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  • telnet to smtp on linux

    I have a sendmail daemon running on Linux, I can telnet @ port 25 from local shell, however if I telnet from a remote system @ port 25, it doesn't work. There is no firewall in between. Kindly advice.

  • #2
    Re: telnet to smtp on linux

    Are you telnetting to the external IP???

    Comment


    • #3
      Re: telnet to smtp on linux

      are you certain that there's no IPTables or similar configured on the linux host itself ?
      nothing in the sendmail.cf file ?
      Please do show your appreciation to those who assist you by leaving Rep Point https://www.petri.com/forums/core/im.../icon_beer.gif

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      • #4
        Re: telnet to smtp on linux

        No IP tables, there is only one NIC configured.

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        • #5
          Re: telnet to smtp on linux

          Wow your blinding me with all the information you've posted.

          Try and help us help you by posting as much information about what you are doing to try and resolve the issue as possible please.

          Are you able to telnet to the external interface of the exchange server from outside your LAN???

          Are you able to telnet to the internal interface from inside your LAN???

          Are you clients allowed to telnet??? We have access to telnet on port 25 disabled on all client machines to prevent mass mailing.

          Where are you testing telnet from???

          Comment


          • #6
            Re: telnet to smtp on linux

            Alright, It's a Fedora Linux running in a LAN environment with one NIC (IP = 10.0.0.1) running nagios and sendmail daemon. I can telnet to Linux on port 23 and then from the same CLI, I can telnet as telnet localhost 25.
            From here I can test smtp commands and send test emails.
            But I can not telnet as telnet 10.0.0.1 25

            Comment


            • #7
              Re: telnet to smtp on linux

              From where though???

              Are you on the same LAN segment???

              Comment


              • #8
                Re: telnet to smtp on linux

                Yes, no firewall in between.

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                • #9
                  Re: telnet to smtp on linux

                  Can you telnet to the normal telnet port??? If its enabled that is.

                  telnet 10.0.0.1

                  Have you allowed remote connections to the box???

                  Now i'm no where near a lilnux admin so please bear with me.

                  ***EDIT***

                  From the quick, and i mean quick, google search i've done you need to edit the /etc/mail/sendmail.mc file

                  Code:
                  dnl # The following causes sendmail to only listen on the IPv4 loopback address
                   dnl # 127.0.0.1 and not on any other network devices. Remove the loopback
                   dnl # address restriction to accept email from the internet or intranet.
                   dnl #
                   dnl # DAEMON_OPTIONS(`Port=smtp,Addr=127.0.0.1, Name=MTA')dnl -> remarks

                  Taken from here.

                  http://www.linuxquestions.org/questi...efused-562882/
                  Last edited by wullieb1; 13th July 2011, 07:29.

                  Comment


                  • #10
                    Re: telnet to smtp on linux

                    Yes, I can telnet as telnet 10.0.0.1

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                    • #11
                      Re: telnet to smtp on linux

                      Have you edited the sendmail.mc file like i suggested???

                      Comment


                      • #12
                        Re: telnet to smtp on linux

                        Thank You, a great help.

                        Comment


                        • #13
                          Re: telnet to smtp on linux

                          Did it fix it then???

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                          • #14
                            Re: telnet to smtp on linux

                            Yes, it''s fixed.

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