Any program that uses a local network or the Internet does so through a port. A port is a logical system address, a piece of memory through which data is exchanged. Closed ports are those ports that cannot be connected to. The reason may be in the firewall settings of your computer or on the server of the provider. Usually, subscribers can find out about this from their operator, or using additional programs.
Instructions
Step 1
Run the program that will be the server for the data. In other words, in order to check the availability or openness of a port, you need a program to which clients from the network will connect. For example, you want to play an online game. This means that you need to create a server for this game on your PC, to which other players will connect. The same applies to other programs designed to work in the network.
Step 2
Click the Start button and open the Run menu. Enter cmd at the command line to open the Windows System Console. In a black window, type netstat -b - this will start checking the currently open and used ports with the name of the processes. You will see a list in the form of columns with headings: Name, Local address, External address, Status. The name means the name of the communication protocol, TCP or UDP. Also in this column is written the name of the process that is associated with this connection.
Step 3
The local address is your computer and the port number on it. The external address indicates the computer with which the current connection is established. The Status column may contain an Established entry, which means that the port has been successfully opened and communication has been established. Closed, Close_wait messages mean that the packet exchange has been successfully completed. All other ports are currently inactive and closed, that is, they do not perform any data exchange.
Step 4
Note that the netstat check only applies to your computer and does not apply to your ISP's servers. This means that you will not be able to find out the blocked ports in this way. Most companies prohibit listening or port scanning software. However, knowing the exact number and wanting to identify a closed or open port, you can use online verification services.
Step 5
Launch any browser and go to https://www.whatsmyip.org/port-scanner/ or https://portscan.ru. Enter the number you are interested in in the check tool window and press the Enter or Check button. In a few seconds, you will receive a response about the port availability or unavailability.
