Problems when using Telnet to view port information:
1.connection refused means that the port is open but no listening
When I set Kafka, the intranet IP pass, the external network did not appear above information, because my Kafka Host (/ etc / hosts) set the IP of the intranet, Kafka was launched, the intranet IP was listening to 9092,The external network IP is not listened, and the Host’s IP can be ip.
2.No Route to Host means that the port is not open
FireWallD adds a port number
FireWall-cmd –zone = public –Add-port = 9092 / tcp –pers –Permanent