The set of programs at any time works on the computer. If the program contacts the Internet, it selects a certain port. Sometimes the user has a need to define what port is occupied by the specific program or service.
Instruction
1. Open the command line: "Start-up – All programs – Standard – the Command line". Enter the netstat command – aon and click Enter. You will see the list of the existing connections. Look at the column "Local Address" - in it, at the end of every line, numbers of the ports opened on your computer are specified.
2. To learn what program opens these ports, look at the last column - "PID". In it identifiers of processes – that is their numbers are specified. In the same window of the command line enter the tasklist command and again click Enter. You will see a window with the list of the processes started on the computer. After each name there is number, it also is PID. Having looked in the graph "Local Address" of the PID program opening the port interesting you find this identifier in the list of the started processes. Now by name process you will be able to understand what program opens the port interesting you.
3. If the name of process tells nothing to you and you do not know to what program it belongs, enter it into search engine – you obtain all information on this process. As option, use the AnVir Task Manager program – with its help you will be able to trace from where the process interesting you is started.
4. Sometimes there is a need to learn what ports are open on the remote computer. In this case use a port scanner – for example, Nmap and XSpider. For scanning you need to know the IP address of the remote computer. Enter it in a program address field, set necessary options (about them esteem in the instruction to the program) and start scanning. After the program finishes work, you obtain information on the ports opened on the remote machine. Such ports as port 21 – ftp, 23 – telnet, 3389 - Remote Desktop , 4988 – Radmin, etc. are most often open. The law does not prohibit scanning – nevertheless if the administrator of a resource notices scanning, he can prohibit access from your IP address.
5. You can scan also own computer, having set address 127.0.0.1. In this case you obtain all information on open ports that will help you to provide high degree of safety. Always try to close the excess services having Internet access. With it you can be helped by the wwdc program capable to close some ports, vulnerable for the attack, – in particular, 445 and 137. Use it if you work with Windows XP.