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I'm looking to see if anyone knows of slick tricks to test connections to remote server ports from Windows server 2008 and variants that don't include the telnet client installed by default. Reason being, I sometimes have clients that want to connect to port 25 for example on a remote server and say they can't. I used to run a quick test by using "telent mailserver.tld 25" or whatever to see if I could get a response on that port. I don't want to have to install the telnet client just to test this if I dont have to - are there any other native windows utilities that will allow me to connect to a remote port?

EDIT lots of good ideas!

I think I'm going to use the following to decide the best method:

  1. Can I install onto the test server in question?

    a) If so add (and remove after if needed) the telnet client.

  2. Can't install but I have access to the net?

    a) grab the portable Putty and use that to connect to port 25

    b) try to open the mailserver on port 25 in IE (which is always available) and gauge the output

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6 Answers 6

up vote 8 down vote accepted

Nope. Either you're walking them through installing the telnet client native to Windows, or you're having them install Putty or a similar app. The functionality was deemed a security risk and so was turned off.

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1  
Agreed though Putty can run without installing. –  Dan Nov 16 '11 at 16:06
1  
Yeah, I meant install in the general "you have to go grab an application" sort of way. –  Driftpeasant Nov 16 '11 at 16:09
    
That's fair enough! –  Dan Nov 16 '11 at 16:10

You could use a browser and go to http://mailserver.tld:25

Naturally you won't get a web page back, but IE for example has a different error page for 'failed to download page' vs 'can't connect to server' which is how you would decide if connectivity was established or not.

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Interesting suggestion –  MDMarra Nov 16 '11 at 16:46
    
Really, it's the same as using telnet -- connecting to a port with an app that uses a different protocol, but just checking whether the connection worked or not. –  DougN Nov 16 '11 at 16:47

I have spent quite a while on this issue as well. The best thing I came up with is copying down the the PuTTY executable.

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There is a native telnet client to windows, you just have to install it. It takes a few seconds and won't require any media.

If you just want a dumb .exe use putty, but i find its gui much more annoying than just typing 'telnet blahblah'

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Windows 2008 has PowerShell v2 I think? If so, email them this powershell script :

:: powershell script
try { 
  $tcp=new-object System.Net.Sockets.TcpClient 
  $tcp.connect("localhost",25) 
  $tcp.close() 
} 
catch { 
  "Exception occured" 
}
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I would suggest using an external port scanner, like the one provided by Gibson Research. I've been using it for a couple years now.

https://www.grc.com/x/ne.dll?bh0bkyd2

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Nice idea, but that only works to scan your local machine. It does not help for establishing whether Port X is open before servers A and B. –  Driftpeasant Nov 17 '11 at 3:51

protected by Mark Henderson Nov 23 '11 at 2:48

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