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Network Working Group                                         S. BradnerRequest for Comments: 2057                            Harvard UniversityCategory: Informational                                    November 1996Source Directed Access Control on the InternetStatus 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 eachBradner                      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 19963.  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 Communications3.1.1  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 isBradner                      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 othersBradner                      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 theBradner                      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 worldBradner                      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 hisBradner                      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 19964.3  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.eduBradner                      Informational                     [Page 20]