From: jtw@lcs.mit.edu (John Wroclawski)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: Firewall usage
Date: 27 Jul 92 19:20:02 GMT
	<1992Jul23.142026.20112@sci34hub.sci.com>
	<1992Jul24.161006.12786@practic.com>
Organization: MIT Home for Wayward Triumphs


In article <1992Jul24.161006.12786@practic.com> brunner@practic.com (Thomas Eric Brunner) writes:

   >>I wish I had a transcript of Dave Clark's talk at the IETF last week.
   >>He said some great things about firewall gateways and mailbridges, and
   >>how they've essentially destroyed the whole purpose of having an IP
   >>internet, and have forced a lot of us to use mail as a transport-level
   >>protocol.

   Dave is usually correct, but as he thinks quite a bit more than many, and
   says what he thinks, he is frequently not correct. Send him mail and ask
   for a copy, or invite him to write. Perhaps he's been misstated in this
   summary of his remarks.

Dave made two points. The first was that the architecture of the
current internet is end-to-end, and does not have any notion of
firewalls. He argued that because of this, firewalls make some things,
such as introducing new services, much more difficult than they should
be, and as a result people resort to odd things like using mail as a
transport.

Dave's second point is that perhaps it is time to rethink the core
architecture of the internet (or its follow-on) to specifically
-include- mechanism to separate organizational policy functions (such
as authentication, logging, and access control) from the actual
service functions running on the typical host.

His key observation is that if we can provide these "checkpoint"
functions at administrative boundaries as part of a well-designed
architecture, rather than in an ad-hoc manner, we might be able to
achieve two goals at once - provide a network which can -better- meet
the security and usage requirements of a wide range of people, and at
the same time preserve some of the open access which has driven the
incredible growth of the internet so far.

Implicit in this observation is the belief that if we -don't- succeed
in doing something like this, the continuing rapid spread of firewalls
is inevitable, for the simple reason that many people feel they simply
have no choice.

Responding to the same quote, karl@ddsw1.mcs.com (Karl Denninger) writes:

   Hogwash.  If it is that important to an organization, the firewall can 
   provide proxy service for it.  It is >not< that big a deal to provide a
   proxy connection for these kinds of things, >provided< that you have a nice
   clean requirement.  The generic "anyone can do anything" doesn't cut it in
   Corporate America anyway.

I suspect Mr. Denninger will disagree, but I find this to be dangerous
and depressing thinking. A major strength of the Internet is the
ability for new services to come into existance when they're needed,
not several years later when a "nice clean requirement" has been
formulated, written down, approved, standardized, and poked at by a
layer or two of beaurocracy. In other words, the internet is strong
because it can evolve.

Existing firewalls threaten this evolution because they mix up the
notion of enforcing security with the notion of limiting
functionality. This -is- a serious threat. Dave's core argument, that
we should work to develop an architecture which can separate these
functions, seems to offer a useful way out.

John Wroclawski
MIT Lab for Computer Science
jtw@lcs.mit.edu