Any program which uses a local area network or the Internet does it through any port. The port is a logical system address, the section of memory through which there is a data exchange. Those ports with which it is not possible to create connection are called closed. The provider can have a reason in settings of a firewall of your computer or on the server. Usually about it subscribers can learn from the operator, or by means of additional programs.
1. Start the program which will be the server for data. In other words, to check availability or openness of port, the program to which clients from network will connect is necessary. For example, you want to play a network game. Means, you need to create the server of this game on your PC to which other players will be connected. The same concerns other programs designed for net surfing.
2. Click "Start-up" and open the Execute menu. In a line of commands enter cmd, so you will open the system Windows console. In a black window gather netstat - b — it will start check of the ports opened at present and used with the name of processes. You will see the list in the form of columns with headings: Name, Local address, Foreign address, Status. The name means the name of the protocol of communication, TCP or UDP. Also the name of process which is connected with this connection is written in this column.
3. The local address is your computer and the port number on it. The foreign address indicates the computer with which the current connection is established. In the Status column there can be a record Established — it means that the port is successfully open and connection is established. Messages of Closed, Close_wait mean that exchange of packages is successfully complete. All other ports are inactive and closed at present, that is do not make any data exchange.
4. Consider that check by the netstat utility concerns only your computer and does not belong to servers of provider of services the Internet. It means that you will not be able to find out the blocked ports in such a way. Most the companies prohibit to use programs for listening or port scanning. However, knowing exact number and wishing to define the closed port or opened, it is possible to use check online services.
5. Start any browser and pass to the http://www.whatsmyip.org/port-scanner/ or http://portscan.ru page. Enter number interesting you into a window of the instrument of check and click Enter or "Check". In several seconds you receive the answer about availability or unavailability of port.