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Telnet - cannot open port 23, connect failed

    Question

  • I'm having problems with Telent and Window 7. Telnet works, however on one piece of OLD legacy computer UNIX system, it fails. I experienced this same problem on Windows XP, but there was a registry fix for it. This same fix does not work on Windows 7.

    The unix system does use port 23....anyone have a solution?

    Below was the registry fix that fix this problem on Windows XP.

    REGEDIT4

     

    [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters]

    "SackOpts"=dword:00000
    "Tcp1323Opts"=dword:00000

    Thursday, January 26, 2012 12:14 AM

All replies

  • Hi,

     

    What error message did you receive?

     

    You can follow this article to open port 23:

    http://maximumpcguides.com/windows-7/open-a-port-in-windows-7s-firewall/

     

    If the issue persists, try to temporary disable firewall and antivirus of test.

     

    Regards,

    Leo   Huang

     

     


    Leo Huang

    TechNet Community Support

    Friday, January 27, 2012 6:21 AM
  • The firewalls are maintained by corporate by a group policy....on the computer itself (and others) with Window 7, the Firewall is turned off.

    Same with Anti-virus (McAfee)...it cannot be turned off.

    However...in your response, you do realize that I said, that TELNET is working....it just doesn't work when trying to telnet to this particular machine.

    Friday, January 27, 2012 6:34 PM
  • Hello Leo -

    The exact error message I get is the following -

    Connecting to (computer name)....Could not open conneciton to the host, on port 23: Connect failed.

    I have added the following in the Registry under CurrentControlset001 (there is also a 002 that I did not modify)

    [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters]
    "SackOpts"=dword:00000
    "Tcp1323Opts"=dword:00000

    ************************************

    I did reboot the computer and same problem.
    As I stated, this fixed the problems in XP, but does not fix it in Windows 7

    Suggestions?

    Tuesday, February 07, 2012 7:38 PM
  • 1. Use network monitor on W 7 and UNIX side to pinpoint is there is any communication.

    2. CurrentControlSet1 is not effective and the chnage of SackOpts would not be seen I guess

    3. If nothing helps test putty to test connection.

    Regards

    Milos

    Tuesday, February 07, 2012 9:18 PM
  • Hi Milos...

    (edited...added more information at the bottom). I have encluded some parameters off the unix machine.

    Thanks for helping me out.

    I tried PUTTY... I configured the Telnet for every possible combinations and the at didn't work either.

    When you say the CurrentControlSet1 is not effective...can you please give me more details.

    As I mentioned in my original POST....I had this same problem with windows xp....but the registry fix shown allowed Telnet to work. I don't know why its not working in Windows 7. I was reading that Windows 7 has Auto Windowing and I'm working if perhaps the negoation isn't taking place. This is an old unix platform and I'll have to check to see if there is any monitoring applications...but off hand I can't think of any.

    TANGO># netstat -a
    Active connections (including servers)
    Proto Sock#  Chan#   Local Address      Foreign Address    (state)
    tcp        1      0  *.*                *.*               Listening
    tcp        2      1  *.*                *.*               Listening
    tcp        3      2  *.*                *.*               Listening
    tcp        4      3  *.*                *.*               Listening
    tcp        5      4  *.*                *.*               Listening
    tcp        8     47  208.246.0..telnet  33.149.0.0.2032   Bound
    udp        6     55  *.talk             *.*               Bound
    udp        7     56  *.ntalk            *.*               Bound
    TANGO>#

    TANGO># netstat -all
    transmissions        0x00164bcc  1461196
    mult xmit retries    0x000000be      190
    sngl xmit retries    0x00000080      128
    failed retries       0x00000000        0
    deferrals            0x00000226      550
    xmit buf err         0x00000000        0
    silo underrun        0x00000000        0
    late collisions      0x00000000        0
    lost carrier         0x00000000        0
    babble               0x00000000        0

    telnet> display
    will flush output when sending interrupt characters.
    won't send interrupt characters in urgent mode.
    won't map carriage return on output.
    won't recognize certain control characters.
    won't turn on socket level debugging.
    won't print hexadecimal representation of network traffic.
    won't show option processing.

    [^E]    echo.
    [^]]    escape.
    [^H]    erase.
    [^C]    interrupt.
    [^U]    kill.
    [^\]    quit.
    [^D]    eof.
    telnet>


    Tuesday, February 07, 2012 9:27 PM
  • I'm having problems with Telent and Window 7. Telnet works, however on one piece of OLD legacy computer UNIX system, it fails. I experienced this same problem on Windows XP, but there was a registry fix for it. This same fix does not work on Windows 7.

    The unix system does use port 23....anyone have a solution?

    Below was the registry fix that fix this problem on Windows XP.

    REGEDIT4

     

    [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters]

    "SackOpts"=dword:00000
    "Tcp1323Opts"=dword:00000

    Hi, i got the same problem with you, but in Windows XP, how i could use thats  from regedit ? I have create two value based on your quote but i couldn't solved the problem. Any telnet port couldn't do, services telnet i have start it automatically.

    Hope could get the solution.

    Thanks

    Monday, August 05, 2013 11:38 AM
  • You may activate the telnet server 

    http://www.youtube.com/watch?v=OCHGVy_QQ-g&feature=youtu.be


    The complexity resides in the simplicity Follow me at: http://smartssolutions.blogspot.com

    Wednesday, May 28, 2014 9:31 PM