"top secret" security does require blocking SSH

[rdobbins () netmore net]

You are correct, it cannot.

I've spent a good portion of my career working on networks which are
CLASSIFIED or higher.  There are very strong restrictions on
simultaneous interconnection between systems of varying
classifications.  In most cases, complete -physical- isolation is
required, although waivers may be obtained on a case-by-case basis.  The
enforcement of these policies of course varies between agencies,
bureaus, and departments.  I remember just a year-and-a-half ago
installing fibre switchboxes on some USAF nodes which at various times
needed to have connectivity to networks of varying security levels. 
This is slowly changing at the lower levels due to the advances in
proxying technology, etc., but when you reach TS/SCI or SAP/SAR it's a
different story, and understandably so.

As a side note, the reason the first version of Microsoft Exchange, 4.0,
was so late was due in large part to the fact that Microsoft wanted to
bid on the Defense Messaging System, or DMS contract.  DMS supports all
levels of classification and types from UNCLASSIFIED all the way through
FLASH, CRITIC, etc.  The powers that be understand that an
application-level service like messaging has to be able to cross such
boundaries, but only with strong rules which prevent the dissemination
of information of higher sensitivity to those who aren't cleared for
same.

To the best of my knowledge, there are no networks in DoD, the armed
forces, or various other arms of the U.S. government which are ranked as
SECRET or above which have any form of Internet connectivity at anything
less than two removes.  One of the reasons that it's so hard for them to
come up with a coherent and workable overall information security policy
is because of the (very necessary, more so than the typical slashdotter
tends to believe) compartmentalization of information - and hence, IT
resources - within various organizations which deal with sensitive
information and issues.

"Greg A. Woods" wrote:
> [ On Sunday, July 9, 2000 at 08:22:46 (-0700), Roeland M.J. Meyer wrote: ]
> > Subject: RE: RBL-type BGP service for known rogue networks?
> >
> > In many organizations, a system isn't considered secure unless
> > port 22 is blocked, at the firewall. It is, after all, the secure
> > port, that must mean that you have to block it to be secure,
> > right?
>
> Yes, that's exactly right, but not for the reasons you imply.
>
> If the primary concern of a security policy is that covert channels must
> be prevented then it is absolutely mandatory that port-22 be blocked
> since it is by definition a covert channel.
>
> However having any kind of Internet connection, proxied or not, into a
> site where sensitive information must not be allowed to be leaked is in
> effect a violation of the policy.
>
> Unfortunately we're rapidly approaching (if we're not already there) a
> state of affairs where it is impossible to technically prevent inbound
> and outbound covert channels wherever people are required to interact in
> a privileged way with security sensitive systems.  A paper given at last
> year's ACM New Security Paradigms Workshop by Dean Povey ("Optomistic
> Security: A New Access Control Paradigm") suggests that it might be
> better to adopt the view that security officers should "Make the users
> ask forgivness not permission."  Whether this paradigm can successfully
> be delployed in top secret (or higher) environments or not is yet to be
> discussed.  I suspect it can but then I'm not an expert in traditional
> forms of high security.
>
> --
>                                                         Greg A. Woods
>
> +1 416 218-0098      VE3TCP      <gwoods () acm org>      <robohack!woods>
> Planix, Inc. <woods () planix com>; Secrets of the Weird <woods () weird com>

-- 
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Roland Dobbins <mordant () gothik org> // 818.535.5024 voice

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