From owner-nanog@merit.edu Wed Aug 6 19:10 EDT 1997 Date: Wed, 6 Aug 1997 19:09:15 -0400 (EDT) From: Jon Lewis <jlewis@inorganic5.fdt.net> To: Andy Pitts <andy@rbdc.rbdc.com> cc: nanog@merit.edu Subject: Re: Implementing anti-abuse techniques on ISP networks.... MIME-Version: 1.0

On Wed, 6 Aug 1997, Andy Pitts wrote:

...

I too, am a small Internet Service Provider, and I too, don't want to block sites that my users may want to access. But there seems to be a few domains that do nothing but generate spam. Am I not providing a service to my users if I prevent them from being smothered with spam from those sites?

The issue is that there are ISPs that have filters such that their dialup customers cannot talk to port 25/tcp of systems elsewhere on the net. Customers have to use the provider's SMTP servers. The question is, is this a good thing? I don't think anyone would argue against UUNet and PSI doing this with the *.ms.uu.net dialups or the *.pub-isp.psi.net...but would you do this on your own network?

I've blocked 4 ms.uu.net /16's and 12 pub-isp.psi.net /24's from talking directly to FDT's mail servers. Unfortunately, most of the junk from PSI is relayed through other sites anyway.

I'm not blocking anyone from port 25, *but* I have installed the ruleset in out sendmail to make it reject any mail that does not originale or terminate in our domain. This put a halt to the rash or relaying problems we had some months ago, but down not affect our users in any way. -- Andy Pitts : "Knowledge is a deadly friend andy@rbdc.rbdc.com : When no one sets the rules." http://www.rbdc.com : --King Crimson--