---
title: "Get started"
source_url: https://dev.digicert.com/trustcore-sdk/nanomqtt/get-started.html
---

Follow this chapter to compile the synchronous sample client and verify broker connectivity.

## Before you begin

Ensure you have:


- **TrustCore SDK U6** release or later (NanoMQTT is built in by default). To rebuild only NanoMQTT, run `./build.sh nanomqtt` from `projects/mqtt_client/`.


- A **POSIX shell** and a **C11‑compatible tool‑chain**.


- Access to a public or private MQTT broker. We have taken the example of *https://test.mosquitto.org*.


## Community edition: Build the sample client (with SSL)

```
cmake -DBUILD_SAMPLES=ON <options> -B build -S .
cmake --build build
```

This creates the `mqtt_client` in `samples/bin/mqtt_client`.

CMake flags

| CMake flag | Purpose |
| --- | --- |
| *-DENABLE_MQTT_STREAMING=ON* | Enables MQTT streaming mode |
| *-DENABLE_MQTT_UNITTEST=ON* | Enables MQTT client unit tests |
| *-DENABLE_MQTT_TEST=ON* | Enables MQTT client functional tests |

## Standard Edition: Build the sample client (with SSL)

```bash
cd mocn-mss
./scripts/nanomqtt/mqtt_client/build_mqtt_client.sh --ssl
```

The script creates the `mqtt_client_sample` in `mocn-mss/bin/`.

## Quick publish/subscribe demo

Export a few helper variables:

```
export MQTT_SERVER=test.mosquitto.org   # any MQTT‑5 capable broker
export MQTT_PORT=1883                  # TCP
export MQTT_SSL_PORT=8883
```

### Set the library path


> **Info**
>
> Note: For ARM builds, use the `aarch64` instead of `linux-x86_64`.


```
export LD_LIBRARY_PATH=lib/:crypto_lib/linux-x86_64/:$LD_LIBRARY_PATH
```

### Start a subscriber (plain TCP)

```
./samples/bin/mqtt_client \
--mqtt_servername ${MQTT_SERVER:-test.mosquitto.org} \
--mqtt_port ${MQTT_PORT:-1883} \
--mqtt_sub_topic demo/topic \
--mqtt_clean_start
```

### Get the CA certificate

Get the CA certificate from the official Mosquitto test broker:

```
wget https://test.mosquitto.org/ssl/mosquitto.org.crt -O mosquitto_ca.crt
```

### Publish a message over TLS

```
./samples/bin/mqtt_client \
--mqtt_servername ${MQTT_SERVER:-test.mosquitto.org} \
--mqtt_port ${MQTT_SSL_PORT:-8883} \
--mqtt_transport SSL \
--ssl_ca_file mosquitto_ca.crt \
--mqtt_pub_topic demo/topic \
--mqtt_pub_message "Hello NanoMQTT" \
--mqtt_clean_start
```

## What's next?

- [Embed NanoMQTT in C](https://dev.digicert.com/md/trustcore-sdk/nanomqtt/embed-nanomqtt-in-c.md)
- [Integration notes](https://dev.digicert.com/md/trustcore-sdk/nanomqtt/integration-notes.md)
- [Troubleshoot](https://dev.digicert.com/md/trustcore-sdk/nanomqtt/troubleshoot.md)