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Re: External connection to Postfix problem

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  • Wietse Venema
    ... Report the output from telnet postfix-ip-address 25 from a different machine on your local network. Wietse
    Message 1 of 5 , Jun 20, 2013
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      Gary Brinker:
      > The issue is that I can telnet into it internally with no problem
      > but cannot reach it externally. I hooked up wireshark and if I'm
      > interpreting it correctly I do find the initial SYN come in but
      > no connection is established.

      Report the output from "telnet postfix-ip-address 25" from a
      different machine on your local network.

      Wietse
    • Scott Kitterman
      ... I think it s stunningly unlikely that you are having an issue related to upstream Postfix issues. I would recommend using an Ubuntu server specific venue
      Message 2 of 5 , Jun 20, 2013
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        On Thursday, June 20, 2013 10:19:25 AM Gary Brinker wrote:
        > Because of a hardware failure on an old installation of a postfix gateway I
        > took the opportunity to install an up to date version on an Ubuntu server.
        > I am not too far into the configuration but am having a basic problem with
        > accessing it from external sites. I think I can eliminate the usual DNS and
        > router configurations as it did work correctly with the old system. The
        > issue is that I can telnet into it internally with no problem but cannot
        > reach it externally. I hooked up wireshark and if I'm interpreting it
        > correctly I do find the initial SYN come in but no connection is
        > established. My reading suggests that I may have an ownership or
        > permissions problem, but I'm not finding success in isolating the issue.
        > Can anyone point out specifically what I should be looking at to diagnose
        > and correct this so I can get on to the meat of the configuration. Thanks
        > for any suggestions.

        I think it's stunningly unlikely that you are having an issue related to
        upstream Postfix issues. I would recommend using an Ubuntu server specific
        venue to try and fix the problem. One would be:

        https://lists.ubuntu.com/mailman/listinfo/ubuntu-server

        Scott K
      • Gary Brinker
        ... The output from the internal address is the 250 greeting banner and using the external IP is could not open connection : connection failed Gary
        Message 3 of 5 , Jun 20, 2013
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          > Report the output from "telnet postfix-ip-address 25" from a
          > different machine on your local network.
          >
          > Wietse
           

          The output from the internal address is the 250 greeting banner and using the external IP is
          could not open connection : connection failed
           
          Gary
        • Wietse Venema
          ... This confirms that Postfix accepts network connections, and that the problem is outside of Postfix. It could be any of: - Incorrect default route
          Message 4 of 5 , Jun 20, 2013
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            Wietse:
            > Report the output from "telnet postfix-ip-address 25" from a
            > different machine on your local network.

            Gary Brinker:
            > The output from the internal address is the 250 greeting banner
            > and using the external IP is could not open connection : connection
            > failed Gary

            This confirms that Postfix accepts network connections, and
            that the problem is outside of Postfix.

            It could be any of:
            - Incorrect default route configured on the Postfix host
            - Incorrect firewall configuration on the Postfix host
            - Incorrect LAN router configuration (NAT/forwarding)
            - Conflict with ISP-side configuration
            - ....

            This is a matter of systematic trouble shooting, or random experiments
            and dumb luck.

            Wietse
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