Open a test TCP connection to a specified IP/Port

Question

I'm looking for a tool that works across windows (xp through 7) that will allow me to open a TCP connection to a specified ip and port. This functionality used to exist in windows xp (netsh diag connect iphost ), but the Netsh diag commands seem to have been removed in vista/7. I've been looking around for something similar, and I've searched Super User, but I can't seem to find anything.

Something that's already built into windows would be ideal, but a small executable that does this (preferably command line, standalone executable).

Edit: I should have specified further. I'm familiar with Telnet and putty, and it is what I currently use, however, I'm in an environment where I have to guide non-technical users through troubleshooting very technical problems over the phone, without any form of remote access (sounds fun, right?). While telnet works, it doesn't explicitly state whether or not the TCP connection was successful; you have to look at the title bar and the contents of the terminal output, which, for some reason, seems to be impossible to users. I'm looking for something with a clear "TCP Connection completed successfully/failed" type response, if such a tool exists.

Edit #2: Thanks to everyone who answered. All suggestions were good, despite the fact that I didn't post as clear a question as I should have. Thanks for the help.

Solution 1

Netcat

nc mail.server.net 25

Socat

socat - TCP4:www.domain.org:80

(Windows version)

Reading socat's examples page never fails to boggle my mind.

Solution 2

pkgmgr is now replaced by dism.

Install telnet from command line (run it as administrator):

dism /online /Enable-Feature /FeatureName:TelnetClient

Then you can test TCP connection by:

telnet example.com 80

Solution 3

Just use Putty it's tiny (and has a portable app version). It lets you specify port and can use telnet which is a TCP connection. It also has other useful functions like serial connections (no hyper terminal in Windows 7), SSH, And Rlogin. It even has a RAW function that lets establish RAW TCP connections.

Also just so your aware: Telnet is included in XP, you can use it from the command line IE:

telnet mailserver.server.com 25

Which would establish a TCP connection on port 25.

Solution 4

Late answer, but still a good one:

PowerShell v3

Test-NetConnection google.com -Port 80

Will actually perform a TCP test and provide results:

TcpTestSucceeded : True

I do need to note that PowerShell v3, which has the NetTCPIP module this command needs, does not come installed by default prior to Windows 8. However, you can install PowerShell v3 on Windows 7.

This does not provide a solution for earlier versions of Windows, but for others who land here as I did from the interwebs, it's an easy test tool.

Solution 5

There used to be telnet in Windows, not sure if that's been removed in later versions. Try looking for it.

You could download Cygwin and run the utilities in there, including netcat and telnet.

There is a Windows version of NetCat available, but I didn't see a canonical URL for it, so I did not include a specific one.

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Comments

[Scott Chamberlain]

telnet still comes with windows it is just not enabled by default. Just type pkgmgr /iu:"TelnetClient" in a command window and it will prompt you with a UAC dialog and it will will be installed. Or you can do it through the "Turn Features on and off" dialog under programs and features.

[Supercereal]

@scott this is useful info... Thank you for sharing I had no idea it was still there in Windows 7!

[TheEmpireNeverEnded]

@ScottChamberlain, I did know about installing telnet in win7, but not about how to do it from the cmd line. Very helpful. Thank you.

[TheEmpireNeverEnded]

I'd like to test these further and see the output I get from NC and socat, but I can't at the moment thanks to the wonders of corporate firewalls.

[TheEmpireNeverEnded]

I'm accepting this as the answer. Netcat is awesome. I haven't tested the windows version yet, but I played with nc on Fedora 16, and with the -v switch, it's pretty much exactly what I'm looking for.

[JGurtz]

I found most useful in a shell scripting scenario to use nc -v -w 5 <host> <port> as result output can be compiled and reported nicely. Adjust -w <timeout in secs> value to your environment (this applies to both reachable and non-reachable endpoints and limits the speed of scanning).

[DavidPostill]

Please read the question again carefully. Your answer does not answer the original question. The OP is asking about Windows and he says he's looking for something other than telnet in his question.

[mixel]

@DavidPostill Sorry, I know. I left my answer because I googled "windows test tcp connection" and this question is on top. I think that many people come here and do not find satisfying solution (look at upvotes for Scott Chamberlain comments).

[Zyo]

+1 for instruction on installing telnet!

[looooongname]

I've tried Putty, but how do you get the Putty window to stay open after the remote connection gets closed?

[TheEmpireNeverEnded]

If windows xp to 7 was not a requirement in the original aging question, this would be the best modern-day answer, especially because it's built-in.