UDP Log Viewer

Important

This entire codebase was written by AI in a single lazy evening because I needed the tool and couldn't be bothered to build it properly. It works for me, but use it at your own risk. I take no responsibility for anything it does or doesn't do. Not intended for production use.

A local web app that receives syslog UDP packets and displays them in a real-time browser-based log viewer. Tailored for OpenNeato — custom firmware for Neato robot vacuums that streams structured logs over UDP.

Features

• Parses RFC 3164 syslog format (<PRI>hostname: message)
• Structured view for OpenNeato JSON payloads — CMD, REQ, and EVT rows with expandable detail panels
• Color-coded severity: CRIT, ERROR, WARN, NOTICE, INFO, DEBUG, RAW
• Filter tabs (ALL / CMD / REQ / EVT) and a live search box
• Raw / Parsed toggle to see the original UDP packet
• Auto-scroll that pauses when you scroll up
• Clear button wipes the log and the server-side ring buffer
• Keeps the last 500 lines in memory — a freshly opened tab gets recent history

Install & Run

Requires Node.js 18+.

npm install

Port 514 requires root on Linux. Use --udp-port to pick an unprivileged port instead:

# Development (no root needed)
npm run dev -- --udp-port 5140

# Or on port 514 with sudo (preserves PATH so npm is found)
sudo env "PATH=$PATH" npm run dev

Then open http://localhost:3000 in your browser. The HTTP port defaults to 3000 and can be changed with --port:

npm run dev -- --port 8080 --udp-port 5140

Production build

npm run build
node dist/server.js --udp-port 5140

OpenNeato setup

In your OpenNeato firmware configuration, point the syslog destination at this machine's IP address and the chosen port. OpenNeato sends standard RFC 3164 packets with a JSON body:

<PRI>hostname: {"t":...,"typ":"command"|"request"|"event","d":{...}}

The viewer automatically detects the JSON structure and renders CMD / REQ / EVT rows with timing badges and expandable detail panels.

Testing without hardware

Send test packets with nc:

# Structured OpenNeato-style packets
echo -n '<134>openneato: {"t":1000,"typ":"request","d":{"method":"GET","path":"/api/status","status":200,"ms":12}}' | nc -u -w1 127.0.0.1 5140
echo -n '<134>openneato: {"t":1001,"typ":"command","d":{"cmd":"GetState","status":"ok","ms":23}}' | nc -u -w1 127.0.0.1 5140
echo -n '<133>openneato: {"t":1002,"typ":"event","d":{"category":"history_start","mode":"spot"}}' | nc -u -w1 127.0.0.1 5140

# Plain syslog (falls back to flat rendering)
echo -n '<131>openneato: i2c timeout' | nc -u -w1 127.0.0.1 5140

# Non-syslog packet (appears as a magenta [RAW] line)
echo -n 'not a syslog packet' | nc -u -w1 127.0.0.1 5140

Syslog severity mapping

PRI % 8	Level	Color
0–2	CRIT	red
3	ERROR	red
4	WARN	amber
5	NOTICE	blue
6	INFO	green
7	DEBUG	gray
—	RAW	magenta (parse failed)

Run tests

npm test