This makes sense, since the lower-numbered ports were assigned first. The SMTP protocol for email, for example, is exclusively used by port The only problem crops up when two or more services on the same network are using the same port.
Since there are so many thousands of common port numbers, the easiest approach is to remember the ranges. Which will tell you if a given port is reserved or not. Thanks to Google, you can also look up which services use a specific port in no time at all. The good news is that Windows has a pretty useful command built into it that will show you what ports are currently being used on your computer by various applications and services.
So the last thing we want to do is check if any external blocking is happening. If some ports are listed, it means they are being blocked. While the Command Prompt is a good quick and dirty tool, there are more refined third-party applications that can help you get a picture of your port configuration. The two highlighted here are just popular examples. We tried several free tools before settling on SolarWinds, but it was the only tool that both worked properly under Windows 10 and had an easy interface.
It was also the only one not to trigger a false positive virus flag. One of the big problems with port scanning software is that security companies tend to see them as malware. So most users ignore any virus warning that come with such tools. SolarWinds might come with some strings attached, but it actually works as advertised and is easy to use.
This is, as you can probably tell, a website service rather than an application. Administrators can run the following command to show opened ports only without all other details:. One important point is that the Windows Firewall may block a port even if it is in the listening state. In the Windows Defender Firewall with Advanced Security , there has to be a corresponding inbound firewall rule to match the listening port Anything with a green checkmark is an open rule.
To check that the port is open from a remote computer, an administrator can run the telnet command from a remote computer against the IP address of the Windows computer. For example, to check if port 22 is open, I will run the telnet command from a remote computer as follows:. If telnet is not available, download PuTTY. It is a far superior Telnet, SSH, etc.
Do you want a tool for doing it? Otherwise, you need some other server to call you back to see if a port is open Another option is tcping.
PsPing from Sysinternals is also very good. You can ping a server and a port and it will tell you the state of the port. There is a command-line utility and a UI for it. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. How do I determine if a port is open on a Windows server? Asked 13 years, 2 months ago. Active 2 years ago. Viewed 2. Peter Mortensen Jason Jason See also serverfault.
Add a comment. Active Oldest Votes. Assuming that it's a TCP rather than UDP port that you're trying to use: On the server itself, use netstat -an to check to see which ports are listening. On that latter test, then in general: connection refused means that nothing is running on that port accepted means that something is running on that port timeout means that a firewall is blocking access On Windows 7 or Windows Vista the default option 'telnet' is not recognized as an internal or external command, operable program or batch file.
Alnitak Alnitak k 70 70 gold badges silver badges bronze badges. In Win7 or Vista defaul option 'telnet' is not recognized as an internal or external command,operable program or batch file. In the list, scroll down and select Telnet Client and click OK — volody. PankajKohli use PuTTy telnet client instead. It does not need to be installed. Alnitak I just wanted to check as I think this already answers my question.
0コメント