From: vjs@rhyolite.wpd.sgi.com (Vernon Schryver)
Subject: Re: Firewall usage
Organization: Silicon Graphics, Inc.  Mountain View, CA
Date: Tue, 28 Jul 1992 18:05:04 GMT

In article <Bs3vCz.K13@cs.columbia.edu>, ji@cs.columbia.edu (John Ioannidis) writes:
> ...
> * A firewall is no excuse for lax internal security. To wit:
>   - In a large organization, there are bound to be "bad guys" (either
>     through malice, negligence, or sheer stupidity) inside the
>     organization as well. No firewall is going to protect you against
>     those. 

True, but irrelevant.  The only effective means to protect against bad
insiders are administrative.  Technical solutions to administrative
problems are always less effective.

Most murders and non-sexual assualts are committed by people acquainted
with the victim.  Do you conclude that you need dead bolts on your
bedroom doors?  Must you sleep alone or with an awake, armed guard?
There are far more external network damage and attacks than internal.

Open networks are no fun to break.  A "disgruntled employee" is not
going to "break into" a system to "erase critical files" if those files
are properly achived.  Such a bad guy is not going to use the network
to get even, but will do commit any of the many more familiar, easier
to commit, harder to detect forms of white collar crime.  (You are
talking about criminal acts.)

"Security" does nothing to protect against negligence or stupidity,
because those who who are acting stupid or negilgent almost always have
all of the passwords, keys, and badges.  It is reckless to
unnecessarily run as root, because of the danger of typo's, but that
has nothing to do with "security.'

Fasist internal security systems generally exist for internal political
reasons, to entertain and justify SystemAdministators.  There are
development organizations where the programmers are not allowed to know
the root passwords of their workstations, but all such organizations I
have seen have been less then unproductive.

>   - A firewall only protects you against *known* external threats. 
> 
>   - If your internal network is insecure, you are vulnerable to anyone
>     who can get physical access to it. Today this involves tapping
>     ethernet cables, but tomorrow it may just involve dropping by with
>     a laptop with a wireless interface. I have a vested interest in
>     seeing wireless LANs  take off -- I don't want t hem stifled
>     because of security concerns.

Maybe you should find other vested interest, if your wireless stuff
requires that machines on local networks be protected.

>   - Think of the Maginot Line.
> 
> * The network should switch bits and enforce routing policies -- not
>   cover up for insecure applications.

So, you have locks on your bedroom door, to protect you against your
relatives.

> * It should not be the job of the millions of system administrators to
>   patch known holes -- the vendors should be doing that. There is
>   simply no excuse for vendors shipping us insecure code. (Is it true
>   that SunOS is still distributed with /etc/hosts.equiv containing a
>   single '+"? Why do we still have login programs that only accept
>   eight-character passwords, password files that are publicly
>   readable, things like NIS that allow uncontrolled access to their
>   information, etc? At least we don't get sendmail shipped with the
>   debug option turned on any more.


So you think you can sell an obligatorily secure system?  Like the SCO
C2 UNIX?  Where the customer cannot run with open doors?  Wrong.

Systems should come in the box with a reasonable amount of security.
That does not imply everyone must or should or be required to use it.


> * Having firewalls reduces the urgency (that is, the pressure on the
>   vendors) of patching those security holes. It's a vicious cycle.

Wrong.  We vendors can fix holes since we generally have source for our
products, and we generally feel more pressure to fix holes for
customers than you can imagine, but we run with firewalls.

> * We've seen analogies such as putting locks on the front door rather
>   than each individual room, and that it's perfectly acceptable
>   capitalist behavior to put a firewall gateway in front of your
>   network. I claim that this is far from being capitalistic; you're
>   beeing communist inside, and hiding behind an Iron Curtain.

So, you have locks on your bedroom door, but not on your front door.
Well, from the stories I've read, that makes a certain amount of sense
for New York City.

> ...
> * Firewalls are an easy solution to a very real and very serious
>   problem. My point, if a bit idealistic, is that we should *fix* the
>   problem, rather than patch its manifestations.
> 
> * Security, like good manners, starts at home. 

Having good security available is not the same thing as being required
to use it.  It is good that locks and safes are available for those
who need them.  It would be bad and stupid to expect everyone to
use case-hardened bars on their first floor windows, just because
they are necessary in New York.


Vernon Schryver,  vjs@sgi.com