From: Bill Stewart <stewarts@ix.netcom.com>
Date: Sat, 13 Apr 1996 02:06:40 +0800
To: shamrock@netcom.com (Lucky Green)
Subject: Re: Protocols at the Point of a Gun
Message-ID: <199604111939.MAA14774@toad.com>
MIME-Version: 1.0
Content-Type: text/plain


There are serious technical problems with the suggestion that labelling packets
as "Adult" or "Child" using IP options and filtering at ISPs for censorship.

IP works on a per-machine basis (technically, a per-network-interface basis,
though for most client machines that's the same thing.)  That means that a 
web or nntp server including some "Adult" material and some "Child" material
either needs
a way for an application process to communicate this to the network drivers,
or needs to label all packets as "Adult" to avoid the politically incorrect risk
of mislabelling a packet as "Child" when it's not.  The standard TCP/IP API 
programming interface software on Windows, Mac, and Unix machines doesn't
provide 
for applications to _tell_ the network drivers about IP options, so even if
IPng had censorship features added, the applications couldn't use it.
(There are a few military multi-level security versions of Unix that give
you more flexibility for this sort of thing, but they tend to provide
mandatory security so you _can't_ send a packet marked "UNCLASSIFIED" from a
"TOP SECRET" session.)  

Another problem is that it only addresses single-user client machines,
rather than multi-user operating systems such as Linux, which has a million
or so
users out there.  The model works fine when you treat a PC as a fancy version of
a dumb terminal, but a machine shared by multiple users (whether many at one
time,
or one at a time) uses a single connection to support all of them - that
means you
can't have censored material available to the child and uncensored material
available to the parent unless the networking software can pass the censorship
labels on to the application program - but again, the standard operating system
interfaces (developed over many years by thousands of The Free World's finest
developers :-) don't have a way to implement it, because it was never a
design goal.

Trying to implement censored sessions at a transport level instead has its
own problems.
First of all, TCP provides reliable sessions; censoring packets based on IP
labels
in the middle of a transaction means that TCP will retransmit until the
packet gets
through or it gives up and drops the connection, so any "Adult" packets would
dump a Registered Child out of the browser, even if they were unintentional
(e.g. from an Adult who labels all packets "Adult" to avoid being liable for
mistakes,
or packets from Europe that were default-labelled by a service provider to avoid
having to read them all, or from the Library of Congress Online Edition if
the Librarian
labels each packet correctly.)  On the other hand, UDP packet exchange,
which doesn't
use sessions, would require validating the user's ID and authorization on
each packet.

Furthermore, if the censorship information is carried at the transport level,
or at a higher level (i.e. headers in the message itself), the only way the
ISP's routers, which work at the IP level, can censor packets is to perform the
equivalent of the Post Office steaming open envelopes before delivering them
to your house, and refusing to deliver them if there's a child living in the
house
and the letter either contains a bad word or is written in a language the
Post Office doesn't understand, such as Finnish or Japanese or PGP.
 

At 04:03 PM 4/10/96 -0700, Lucky Green wrote:
>At 9:48 4/10/96, Duncan Frissell wrote:
>>We know that governments would like to impose things like the Simple
>>Tax Transfer Protocol on the Net as well as Is A Person (and Is A Minor)
>>Protocols.
>
>There is one thing about the proposed minor flag addition to IP that I
>don't understand. [No, I am not surprised by this. Mandatory authorization
>to establish a connection and an "Internet Driver License", probably in the
>form or a smart card are coming].
>If my computer creates the IP packet, what is there to prevent me from
>modifying the value of the "Minor/Adult" flag at my leisure?

If you create outgoing packets that are labelled "Minor", and contain
"Restricted to Government-Certified Adults Only, and No Felons or
Foreigners Allowed" material, you can get busted for it.
So you have to either restrict all your outgoing packets to be labelled 
"RtG-C Adults O,aNFoFA", or else make sure all the material you transmit
passes the "Government-Approved-for-Minors, Foreigners, and Victorian
ladies" filter.

On the other hand, if you don't log in to your ISP with a
"government-certified adult,
non-felon, non-foreigner, politically stable, not-a-Commie-or-Jew" id,
it'll block any packets not approved for you.  Any news or web server will also
have refuse to send any "Adult"-labelled material to you if the requests
arrived on a "Kid"-labelled connection - this means that either the server
machine
will have to only carry Kid-approved traffic, or only talk to Adults,
or add an "Adult" label to all outgoing packets whether marked "Kid" or not,
or else it will have to break protocol boundaries by passing IP-layer
information
up to the application.





#					Thanks;  Bill
# Bill Stewart, stewarts@ix.netcom.com, +1-415-442-2215