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I need a utility built into several versions of Windows (XP to Win7 specifically) that can tell me if a particular port is in use. I've found a few different ways for each OS, but I'm looking for a single command that works across all of them.

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by the way: i have seen this thread…, but it does not answer my queestion ;-) – dmeu May 25 '11 at 11:18
There is not one tool, just a bunch of well-documented commands that have been around forever. What EXACTLY are you trying to do? – KCotreau May 25 '11 at 12:00
I want to see if a port is in use or not. and it must work on all windows system mentioned – dmeu May 25 '11 at 15:05
up vote 5 down vote accepted

Perhaps Netstat? netstat -h will give options.

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Ok, netstat is also an option thanks a lot! Somebody who knows about windows could confirm if it is present in all the windows systems? Thanks – dmeu May 26 '11 at 12:51
It's kind of a standard tool from the earlier days of UNIX, so I'd be surprised if it didn't go back to NT 3.x – Bart Silverstrim May 26 '11 at 12:53
netstat -ab will dump a list of binaries and their ports. I'm sure there are gui versions of netstat, but I've no experience with any. – OldTroll May 26 '11 at 13:18
@dmeu, netstat is available on every version of Windows since at least NT4/Win95. – John Gardeniers May 26 '11 at 13:22
netstat was also there in 3.5 but prtqry is more specific – Jim B May 26 '11 at 13:24

If you use netstat -n it will tell you the current in use ports. The -n tells it not to try to resolve hostnames from IPs. You could also run it with -a to have it TRY to resolve hostnames.

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also very correct! but i can only select one answer as correct one... :-( – dmeu May 26 '11 at 13:42
netstat -bona

This will link ports to processes. Very useful if you want to know what process is running on port X.

For easy reviewing I redirect the output to a file

netstat -bona > file.txt
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