How do I determine if a port is open on a Windows server?

Question

I'm trying to install a site under an alternative port on a server, but the port may be closed by a firewall. Is there a way to ping out or in, on a specific port, to see if it is open?

See also http://serverfault.com/questions/309357/ping-a-specific-port — Vadzim, Sep 07 '15 at 11:00

score 789 · Accepted Answer · edited Aug 03 '19 at 16:11

789

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.
From outside, just use telnet host port (or telnet host:port on Unix systems) to see if the connection is refused, accepted, or timeouts.

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. To solve this, just enable it: Click *Start** → Control Panel → Programs → Turn Windows Features on or off. In the list, scroll down and select Telnet Client and click OK.

edited Aug 03 '19 at 16:11

Peter Mortensen

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answered Nov 07 '08 at 18:55

Alnitak

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In Win7 or Vista defaul option 'telnet' is not recognized as an internal or external command,operable program or batch file. To solve this, just enable it : Click Start, Control Panel, Programs, and then Turn Windows Features on or off. In the list, scroll down and select Telnet Client and click OK – volody Nov 03 '10 at 01:41
@volody any suggestion on how do that w/o admin rights? – thisdotnull Apr 24 '14 at 07:44
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@PankajKohli use [PuTTy](http://www.chiark.greenend.org.uk/~sgtatham/putty/download.html) telnet client instead. It does not need to be installed. – Colin Pickard May 12 '14 at 14:28
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What does `Could not open connection to the host, on port *x*: Connect failed` indicate? – Kenny Evitt Jul 08 '14 at 13:39
The proper syntax for mine is "telnet host port", if it connects your screen will go black or have some gibberish reply. – Ray Foss Jul 30 '14 at 11:49
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@Alnitak I just wanted to check as I think this already answers my question. When I do `telnet api-3t.sandbox.paypal.com 443` I get `Connecting to api-3t.sandbox.paypal.com...Could not open connection to the host on port 443: Connect failed` Is this because the firewall is blocking it? – Popeye Jan 21 '15 at 09:10
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there is a difference if you open telnet.exe and then type `o host port` vs open command line (cmd.exe) and then type `telnet host port` – Pawel Cioch Jul 21 '15 at 13:42
"connection timed out = firewall is blocking access" but whose firewall the source(outside pc) or the destination's( the PC i am tring to telnet) ? – avadhut007 Nov 11 '20 at 10:10
what about udp? – Dmitry Surin Nov 20 '20 at 15:54
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@DmitrySurin UDP is way harder, and depends on whether the far end is configured to send ICMP "destination unreachable" messages, and on the near end process having sufficient privilege to be able to receive those. – Alnitak Nov 21 '20 at 09:17

score 227 · Answer 2 · edited Jul 20 '22 at 17:26

227

On Windows you can use

netstat -na | findstr "your_port"

to narrow down the results. You can also filter for LISTENING, ESTABLISHED, TCP and such. Mind it's case-sensitive though.

edited Jul 20 '22 at 17:26

Ali

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answered Apr 11 '13 at 15:27

J.Celmer

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you cant use find like this, it will be searching for files, you should use grep – Moataz Elmasry Sep 17 '13 at 13:53
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@MoatazElmasry, that's true on Linux, but this is on a Windows server, where find is the correct command. Grep is not available on Windows. I just ran the exact command mentioned here, and it worked perfectly. – Ben Wyatt Jan 30 '14 at 15:28
You can also run: netstat -an | select-string -pattern "your_port" – rleelr May 29 '15 at 08:24
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When I used that command i.e netstat -an | find "19345" , I didnt get any result. what does it mean? – nanosoft Jul 22 '15 at 10:22
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`find` did not work in Windows 10 for me, but `netstat -na | findstr "8080"` worked – arun Mar 30 '16 at 20:18
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nothing happens, not with find or findstr – usefulBee Apr 06 '16 at 20:19
This works on Windows 10 as well, they have brought piping and `find` to Windows – Hamman Samuel May 14 '16 at 12:26
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`| findstr ":8080"` – Czechnology Aug 12 '19 at 12:44

knocte · Answer 3 · 2020-01-07T10:18:02.770

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If you're checking from the outside, not from the server itself, and you don't want to bother installing telnet (as it doesn't come with the last versions of Windows) or any other software, then you have native PowerShell:

Test-NetConnection -Port 800 -ComputerName 192.168.0.1 -InformationLevel Detailed

(Unfortunately this only works with PowerShell 4.0 or newer. To check your PowerShell version, type $PSVersionTable.)

PS: Note, these days there are some claims on the twittersphere that hint that this answer could be improved by mentioning "Test-Connection" from PowerShell Core, or the shortcut "tnc". See https://twitter.com/david_obrien/status/1214082339203993600 and help me edit this answer to improve it please!

(If you have a PSVersion < 4.0, you're out of luck. Check this table:

Even though you can upgrade your version of PowerShell by installing the Windows Management Framework 4.0, it didn't do the trick for me, Test-NetConnection cmdlet is still not available).

edited Jan 07 '20 at 10:18

answered Feb 25 '16 at 10:09

knocte

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This is the best answer. Installing telnet isn't always straight-forward on other people's servers! – TrojanName Feb 25 '19 at 11:59
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Definitely must be the best answer. – QtRoS Nov 08 '19 at 08:48
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This is a more reliable option than telnet, telnet would just hung not reporting anything while this reports that the port is available in my case. – axk Jan 03 '20 at 17:50
Great, for Windows 10 this is so far the best solution, without messing up installing third party extensions (on Linux I would have used telnet or nc). – Andrea Jun 16 '21 at 08:52
it was very helpful to find this page. I wouldn't close it. – Mariusz May 25 '22 at 09:31
what page? close what? – knocte May 26 '22 at 06:32

score 45 · Answer 4 · edited Aug 03 '19 at 16:21

45

I did like that:

netstat -an | find "8080"

from telnet

telnet 192.168.100.132 8080

And just make sure that the firewall is off on that machine.

edited Aug 03 '19 at 16:21

Peter Mortensen

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answered Mar 06 '14 at 12:30

Sarvar Nishonboyev

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When I used that command i.e netstat -an | find "19345" , I didnt get any result. what does it mean? – – nanosoft Jul 22 '15 at 10:29
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it means that this port is free – Sarvar Nishonboyev Jul 31 '15 at 06:48
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I get an error when I run `netstat -an | find "8080"` it says, `no such file named "8080"` – Pragyaditya Das Oct 11 '16 at 10:47

score 41 · Answer 5 · edited Apr 19 '17 at 01:16

41

On a Windows machine you can use PortQry from Microsoft to check whether an application is already listening on a specific port using the following command:

portqry -n 11.22.33.44 -p tcp -e 80

edited Apr 19 '17 at 01:16

wjandrea

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answered May 29 '14 at 04:48

Gunjan Moghe

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Firewalled ports will generally appear as "FILTERED". – dlanod Apr 21 '15 at 03:52
You could use this tool to check UDP port as well: `portqry -n 11.22.33.44 -p udp -e 19132` – HelloWorld101 May 25 '17 at 16:48

score 24 · Answer 6 · edited Aug 03 '19 at 16:13

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If telnet is not available, download PuTTY. It is a far superior Telnet, SSH, etc. client and will be useful in many situations, not just this one, especially if you are administering a server.

edited Aug 03 '19 at 16:13

Peter Mortensen

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answered Jan 11 '11 at 14:31

Machtyn

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Yes, but not for pasting Forth code, say, with [AmForth](http://amforth.sourceforge.net/) (unless using PuTTY in combination with [Edit Overflow](http://pmortensen.eu/)). – Peter Mortensen Aug 03 '19 at 16:14

score 16 · Answer 7 · edited Aug 03 '19 at 16:21

16

Use this if you want to see all the used and listening ports on a Windows server:

netstat -an |find /i "listening"

See all open, listening, established ports:

netstat -a

edited Aug 03 '19 at 16:21

Peter Mortensen

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answered Jun 23 '14 at 06:11

zehnaseeb

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score 13 · Answer 8 · edited Aug 15 '12 at 12:51

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Do you want a tool for doing it? There is a website at http://www.canyouseeme.org/. Otherwise, you need some other server to call you back to see if a port is open...

edited Aug 15 '12 at 12:51

mathieu

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answered Nov 07 '08 at 18:54

Douglas Mayle

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score 8 · Answer 9 · edited Aug 03 '19 at 16:16

8

On Windows Server you can use

netstat -an | where{$_.Contains("Yourport")}

edited Aug 03 '19 at 16:16

Peter Mortensen

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answered May 03 '13 at 14:59

Derbium

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Doesn't address the firewall issue in any way. – user207421 May 29 '14 at 05:36
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This works on powershell – Paco Zarate Aug 08 '14 at 15:37
Or do you mean "a Windows server"? – Peter Mortensen Aug 03 '19 at 16:17

score 4 · Answer 10 · edited Aug 03 '19 at 16:22

4

PsPing from Sysinternals is also very good.

edited Aug 03 '19 at 16:22

Peter Mortensen

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answered Dec 12 '14 at 08:21

Good tool. Example code would be: PsPing -n 20 -i 0 servername:port – Asher Oct 16 '19 at 06:31

score 4 · Answer 11 · answered Sep 07 '15 at 10:59

4

Another option is tcping.

For example:

tcping host port

answered Sep 07 '15 at 10:59

Vadzim

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score 1 · Answer 12 · edited Aug 03 '19 at 16:18

1

Here is what worked for me:

Open a command prompt
Type telnet
Microsoft Telnet>open <host name or IP address><space><port>

It will confirm whether the port is opened.

edited Aug 03 '19 at 16:18

Peter Mortensen

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answered Jul 02 '13 at 15:38

Praveen Tiwari

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score 0 · Answer 13 · edited Dec 18 '19 at 22:15

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Another utility that I found and is good and small as well, is PortQry Command Line Port Scanner version 2.0.

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.

edited Dec 18 '19 at 22:15

Peter Mortensen

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answered Jun 07 '16 at 20:23

Gilberto

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How do I determine if a port is open on a Windows server?

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