Re: [Exim] Just a warning to those who use host lists for re…

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Autor: Philip Hazel
Data:  
Para: michael
CC: exim-users
Asunto: Re: [Exim] Just a warning to those who use host lists for relay control
On 12 Aug 1999 michael@??? wrote:

> A couple days ago, I removed a network from the host_accept_relay file.
> That caused a negated entry to become the last. As a result, suddenly
> we became an open relay. :(
>
> I know, it's documented in the domain list chapter. It's still easy to
> get bitten by this feature. Now I set 127.0.0.1 as the last entry and
> put a telling comment there.
>
> I know this is common ACL semantics, but perhaps still something could
> be done about it?


The problem I had when I implemented this was that I figured people
would most likely write things like

host_accept = !a.b.c.d

expecting it to block out just one host. So I made it equivalent to

host_accept = !a.b.c.d : *

Without that convention, a setting like that doesn't have anything like
the expected effect.

So, the question is: Is it easier to get bitten by the feature or
without the feature?

Whatever the answer to that is, I think that it is now too late to
change.

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