rfc2057
Network Working Group S. Bradner
Request for Comments: 2057 Harvard University
Category: Informational November 1996
Source Directed Access Control on the Internet
Status of this Memo
This memo provides information for the Internet community. This memo
does not specify an Internet standard of any kind. Distribution of
this memo is unlimited.
1. Abstract
This memo was developed from a deposition that I submitted as part of
a challenge to the Communications Decency Act of 1996, part of the
Telecommunications Reform Act of 1996. The Telecommunications Reform
Act is a U.S. federal law substantially changing the regulatory
structure in the United States in the telecommunications arena. The
Communications Decency Act (CDA) part of this law has as its aim the
desire to protect minors from some of the material carried over
telecommunications networks. In particular the law requires that the
sender of potentially offensive material take "effective action" to
ensure that it is not presented to minors. A number of people have
requested that I publish the deposition as an informational RFC since
some of the information in it may be useful where descriptions of the
way the Internet and its applications work could help clear up
confusion in the technical feasibility of proposed content control
regulations.
2. Control and oversight over the Internet
No organization or entity operates or controls the Internet. The
Internet consists of tens of thousands of local networks linking
millions of computers, owned by governments, public institutions,
non-profit organizations, and private companies around the world.
These local networks are linked together by thousands of Internet
service providers which interconnect at dozens of points throughout
the world. None of these entities, however, controls the Internet;
each entity only controls its own computers and computer networks,
and the links allowed into those computers and computer networks.
Although no organizations control the Internet, a limited number of
organizations are responsible for the development of communications
and operational standards and protocols used on the Internet. These
standards and protocols are what allow the millions of different (and
sometimes incompatible) computers worldwide to communicate with each
Bradner Informational [Page 1]
RFC 2057 Source Directed Access Control November 1996
other. These standards and protocols are not imposed on any computer
or computer network, but any computer or computer network must follow
at least some of the standards and protocols to be able to
communicate with other computers over the Internet.
The most significant of the organizations involved in defining these
standards include the Internet Society (ISOC), the Internet
Architecture Board (IAB), Internet Engineering Steering Group (IESG),
and the Internet Engineering Task Force (IETF). The following
summary outlines the relationship of these four organizations:
The Internet Society (ISOC) is a professional society that is
concerned with the growth and evolution of the worldwide Internet,
with the way in which the Internet is and can be used, and with the
social, political, and technical issues which arise as a result. The
ISOC Trustees are responsible for approving appointments to the IAB
from among the nominees submitted by the IETF nominating committee
and ratifying the IETF Standards Process.
The Internet Architecture Board (IAB) is a technical advisory group
of the ISOC. It is chartered to provide oversight of the
architecture of the Internet and its protocols, and to serve, in the
context of the Internet standards process, as a body to which the
decisions of the IESG may be appealed. The IAB is responsible for
approving appointments to the IESG from among the nominees submitted
by the IETF nominations committee and advising the IESG on the
approval of Working Group charters.
The Internet Engineering Steering Group (IESG) is responsible for
technical management of IETF activities and the Internet standards
process. As a part of the ISOC, it administers the process according
to the rules and procedures which have been ratified by the ISOC
Trustees. The IESG is directly responsible for the actions
associated with entry into and movement along the Internet "standards
track," including final approval of specifications as Internet
Standards.
The Internet Engineering Task Force (IETF) is a self-organized group
of people who make technical and other contributions to the
engineering and evolution of the Internet and its technologies. It
is the principal body engaged in the development of new Internet
standard specifications. The IETF is divided into eight functional
areas. They are: Applications, Internet, IP: Next Generation,
Network Management, Operational Requirements, Routing, Security,
Transport and User Services. Each area has one or two area
directors. These area directors, along with the IETF/IESG Chair,
form the IESG.
Bradner Informational [Page 2]
RFC 2057 Source Directed Access Control November 1996
In addition to these organizations, there are a variety of other
formal and informal groups that develop standards and agreements
about specialized or emerging areas of the Internet. For example,
the World Wide Web Consortium has developed agreements and standards
for the Web.
None of these organizations controls, governs, runs, or pays for the
Internet. None of these organizations controls the substantive
content available on the Internet. None of these organizations has
the power or authority to require content providers to alter, screen,
or restrict access to content on the Internet other than content that
they themselves create.
Beyond the standards setting process, the only Internet functions
that are centralized are the allocation of numeric addresses to
networks and the registration of "domain names." Three entities
around the world share responsibility for ensuring that each network
and computer on the Internet has a unique 32-bit numeric "IP" address
(such as 123.32.22.132), and for ensuring that all "domain names"
(such as "harvard.edu") are unique. InterNIC allocates IP addresses
for the Americas, and has counterparts in Europe and Asia. InterNIC
allocates large blocks of IP addresses to major Internet providers,
who in turn allocate smaller blocks to smaller Internet providers
(who in turn allocate even smaller blocks to other providers or end
users). InterNIC does not, however, reliably receive information on
who receives each numeric IP address, and thus cannot provide any
central database of computer addresses. In addition, a growing
number of computers access the Internet indirectly through address
translating devices such as application "firewalls". With these
devices the IP address used by a computer on the "inside" of the
firewall is translated to another IP address for transmission over
the Internet. The IP address used over the Internet can be
dynamically assigned from a pool of available IP addresses at the
time that a communication is initiated. In this case the IP
addresses used inside the firewall is not required to be globally
unique and the IP addresses used over the Internet do not uniquely
identify a specific computer. Neither the InterNIC nor its
counterparts in Europe and Asia control the substantive content
available on the Internet, nor do they have the power or authority to
require content providers to alter, screen, or restrict access to
content on the Internet.
Bradner Informational [Page 3]
RFC 2057 Source Directed Access Control November 1996
3. Characteristics of Internet communications
There are a wide variety of methods of communications over the
Internet, including electronic mail, mail exploders such as listserv,
USENET newsgroups, Internet Relay Chat, gopher, FTP, and the World
Wide Web. With each of these forms of communication, the speaker has
little or no way to control or verify who receives the communication.
As detailed below, for each of these methods of communications, it is
either impossible or very difficult for the speaker to restrict
access to his or her communications "by requiring use of a verified
credit card, debit account, adult access code, or adult personal
identification number." Similarly, for each of these methods of
communication, there are no feasible actions that I know of that the
speaker can take that would be reasonably effective to "restrict or
prevent access by minors" to the speaker's communications.
With each of these methods of communications, it is either
technologically impossible or practically infeasible for the speaker
to ensure that the speech is not "available" to a minor. For most of
these methods--mail exploders such as listserv, USENET newsgroups,
Internet Relay Chat, gopher, FTP, and the World Wide Web--there are
technological obstacles to a speaker knowing about or preventing
access by minors to a communication. Yet even for the basic point-
to-point communication of electronic mail, there are practical and
informational obstacles to a speaker ensuring that minors do not have
access to a communication that might be considered "indecent" or
"patently offensive" in some communities.
3.1 Point-to-Point Communications
3.1.1 Electronic Mail.
Of all of the primary methods of communication on the Internet, there
is the highest likelihood that the sender of electronic mail will
personally know the intended recipient (and know the intended
recipient's true e-mail address), and thus the sender (i.e., the
speaker or content provider) may be able to transmit potentially
"indecent" or "patently offensive" content with relatively little
concern that the speech might be "available" to minors.
There is significantly greater risk for the e-mail speaker who does
not know the intended recipient. As a hypothetical example, if an
AIDS information organization receives from an unknown individual a
request for information via electronic mail, the organization has no
practical or effective way to verify the identity or age of the e-
mail requester.
Bradner Informational [Page 4]
RFC 2057 Source Directed Access Control November 1996
An electronic mail address provides no authoritative information
about the addressee. Addresses are often chosen by the addressees
themselves, and may or may not be based on the addressees' real
names. For millions of people with e-mail addresses, no additional
information is available over the Internet. Where information is
available (via, for example, inquiry tools such as "finger"), it is
usually provided by the addressee, and thus may not be accurate
(especially in a case of a minor seeking to obtain information the
government has restricted to adults).
There exists no universal or even extensive "white pages" listing of
e-mail addresses and corresponding names or telephone numbers. Given
the rapidly expanding and global nature of the Internet, any attempt
as such a listing likely will be incomplete (and likely will not
contain information about the age of the e-mail addressee). Nor is
there any systematic, practical, and efficient method to obtain the
identity of an e-mail address holder from the organization or
institution operating the addressee's computer system.
Moreover, it is relatively simple for someone to create an e-mail
"alias" to send and receive mail under a different name. Thus, a
given e-mail address may not even be the true e-mail address of the
recipient. On some systems, for example, an individual seeking to
protect his or her anonymity could easily create a temporary e-mail
address for the sole purpose of requesting information from an AIDS
information resource. In addition, there exist "anonymous remailers"
which replace the original e-mail address on messages with a randomly
chosen new one. The remailer keeps a record of the relationship
between the original and the replacement name so that return mail
will get forwarded to the right person. These remailers are used
frequently for discussion or support groups on sensitive or
controversial topics such as AIDS.
Thus, there is no reasonably effective method by which one can obtain
information from existing online information sources about an e-mail
address sufficient to ensure that a given address is used by an adult
and not a minor.
Absent the ability to comply with the Communications Decency Act
based on information from existing online information sources, an e-
mail speaker's only recourse is to interrogate the intended e-mail
recipient in an attempt to verify that the intended recipient is an
adult. Such verification inherently and unavoidably imposes the
burden of an entirely separate exchange of communications prior to
sending the e-mail itself, and is likely to be unreliable if the
recipient intends to deceive the speaker.
Bradner Informational [Page 5]
RFC 2057 Source Directed Access Control November 1996
This separate preliminary communication is required because with
electronic mail, there is a complete electronic and temporal
"disconnect" between the sender and recipient. Electronic mail can
be routed through numerous computers between the sender and the
recipient, and the recipient may not "log in" to retrieve mail until
days or even weeks after the sender sent the mail. Thus, at no point
in time is there any direct or even indirect electronic linkage
between sender and recipient that would allow the sender to
interrogate the recipient prior to sending an e-mail. Thus,
unavoidably, the Communications Decency Act requires that the sender
incur the administrative (and in some cases financial) cost of an
entirely separate exchange of communications between sender and
recipient prior to the sender having sufficient information to ensure
that the recipient is an adult. Even if the sender were to
establish that an e-mail addressee is not a minor, the sender could
not be sure that the addressee was not sharing their computer account
with someone else, as is frequently done, who is a minor.
If an e-mail is part of a commercial transaction of sufficient value
to justify the time and expense of obtaining payment via credit card
from the e-mail addressee, an e-mail sender may be able to utilize
the credit card or debit account options set out in the
Communications Decency Act. At this time, however, one cannot verify
a credit or debit transaction over the Internet, and thus an e-mail
speaker would have to incur the expense of verifying the transaction
via telephone or separate computer connection to the correct banking
entity. Because of current concerns about data security on the
Internet, such an e-mail credit card transaction would likely also
require that the intended e-mail recipient transmit the credit card
information to the e-mail sender via telephone or the postal service.
Similarly, utilizing the "adult access code" or "adult personal
identification number" options set out in the statute would at this
time require the creation and maintenance of a database of adult
codes. While such a database would not be an insurmountable
technological problem, it would require a significant amount of human
clerical time to create and maintain the information. As with the
credit or debit transactions, an adult code database would also
likely require that information be transmitted by telephone or postal
mail.
Moreover, such an adult access code would likely be very ineffective
at screening access by minors. For the adult access code concept to
work at all, any such code would have to be transmitted over the
Internet, and thus would be vulnerable to interception and
disclosure. Any sort of "information based" code--that is, a code
that consists of letters and numbers transmitted in a message--could
be duplicated and circulated to other users on the Internet. It is
Bradner Informational [Page 6]
RFC 2057 Source Directed Access Control November 1996
highly likely that valid adult access codes would themselves become
widely distributed on the Internet, allowing industrious minors to
obtain a valid code and thus obtain access the material sought to be
protected.
A somewhat more effective alternative to this type of "information
based" access code would be to link such a code to the unique 32-bit
numeric "IP" addresses of networks and computers on the Internet.
Under this approach, "adult" information would only be transmitted to
the particular computer with the "approved" IP address. For tens of
millions of Internet users, however, IP addresses for a given access
session are dynamically assigned at the time of the access, and those
users will almost certainly utilize different IP addresses in
succeeding sessions. For example, users of the major online services
such as America Online (AOL) are only allocated a temporary IP
address at the time they link to the service, and the AOL user will
not retain that IP address in later sessions. Also, as discussed
above, the use of "firewalls" can dynamically alter the apparent IP
address of computers accessing the Internet. Thus, any sort of IP
address-based screening system would exclude tens of millions of
potential recipients, and thus would not be a viable screening
option.
At bottom, short of incurring the time and expense of obtaining and
charging the e-mail recipient's credit card, there are no reasonably
effective methods by which an e-mail sender can verify the identity
or age of an intended e-mail recipient even in a one-to-one
communication to a degree of confidence sufficient to ensure
compliance with the Communications Decency Act (and avoid the Act's
criminal sanction).
3.2 Point-to-Multipoint Communications
The difficulties described above for point-to-point communications
are magnified many times over for point-to-multipoint communications.
In addition, for almost all major types of point-to-multipoint
communications on the Internet, there is a technological obstacle
that makes it impossible or virtually impossible for the speaker to
control who receives his or her speech. For these types of
communications over the Internet, reasonably effective compliance
with the Communications Decency Act is impossible.
3.2.1 Mail Exploders
Essentially an extension of electronic mail allowing someone to
communicate with many people by sending a single e-mail, "mail
exploders" are an important means by which the Internet user can
exchange ideas and information on particular topics with others
Bradner Informational [Page 7]
RFC 2057 Source Directed Access Control November 1996
interested in the topic. "Mail exploders" is a generic term covering
programs such as "listserv" and "Majordomo." These programs typically
receive electronic mail messages from individual users, and
automatically retransmit the message to all other users who have
asked to receive postings on the particular list. In addition to
listserv and Majordomo, many e-mail retrieval programs contain the
option to receive messages and automatically forward the messages to
other recipients on a local mailing list.
Mail exploder programs are relatively simple to establish. The
leading programs such as listserv and Majordomo are available for
free, and once set up can generally run unattended. There is no
practical way to measure how many mailing lists have been established
worldwide, but there are certainly tens of thousands of such mailing
lists on a wide range of topics.
With the leading mail exploder programs, users typically can add or
remove their names from the mailing list automatically, with no
direct human involvement. To subscribe to a mailing list, a user
transmits an e-mail to the automated list program. For example, to
subscribe to the "Cyber-Rights" mailing list (relating to censorship
and other legal issues on the Internet) one sends e-mail addressed to
"listserv@cpsr.org" and includes as the first line of the body of the
message the words "subscribe cyber-rights name" (inserting a person's
name in the appropriate place). In this example, the listserv
program operated on the cpsr.org computer would automatically add the
new subscriber's e-mail address to the mailing list. The name
inserted is under the control of the person subscribing, and thus may
not be the actual name of the subscriber.
A speaker can post to a mailing list by transmitting an e-mail
message to a particular address for the mailing list. For example,
to post a message to the "Cyber-Rights" mailing list, one sends the
message in an e-mail addressed to "cyber-rights@cpsr.org". Some
mailing lists are "moderated," and messages are forwarded to a human
moderator who, in turn, forwards messages that moderator approves of
to the whole list. Many mailing lists, however, are unmoderated and
postings directed to the appropriate mail exploder programs are
automatically distributed to all users on the mailing list. Because
of the time required to review proposed postings and the large number
of people posting messages, most mailing lists are not moderated.
Bradner Informational [Page 8]
RFC 2057 Source Directed Access Control November 1996
An individual speaker posting to a mail exploder mailing list cannot
control who has subscribed to the particular list. In many cases,
the poster cannot even find out the e-mail address of who has
subscribed to the list. A speaker posting a message to a list thus
has no way to screen or control who receives the message. Even if
the mailing list is "moderated," an individual posting to the list
still cannot control who receives the posting.
Moreover, the difficulty in knowing (and the impossibility of
controlling) who will receive a posting to a mailing list is
compounded by the fact that it is possible that mail exploder lists
can themselves be entered as a subscriber to a mailing list. Thus,
one of the "subscribers" to a mailing list may in fact be another
mail exploder program that re-explodes any messages transmitted using
the first mailing list. Thus, a message sent to the first mailing
list may end up being distributed to many entirely separate mailing
lists as well.
Based on the current operations and standards of the Internet, it
would be impossible for someone posting to a listserv to screen
recipients to ensure the recipients were over 17 years of age. Short
of not speaking at all, I know of no actions available to a speaker
today that would be reasonably effective at preventing minors from
having access to messages posted to mail exploder programs.
Requiring such screening for any messages that might be "indecent" or
"patently offensive" to a minor would have the effect of banning such
messages from this type of mailing list program.
Even if one could obtain a listing of the e-mail addresses that have
subscribed to a mailing list, one would then be faced with the same
obstacles described above that face a point-to-point e-mail sender.
Instead of obtaining a credit card or adult access code from a single
intended recipient, however, a posted to a mailing list may have to
obtain such codes from a thousand potential recipients, including new
mailing list subscribers who may have only subscribed moments before
the poster wants to post a message. As noted above, complying with
the Communications Decency Act for a single e-mail would be very
difficult. Complying with the Act for a single mailing list posting
with any reasonable level of effectiveness is impossible.
3.2.2 USENET Newsgroups.
One of the most popular forms of communication on the Internet is the
USENET newsgroup. USENET newsgroups are similar in objective to mail
exploder mailing lists--to be able to communicate easily with others
who share an interest in a particular topic--but messages are
conveyed across the Internet in a very different manner.
Bradner Informational [Page 9]
RFC 2057 Source Directed Access Control November 1996
USENET newsgroups are distributed message databases that allow
discussions and exchanges on particular topics. USENET newsgroups
are disseminated using ad hoc, peer-to-peer connections between
200,000 or more computers (called USENET "servers") around the world.
There are newsgroups on more than twenty thousand different subjects.
Collectively, almost 100,000 new messages (or "articles") are posted
to newsgroups each day. Some newsgroups are "moderated" but most
are open access.
For unmoderated newsgroups, when an individual user with access to a
USENET server posts a message to a newsgroup, the message is
automatically forwarded to adjacent USENET servers that furnish
access to the newsgroup, and it is then propagated to the servers
adjacent to those servers, etc. The messages are temporarily stored
on each receiving server, where they are available for review and
response by individual users. The messages are automatically and
periodically purged from each system after a configurable amount of
time to make room for new messages. Responses to messages--like the
original messages--are automatically distributed to all other
computers receiving the newsgroup. The dissemination of messages to
USENET servers around the world is an automated process that does not
require direct human intervention or review.
An individual who posts a message to a newsgroup has no ability to
monitor or control who reads the posted message. When an individual
posts a message, she transmits it to a particular newsgroup located
on her local USENET server. The local service then automatically
routes the message to other servers (or in some cases to a
moderator), which in turn allow the users of those servers to read
the message. The poster has no control over the handling of her
message by the USENET servers worldwide that receive newsgroups.
Each individual server is configured by its local manager to
determine which newsgroups it will accept. There is no mechanism to
permit distribution based on characteristics of the individual
messages within a newsgroup.
The impossibility of the speaker controlling the message distribution
is made even more clear by the fact that new computers and computer
networks can join the USENET news distribution system at any time.
To obtain newsgroups, the operator of a new computer or computer
network need only reach agreement with a neighboring computer that
already receives the newsgroups. Speakers around the world do not
learn that the new computer had joined the distribution system.
Thus, just as a speaker cannot know or control who receives a
message, the speaker does not even know how many or which computers
might receive a given newsgroup.
Bradner Informational [Page 10]
RFC 2057 Source Directed Access Control November 1996
For moderated newsgroups, all messages to the newsgroup are forwarded
to an individual who can screen them for relevance to the topics
under discussion. The screening process, however, does not increase
the ability of the original speaker to control who receives a given
message. A newsgroup moderator has as little control as the original
speaker over who receives a message posted to the newsgroup.
Based on the current operations and standards of the Internet, it
would be impossible for someone posting to a USENET newsgroup to
screen recipients to ensure that the recipients were over 17 years of
age. Short of not speaking at all, I know of no actions available to
a speaker today that would be reasonably effective at preventing
minors from having access to USENET newsgroup messages. Requiring
such screening for any messages that might be "indecent" or "patently
offensive" to a minor would have the effect of banning such messages
from USENET newsgroups.
A speaker also has no means by which he or she could require
listeners to provide a credit card, debit account, adult access code,
or adult personal identification number. Each individual USENET
server controls access to the newsgroups on that server, and a
speaker has no ability to force a server operator to take any
particular action. The message is out of the speaker's hands from
the moment the message is posted.
Moreover, even if one hypothesized a system under which a newsgroup
server would withhold access to a message until the speaker received
a credit card, debit account, adult access code, or adult personal
identification number from the listener, there would be no feasible
way for the speaker to receive such a number. Because a listener may
retrieve a message from a newsgroup days after the speaker posted the
message, such a hypothetical system would require the speaker either
to remain at his or her computer 24 hours a day for as many as ten
days after posting the message, or to finance, develop, and maintain
an automated system to receive and validate access numbers. All of
this effort would be required for the speaker to post even a single
potentially "patently offensive" message to a single newsgroup.
Moreover, even if such a hypothetical system did exist and a speaker
were willing to remain available 24 hours a day (or operate a costly
automated system) in order to receive access numbers, not all
computers that receive USENET newsgroups could reasonably transmit
such access numbers. Some computers that receive newsgroups do so
only by a once-a-day telephone connection to another newsgroup
server. Some of these computers do not have any other type of
Internet connection, and indeed some computers that receive USENET
newsgroups do not even utilize the TCP/IP communications protocol
that is required for direct or real time communications on the
Bradner Informational [Page 11]
RFC 2057 Source Directed Access Control November 1996
Internet. These computers would have no means by which a prospective
listener's access code could be communicated back to a speaker.
It is my opinion that if this hypothetical access system ever were
created, it would be so burdensome as to effectively ban from USENET
newsgroups messages that might be "indecent" or "patently offensive."
Moreover, the communications standards and protocols that would allow
such a hypothetical access system have not as of today been
developed, and no Internet standards setting body of which I am aware
is currently developing such standards and protocols. Specifically,
such a hypothetical access system is not part of the "next
generation" Internet Protocol that I helped to develop.
3.2.3 Internet Relay Chat.
Another method of communication on the Internet is called "Internet
Relay Chat" (or IRC). IRC allows for real time communication between
two or more Internet users. IRC is analogous to a telephone party
line, using a computer and keyboard rather than a telephone. With
IRC, however, at anyone time there are thousands of different party
lines available, in which collectively tens of thousands of users are
engaging in discussions, debates, and conversations on a huge range
of subjects. Moreover, an individual can create a new party line to
discuss a different topic at any time. While many discussions on IRC
are little more than social conversations between the participants,
there are often conversations on important issues and topics.
Although I have not personally operated an IRC server in my career, I
am familiar enough with the operations of IRC servers to be able to
identify the obstacles that a speaker would encounter attempting to
identify other participants and to verify that those participants
were not minors.
There exists a network of dozens of IRC servers across the world. To
speak through IRC, a speaker connects to one of these servers and
selects the topic the speaker wishes to "join." Within a particular
topic (once a speaker joins a topic), all speakers on that topic can
see and read everything that everyone else transmits. As a practical
matter, there is no way for each person who joins a discussion to
interrogate all other participants (sometimes dozens of participants)
as to their identity and age. Because people join or drop out of
discussions on a rolling basis, the discussion line would be
overwhelmed with messages attempting to verify the identity of the
participants.
Also as a practical matter, there is no way that an individual
speaker or an individual IRC server operator could enforce an "adults
only" rule for a selection of the discussion topics. Dozens of IRC
servers are interconnected globally so that people across the world
Bradner Informational [Page 12]
RFC 2057 Source Directed Access Control November 1996
can talk to each other. Thus, a speaker connected to an IRC server
in the United States can speak directly to a listener in Asia or
Europe. There is no practical way that a speaker in the United
States can be reasonably certain that a given IRC discussion is in
fact "adults only."
Nor can a speaker, prior to or at the time of joining an IRC
discussion, ascertain with any confidence the identity of the other
participants in the discussion. Individual participants in an IRC
conversation are able to participate anonymously by using a
pseudonym. A new speaking joining the conversation can see a list of
pseudonyms of other participants, but has no possibly way of
determining the real identify (or even the real e-mail address) of
the individuals behind each pseudonym.
Based on the current operations and standards of the Internet, it
would be impossible for someone participating in a IRC discussion to
screen recipients with a level of certainty needed to ensure the
recipients were over 17 years of age. Short of not speaking at all,
I know of no actions available to a speaker today that would be
reasonably effective at preventing minors from having access to
speech in an IRC discussion. Requiring such screening of recipients
by the speakers for any IRC discussions that might be "indecent" or
"patently offensive" to a minor would have the effect of banning such
discussions.
4.0 Information Retrival Systems
With FTP (or File Transfer Protocol), gopher, and the World Wide Web,
the Internet is a vast resource for information made available to
users around the world. All three methods (FTP, gopher, and the Web)
are specifically geared toward allowing thousands or millions of
users worldwide to access content on the Internet, and none are
specifically designed to limit access based on criteria such as the
age of the Internet user. Currently much of this information is
offered for free access.
4.1 Anonymous FTP
"Anonymous FTP" is a basic method by which a content provider can
make content available to users on the Internet. FTP is a protocol
that allows the efficient and error free transfer of files from one
computer to another. To make content available via FTP, a content
provider establishes an "Anonymous FTP server" capable of receiving
FTP requests from remote users. This approach is called "anonymous"
because when a remote user connects to an FTP server, the remote user
enters the word "anonymous" in response to the server's request for a
user name. By convention, the remote user is requested to enter his
Bradner Informational [Page 13]
RFC 2057 Source Directed Access Control November 1996
or her e-mail address when prompted for a "password." The user is
then given access to a restricted portion of the server disk and to
the files in that area. Even though the user may have entered their
e-mail address in response to the password prompt, there is no
effective validation or screening is possible using the FTP server
software that is currently available. Using currently available FTP
software, a content provider has no way to screen access by
"anonymous" users that may be minors. Even if a content provider
could determine the age of a particular remote user, the currently
available FTP software cannot be set to limit the user's access to
non-"adult" file areas.
FTP server software can allow non-"anonymous" users to access the FTP
server, and in that mode can require the users to have individual
passwords that are verified against a pre-existing list of passwords.
There are two major problems, however, that prevent this type of
non-"anonymous" FTP access from being used to allow broad access to
information over the Internet (as anonymous FTP can allow). First,
with current server software each non-"anonymous" FTP user must be
given an account on the server computer, creating a significant
administrative burden and resource drain. If more than a limited
number of users want access to the FTP system, the requirement of
separate accounts would quickly overwhelm the capacity of the server
to manage the accounts--the FTP server software was not designed to
manage thousands or millions of different user/password combinations.
Second, under existing FTP server software, each of these named users
would have complete access to the server file system, not a
restricted area like the anonymous FTP function supports. This would
create a significant security problem. For these two reasons, as a
practical matter FTP cannot be used to give broad access to content
except via the anonymous FTP option (which, as noted above, does not
allow for screening or blocking of minors).
As discussed below with regard to the World Wide Web, even if someone
re-designed the currently available FTP server software to allow the
screening of minors, the administrative burden of such screening
would in many cases overwhelm the resources of the content provider.
Bradner Informational [Page 14]
RFC 2057 Source Directed Access Control November 1996
Based on the current operations and standards of the Internet, it is
not possible or practically feasible for someone operating an
anonymous FTP file server to screen recipients with a level of
certainty needed to ensure the recipients were over 17 years of age.
Short of not operating an anonymous FTP server at all, I know of no
actions available to a content provider today that would be
reasonably effective at preventing minors from having access to
"adult" files on the FTP server. Requiring such screening by
anonymous FTP server operators to prevent minors from accessing FTP
files that might be "indecent" or "patently offensive" to a minor
would have the effect of banning such anonymous FTP access.
4.2 Gopher.
The gopher program is similar to FTP in that it allows for basic
transfer of files from one computer to another, but it is also a
precursor to the World Wide Web in that it allows a user to
seamlessly jump from one gopher file server to another in order to
locate the desired information. The development of gopher and the
linking of gopher servers around the worlds dramatically improved the
ability of Internet users to locate information across the Internet.
Although in many ways an improvement over FTP, gopher is simpler than
FTP in that users need not enter any username or password to gain
access to files stored on the gopher server. Under currently
available gopher server software, a content provider has no built-in
ability to screen users. Thus a content provider could not prevent
minors from retrieving "adult" files.
As discussed below with regard to the World Wide Web, even if the
gopher server software allowed the screening of minors, the
administrative burden of such screening would in many cases overwhelm
the resources of the content provider.
Based on the current operations and standards of the Internet, it is
not possible for someone operating a gopher file server to screen
recipients with a level of certainty needed to ensure the recipients
were over 17 years of age. Short of not operating a gopher server at
all, I know of no actions available to a content provider today that
would be reasonably effective at preventing minors from having access
to "adult" files on a gopher server. Requiring such screening of
users by gopher server operators to prevent minors from accessing
files that might be "indecent" or "patently offensive" to a minor
would have the effect of banning gopher servers wherever there is any
such material.
Bradner Informational [Page 15]
RFC 2057 Source Directed Access Control November 1996
4.3 World Wide Web (WWW).
Fast becoming the most well known method of communicating on the
Internet, the "World Wide Web" offers users the easy ability to
locate and view a vast array of content on the Internet. The Web
uses a "hypertext" formatting language called hypertext markup
language (HTML), and Web "browsers" can display HTML documents
containing text, images, and sound. Any HTML document can include
links to other types of information or resources anywhere in the
world, so that while viewing an HTML document that, for example,
describes resources available on the Internet, an individual can
"click" using a computer mouse on the description of the resource and
be immediately connected to the resource itself. Such "hyperlinks"
allow information to be accessed and organized in very flexible ways,
and allow individuals to locate and efficiently view related
information even if the information is stored on numerous computers
all around the world.
Unlike with USENET newsgroups, mail exploders, FTP, and gopher, an
operator of a World Wide Web server does have some ability to
interrogate a user of a Web site on the server, and thus has some
ability to screen out users. An HTML document can include a fill-in-
the-blank "form" to request information from a visitor to a Web site,
and this information can be transmitted back to the Web server. The
information received can then be processed by a computer program
(usually a "Common Gateway Interface," or "CGI," script), and based
on the results of that computer program the Web server could grant or
deny access to a particular Web page. Thus, it is possible for some
(but not all, as discussed below) World Wide Web sites to be designed
to "screen" visitors to ensure that they are adults.
The primary barrier to such screening is the administrative burden of
creating and maintaining the screening system. For an individual Web
site to create a software system capable of screening thousands of
visitors a day, determining (to the extent possible) whether a
visitor is an adult or a minor, and maintaining a database to allow
subsequent access to the Web site would require a significant on-
going effort. Moreover, as discussed above with regard to electronic
mail, the task of actually establishing a Web visitor's identity or
"verifying" a credit card would require a significant investment of
administrative and clerical time. As there is no effective method to
establish identity over the Internet, nor is there currently a method
to verify credit card numbers over the Internet (and given the
current cost of credit card verifications done by other means), this
type of identification process is only practical for a commercial
entity that is charging for access to the Web information.
Bradner Informational [Page 16]
RFC 2057 Source Directed Access Control November 1996
Beyond the major administrative burden that would be required for a
Web site host to comply with the Communications Decency Act, there
are two additional problems presented by the Act. First, many Web
publishers cannot utilize computer programs such as CGI scripts to
process input from a Web visitor. For example, I have been informed
that the major online services such as America Online and Compuserve
do not allow their customers to run CGI scripts or other processes
that could be a significant drain on the online services' computers
as well as a potential security risk. Thus, for this category of Web
publisher, the Communications Decency Act works as a ban on any
arguably "indecent" or "patently offensive" speech. It is impossible
for this category of Web publisher to control access to their Web
sites.
Moreover, even for Web publishers who can use CGI scripts to screen
access, the existence of Web page caching on the Internet can make
such screening ineffective. "Caching" refers to a method to speed up
access to Internet resources. Caching is often used at one or both
ends of, for example, a transatlantic or transpacific cable that
carries Internet communications. An example of caching might occur
when a Internet user in Europe requests access to a World Wide Web
page located in the United States. The request travels by
transatlantic cable to the United States, and the Web page is
transmitted back across the ocean to Europe (and ultimately to the
user who requested access). But, the operator of the transatlantic
cable will place the Web page in a storage "cache" located on the
European side of the cable. Then, if a second Internet user in
Europe requests the same Web page, the operator of the transatlantic
cable will intercept the request and provide the page from its
"cache" (thereby reducing traffic on the transatlantic cable). This
type of caching typically occurs without the awareness of the
requesting user. Moreover, in this scenario, the original content
provider is not even aware that the second user requested the Web
page--and the original content provider has no opportunity to screen
the access by the second user. Nevertheless, the original content
provider risks prosecution if the content is "adult" content and the
second requester is a minor. The use of caching web servers is
rapidly increasing within the United States (mostly to help moderate
the all too rapid growth in Internet traffic), and thus can affect
entirely domestic communications. For example, a growing number of
universities use caching web servers to reduce the usage of the link
to their Internet service provider. In light of this type of
caching, efforts to screen access to Web pages can only at best be
partially effective.
Bradner Informational [Page 17]
RFC 2057 Source Directed Access Control November 1996
In light of the existence of Web page caching on the Internet, it
would be extremely difficult if not impossible to for someone
operating a World Wide Web server to ensure that no minors received
"adult" content.
Moreover, for those Web page publishers who lack access to CGI
scripts, there is no possible way for them to screen recipients to
ensure that all recipients are over 17 years of age. For these
content providers, short of not supporting World Wide Web access to
their materials, I know of no actions available to them that would be
reasonably effective at preventing minors from having access to
"adult" files on a World Wide Web server. Requiring such screening
by these Web publishers to prevent minors from accessing files that
might be "indecent" or "patently offensive" to a minor would have the
effect of banning their speech on the World Wide Web.
The Web page caching described above contributes to the difficulty of
determining with specificity the number of visitors to a particular
Web site. Some Web servers can count how many different Web clients,
some of which could be caching Web servers, requested access to a Web
site. Some Web servers can also count how many "hits"--or separate
file accesses--were made on a particular Web site (a single access to
a Web page that contains a images or graphic icons would likely be
registered as more than one "hit"). With caching, the actual number
of users that retrieved information that originated on a particular
Web server is likely to be greater than the number of "hits" recorded
for the server.
5.0 Client-end Blocking
As detailed above, for many important methods of communication on the
Internet, the senders--the content providers--have no ability to
ensure that their messages are only available to adults. It is also
not possible for a Internet service provider or large institutional
provider of access to the Internet (such as a university) to screen
out all or even most content that could be deemed "indecent" or
"patently offensive" (to the extent those terms can be understood at
all). A large institution could at least theoretically screen a
portion of the communications over the Internet, scanning for example
for "indecent" words, but not pictures. Such a screening program
capable of screening a high volume of Internet traffic at the point
of its entry into the institution would require an investment of
computing resources of as much as one million dollars per major
Internet information conduit. In addition it would be quit difficult
to configure such a system to only control the content for those
users that are under-age recipients, since in many cases the
information would be going to a server within the university where
many users, under-age and not, would have access to it.
Bradner Informational [Page 18]
RFC 2057 Source Directed Access Control November 1996
Based on my experience and knowledge of the Internet, I believe that
the most effective way to monitor, screen, or control the full range
of information transmitted over the Internet to block undesired
content is at the client end--that is, by using software installed in
the individual user's computer. Such software could block certain
forms of incoming transmissions by using content descriptive tags in
the messages, or could use content ratings developed by third parties
to select what can and cannot be retrieved for display on a user's
computer.
6.0 Tagging Material
I am informed that the government in this action may advocate the use
of special tags or flags in electronic mail messages, USENET
newsgroup postings, and World Wide Web HTML documents to indicate
"adult" material. To my knowledge, no Internet access software or
World Wide Web browsers are currently configurable to block material
with such tags. Thus, the headers and flags the government may
advocate is currently an ineffective means to ensure the blocking of
access by minors to "adult" material. Even in a predictable future
where there are defined standards for such tags and there are
readably available browsers that are configurable to make use of
those tags, a content provider--e.g., a listserv or Newsgroup poster
or a Web page author--will have little power to ensure that the
client software used to receive the postings was in all cases
properly configured to recognize these tags and to block access to
the posting when required. Thus I feel that the tagging that may be
proposed by the government would in fact not be "effective" in
ensuring that the poster's speech would not be "available to a person
under 18 years of age," as the Communications Decency Act requires.
Although I strongly support both voluntary self-rating and third-
party rating (as described in the preceding paragraph), I do not feel
that the use of tags of this type would satisfy the speaker's
obligation to take effective actions to ensure that "patently
offensive" material would not be "available" to minors. Furthermore,
since it is impossible to embed such flags or headers in many of the
documents currently made available by anonymous FTP, gopher and the
World Wide Web without rendering the files useless (executable
programs for example), any government proposal to require the use of
tags to indicate "adult" material would not allow the continued use
of those methods of communication for speech that might be deemed
"indecent" or "patently offensive."
With the exception of electronic mail and e-mail exploders all of the
methods of Internet communications discussed above require an
affirmative action by the listener before the communication takes
place. A listener must take specific action to receive
communications from USENET newsgroups, Internet Relay Chat, gopher,
Bradner Informational [Page 19]
RFC 2057 Source Directed Access Control November 1996
FTP, and the World Wide Web. In general this is also true for e-mail
exploders except in the case where a third party subscribes the user
to the exploder list. These communications over the Internet do not
"invade" a person's home or appear on a person's computer screen
unbidden. Instead, a person must almost always take specific
affirmative steps to receive information over the Internet.
7.0 Acknowledgment
I owe a great deal of thanks to John Morris of Jenner and Block, one
of the law firms involved in the CDA challenge. Without his
extensive help this document would not exist, or if it did, it would
be even more scattered.
8.0 Security Considerations
To be actually able to do the type of content access control that the
CDA envisions would require a secure Internet infrastructure along
with secure ways to determine the minor status of potential
reciepiants around the world. Developing such a system is outside of
the scope of this document.
9.0 Author's Address
Scott Bradner
Harvard University
1350 Mass Ave.
Cambridge MA 02138 USA
Phone: +1 617 495 3864
EMail: sob@harvard.edu
Bradner Informational [Page 20]
ERRATA
