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+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]
+