🚀 go-pugleaf

kanagn@athina.cc.uch.gr (Kostas Anagnostakis) writes:
>Why not implement SMTP allowing only connections from PRIVILEGED ports.

Three problems:

1) If you start doing this on your machine, you will stop being able to
exchange mail with people who aren't doing this.  I assume that sendmail
usually connects from unprivileged ports.  On our machine (running zmailer)
it looks like sendmail isn't even setuid.

2) The concept of "privileged port" is not universal to TCP; many machines
don't even have the concept of privileged users, and even some which do don't
have the concept of privileged ports.  So anyone can connect from a "privileged
port" on these machines.

3) Why do you trust privileged users more than other people?  I'm very wary of
systems which appear to increase the authenticity of communications without
necessarily doing so.  If someone forges a mail message in my name which says
something that it's important for me to establish that I did not say, I would
like to be able to say "everyone knows that forging e-mail is easy"; it would
be terrible for others to be able to say "e-mail authenticity is guaranteed
these days since smtp allows only connections from privileged ports".  These
forgers will include system administrators and also people who break in to
privileged accounts.


There are cryptographic techniques only suffering from the first problem.  If
we're going to lose compatibility, we should do it right.