MQTT connection disconnected after connected successfully over secure port 8883 with tls self-signed certificate

[VijayGawade]

Hi All

I am using Qt 5.9 with QMQTT-Emqx MQTT library for MQTT communication.

Currently, we have locally installed a mosquitto broker and configured it to use an SSL certificate with the client certificate required on Port 8883.

In our app, we connected to the broker with CA & Client certificate with the following code

    QSslConfiguration sslConfig;
    sslConfig.defaultConfiguration();
    sslConfig.setProtocol(QSsl::TlsV1_2);
    sslConfig.setPeerVerifyMode(QSslSocket::AutoVerifyPeer);
    sslConfig.setCaCertificates(caCertsList);
    sslConfig.setLocalCertificate(certs.first());
    sslConfig.setPrivateKey(QSslKey(clientKeyFile.readAll(), QSsl::Rsa));

    m_client = new QMQTT::Client("192.168.1.13", 8883, sslConfig, true);
    m_client->setClientId(MQTTConstant::clientId);

    connect(m_client, &QMQTT::Client::connected, this, &MqttController::onConnected);
    connect(m_client, &QMQTT::Client::disconnected, this, &MqttController::onDisconnected);
    connect(m_client, &QMQTT::Client::error, this, &MqttController::onError);

    m_client->setKeepAlive(10);
    m_client->setAutoReconnectInterval(1000);
    m_client->setCleanSession(true);
    m_client->setAutoReconnect(true);
    m_client->connectToHost();

Also I checked SSL library details as follows:

SSL Library Build Version: "OpenSSL 1.0.2j 26 Sep 2016" SSL Support: true SSL Library Version: "OpenSSL 1.0.2e 3 Dec 2015" In onConnected() function I also able to publish messages successfully But after that following logs are appearing

2022-06-30T16:24:00.639+05:30 ~ INF ~ controller.mqtt ~ Disconnected from MQTT Broker !!! isConnectedToHost false 2022-06-30T16:24:00.643+05:30 ~ INF ~ controller.mqtt ~ MqttController: Connected to MQTT Broker !!! 2022-06-30T16:24:00.646+05:30 ~ INF ~ controller.mqtt ~ Subscribing to sensor/rtdata topic: true 2022-06-30T16:24:00.652+05:30 ~ WRN ~ controller.mqtt ~ Device is listening messages for Topic: "sensor/rtdata" 2022-06-30T16:24:00.654+05:30 ~ WRN ~ controller.mqtt ~ New Message Arrived... Topic: "sensor/rtdata" Payload: "This is test msg from windows-laptop" 2022-06-30T16:24:00.657+05:30 ~ DBG ~ controller.mqtt ~ MQTT SSL Error: QMQTT::ClientError(SocketRemoteHostClosedError) isConnectedToHost true 2022-06-30T16:24:00.661+05:30 ~ DBG ~ controller.mqtt ~ MQTT SSL Error: QMQTT::ClientError(SocketRemoteHostClosedError) isConnectedToHost true 2022-06-30T16:24:00.664+05:30 ~ INF ~ controller.mqtt ~ Disconnected from MQTT Broker !!! isConnectedToHost false 2022-06-30T16:24:00.667+05:30 ~ INF ~ controller.mqtt ~ MqttController: Connected to MQTT Broker !!! 2022-06-30T16:24:00.669+05:30 ~ WRN ~ controller.mqtt ~ Device is not connected to MQTT Broker !!! 2022-06-30T16:24:00.671+05:30 ~ INF ~ controller.mqtt ~ Subscribing to sensor/rtdata topic: false 2022-06-30T16:24:00.744+05:30 ~ DBG ~ controller.mqtt ~ MQTT SSL Error: QMQTT::ClientError(SocketRemoteHostClosedError) isConnectedToHost false 2022-06-30T16:24:00.747+05:30 ~ DBG ~ controller.mqtt ~ MQTT SSL Error: QMQTT::ClientError(SocketRemoteHostClosedError) isConnectedToHost false 2022-06-30T16:24:00.750+05:30 ~ INF ~ controller.mqtt ~ Disconnected from MQTT Broker !!! isConnectedToHost false 2022-06-30T16:24:00.752+05:30 ~ INF ~ controller.mqtt ~ MqttController: Connected to MQTT Broker !!! 2022-06-30T16:24:00.754+05:30 ~ WRN ~ controller.mqtt ~ Device is not connected to MQTT Broker !!! 2022-06-30T16:24:00.756+05:30 ~ INF ~ controller.mqtt ~ Subscribing to sensor/rtdata topic: false 2022-06-30T16:24:00.788+05:30 ~ DBG ~ controller.mqtt ~ MQTT SSL Error: QMQTT::ClientError(SocketRemoteHostClosedError) isConnectedToHost false 2022-06-30T16:24:00.791+05:30 ~ DBG ~ controller.mqtt ~ MQTT SSL Error: QMQTT::ClientError(SocketRemoteHostClosedError) isConnectedToHost false 2022-06-30T16:24:00.794+05:30 ~ INF ~ controller.mqtt ~ Disconnected from MQTT Broker !!! isConnectedToHost false 2022-06-30T16:24:00.798+05:30 ~ INF ~ controller.mqtt ~ MqttController: Connected to MQTT Broker !!! 2022-06-30T16:24:00.800+05:30 ~ WRN ~ controller.mqtt ~ Device is not connected to MQTT Broker !!! 2022-06-30T16:24:00.802+05:30 ~ INF ~ controller.mqtt ~ Subscribing to sensor/rtdata topic: false 2022-06-30T16:24:00.907+05:30 ~ DBG ~ controller.mqtt ~ MQTT SSL Error: QMQTT::ClientError(SocketRemoteHostClosedError) isConnectedToHost false 2022-06-30T16:24:00.910+05:30 ~ DBG ~ controller.mqtt ~ MQTT SSL Error: QMQTT::ClientError(SocketRemoteHostClosedError) isConnectedToHost false 2022-06-30T16:24:00.913+05:30 ~ INF ~ controller.mqtt ~ Disconnected from MQTT Broker !!! isConnectedToHost false

[mwallnoefer]

Sorry, I have overseen this issue. TLS is always a complicated topic, so I forward it to our experts.

@KonstantinRitt @ejvr any thoughts?

[KonstantinRitt]

It is hard to guess what goes wrong there without knowledge of what's actually set to ssl config. First of all, try connecting to your broker with any other MQTT client. If that works, connect to QSslSocket's encrypted, encryptedBytesWritten, peerVerifyError and sslErrors signals (somewhere at src/mqtt/qmqtt_ssl_socket.cpp#L48) and set breakpoints there (or put a meaningful debug message instead).

Either ensure "192.168.1.13" is the adequate host name for your self-signed certificate.