Server: emqx

Client: php-mqtt/client 3.x

PHP≥7.4

​

• need
  • The project needs to customize the offline and online of the subscription client
• code

  $server   = 'emqx server url';
  $port     = 1883;
  $clientId = 'sys_client';
  $username = 'test';
  $password = '12345678';
  $topics='$SYS/brokers/+/clients/#';//Subscription client online and offline
  $mqtt = new \PhpMqtt\Client\MqttClient($server, $port, $clientId);
  $connectionSettings = (new \PhpMqtt\Client\ConnectionSettings)
      ->setUsername($username)
      ->setPassword($password);
  
  $mqtt->connect($connectionSettings, true);
  $mqtt->subscribe($topics, function ($topic, $message) {
  			echo sprintf("Received message on topic [%s]: %s\n", $topic, $message);
  		}, 0);
  $mqtt->loop(true);
  $mqtt->disconnect();
  

• Why is there an exception?

  Received subscribe acknowledgement with invalid QoS values from the broker.
  

• How to solve it?
  • Refer to the ACL documentation of EMQX for rule setting: https://www.emqx.io/docs/zh/v4.3/advanced/acl-file.html
  • Default acl.conf

    {allow, {user, "dashboard"}, subscribe, ["$SYS/#"]}.
     
    {allow, {ipaddr, "127.0.0.1"}, pubsub, ["$SYS/#", "#"]}.
     
    {deny, all, subscribe, ["$SYS/#", {eq, "#"}]}.
     
    {allow, all}.
    

  • Modify acl.conf, for the sake of security, I only allow the specified ip subscription here$SYS/brokers/+/clients/#

    {allow, {user, "dashboard"}, subscribe, ["$SYS/#"]}.
     
    {allow, {ipaddr, "127.0.0.1"}, pubsub, ["$SYS/#", "#"]}.
    
    #Specify ip subscription
    {allow, {ipaddr, "127.0.0.1"}, subscribe, ["$SYS/brokers/+/clients/#"]}.
    #Allow all clients to subscribe
    #{allow, all, subscribe, ["$SYS/brokers/+/clients/#"]}.
    
    {deny, all, subscribe, ["$SYS/#", {eq, "#"}]}.
     
    {allow, all}.
    

  • Then, run it through the command line, it should not report an error