This problem occurs when the connection address, port number, username, or password is incorrect, or when the maximum allowed number of connections is exceeded.

• Incorrect connection address

  Error message displayed for an incorrect connection address in intra-VPC access:

  [root@ecs-heru RabbitMQ-Tutorial]# java -cp .:rabbitmq-tutorial.jar Send 192.168.125.110 5672 user *******
  Exception in thread "main" java.net.NoRouteToHostException: No route to host (Host unreachable)
  at java.net.PlainSocketImpl.socketConnect(Native Method)
  at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)
  at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)

  Error message displayed for an incorrect connection address in public access:

  [root@ecs-heru RabbitMQ-Tutorial]# java -cp .:rabbitmq-tutorial.jar Send 139.xxx.178 5672 user *******
  Exception in thread "main" java.net.SocketTimeoutException: connect timed out
  at java.net.PlainSocketImpl.socketConnect(Native Method)
  at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)

• Incorrect port number

  Error message displayed for an incorrect port number in intra-VPC access:

  [root@ecs-heru RabbitMQ-Tutorial]# java -cp .:rabbitmq-tutorial.jar Send 192.168.125.111 5673 user *******
  Exception in thread "main" java.net.ConnectException: Connection refused (Connection refused)
  at java.net.PlainSocketImpl.socketConnect(Native Method)
  at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)
  at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)

  Error message displayed for an incorrect port number in public access:

  [root@ecs-heru RabbitMQ-Tutorial]# java -cp .:rabbitmq-tutorial.jar Send 139.xxx.179 5673 user *******
  Exception in thread "main" java.net.SocketTimeoutException: connect timed out
  at java.net.PlainSocketImpl.socketConnect(Native Method)
  at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)
  at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)

• Incorrect username or password

  [root@ecs-heru RabbitMQ-Tutorial]# java -cp .:rabbitmq-tutorial.jar Send 192.168.125.111 5672 user *******
  Exception in thread "main" com.rabbitmq.client.AuthenticationFailureException: ACCESS_REFUSED - Login was refused using authentication mechanism PLAIN. For details
   see the broker logfile.
  at com.rabbitmq.client.impl.AMQConnection.start(AMQConnection.java:351)
  at com.rabbitmq.client.impl.recovery.RecoveryAwareAMQConnectionFactory.newConnection(RecoveryAwareAMQConnectionFactory.java:64)

• Maximum number of connections exceeded

If you have encountered that are not included in the document, please leave a message below.