-----Original Message----- From: Ricky Beam [mailto:jfbeam@gmail.com] Sent: Friday, September 03, 2010 9:30 PM To: Owen DeLong; Patrick W. Gilmore Cc: NANOG list Subject: Re: ISP port blocking practice
On Fri, 03 Sep 2010 08:12:01 -0400, Owen DeLong <owen@delong.com> wrote:
Really? So, since so many ISPs are blocking port 25, there's lots less spam hitting our networks?
Less than there could be. It appears a lot less effective because
Brian J. there
are so many ISPs not doing any blocking. Both of my residential connections are open, and always have been. (even dialup was unblocked. which I always found odd since the UUNET wholesale dialup agreement requires the RADIUS response contain a packet filter limiting port 25 to your mail server(s).)
If I block port 25 on my network, no spam will originate from it. (probablly) The spammers will move on to a network that doesn't block their crap. As long as there are such open networks, spam will be rampant. If, overnight, every network filtered port 25, spam would all but disappear. But spam would not completely disappear -- it would just be coming from known mailservers :-) thus enters outbound scanning and the frustrated user complaints from poorly tuned systems...
--Ricky
This is what we (network admins) get paid to do! If we are running a server that is a security risk to the net, then we can't complain when it gets filtered. It is our job to do our due diligence and ensure our servers are not spam hot-beds or open relays (or other bad stuff, etc...). The port 25 blocking simply prevents the largest volume of hosts in an ISP network, the users, from being a spam delivery platform. - Brian CONFIDENTIALITY NOTICE: This email message, including any attachments, is for the sole use of the intended recipient(s) and may contain confidential and privileged information. Any unauthorized review, copying, use, disclosure, or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message. Thank you.