# Mosquitto Clients

> Auth/lab ref: Mosquitto client tools, primarily `mosquitto_pub` and `mosquitto_sub`, for interacting with MQTT brokers.

- Skill: `aeondave/mosquitto-clients` (Agent Skill)
- Install (CLI): `npx skillmds@latest add aeondave/mosquitto-clients`
- Raw SKILL.md: https://api.skillmd.com/api/skills/aeondave/mosquitto-clients/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: AeonDave (https://skillmd.com/u/aeondave)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/aeondave/mosquitto-clients

---


# Mosquitto Clients

Small, sharp MQTT tooling for quick broker interaction without writing a custom client first.

## When to use mosquitto-clients

Use these tools when you need to:

- subscribe to MQTT topics and observe message flow
- publish controlled messages to a topic
- validate broker auth, TLS, or topic structure quickly

## Quick Start

```bash
# Subscribe to everything verbosely
mosquitto_sub -h broker.local -t '#' -v

# Publish a test message
mosquitto_pub -h broker.local -t test/topic -m 'hello'
```

## High-Value Workflows

### Authenticated subscribe/publish

```bash
mosquitto_sub -h broker.local -p 1883 -u user -P pass -t 'sensors/#' -v
mosquitto_pub -h broker.local -p 1883 -u user -P pass -t 'actuators/cmd' -m 'on'
```

### TLS example

```bash
mosquitto_sub -h broker.local -p 8883 --cafile ca.pem -t '#' -v
```

## Practical Notes

- Start with a broad read-only subscription pattern like `#` only in controlled environments.
- Use `-v` so topic names and payloads stay paired in output.
- Pair with packet capture or device docs when topic semantics are unclear.

## Caveats

- Publishing to a live broker can trigger real actions.
- Some brokers enforce ACLs, retained messages, or TLS requirements that change what you see.
- Topic wildcards are powerful and noisy; use them intentionally.

## Resources

No bundled `scripts/`, `references/`, or `assets/`.
Use the Mosquitto man pages for TLS, session, retained-message, and last-will options.