Re: [Exim] Exim 4.20 - Not denying hosts without reverse DNS…

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Author: Philip Hazel
Date:  
To: Kevin W. Reed
CC: exim-users
Subject: Re: [Exim] Exim 4.20 - Not denying hosts without reverse DNS....
On Wed, 18 Jun 2003, Kevin W. Reed wrote:

> One difference that I have been unable to figure out is that with the old
> configuration, we blocked any site that arrived without a valid reverse
> dns lookup. We didn't care what the result was, just that there was one.


verify = reverse_host_lookup is stricter than you require.

However, I think using host_lookup to force a lookup to be attempted,
combined with

condition = ${if eq{$sender_host_name}{}....

in an ACL should do what you want.

> Is there an example of how I could refer to a list of hosts to see if they
> needed to be sent mail on a non-standard smtp port. Like a file that
> would contain:
>
> hostname1: 2025
> hostname2: 82
>
> If matched, the port command would then be used to send mail to that host
> on the port specified.


"port" is not an expanded option in the smtp transport, so you can't do
this directly. But if the number of possible ports is fixed, you can set
up n transports, differing only in the port settings:

remote_smtp:
driver = smtp

remote_smtp82:
driver = smtp
port = 82

remote_smtp2025:
driver = smtp
port = 2025

... etc

However, using these would have to be done by reference to the domain
rather than a host name:

router:
driver = dnslookup
transport = smtp${lookup{$domain}lsearch{/some/file}}




--
Philip Hazel            University of Cambridge Computing Service,
ph10@???      Cambridge, England. Phone: +44 1223 334714.
Get the Exim 4 book:    http://www.uit.co.uk/exim-book