[Dshield] Denying incoming email by reverse lookup of ISP DHCP-edaddresses

Brian Dessent brian at dessent.net
Fri Jun 17 16:28:47 GMT 2005

Stef wrote:

> so my question is: does anyone know of a "canned" script, or add-on to
> std email servers (sendmail, postfix, etc.), or a standalone third
> party solution, with all the potential format of name-addresses like
> the above, pre-built - before I start writing my own (perhaps going
> after the email header's IP, and doing a reverse lookup of the
> original IP, and rejecting the ones where the IP x.y.z.w resoved to a
> name containing x-w-z-w ... but I am not sure if this is the rule for
> all ISPs)?!?

Every decent MTA on the planet has the capability to consult DNS
blocklists, and so configure it just consult one of the "dynamic IP
address range" DNSBLs such as dul.dnsbl.sorbs.net.


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