To each program working with network the operating system selects local port through which that also carries out connection. Sometimes the user has a need to learn at what port any given program works or what application occupies specific port.
1. Information on the used ports can be necessary in case of suspicion of computer infection with the Trojan programs. In particular, can point such signs as the increased traffic or network activity of the computer to it when you do not use the Internet.
2. At suspicion of computer infection first of all check what local ports on it are open. For this purpose open the command line: "Start-up" - "All programs" - "Standard" - "Command line". Enter in the opened terminal window the netstat command – aon, it will show all current connections.
3. In the first column of the appeared list the connection type is specified. In the second the local address and the used ports. The column "Foreign address" will show the addresses to which your computer connects. In the graph "Status" you can look at the status of connection – whether there is it at the moment - ESTABLISHED, is finished – TIME_WITE or the program listens to port, that is is ready to communication – LISTENING. At last, the column PID shows a process identifier – the number code by means of which you will be able easily to understand what process "hangs" on any given port.
4. Make the tasklist team in the same window, you will see the list of the started processes. In the second column, at once behind names of processes, their identifiers are specified. Let's say you see according to the first list that you open local port 3564. Then you look in the last column (PID) and you find a process identifier – for example, 3388 (at you data will be others). Now you pass to the second table, you look for in the second PID 3388 column and to the left of it you see the name of the program which opened this port.
5. To obtain more information on the addresses to which your computer connects use the relevant network services. For example, to these: http://www.ip-ping.ru/whois/ Enter the necessary IP address in the field, click "Request" and you obtain all available data.