Eli wrote:
>Marc wrote:
>
>
>>"Why not check the sending IP to see if it can receive
>>anything on port 25?" Has anyone try this?
>>
>>
>
>With all the filtering rules you come up with (assuming you implement them),
>I'm amazed you receive any email at all!
>
>With a filter such as this, you'll hit many false positives as someone else
>mentioned. It is quite common in large mail set-ups to have incoming and
>outgoing SMTP from separate systems. Such a test would be ignoring DNS MX
>records, which is what controls what system should be receiving email on
>port 25. If you assume that the system sending the email must also receive
>email, you'll be in for lots of fun!
>
>Eli.
>
>
>
What I'm experimenting with is running nmap on port 25 of the incoming
connection and seeing what it returns which is either open, filtered,
closed, or none. Looking to see if there is an identifyable pattern.
--
Marc Perkel - marc@???
Spam Filter: http://www.junkemailfilter.com
My Blog: http://marc.perkel.com
My Religion: http://www.churchofreality.org
~ "If it's real - we believe in it!" ~
