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I want to know if port 139 TCP is open from a server on one domain to another. How would I do this?

I know that I can use Telnet to test port 25 to a server with Exchange installed - but that only works because Exchange answers the telnet request - is that right?

How do you test the link if there is no program on the other end that will respond to telnet for example?

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up vote 3 down vote accepted

Check out nmap:

nmap -p 25


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That's brilliant - thanks. The line actually needed to be "nmap -Pn139" but that worked perfectly. Thanks for that. – Kieran Walsh Apr 7 '11 at 11:58

Just use

telnet 139

If you're on a Linux/Unix box, I recommend you to check nc

man nc
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As I said in my original post this will only work if there is a program on the remote side that is ready to accept 139 requests - isn't that right? What if there is no such program? – Kieran Walsh Apr 7 '11 at 7:05

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