Mike Cardwell wrote:
> Thomas Jacob wrote:
>
>>> I have my own local dnsbl (using wrblnsd). Certainly from the rbl end it
>>> appears that Exim does in fact make 2 queries, but the TXT query is
>>> unnecessary most of the time (when a lookup returns NXDOMAIN), so unless
>>> your lookups are more than say 20% positive, it's hardly going to save much
>>> bandwidth - my point being, is it worth the effort anyway ?
>> My lookups are more like 80%-90% positive, unfortunately. And it's not
>> so much about bandwidth but about speeding up acl processing (to reduce
>> the number of parallel smtp connections at any one time) and to
>> reduce the load on our name servers, at least that's what I hope it will
>> do ;-)
>
> Instead of using "dnslists", you could perhaps use the dnsdb lookup type
> as a workaround. Example
>
> REVERSE_SENDER_IP =
> ${sg{$sender_host_address}{\N^(\d+)\.(\d+)\.(\d+)\.(\d+)$\N}{\$4\.\$3\.\$2\.\$1}}
>
> That creates a macro which returns $sender_host_address with the octets
> reversed. Then do:
>
> condition = ${lookup
> dnsdb{defer_never,REVERSE_SENDER_IP.zen.spamhaus.org}{true}{false}}
>
> This is equivalent to:
>
> dnslists = zen.spamhaus.org
>
> But only does the A record lookup
>
> If you're using more complicated features of "dnslists", it gets trickier.
>
> Mike
>
There's no need to manually reverse the IP address, it's auto-magic with
dnsdb.
http://www.exim.org/exim-html-current/doc/html/spec_html/ch09.html#SECTdnsdb
<q>
The supported DNS record types are A, CNAME, MX, NS, PTR, SRV, and TXT,
and, when Exim is compiled with IPv6 support, AAAA (and A6 if that is
also configured). If no type is given, TXT is assumed. When the type is
PTR, the data can be an IP address, written as normal; inversion and the
addition of in-addr.arpa or ip6.arpa happens automatically. For example:
${lookup dnsdb{ptr=192.168.4.5}{$value}fail}
If the data for a PTR record is not a syntactically valid IP address, it
is not altered and nothing is added.
</q>
--
The Exim Manual
http://www.exim.org/docs.html
http://www.exim.org/exim-html-current/doc/html/spec_html/index.html
