[p2p-hackers] David Reed Delivers the Goods Again

Seth Johnson seth.johnson at RealMeasures.dyndns.org
Fri Jul 18 03:49:02 EDT 2008

(. . . unto the Energy and Commerce Committee.  Following are links to
a note on David's blog, his testimony, and to video of the hearing
itself that hopefully will become live again.  I only intercepted the
notice I had of this in the wee hours of the day of the hearing,
yesterday, so had no time to announce it.  I have not watched the
hearing, but David's text is a wonder of lucidity, presenting a
picture of the technical aspects that provide for "net neutrality" and
illuminating very nicely where and why policy would impact it.  I
understand the House Members responded very well, and Markey
apparently ended with a rather potent comment noting that the reason
for the American Revolution was largely because the British thought
they could just invade people's houses (!).

I have often noted that the moment the neutrality of the Internet was
assured, for decades hence, was in 1977, in the hallways of the
conference in Marina del Rey, California that Vint Cerf oversaw to
develop Bob Kahn's plan for "TCP".  Four people, Danny Cohen, Steve
Crocker, David Reed, and John Schoch, argued on diverse bases for
separating the original plan for TCP into two layers: a pure datagram
lower layer called IP, and two protocols above, TCP and UDP.  David
Reed made his case on the basis of the generality of this platform for
the full diversity of protocol behaviors it would make possible, and
-- however much that particular point might have gained sway at that
moment -- this is the key point that expresses the essential nature of
the platform.  This design essentially made the flexibility of the
network "the stakes" from that very moment on. [See
http://www.nethistory.info/Archives/tcpiptalk.html for details] --

to the House Committee on Energy and Commerce
on "What Your Broadband Provider Knows About Your Web Use:  Deep
Packet Inspection and Communications Laws and Policies"

> http://www.reed.com/dpr/docs/Papers/ReedDPIHearing.pdf

(Full text pasted below.  -- Seth)

Dr. Reed Goes to Washington:
> http://www.reed.com/blog-dpr/?p=8

Hearing: What Your Broadband Provider Knows About Your Web Use:  Deep
Packet Inspection and Communications Laws and Policies:
> http://energycommerce.house.gov/membios/schedule.shtml  (transient page)

Video (not yet available):
> http://energycommerce.edgeboss.net/wmedia-live/energycommerce/11990/100_energycommerce-2123_060901.asx  (video/not presently available)

Robb Topolski's NebuAd analysis:
> http://www.freepress.net/files/NebuAd_Report.pdf


> http://www.reed.com/blog-dpr/?p=8

Dr. Reed Goes to Washington

Posted on 17 Jul 2008

Well, for the first time in my life I got to testify before a
Congressional Hearing
 The House Subcommittee on Telecommunications
and the Internet held a hearing today about Deep Packet Inspection,
where I was invited to be a witness, along with the CEO of NebuAd and
others, to discuss the issues surrounding ISPs using Deep Packet
Inspection to capture and to modify all of the communications their
customers do across the Internet.  I’ve put the written testimony I
shared with the committee prior to the hearing up on my server - I’d
suggest you read it

If you want to understand how NebuAd works (as an example of DPI in
action), see Robert Topolski’s excellent reverse-engineering of its
use in a report he did for FreePress.org

The whole hearing was webcast
(http://energycommerce.house.gov/membios/schedule.shtml).   I am
hoping that it continues to be available online

I have to grant that the DPI industry has some cojones.  See the
industry association’s website at dpacket.org.


> http://www.reed.com/dpr/docs/Papers/ReedDPIHearing.pdf


Adj. Professor, The Media Laboratory
The Communications Futures Program
Massachusetts Institute of Technology
Weisner Building E15-492
20 Ames Street
Cambridge, Massachusetts 02139


Subcommittee on Telecommunications and the Internet
Committee on Energy and Commerce
U.S. House of Representatives
Washington, DC 20515-6115

17 July 2008

Mr. Chairman and Members of the Subcommittee, I thank you for the
opportunity to address you on the topic of "What Your Broadband
Provider Knows About Your Web Use: Deep Packet Inspection and
Communications Laws and Policies." The subject of this hearing is an
important one to the country and to society as the use of the Internet
becomes, more and more, a central part of every citizen's everyday
life, in commerce, political expression, and culture. For the last 35
years, I have been personally involved in developing many of the key
technologies of the Internet, distributed personal computing, and
information sharing that we now all take for granted.

A brief summary of my main points is in order here.

First, participating in the Internet as a transport or access provider
implies adherence to a set of standard technical protocols and
technical practices that have been and remain essential for the proper
functioning of the world-wide Internet for all its users.

Second, there is a strong distinction made in the Internet's design
between information needed for transporting Internet Datagrams, and
the information the Internet carries between end-point systems
attached to the Internet. This distinction has a major impact on the
scalability, innovation rate, and economic impact of the Internet, as
well as playing an important role in ensuring privacy and safety of
the users of the Internet, and limiting liability for companies that
invest in providing the Internet infrastructure.

Third, technical innovations now available at very low cost in the
marketplace have started to make it possible on a large scale to dig
into the content of end-point to endpoint messages at almost any point
in the Internet transport, do selective recording and analysis of such
messages, and to modify or to inject messages into the Internet that
appear to be messages from a particular source, but in fact are from a
third party, without the ability of the end-point systems to detect
the modifications or insertions.

These technical innovations, which might be called Realtime Packet
Inspection and Realtime Packet Updating, are being packaged into
applications and sold as "solutions" to Internet Access Providers and
Internet Transport Providers by several vendors, notably Phorm,
NebuAd, Sandvine, and Ellacoya Networks, but hardly limited to those
vendors. A subset of these technologies, called Deep Packet Inspection
technologies, are particularly worrisome, because they involve
inspection of end-user to end-user information content, decoding, and
the making of inferences about users' personal interests, private
activities, etc.

In this statement I present, based on my expertise and direct
experience as a developer and researcher for the last 35 years, a
technical and marketplace-oriented discussion of these systems, their
capabilities, and the uses advocated for them by their developers and
by Internet transport operators, including companies. such as cable,
telephone and wireless carriers, that sell high-speed Internet access
as part of a "Broadband" offering.

I focus my attention on the uses proposed for Deep Packet Inspection
and systems supporting those uses that are being marketed to Broadband
Internet Access Providers, since such providers enjoy a strong
monopoly or oligopoly position in the Internet's actual deployment.

Following the discussion, I draw several conclusions that Congress may
want to consider as it explores the use of these technologies.

First, that such technologies are not at all necessary to operating
the Internet or to profitable operation of an Internet operator, and
in fact that they actually violate longagreed standards and principles
that have been part of the Internet's design from the beginning, and
which have led to its enormous impact and continued success.

Second, that deployment of such technologies pose major risks to the
economic success of the Internet as a whole. They do so by normalizing
non-standard and risky technical activity on the part of telecom
operators who may choose to exploit captive customers, rather than
transparently deliver the communications services for which their
customers have paid.

Third, that protecting themselves from the negative impacts of these
technologies on their private business imposes significant additional
costs on the knowledgeable customers of the Internet transport
operators and on the developers of new Internet applications, while at
the same time exploiting the unwitting and captive customers of
service providers who choose to deploy them.

My background

>From the title and overview of this hearing, I understand you are
interested in technical issues (such as the deployment of these
technologies and their potential impact on privacy), in legal issues,
and in policy-related issues. Perhaps you are also interested in their
impact on innovation of Internet services, and in possible technical
and legislative steps that might be taken to mitigate negative impacts
on society.

Other witnesses you will hear are far more qualified than I to discuss
the applicable laws and the various policy implications of these
technologies. My experience and knowledge is largely in the spheres of
technology, architecture and applications, based on more than 35 years
of activity in computer systems, Internet communications, computer
security, and computer applications design, development, and
technology strategy, both in research and industry.

Separation of concerns in the Internet Architecture

Survival of the Internet requires that Internet Access Providers and
Transport Providers continue to take a proper, transparent role as
participants in the Internet.

Internet Access Providers (and in particular Broadband providers
offering so-called high-speed Internet access service) do not create
the Internet for their customers, instead they provide access to the
larger collective system called the Internet, of which they are a
small part.

The Internet itself is the "network of networks" that results from
voluntary interoperability among a wide variety of Autonomous Systems
– networks that are not owned by each other, and which do not even
have contractual obligations to each other in most cases. All it takes
to be part of the Internet as an Autonomous System is to agree to
participate according to the very simple ground rules of the
Internet.1 These ground rules are directly responsible for the
remarkable growth, scalability, and resilient evolution of the
Internet itself, and more importantly the growth of the Internet's
utility as a backbone of commerce, information exchange, and cultural

The fundamental agreement among Autonomous Systems is that they
collectively provide each host, that is each computer that is
connected to any of the many Autonomous Systems, the ability to send
and receive small messages called Internet Datagrams, to any of the
other hosts on any Autonomous System in the Internet. I avoid defining
a whole collection of technical terms by suggesting that you view
these Internet Datagrams as envelopes containing messages from one
host to another on the Internet.

The envelope is stamped on the outside with only four things:

    . an address,
    . a return address,
    . a protocol identifier, and
    . some marks that indicate how the message is handled as
      it is carried through the network.

The content of each message is held "inside the envelope." This
content is meant to be meaningful only to the sending and receiving
hosts, while the envelope exterior is meant to contain all the
information needed for that content to be carried from the source to
the intended destination.

As a condition of participation in the Internet, each Autonomous
System must agree to provide "best efforts" delivery of these Internet
Datagrams (envelopes) without reading or changing their contents –
that is, a sender posts an envelope with its return address and a
specified destination address, and it expects that the envelope will
be routed through the network and delivered eventually to the
specified address.

The concept of "outside the envelope" and "inside the envelope" is a
reflection of much effort on the part of the Internet designers when
the Internet was first created, and is acknowledged by many as one of
the two or three reasons why

    1. the Internet has scaled by many orders of magnitude 
       over the past 30 years without a fundamental 
       architectural change,

    2. the Internet easily evolved to incorporate 
       technological innovations in digital transport suchas 
       optical fiber switching, WiFi, 3G cellular, etc., and

    3. the Internet has catalyzed the invention of a 
       widevariety of consumer and business content 
       distribution, communications applications and 
       resource sharing services that range from the World 
       Wide Web to Instant Messaging, Social Networking, 
       business process outsourcing, etc.

It is worth thinking about these points carefully. The core idea of
the Internet Datagram is a form of radical simplicity. All the
Internet does is carry envelopes of a standard form – in a sense just
like the post office.

Scaling: To make a faster Internet, all one need do is process the
envelopes faster. To make a larger Internet, all one need to do is
improve the processing units that use the address on each envelope to
sort the envelope into one of the many outgoing paths from each
routing point.

Technology evolution: To incorporate a new technology like optical
fiber into the network, all one need do is find a way to put the bits
of an Internet Datagram into a sequence of light pulses that travel
down the fiber. There are numerous technical details involved in doing
so, which are the province of companies like Cisco and other Internet
technology providers.

Application/Service innovation: To build a new application or service,
all one need do is write a program to run on standard computer servers
and standard personal computer clients that communicates using a
protocol based on Internet Datagrams. A protocol is a set of
conventions or rules that specify messages that are sent inside the
envelopes, in particular saying what the messages mean to the
recipient, and what actions the recipient of a message should take
upon the receipt of a message. Each new kind of application or service
on the Internet is created by inventing a new protocol.

The Internet transport infrastructure does its job without needing to
understand or to generate protocol-required messages in Application or
Service protocols. Therefore, applications and services can be
invented and deployed without having to negotiate consent or ask for
favors from the infrastructure. The infrastructure – all of the AS's –
does the same thing for every application: transport the envelopes.

It is this separation of concerns that is the essence of the success
of the Internet.

Real-Time Packet Inspection and Real-Time Packet Updating

Because silicon computing technology has followed Moore's Law, with
the size and performance of computers improving by a factor of four
every three years, the ability to process information carried in
messages has improved drastically in the last 35 years. That means
that today's silicon chips can, in principle, examine and process a
message of a particular size about 8 million times more efficiently
than the silicon chips at the time I began working on research
computer networks in 1973.

The result of this technology evolution is that it is now quite
reasonable to construct specialized computing devices that can scan
tens of millions or even billions of bits of data per second passing
through a network switch, running complex pattern matching and
decision algorithms on each Internet Datagram during the time the
Internet Datagram is received into a network switch and transmitted
out over a fiber or cable to the next switch on the path between the
source and destination. Since each Internet Datagram is stored in
specialized buffer memory before being retransmitted, specialized
devices can put put selected Datagrams aside for complex processing
and modification before forwarding them on to the destination as

When such devices are produced in volume, the cost per device can be
made quite small. Such devices capable of monitoring, decoding, and
matching Internet Datagrams are a natural result of the evolution of
high performance Internet switches, but are capable of far more
general operations than delivering datagrams to their intended

These devices are what I call Real-Time Packet Inspection and
Real-Time Packet Updating systems.

Deep Packet Inspection: Inspecting "inside the envelope"

As mentioned earlier, a core element of the Internet architecture is
that the content "inside the envelope" of an Internet Datagram is not
to be read or modified by any of the AS's that carry the Internet
Datagram from source end-point to destination end-point.

The term Deep Packet Inspection was invented to describe real-time
packet inspection systems that inspect and use content from "inside
the envelope." Since that content is intended only for the destination
end-point, it is never necessary for AS's to inspect or analyze such
content to perform their function of delivery, just as it is never
necessary for the Post Office to inspect the contents of a First Class
Letter in order to properly deliver the letter to its destination.

Nevertheless, a variety of companies have developed systems based on
Deep Packet Inspection and have begun to market them to network
transport operators and others. These systems are marketed for a
variety of applications, which I will discuss below.

Often lumped into the category of Deep Packet Inspection are other
techniques that involve real-time modification of the content "inside
the envelope" of Internet Datagrams, and even creation of Internet
Datagrams with content not requested by the source whose address
appears on the "outside of the envelope".

Though some call this modification or synthesis of Internet Datagrams
"forgery" of Internet Datagrams, the legality of performing such
operations involves non-technical, legal issues where I am not an

Instead I will point out that the Internet Architecture, as defined by
the IETF and other bodies who oversee the Internet's evolution,
neither requires nor allows Internet Datagrams to be modified or
created by AS's in this manner. I will discuss the implications and
risks to end-users and the Internet as a whole of such action further

Thus Deep Packet Inspection goes against the separation of concerns
that has been a hallmark and generator of the Internet's success.

Proposed uses of Deep Packet Inspection

When there is a technical capability of the sort we are discussing
that is relatively inexpensive and quite powerful, there are many
potential applications. Let me briefly list some of the potential
applications where this technology appear to generate interest.

Surveillance by law enforcement and intelligence collection agencies
is an application area where there is strong technical value of Deep
Packet Inspection, though there is no need for updates or insertion.
This application includes highly selective capture and recording of
selected packets – often called "lawful intercept" by
telecommunications carriers – and broad data recording and capture –
often called "data mining." Since this is typically a government
function, I believe this application is out of scope for this hearing,
but CALEA apparently does require that Internet operators enable the
application of some forms of Deep Packet Inspection for this purpose.

Another category of application that has been marketed by vendors such
as Sandvine is "traffic management" by Internet Access Providers,
which was the subject of recent hearings by the FCC, where I have
testified in regard to the use of such technology by Comcast to
disrupt certain categories of traffic on its Internet Access Service.
That particular use involves inspection "inside the envelope" of
Internet Datagrams and the technique of injecting packets that appear
to be generated by the TCP protocol software as if they were sent by
end-points intending to cancel the connections, with the result being
that certain traffic, including BitTorrent traffic carrying large
files, is disrupted severely.

Given that advertising and marketing play a large and extremely
valuable part in electronic commerce using the World-Wide Web and
electronic messaging, the application of such technology to analyze
user behavior in order to target marketing more precisely is a hot
application area.

At least two separate companies, NebuAd and Phorm, have developed
systems that use Deep Packet Inspection that can be deployed within
any AS to scan and analyze all Internet Datagrams, both inside the
envelope and outside the envelope. The results are stored in a local
database, or sent to a centralized database, recording patterns of
access that are analyzed to determine each user's interests, then
saved. Each of these systems also provides the ability to modify or
synthesize the content of Internet Datagrams containing user-requested
information from vendors and information services such as Amazon,
Google, and even small business websites in order to insert
advertising on the behalf of the access provider.

It is important to note that the interception of content and
modification of returned content in these systems is done under the
control of the Internet Access network that installs NebuAd or Phorm.
The interception and modification is beyond the control of either the
consumer/user or the vendor/service who are the two primary parties.
While these systems may incorporate "opt-out" provisions, privacy
safeguards of the databases they construct, etc., it is important to
know that their service is not a normal or accepted part of the
Internet Architecture.

Another proposed use of Deep Packet Inspection technology is the
scanning of traffic for undesirable, unwanted, or unlawful content. It
has been proposed that Deep Packet Inspection can be used to detect
unlicensed distribution of copyrighted content such as digitized
movies, unwanted bulk email (spam), computer viruses, pornography,
child pornography, etc. between witting and unwitting endpoints. There
have been proposals that colleges, universities, and businesses, as
well as Internet AS's be mandated to install such systems either by
law or by legal precedents making them liable for carrying such
traffic between end-points.

Finally, Deep Packet Inspection technologies are used for monitoring
the performance and health of Internet operations. With such
diagnostic tools, engineers can measure activity on the network, plan
for facilities investments, etc. Such tools can be quite helpful in
finding faults within the network and predicting areas of growth that
support AS's

This list of potential applications covers the applications of which I
am current aware. Since Deep Packet Inspection is a general-purpose
capability grounded in Moore's Law and tied to the advancement of the
technologies already built into the Internet switching gear being sold
to customers, it will always be tempting for entrepreneurs to invent
new applications for this general approach of reading, capturing,
modifying, and injecting Internet Datagrams as they flow through the

Risks associated with Deep Packet Inspection

As noted earlier, a very useful way to think about the how the
Internet is structured is to imagine Internet Datagrams as packages or
envelopes carried by a sequence of third party delivery services from
and end-point computer to another end-point computers. In this
analogy, the Autonomous Systems are like individual package delivery
services, such as UPS, FedEx, DHL, Yellow Trucking, etc. On the
"outside" of packages is a set of labels that are intended for use in
forwarding the package on to its destination. A carrier that picks up
a package may transfer the package from one carrier to another,
choosing the path best suited for timely delivery of the package to
its destination.

In this analogy, Deep Packet Inspection technologies can be accurately
thought of as devices that are placed in trucks, airplanes,
warehouses, etc. of the various forwarding services that very quickly
and efficiently examine the contents of the packages (perhaps by
X-ray, by actually opening the package and taking pictures of its
content, ...), record the results of that examination in a database
held by a third party, and analyze all of the information captured
using statistical methods. This information is then used to select
particular packages for special handling, discarding, or re-routing,
to change, delete, or insert contents into the packages, and to create
packages that appear to be from a particular source, but which are in
fact generated by within the network itself.

A useful example in this analogy would be if all of the packages you
ship and receive through an independent shipping agent (such as
Mailboxes, Etc.) were scanned, and the contents used to understand
your buying habits, and further that the shipping agent had a contract
with various companies to insert or replace the contents of your
packages with "improved" contents.

I suspect that there may be some users who would be delighted to
receive items they did not request in their packages, and that
merchants might be happy to find that the computer that they ship to a
customer is magically "improved" or replaced by an upgraded model
along the way.

However, the normal understanding in dealing with shipping agents is
that the contents of packages are not to be examined, studied,
reported to third parties, replaced or modified according to the
desires of third parties.

There is another problem, however, that to me is more problematic.
That is that unlike the shipping agent example above, the Internet is
based on end-to-end protocols that are more complex than simply the
delivery of packages. In these protocols, the contents of packages
contain requests for remote end-point service systems to perform
actions on the user's behalf, which generate responses and then more
requests. As an example, consider a user who coordinates his or her
finances among of number of banks and brokers via protocols carried in
these packages. He or she might first send a deposit to one account,
then request a transfer to another bank once the deposit is confirmed,
and then send instructions about investing the money to the second
bank. This sequence of steps is called a protocol.

What Deep Packet Inspection technologies attempt to do is to
second-guess the intent of the end-users of these services (the
investor and the bank), to draw inferences about the intent of those
protocols and to modify (hopefully safely) the packages without
causing harm to the protocol transactions.

The source of the problem is that vendors of Deep Packet Inspection
systems cannot presume to understand, merely by looking at the
contents of packages what they actually mean or intend to happen at
the source and endpoint.

This is the real risk: an service or technology unnecessary to the
correct functioning of the Internet is introduced at a place where it
cannot function correctly because it does not know the endpoints'
intent, yet it operates invisibly and violates rules of behavior that
the end-users and end-point businesses depend on to work in a specific

As a simple example, I cannot send email from many hotels, because of
a Deep Packet Inspection technology deployed in many hotels' Internet
Access service. That service (intended to block spammers who might
operate from hotel rooms) intercepts my packages intended for my email
server, and responds, pretending to be any and all destination email
servers, offering to accept my email messages on behalf of the
recipients, which it will then scan for evidence of viruses and spam.
In my case, I use a special secure, encrypted email delivery service
that is more secure than most, so my mail sending software recognizes
the deception and refuses to deliver the mail to the deceptive
provider that requires me to send my mail "in the clear" so it can be

Hotel providers claim that they are "doing a service" by blocking
spam, but in doing so they reduce my own personal security, both by
requiring that my mail be sent in the clear, and by introducing the
risk that my mail will be scanned and modified by an interceptor I
cannot easily avoid. Some hotel providers even claim that they are
legally mandated by liability law to inspect my email that originates
through the hotel system.

In addition, if my email requests happen to involve the transmission
of messages that the operator deems to be spam, my message, which may
be quite important to my business, will be blocked without my
knowledge or any possibility to appeal the erroneous inference.

That example, though a simple example, captures the risks that I want
to highlight:

    . Systems based on Deep Packet Inspection work by 
      drawing inferences from packet contents that are not 
      intended to be understood by anyone other than the 
      destination host

    . Deep Packet Inspection systems cannot reliably 
      determine the intent or meaning of those Internet 

    . Deep Packet Inspection systems work by deliberately 
      interfering with end-to-end communications, but by 
      definition attempt to deceive the endpoint systems 
      about what the original Internet Datagrams contain. 
      The endpoints cannot tell if such systems have either 
      captured their content information, or modified or 
      created information that was not sent or intended by 
      the author of the Internet Datagram.

    . Deep Packet Inspection systems cannot be made 
      reliable, either in their inference or in their 

Impacts on Users and Services Built on the Internet

In order to block interception and modification of the contents of
their Internet Datagrams, end-point hosts can take steps such as
encrypting contents of packets, using digital signatures, and choosing
providers that vow not to scan or modify packets.

Besides raising the cost of using the Internet for existing and new
applications, there are three problems with this.

First, existing applications have been designed with the expectation
that Deep Packet Inspection is not a legitimate activity by a service

Second, there is only one Internet, which consists of many Autonomous
Systems. Choosing a different point of connection cannot, given the
nature of the Internet, ensure that all users one might want to send
Internet Datagrams to have successfully chosen providers that have not
deployed Deep Packet Inspection systems that scan or modify Internet
Datagrams. Thus, consumer choice is not an option. Since the risks of
incorrect operation of Deep Packet Inspection can disrupt critical
protocols (including protocols yet to be deployed or invented), mere
consumer choice may not be enough to fix the problem.

Third, encryption from end-to-end, while a potential solution, has
public policy implications. This committee and Congress have gone
through those issues many times. I personally would like to see all
communications activities fully protected by strong encryption, but I
fear that reaching that point will encounter many obstacles. If the
primary problem the encryption is to deal with is an unnecessary
technology such as Deep Packet Inspection, a simpler solution would be
to bar the use of Deep Packet Inspection systems.


1 The core ground rules of the Internet were laid out in the original
design begun in 1975 by Vint Cerf and Bob Kahn of ARPA. I participated
in that original development of, and have since written extensively
about, these Internet ground rules.

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