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jack
Asked: 2010-05-18 08:47:00 +0800 CST

netcat/socat no response from other networking services

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First, I thought that this was Vmware problem.

But now, after testing on several physical machines, I realized certain services didn't return response data when using socat/netcat 1.1 which is supposed to the latest version since last updated. 

root@test3:~# netcat 192.168.1.2 25
220 762462a8c4d Microsoft ESMTP MAIL
Service, Version: 6.0.2600.5949 ready
at  Fri, 12 May 2010 18:04:20 +0600


EHLO localhost

sdfsafsd

^

root@test3:~#

I've tested it on both windows and linuxes. I found no problem with telnet.

networking

2 Answers

  1. Windows and it's services like to have a line-feed (LR) accompanying any carriage-returns (CR). Your shell won't generate the LF automatically. As a result of this, in your example, no commands would have been submitted to the receiving server.

    You can insert an LR manually alongside your CR by typing Ctrl+v, Enter, Enter at the end of each line. It will be displayed as ^M and then a newline. Then you should receive the relevant responses from the server.

    If you're using OpenSSL's s_client for talking to SSL services then you can use the argument -crlf to do it automagically for you.

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  2. are you sure you don't need to run the command like netcat 192.168.1.2 25 and then type EHLO ?

    from your question, it looks like you're typing your command as netcat 192.168.1.2 25 220 762462a8c4d Microsoft ESMTP MAIL Service, Version: 6.0.2600.5949 ready at Fri, 12 May 2010 18:04:20 +0800 EHLO SAYHELLO VRFY TEST@LOCALHOST and not netcat 192.168.1.2 25

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