[Mimedefang] FTC asks ISPs to crack down on zombie PCs

Kelsey Cummings kgc at sonic.net
Thu May 26 13:58:52 EDT 2005


On Thu, May 26, 2005 at 01:23:56PM -0400, James Ebright wrote:
> > Now, if 25 inbound was shut down (which I could see an 
> > ISP doing) then I would seriously be in trouble because there'd be 
> > no inbound email any longer.
> 
> Why would an ISP shutdown port 25 inbound? I see no logical reason to do so,
> spam does not get delivered directly to a users desktop (at this time at
> least). The zombies are not controlled via port 25 inbound (at least any I
> have seen). In other words, I know of no good reason to shutdown port 25
> inbound... now port 25 outbound, yes, definately for dynamic IP space.

You must block port 25 in both directions to prevent 'triangular routing
attacks' from working.

-- 
Kelsey Cummings - kgc at sonic.net           sonic.net, inc.
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