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rfc: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]

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