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

Jeremy Harris wrote:

> Toralf Lund wrote:
>
>> kmb wrote:
>>
>>> Yes there is a correct way to configure a MTA behind a NAT router and a
>>> Dynamic IP address setup... Please use an Upstream Smart host.
>>>
>> I've considered that. However, isn't there also an HELO/EHLO involved
>> when the local MTA passes on data to the smart host, and shouldn't
>> that be valid, too?
>
>
> Strictly, yes. However, smarthosts and their clients are really
> operating outside the design boundaries of SMTP and as such can
> use more lax rules by arrangement. That is, you need to ask
> the operator of your smarthost what they'll accept.

Yes, of course...

>
>> Something else I've been wondering about is if the smarthost may be
>> dynamically configured, too. Like, can I tell exim to always use the
>> official MX for the current domain? (I'm looking for a setup that
>> works without modifications when you e.g. move the PC between your
>> ISP at home and the LAN at the work.)
>
>
> Exim is flexible enough, certainly. "A simple matter of programming".

Hmmm. Seems like I might use something like

smarthost:
driver = manualroute
self = pass
transport = remote_smtp
route_list = * <domain>/MX

in recent Exim versions. (I'm not sure if MX lookup could be done that
way the last time I thought about doing this.) That's assuming the MX
may also be used as a smarthost, of course. And "<domain>" would have to
be replaced by the domainname associated with the current host. I'm
actually not quite sure what the best way of obtaining it is. Also, I
would probably still have to worry about the address-translation.

- Toralf