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Re: Question about NAT

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  • Noel Jones
    ... Use your external hostname. Hopefully this is also the reverse DNS hostname of your public IP. ... www.dnsstuff.com www.dnsreport.com Or try to connect
    Message 1 of 4 , Nov 30, 2006
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      At 03:25 PM 11/30/2006, Gallagher, Tim F \(NE\) wrote:
      >I have a problem, let me start:
      >I have a windows based email server merak mail server. I
      >have an MX
      >record that points to the public side of my router and the
      >email server
      >is on the private side. I opened ports on the router so
      >mail messages
      >can come in and mail can leave. When I install Postfix I
      >need to give
      >it the name of the server and FQD of what the MX record sees.
      >
      >Lets say my MX record points to mail.mydomain.com 72.114.36.87.
      >My server is mailer.internal.mydomain.com 192.168.0.6
      >I have an internail dns server that points
      >mailer.internail.mydomain.com
      >to 192.168.0.6
      >
      >Question #1 What should I call the mail server when I am
      >prompted for
      >this "myhostname = server.yourdomain.com" when I install
      >postfix

      Use your "external" hostname. Hopefully this is also the
      reverse DNS hostname of your public IP.


      >Question #2 What can I go to make sure this works, IP wise.

      www.dnsstuff.com
      www.dnsreport.com
      Or try to connect to port 25 from some third-party internet
      IP. You can't test external connectivity from within your
      network.

      Be sure to set proxy_interfaces to your external IP in main.cf.
      http://www.postfix.org/postconf.5.html#proxy_interfaces


      --
      Noel Jones
    • Sheldon T. Hall
      Gallagher, Tim F (NE) says ... ... I m not sure I exactly understand your problem, but since I have what may be a similar setup, let me tell you what I m doing
      Message 2 of 4 , Nov 30, 2006
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        Gallagher, Tim F (NE) says ...
        >
        > I have a problem, let me start:
        > I have a windows based email server merak mail server. I have an MX
        > record that points to the public side of my router and the
        > email server
        > is on the private side. I opened ports on the router so mail messages
        > can come in and mail can leave. When I install Postfix I need to give
        > it the name of the server and FQD of what the MX record sees.
        >
        > Lets say my MX record points to mail.mydomain.com 72.114.36.87.
        > My server is mailer.internal.mydomain.com 192.168.0.6
        > I have an internail dns server that points
        > mailer.internail.mydomain.com
        > to 192.168.0.6
        >
        > Question #1 What should I call the mail server when I am prompted for
        > this "myhostname = server.yourdomain.com" when I install postfix
        > Question #2 What can I go to make sure this works, IP wise.

        I'm not sure I exactly understand your problem, but since I have what may be
        a similar setup, let me tell you what I'm doing here, and perhaps it will
        give you ideas.

        The public address of my network is 206.124.138.95.

        The private network is 192.168/16, and the whole thing is NATted in the
        usual way.

        Using my router's port forwarding capabilities, various incoming conection
        requests are forwarded to particular machines inside the network.

        The mailserver, tandem.artell.net, is at 192.168.0.40. It has only the one
        NIC in use.

        I have public DNS servers, on the public internet; they point
        tandem.artell.net to 206.124.138.95. As a result, mail addressed to anyone
        at that machine, and coming from the 'net-at-large, comes through the
        router, is directed to 192.168.0.40, and is handled without drama.

        I also have private DNS servers, on 192.168/16, which resolve
        tandem.artell.net to 192.168.0.40. Since machines inside my LAN use those
        nameservers, they connect directly to the mailserver without sending their
        packets outside.

        Does that help at all?

        -Shel
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