On Tue, 19 Apr 2005, Ian FREISLICH wrote:
> Dennis Davis wrote:
> > But you can already do this. What's wrong with:
> >
> > smtp_accept_max_per_host = \
> > ${lookup{$sender_host_address}lsearch*{ ...
>
> Right! I must have misread the docs (or at some point in the past
> the option wasn't expanded).
>
Though that works, make sure you understand the implications of the
warning that is in the manual:
Warning: When setting this option you should not use any expansion
constructions that take an appreciable amount of time. The expansion and
test happen in the main daemon loop, in order to reject additional
connections without forking additional processes (otherwise a denial-of-
service attack could cause a vast number or processes to be created).
While the daemon is doing this processing, it cannot accept any other
incoming connections.
If your lsearch file is small, it may remain in main memory and so your
lookup will be fast. But if it gets large you might suffer a performance
degradation. And I certainly would not advise anything like a database
lookup.
--
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
