Ports scanner
Ports Check - is a simple and free online tool for checking open ports on your computer or remote computer / device will be useful when testing port forwarding settings on a machine. For example, if you encounter a problem connecting to the program (e-mail, IM client, etc.), it is possible that the port required by the application is blocked by a firewall or ISP, in such cases this tool can help you diagnose the problem . This can also be useful for security reasons if you are worried about whether a particular port is open or closed.