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  • telnet - Connection to host lost

    I am having an issue connecting to a Windows 2003 server using telnet. When the machine is rebooted telnet works fine. However after a period of time a few hours maybe, suddenly nobody can connect. The telnet service is used so admin users can connect to run batch files (basically our helpdesk department).

    My only suspicion is that maybe they are not exiting telnet correctly once they have finished and just click the X button to close the CMD window and this is leaving processes open.

    I have tried connecting using the name of the machine, the IP address and as local host but all of these will give me the following error.

    Connection to host lost

    I have tried restarting the telnet service but no luck.

    Here are my settings

    tlntadmn.exe

    The following are the settings on localhost

    Alt Key Mapped to 'CTRL+A' : YES
    Idle session timeout : 1 hours
    Max connections : 5
    Telnet port : 23
    Max failed login attempts : 3
    End tasks on disconnect : YES
    Mode of Operation : Console
    Authentication Mechanism : NTLM, Password
    Default Domain : MACHINE_NAME
    State : Running

  • #2
    Re: telnet - Connection to host lost

    What does netstat, netstat -o and netstat -a show on the server?

    Just running telnet from a WXP CMD box against my W2K3 box and typing "EXIT" (Connection to host lost), I see the telnet connections hanging on for a while at the server but now w/ a PID of 0. In a few minutes, I see the connections close.

    My tlntadmn output is the same as yours other than max connections = 2

    I'm connecting using NTLM (local account w/ same password on both client and server).
    Cheers,

    Rick

    ** Remember to give credit where credit is due and leave reputation points sigpic where appropriate **

    2006-2099 R Valstar. This post is offered "as is" for discussion purposes only with no express or implied warranty of any kind including, but not limited to, correctness or fitness for use. Nothing herein shall be construed as advice. Attempting any activity based on information in this post is done at your own risk.

    Comment


    • #3
      Re: telnet - Connection to host lost

      netstat show no connection from telnet. One thing I did just notice is when I tried to telnet I got the following message

      You are about to send your password information to a remote computer in Internet
      zone. This might not be safe. Do you want to send anyway(y/n):

      I clicked 'no' this time and it prompted me for a username and password. I typed in a local username and password and this logged me successfully.

      I checked netstat and could see a connection to the box from telnet.

      Could this be an issue with windows authentication?

      Comment


      • #4
        Re: telnet - Connection to host lost

        I have also just tried the same but then log in in with my domain admin username and get a connection lost error.

        Comment


        • #5
          Re: telnet - Connection to host lost

          I was more interested in netstat when you hit failure mode.

          Does netstat -a still show telnet as "LISTENING"?

          On a netstat -o, do you see a ton of server:telnet's at what state and PID? You'll see "ESTABLISHED" and a non-zero PID for active connections, "TIME_WAIT" and 0 for closed ones that have not yet terminated.

          Regarding authentication, I didn't think that was an issue. You could try changing the default domain from the server to your domain. If you don't want to allow cleartext passwords, do a sec = -passwd
          Cheers,

          Rick

          ** Remember to give credit where credit is due and leave reputation points sigpic where appropriate **

          2006-2099 R Valstar. This post is offered "as is" for discussion purposes only with no express or implied warranty of any kind including, but not limited to, correctness or fitness for use. Nothing herein shall be construed as advice. Attempting any activity based on information in this post is done at your own risk.

          Comment


          • #6
            Re: telnet - Connection to host lost

            Thanks for the quick repsonse.

            Running netstat - a i get

            TCP MACHINE_NAME:telnet MACHINE_NAME.domain:0 LISTENING

            Running netstat -o

            TCP MACHINE_NAME:telnet MACHINE_NAME.domain:2796 TIME_WAIT 0
            TCP MACHINE_NAME:telnet MACHINE_NAME.domain:2815 TIME_WAIT 0

            I then type telnet <machinename> and get:

            You are about to send your password information to a remote computer in Internet
            zone. This might not be safe. Do you want to send anyway(y/n):

            running netstat -o I get the following:

            TCP MACHINE_NAME:telnet MACHINE_NAME.domain:2880 ESTABLISHED 2776
            TCP MACHINE_NAME:2880 MACHINE_NAME.domain:telnet ESTABLISHED 5784


            after pressing y get :

            TCP MACHINE_NAME:telnet MACHINE_NAME.domain:2880 FIN_WAIT_2 2776
            TCP MACHINE_NAME:2880 MACHINE_NAME.domain:telnet CLOSE_WAIT 5784

            and then

            TCP MACHINE_NAME:telnet MACHINE_NAME.domain:3246 TIME_WAIT 0
            TCP MACHINE_NAME:telnet MACHINE_NAME.domain:3631 TIME_WAIT 0

            Comment


            • #7
              Re: telnet - Connection to host lost

              So the situation you're in now is what I called "failure mode"?

              I'm not liking that you are being asked for a password.

              I'd change the default domain to your AD domain and see if you can authenticate. Otherwise you're gonna have to set a cleartext user and password (-u and -p) and try entering that.

              If everyone connecting is on your AD domain and you get NTLM authentication working, I'd remove the ability to enter a cleartext password via "sec = -passwd"
              Cheers,

              Rick

              ** Remember to give credit where credit is due and leave reputation points sigpic where appropriate **

              2006-2099 R Valstar. This post is offered "as is" for discussion purposes only with no express or implied warranty of any kind including, but not limited to, correctness or fitness for use. Nothing herein shall be construed as advice. Attempting any activity based on information in this post is done at your own risk.

              Comment


              • #8
                Re: telnet - Connection to host lost

                I've just tried changing the domain to the AD domain and still no luck.

                Regarding your comment "I'm not liking that you are being asked for a password". its only asks me for a password when I click 'N' after the following prompt:

                You are about to send your password information to a remote computer in Internet
                zone. This might not be safe. Do you want to send anyway(y/n):

                This in turn only happens when I connect form another Windows 2003 box. If I try from my workstation it just goes straight to:

                Connection to host lost.

                I'm trying to avoid clear text telnet for security reasons. So I think I might have to find another approach.

                Comment


                • #9
                  Re: telnet - Connection to host lost

                  Originally posted by ORADBA View Post
                  Regarding your comment "I'm not liking that you are being asked for a password". its only asks me for a password when I click 'N' after the following prompt:

                  You are about to send your password information to a remote computer in Internet
                  zone. This might not be safe. Do you want to send anyway(y/n):

                  This in turn only happens when I connect form another Windows 2003 box. If I try from my workstation it just goes straight to:
                  Now that I re-read this, I'm wondering...

                  On the W2K3 "client" box, go into IE and add the server to the Trusted sites (not \\server, just server -- uncheck that require http... bit) and jack Trusted Sites Security Level to Low.

                  Does the problem go away?
                  Cheers,

                  Rick

                  ** Remember to give credit where credit is due and leave reputation points sigpic where appropriate **

                  2006-2099 R Valstar. This post is offered "as is" for discussion purposes only with no express or implied warranty of any kind including, but not limited to, correctness or fitness for use. Nothing herein shall be construed as advice. Attempting any activity based on information in this post is done at your own risk.

                  Comment


                  • #10
                    Re: telnet - Connection to host lost

                    Morning,

                    Just tried the Internet Explorer idea but still not working

                    Comment


                    • #11
                      Re: telnet - Connection to host lost

                      When we started all this, you had probs telneting into a server (from a workstation?) after some period that persisted till you rebooted the server. Somewhere in there you had the issue of telneting from one server to another.

                      Would you recap the situation? How long is your MTBF? If you reboot which machine(s)?, do your problems go away completely? What probs do you have regardless of reboot?

                      Here's a recent thread on a poor poster where telnet got hosed after an Exchange upgrade:

                      http://forums.petri.com/showthread.php?t=13661

                      Not your OS but maybe it sparks some ideas. Look through your Event Log and see if you can recall a patch / upgrade / system change that coincided with your problem -- it did at one time work properly, no?

                      And I take it you've experimented w/ disabling Windows Firewall and IE Enhanced Security Configuration? And I take it you are virus / spyware free? And NAV / SAV is not your AV solution (seems to be tied to many weird happenings as of late)?

                      Hope something in here sparks an idea.

                      That's it for me for now.
                      Cheers,

                      Rick

                      ** Remember to give credit where credit is due and leave reputation points sigpic where appropriate **

                      2006-2099 R Valstar. This post is offered "as is" for discussion purposes only with no express or implied warranty of any kind including, but not limited to, correctness or fitness for use. Nothing herein shall be construed as advice. Attempting any activity based on information in this post is done at your own risk.

                      Comment


                      • #12
                        Re: telnet - Connection to host lost

                        Thanks for the information. I'll try to clarify a little. The underlying problem is telneting to my windows 2003 server.

                        I have tried this from my workstation, from a windows 2000 machine and from a windows 2003 server and get "Connection to host lost".

                        I have tried locally on the server itself connecting as the IP address, the machine name and as localhost. None work and give the "Connection to host lost"

                        The only difference is if I connect from windows 2003 I get this message first:

                        You are about to send your password information to a remote computer in Internet
                        zone. This might not be safe. Do you want to send anyway(y/n):

                        I type "y" and get

                        "Connection to host lost"

                        If I type 'n'

                        I am prompted to login in. If I use a domain log n I get

                        "Connection to host lost"

                        if I try a local user I can log in.

                        This is our newly installed production server so it should be clean from viruses etc.

                        It did seem to work last time I rebooted. However I wasn't present at the last reboot and by the time I had got in I don't know whether telnet had worked on startup and then stopped working later. Or if the reboot hadn't fixed it at all. So I' can't tell you what MTF is until i'm next present at a reboot, probably next weekend. (hope that all made sense).

                        The event log seems ok and AV is Mcafee. Windows firewall is disabled. I'm assured IE Enhanced Security Configuration is set exactly the same as another server I connect to using telnet (which works).

                        Thanks for that thread you send, but still no luck. I'm trying to purchase a whole bunch of extra terminal services licences so we don't have to use telnet at all(not a cheap work around but has other advantages)

                        Comment


                        • #13
                          Re: telnet - Connection to host lost

                          Telnet isn't really a stong offering in the MS world and TS is certainly better.

                          I just hate that we can't figure this one out as telnet is as basic as a day is long.

                          Best of luck to you.
                          Cheers,

                          Rick

                          ** Remember to give credit where credit is due and leave reputation points sigpic where appropriate **

                          2006-2099 R Valstar. This post is offered "as is" for discussion purposes only with no express or implied warranty of any kind including, but not limited to, correctness or fitness for use. Nothing herein shall be construed as advice. Attempting any activity based on information in this post is done at your own risk.

                          Comment


                          • #14
                            Re: telnet - Connection to host lost

                            I agree entirely, but thanks for your patience anyway.

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