Re: OSF for an ISP (was Re: ..idea; ddos spam hosts off Internet?)
Dave Watkins wrote:
If I remember right (and someone correct me if I'm wrong) a mail server
doesn't have to have an MX record. If no MX record exists then the
sending server drops back to normal host records and this is perfectly
legitimate. So the MX record checking may not work so well
Dave, your theory is right, you don't have to have an MX record in your
DNS zone in order to receive mail, but Pulu wants to "tcpping", so his
idea is to check if there is an open port 25, i.e. check if the sending
server is an mailserver. This would not be the case with infected
outlooks ;) but also not for hosts behind NAT FW.
@Pulu: Is that your idea?
The problem is more that a sending host has not neccessarily to be an
receiver. (remindes me on goatse.cx ;-)) nor that is has to be smtp
(submission et al?)
In Germany several large scale ISPs began to block all mail comming
directly from an dialup ip, so I think it would be an accepted way to
try what Pulu wants to do.
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