How to check if ports are open in Windows-systems: the simplest methods

Probably do not need to say that sometimes a user needs to use special ports in order to gain access, for example, to online games. Sometimes specialized Internet clients or complex specific programs require this. Let's try to figure out how to check if the ports in the system are open. As it turns out, this is not so difficult.

How can I check if the ports are open? Command line

So, let's start, perhaps, with the simplest thing that only is available to the user. As a rule, in most cases the solution of the question of how to check whether the ports are open in the system is reduced to the use of the command line, the functional set of which is quite diverse and allows not only to view specific information, but also to correct a lot of errors or malfunctions.

Access to it is done by prescribing the cmd command in the menu bar "Run", which in turn is called either from the main menu "Start", or a combination of Win + R. To check if the Windows port is opened, the user is interested, for You can display the full list of ports, where you will find the desired one. To do this, use the netstat -a command. After it is executed, a full list of ports with their status will be displayed.

Using online resources

In some cases, the question of how to check whether the port used by any program or online game is open (especially if it is required that it be accessible from the Internet), without the help of special online resources can not be solved. This is due only to the fact that the availability of a port was checked, so to speak, from the outside - when trying to access the local machine, and not vice versa.

For such purposes, you can use a lot of sites that check the connection and status of the proposed open port. For example, as a quick scan tool, you can use the Port-scanner section located on the WhatsMyIP.org resource. Here in the Custom Port Test section there is a special field in which the user needs to enter the port of interest, by pressing the Start Test button. Needless to say, this process will take a little time. Upon completion, the result will be issued.

How to check if the Telnet port is open in Windows XP

Finally, let's proceed to checking open ports on remote computers. In Windows XP, as well as in any other system, this is done elementary.

How can I check if the ports required to access certain Internet features or resources are open? Yes, it's easier than that. Again, the command line will be used as the main tool . But this time it will need to enter the Telnet command "server name" "port number" (for example, to check the connection through SMTP with port number 25 it looks like telnet smtp.name.ru 25, where the name is entered the domain name ). As you can see, everything is simple.

Problems in Windows Vista and above

In Vista and higher operating systems, there may be problems. This is due only to the fact that the Telnet service is simply disabled by default. Therefore, in order to check whether the ports of interest to the user are open, it will first have to be installed (activated).

In the simplest version, go to the programs and components section, and then tick the telnet client itself. If it does not turn on for some reason, use the following on the command line: dism / online / Enable-Feature / FeatureName: TelnetClient.

In case the client is not listed at all, go to the Registry Editor (the regedit command in the "Run" menu), then go down the HKLM / SYSTEM branch through the CurrentControlSet subfolder to the Windows directory. In the window on the right, we find the parameter CSDVersion and assign it to the value 200 instead of the value 200. Next, we use the same method as for the "expiry".

Why are some ports unavailable?

As a result, you can judge the status of a port. If at the moment one of them is not available, but it needs to be used, there can be quite a lot of reasons for this. Most often this is due to the effects of viruses. Sometimes you should check the TCP / IP settings. In some cases, you need to verify the correct settings of the router, especially in the case of port forwarding on the router. Also, you should pay attention to the settings of the firewall - it is possible that it blocks the port. Finally, there is a possibility that the port is actually in the open state, and the time of its ping (response) is overestimated.

However, this is not the issue now, since correction of such errors and failures is a separate issue. As for checking the ports themselves, as can be seen from the above, it is quite simple. Therefore, if, for example, an unprepared user has such a problem, it is not necessary to panic because of ignorance of the matter. Any of the proposed solutions allows such operations to be performed in a matter of seconds. In general, it is obvious that when checking, for example, online, the user must know exactly which port he needs. But sometimes the problem can be connected also with the fact that this port is blocked by the provider. Then it is necessary to solve the problem at this level.