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From: salex@RICE.ARPA (Scott Alexander)
Newsgroups: net.mail.headers
Subject: Re: SMTP source verification.
Message-ID: <327@brl-tgr.ARPA>
Date: Tue, 30-Jul-85 21:52:43 EDT
Article-I.D.: brl-tgr.327
Posted: Tue Jul 30 21:52:43 1985
Date-Received: Thu, 1-Aug-85 20:48:05 EDT
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So you check my ip addr and it agrees with my name in the host table.  But
if this is my workstation, I can cause it to build ip packets w/ any addr I
like.  So now instead of just faking the HELO command I have to fake ip
packets, too.  On an ethernet, even checking the ethernet addr doesn't tell
you anything since I can often reset it.

There is no way to get around faking mail.  You can make it harder.  The
people with whom I have dealt who are willing to go to the trouble to fake
mail are willing to format ip packets also.

Scott Alexander
Rice University

salex@rice
(713) 527-6012