🚀 go-pugleaf

kanagn@athina.cc.uch.gr (Kostas Anagnostakis) writes:

    Why not implement SMTP allowing only connections from PRIVILEGED
    ports. As far as I have gone into the matter, this would be a
    solution because a normal user is not able to use a socket port <
    1000 so his attempt to connect to a SMTP server will fail.

As many others have pointed out, this isn't a universal solution.
However, when I was postmaster of a major company I attempted to
address this in an upward compatible way. I modified our SMTP to use
privileged ports, and note whether a message came in over a privileged
port. If it did not, it added:

Comment: This message was received over an unauthenticated port at <site>.

In this way, you might be able to tell if someone was spoofing a
message.  Of course, anyone who was running a workstation without the
modified SMTP also generated messages like this. It didn't interfere
with delivery, but did note when something "different" had happened. I
would guess about 30-40% of the outbound messages carried this warning,
owing to lazy sysadmins (who didn't upgrade) or machines that couldn't,
or machines morally or politically opposed to "software tampering".

Well, the users universally hated it. Said it made us look
unprofessional and insecure. Jumped all over my management until they
made me make the message go away.

Looks are much more important than security, after all!

Rick