Connection is refused in a connection trial or test

Symptom

The Connection refused error is returned for a connection trial or test.

The following error message is returned:

Failed to execute the SQL statement. Error details: Could not connect to address=(host=some.domain.com)(port=2883)(type=master) : Socket fail to connect to host:some.domain.com, port:1883. Connection refused (Connection refused)

Possible causes

Connection refused indicates that the network is disconnected. Possible causes:

1. The destination address is unreachable.

2. The port of the destination address is not listened on.

3. The firewall policy of the target server denies the connection request from the client.

   Note

   For causes 1 or 2, the HOST or IP parameters may have been incorrectly configured.

Solutions

1. Use the ping command to check whether the destination address is reachable. If the address cannot be pinged, the network is disconnected. In this case, contact the network administrator to check the network configuration.

   ping ${your.ob.ip.address}
   

   

2. Use the telnet command to check whether the destination port is listening. If the telnet command fails, the destination port is unreachable.

    telnet ${your.ob.ip.address} ${your.ob.port}
   

   

3. Use the iptables command to check the firewall configuration.

4. On the target server, run the iptables -nvL command to view the firewall policy. For more information about the related parameters, see: