[37797] in North American Network Operators' Group
Re: Stealth Blocking
daemon@ATHENA.MIT.EDU (Eric A. Hall)
Thu May 24 12:51:06 2001
Message-ID: <3B0D3ADB.F4B4F529@ehsco.com>
Date: Thu, 24 May 2001 09:46:19 -0700
From: "Eric A. Hall" <ehall@ehsco.com>
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Returning to operational traffic:
> One thing that I think *will* help, particularly in the short term, is
> port 25 blocking of dialup ports. It's my personal opinion that this
> will have the greatest impact on spammers who abuse open relays. I've
> watched this happen over the last few months, as various large networks
> have secured their dialup ports. It's impressive.
TCP rate-limiting on outbound traffic to *:25 would also be extremely
effective, particularly on unclassified customer traffic, and without the
heavy-handed nature of denying all dial-up traffic. Rate-limiting doesn't
interfere with low-volume legitimate mail, but it really cramps spam.
--
Eric A. Hall http://www.ehsco.com/
Internet Core Protocols http://www.oreilly.com/catalog/coreprot/
