Implementing anti-abuse techniques on ISP networks....

Greg A. Woods woods at
Wed Aug 6 23:52:20 UTC 1997

[ On Wed, August 6, 1997 at 19:09:15 (-0400), Jon Lewis wrote: ]
> Subject: Re: Implementing anti-abuse techniques on ISP networks....
> 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 * dialups or the *

... and Earthlink, and Netcom, and Worldnet, and all the rest, and yes,
that's exactly what I'm getting at!  ;-)

> but would you do this on your own network? 

One of the first installed, most common, and most often requested
filters for firewalls I help design, configure, debug, and install,
etc. for small and large corporate networks is one to prevent all
internal hosts but the mail gatetway from making outbound connections on
port 25.  To them it's just as important as having coporate paper-based
communications go out on corporate letterhead (though of course the
degree of control it affords is far more insidious! ;-).

							Greg A. Woods

+1 416 443-1734      VE3TCP      <gwoods at>      <robohack!woods>
Planix, Inc. <woods at>; Secrets of the Weird <woods at>

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