Re: Forrester Research foresees death of firewalls

["Stephen P. Berry" <spb () incyte com>]

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In message <doug-990622084728.A6D1739 () netman eng auburn edu>, 
Doug Hughes writes:

> > As for bridge building -- seeing that one bridge in WA turn into the largest
> > physical example of a standing wave I've ever come across and subsequently
> > tumble into whatever river it was spanning should be enough of a reason to
> > justify putting a bit of thought into proper bridge design.  If there are
> > any engineers out there I'm sure they've seen the film I'm referring to :)

> Tacoma Narrows. Classic film clip. Bouncing betty I believe they called
> her. Most films on the folly of human engineering have a clip on
> bouncing betty. Unfortunately the wind through the gap managed to vibrate
> the suspension of the bridge at its resonance frequency. Natural
> resonance is a dangerous thing: one of the reasons that marching infantry
> are forced to break step when crossing a bridge. Good thing firewalls
> don't have a resonance frequency or we'd all be in deep guano.

The bridge's nickname is (or at least was) `Galloping Gertie', not
`Bouncing Betty'[1].  It is worth noting that it earned this nickname
before construction was even completed.  Apparently the engineers in
charge of the project (among them Leon Moisseiff, who was then a leading
light in bridgebuilding) believed that the oscillations would cease
when the bridge was completed.

When that turned out not to be the case, the bridge was nevertheless
left open for use, and in fact saw roughly three times the volume
of traffic the State of Washington has estimated---folks would pay the
toll to cross the bridge for the thrilling ride it offered.

Beyond the fundamental design problems[2], it's interesting to note how
the engineers (and their managers) coped with the problems they encountered:

        Problem:   The bridge oscillated during construction.
        Solution:  Keep building.  Maybe it will go away.

        Problem:   It didn't go away.
        Solution:  Install hydraulic dampers.

        Problem:   That didn't work.
        Solution:  Well, how about some tie-downs on the side spans?

        Problem:   No good.
        Solution:  Well...we've got a lot of money invested in this
                   project, and people are paying the tolls anyway....

        Problem:   The bridge just shook itself to pieces.
        Solution:  Okay.  Maybe we have to redesign the thing.
         

Without actually mentioning Microsoft, I can think of a couple of
analogies in the IT industry in general, and in IT security in particular.

The actions of the Tacoma Narrows engineers look fairly foolish in
retrospect.  But how many IT shops are currently doing essentially the
same thing?  How many of us are working with what we know to be an
essentially flawed design, but are trying to keep it together using
quasi-effective workarounds?

        Problem:   There are bad guys on the internet trying to do
                   Bad Things to our organisation.
        Solution:  Maybe they'll just go away or bug someone else.

        Problem:   They're didn't.  Where are the backups?
        Solution:  Maybe we could hire a consultant to set up a
                   packet filter....

        Problem:   Well, that seems to have helped with the PoD-type
                   attacks, but they've still compromised the mail
                   server.
        Solution:  Then we need a application gateway as well.  Hire
                   another consultant.

        Problem:   Well, now everyone been infected by this Melissa
                   thing....




- -Steve

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1     Around 1940 (when the first Tacoma Narrows bridge collapsed), Bouncing
      Betties were most commonly encountered by combat engineers, as
      this was the nickname for the German Schützenmine 35.  I believe
      the term has subsequently been used generically to mean any
      two-stage landmine which becomes airborne before the payload
      charge detonates.
2     No aerodynamic studies were done of the structure prior to commencement
      of construction.  The second Tacoma Narrows bridge was, I believe,
      the first bridge in the world designed in conjunction with such
      studies.


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