Re: [exim] Limiting outside world to ports 465 and 587

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Author: Jeremy Harris
Date:  
To: exim-users
Subject: Re: [exim] Limiting outside world to ports 465 and 587
On 13/03/2022 01:00, The Doctor via Exim-users wrote:
> I was wonder if it is doable that the outside world
> can only see ports 587 and 465
> while limiting port 25 to localhost only.


You can do tests on those combinations in the connect ACL,
from which a deny will mean the connection is not accepted
at the SMTP level. However, an SMTP 5xx is sent to say so -
which says that the port it open; it might leak more
information than you are wanting.

I think you'd have to use firewall facilities - iptables or
similar - to make it look like there was no MTA on the port.
--
Cheers,
Jeremy