Re: [Exim] Stopping reverse DNS lookups

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Autor: Philip Hazel
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A: Ian Marsh
CC: Exim Users
Assumpte: Re: [Exim] Stopping reverse DNS lookups
On Fri, 8 Oct 1999, Ian Marsh wrote:

> From running an 'exim -bh <ip>' test it appears that the fact that we
> have entries in the 'relay_domains' and 'host_accept_relay' lists is
> making exim to the reverse lookups. All this appears to be regardless of
> what I put in the 'host_lookup' entry:


Indeed: host_lookup *forces* a host lookup, but not matching it doesn't
prevent a host lookup if the host name is needed. If you have anything
other than IP addresses and complete (non-wildcard) names in
host_accept_relay then the host name has to be looked up if the checking
gets to those items. In other words, if if needs to check the host name
and it hasn't looked it up, it has to look it up.

If you are in fact allowing relaying from the IP addresses that you
don't want looked up, you could put the IP addresses early in the list.


-- 
Philip Hazel            University of Cambridge Computing Service,
ph10@???      Cambridge, England. Phone: +44 1223 334714.
Government Policy: If it ain't broke, fix it till it is.