Re: [exim] Exim server behind NAT router (and HELO)

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Autor: Fred Viles
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A: exim-users
Assumpte: Re: [exim] Exim server behind NAT router (and HELO)
On 15 Mar 2005 at 22:02, Toralf Lund wrote about
    "[exim] Exim server behind NAT route":


|...
| Is anyone else running Exim in such a setup? What's the best way to get
| a correct HELO?


What is your definition of "correct"?

If it's a name that translates to your router's current dynamic IP, I
can't think of any way short of superhuman efforts or a dynamic DNS
service. E.g. a program to extract your current WAN IP from the
router's web interface or an external site that reports the
connecting IP, then doing a reverse lookup (which may not even yield
an answer, depending on your ISP). Or you can set up an account with
a dynamic DNS service like <http://www.dyndns.org/>, then you'd have
a fixed name that always looks up to your current address.

The NAT router isn't the problem, BTW, it's the dynamic IP address.
FWIW, any site that insists that the HELO/EHLO name looks up to the
connecting IP address is not very concerned about rejecting
legitimate email. But rejecting mail from dynamic IP addresses is
not at all uncommon. It's unfortunate but true that running an SMTP
server on a dynamic IP address is increasingly unworkable on today's
internet.

- Fred