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From: RWK@SCRC-RIVERSIDE.ARPA (Robert W. Kerns)
Newsgroups: net.mail.headers
Subject: Firewalls in sendmail
Message-ID: <8643@brl-tgr.ARPA>
Date: Mon, 25-Feb-85 19:35:28 EST
Article-I.D.: brl-tgr.8643
Posted: Mon Feb 25 19:35:28 1985
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    Date: Sun 24 Feb 85 12:07:04-EST
    From: Greg Skinner <Gds@MIT-XX.ARPA>
A minor problem with this first statement...

    It [CHAOS mail access] certainly could have been disallowed, since
    general use of the
    chaosnet is not permitted for undergraduates (it requires a special
    bit which enables one to write to the cha: device which is the chaos
    network device on a DEC-20).  Undergraduates are not allowed to make
    file transfers, telnet to other hosts, etc. unless they have that bit.
    Since mail works the same way, it could have been restricted the same
    way.

Untrue!  Mail does not work the same way!  The (implementation) reason
students can send mail via the CHAOSnet is because it isn't THEY who
send the mail, it's the mailer daemon, which is a part of the system.
It would be rather difficult to restrict some people and not others,
involving all sorts of issues of validation, etc.  TOPS-20 is by no
means unique in this regard, at MIT or elsewhere, nor is TOPS-20 the
only system that undergraduates use.

Putting in firewalls into every operating system on every machine
that undergraduates have occasion to use is not likely to be worth
the work, especially on systems that don't give you the sources to
their mailer!  And personal computers really make a mockery of these
efforts, unless you care to forbid the connection of personal coputers
to the network.  This would certainly NOT be feasible at MIT!

Also, it is not clear just what constitutes "undergrad use of the
arpanet".  If an undergrad sends mail to his TA, and his TA forwards his
mail to MIT-Multics (quite reasonable), is it the undergrad or the TA
that's using the network.  What if the undergrad sends mail to
HEADER-PEOPLE@XX, assuming XX has such a forwarding entry to MC?

    The policy of the undergraduate comp center was (at least up until a
    couple of years ago) to deny chaosnet access to any undegraduates
    using the 20 unless they actually worked there as staff, consultant,
    or some other software support.  With the growing number of
    undergraduate research opportunities at MIT, the number of chaosnet
    access bits increased (the only other way to get chaosnet access was
    to justify the need for it by having a non-guest account on another
    chaosnet machine).  Nowadays many undergrads get chaosnet bits -- I'm
    not saying this is right or wrong, just the way things are.

Indeed, forbidding access on the basis of restricting individuals
to mail between certain groups of users, certain machines, certain
networks, or using any other arbitrary predetermined boundaries, is
doomed to perpetual inappropriateness.  Either you have to restrict
communications that would be better left unrestricted, or you have
to permit ones you did not intend.

    Speaking personally, having chaosnet access (implying ARPA access)
    benefitted me greatly as an undergrad because I was able to get useful
    technical information (unix-wizards, header-people, etc.) which I
    wouldn't have got otherwise until my undergrad years had just about
    ended.  I wouldn't have known half of what I knew coming out of school
    without those bits.  Many other MIT undergrads feel the same way --
    I'll forward the question to some of them so you can hear from them.

This is right on, although I don't think you made the point
strongly enough.  I think mail access is an ESSENTIAL part of
the undergraduate curriculum.  I don't want to hire a new grad
who has just been exposed to the little world on MIT-EE, and
who has no idea how to behave in the larger world.

    --gregbo
    gds@mit-xx.arpa
    gregbo%houxm.uucp@harvard.arpa
    {allegra,cbosgd,ihnp4}!houxm!gregbo
    -------