Re: Preventing DNS lookup prior to sending 220 banner in exim4 on etch
On Tue, Jun 17, 2008 at 01:37:59PM -0300, Eduardo M KALINOWSKI wrote:
> On Tue, 17 Jun 2008 17:34:02 +0200, chris+lists@chrissearle.org
> (chris+lists@chrissearle.org) wrote:
> >I have exim4 (exim4-daemon-heavy) running on etch.
> >
> >This machine has only a few users who send directly. One of them has
> >an ISP who seems to have a broken DNS setup.
> >
> >The symptom I see is that when this user connects to the server (port 25
> >or 587) there is a large delay before the 220 banner is shown e.g.:
> >
> >[snip]
> >
> >Is it possible to whitelist a range or turn off the check?
>
> There is a debconf option that minimizes DNS lookups. It should solve
> this problem, but it might disable the lookups also in places where
> you might want them.
OK - just tried that. Seems to set the host_lookup to empty instead of *
and yes - the 220 banner is now instant.
I wonder if there is a way to say that host_lookup is everything except
a range though? It would be great to be able to say all hosts except the
IPs in this ISP's dial up ranges.
Anyhow - I'm going to leave it running for a couple of weeks (am off net
for two weeks soon) and will see if it causes any issues.
Thanks for your pointer ;)
--
Chris Searle
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