On 2021-11-11 at 06:06:45 UTC-0500 (Thu, 11 Nov 2021 12:06:45 +0100)
Togan Muftuoglu <tog...@dinamizm.com>
is rumored to have said:
Hi,
How can I reject connections from generic Forward Confirmed Reverse
DNS
(FCrDNS) like “123-45-67-8.your.isp.com”.
For the most cases spamhaus is able to block it but with the cloud
providers
with FCrDNS as follows not all of them are not blocked.
123-45-67-89.ip.linodeusercontent.com
ec2-12-34-56-789.us-west-2.compute.amazonaws.com
How can I reject these connections
The canonical answer is "check_client_access with a pcre table" but if
you want something comprehensive that you don't need to actively manage
yourself you should consider the "Enemies List" service:
http://enemieslist.com. They use a rich set of non-obvious name patterns
and important exceptions. You likely do NOT want to arbitrarily reject
all mail from all hosts with programmatically IP-derived names, unless
you are intending to engage in a secondary boycott of major mail service
providers' (e.g. Microsoft) customers.
(and no, I'm not affiliated with them in any way.)
--
Bill Cole
b...@scconsult.com or billc...@apache.org
(AKA @grumpybozo and many *@billmail.scconsult.com addresses)
Not Currently Available For Hire
