Re: [Exim] Exim 4 - Local Domains - Suggestion

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Author: Philip Hazel
Date:  
To: Marc Perkel, Jeremy C. Reed
CC: exim-users
Subject: Re: [Exim] Exim 4 - Local Domains - Suggestion
On Wed, 10 Oct 2001, Marc Perkel wrote:

> What I think would be handy is if I could set it so that any domain that resolved to an IP on the local
> machine was consiidered to be a locak domain. In fact - this should be the default behavior I think.


You can do this in Exim 4.

Making it the default is a security exposure. It allows anybody with
control over a DNS zone to set up a domain which is local on your host.

On Wed, 10 Oct 2001, Jeremy C. Reed wrote:

> But what if it's a secondary MX (because a higher priority MX can't be
> reached)? (Then it should have just queued and not attempted local
> delivery.)


In Exim 4 you can tell the difference. This is in the document I
published:

. In a domain list, the special item @ matches the primary host name, and the
special item @[] matches any local interface address enclosed in square
brackets (as in domain literal email addresses). The special item @mx_any
matches any domain that has an MX record pointing to the local host. The
special items @mx_primary and @mx_secondary are similar, except that the
first matches only when the primary MX is to the local host, and the second
only when the primary MX is not the local host, but a secondary MX is.

> What if someone sent a mail through your system using an unknown domain
> that resolved to your IP?


Quite.

-- 
Philip Hazel            University of Cambridge Computing Service,
ph10@???      Cambridge, England. Phone: +44 1223 334714.