esp-idf/examples/protocols/mqtt/ssl_mutual_auth/README.md

Supported Targets	ESP32	ESP32-C2	ESP32-C3	ESP32-C6	ESP32-H2	ESP32-S2	ESP32-S3

ESP-MQTT SSL Sample application (mutual authentication)

(See the README.md file in the upper level 'examples' directory for more information about examples.)

This example connects to the broker test.mosquitto.org using ssl transport with client certificate and as a demonstration subscribes/unsubscribes and send a message on certain topic. (Please note that the public broker is maintained by the community so may not be always available, for details please visit http://test.mosquitto.org)

It uses ESP-MQTT library which implements mqtt client to connect to mqtt broker.

How to use example

Hardware Required

This example can be executed on any ESP32 board, the only required interface is WiFi and connection to internet.

Configure the project

• Open the project configuration menu (idf.py menuconfig)

• Configure Wi-Fi or Ethernet under "Example Connection Configuration" menu. See "Establishing Wi-Fi or Ethernet Connection" section in examples/protocols/README.md for more details.

• Generate your client keys and certificate

Navigate to the main directory

cd main

Generate a client key and a CSR. When you are generating the CSR, do not use the default values. At a minimum, the CSR must include the Country, Organisation and Common Name fields.

openssl genrsa -out client.key
openssl req -out client.csr -key client.key -new

Paste the generated CSR in the Mosquitto test certificate signer, click Submit and copy the downloaded client.crt in the main directory.

Please note, that the supplied files client.crt and client.key in the main directory are only placeholders for your client certificate and key (i.e. the example "as is" would compile but would not connect to the broker)

The server certificate mosquitto.org.crt can be downloaded in pem format from mosquitto.org.crt.

Build and Flash

Build the project and flash it to the board, then run monitor tool to view serial output:

idf.py -p PORT flash monitor

(To exit the serial monitor, type Ctrl-].)

See the Getting Started Guide for full steps to configure and use ESP-IDF to build projects.

Example Output

I (3714) event: sta ip: 192.168.0.139, mask: 255.255.255.0, gw: 192.168.0.2
I (3714) system_api: Base MAC address is not set, read default base MAC address from BLK0 of EFUSE
I (3964) MQTT_CLIENT: Sending MQTT CONNECT message, type: 1, id: 0000
I (4164) MQTTS_EXAMPLE: MQTT_EVENT_CONNECTED
I (4174) MQTTS_EXAMPLE: sent publish successful, msg_id=41464
I (4174) MQTTS_EXAMPLE: sent subscribe successful, msg_id=17886
I (4174) MQTTS_EXAMPLE: sent subscribe successful, msg_id=42970
I (4184) MQTTS_EXAMPLE: sent unsubscribe successful, msg_id=50241
I (4314) MQTTS_EXAMPLE: MQTT_EVENT_PUBLISHED, msg_id=41464
I (4484) MQTTS_EXAMPLE: MQTT_EVENT_SUBSCRIBED, msg_id=17886
I (4484) MQTTS_EXAMPLE: sent publish successful, msg_id=0
I (4684) MQTTS_EXAMPLE: MQTT_EVENT_SUBSCRIBED, msg_id=42970
I (4684) MQTTS_EXAMPLE: sent publish successful, msg_id=0
I (4884) MQTT_CLIENT: deliver_publish, message_length_read=19, message_length=19
I (4884) MQTTS_EXAMPLE: MQTT_EVENT_DATA
TOPIC=/topic/qos0
DATA=data
I (5194) MQTT_CLIENT: deliver_publish, message_length_read=19, message_length=19
I (5194) MQTTS_EXAMPLE: MQTT_EVENT_DATA
TOPIC=/topic/qos0
DATA=data