usr/sbin/event-forwarder.lua	Original Lua prototype
etc/init.d/event-forwarder	Init script
etc/config/event-forwarder	UCI config
server/index.js	Central Node.js receiver
README.md	This file

Configuration

UCI Config

# /etc/config/event-forwarder
config event-forwarder 'general'
    option enabled '1'

config server
    option url 'wss://your-server.com/ws'
    option token 'CHANGE_ME_SECRET_TOKEN'

config router
    option id 'router-hostname'

Environment Variables

export SERVER_URL="wss://your-server.com/ws"
export SERVER_TOKEN="your-token"
export ROUTER_ID="router-name"

Event Types

Event	Source	Payload
dhcp_lease	dnsmasq	mac, ip, hostname, action
wifi_connect	hostapd	mac, signal, ssid
wifi_disconnect	hostapd	mac, reason
interface_up	netifd	device
interface_down	netifd	device

API Specification

WebSocket Message Format

{
  "router_id": "router-name",
  "hostname": "openwrt-device",
  "event_type": "dhcp_lease",
  "timestamp": "2026-06-04T18:00:00Z",
  "payload": {
    "mac": "AA:BB:CC:DD:EE:FF",
    "ip": "192.168.1.100",
    "hostname": "iphone",
    "action": "new"
  }
}

Server Endpoint

// Expects WebSocket connection
wss://your-server.com/ws

// Or HTTP POST fallback
POST /api/events
Authorization: Bearer <token>
Content-Type: application/json

Offline Behavior

1. Internet disconnects → Events saved to local buffer
2. Router reboots → Buffer persists in /tmp/event_buffer
3. Internet restores → Buffer flushed in order
4. Never lose events ✓

Troubleshooting

# Check if running
pgrep -a client2server

# View logs
logread -f -e client2server

# Check buffer
cat /tmp/event_buffer

# Manual test
lua /usr/sbin/client2server.lua

# Force stop
killall -9 client2server

Dependencies

• OpenWrt: lua, luasocket
• Server: express, ws (npm)

License

MIT - Luis Rosales 2026