You can check if a port is open on a device by issuing the telnet command. If it is open, you will see a blank screen after issuing the command:
telnet [domainname or ip] [port]
- [domainname or ip] is the domain name or IP address of the server to which you are trying to connect
- [port] is the port number where the server is listening
If the port is open, you will see a blank screen. This means that the connection is successful. If the port is closed, you will receive a Connect failed message.