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RFC2057 - Source Directed Access Control on the Internet

王朝other·作者佚名  2008-05-31
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Network Working Group S. Bradner

Request for Comments: 2057 Harvard University

Category: Informational November 1996

Source Directed Access Control on the Internet

Status of this Memo

This memo provides information for the Internet community. This memo

does not specify an Internet standard of any kind. Distribution of

this memo is unlimited.

1. Abstract

This memo was developed from a deposition that I submitted as part of

a challenge to the Communications Decency Act of 1996, part of the

Telecommunications Reform Act of 1996. The Telecommunications Reform

Act is a U.S. federal law substantially changing the regulatory

strUCture in the United States in the telecommunications arena. The

Communications Decency Act (CDA) part of this law has as its aim the

desire to protect minors from some of the material carried over

telecommunications networks. In particular the law requires that the

sender of potentially offensive material take "effective action" to

ensure that it is not presented to minors. A number of people have

requested that I publish the deposition as an informational RFCsince

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

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.

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.

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.

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.

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

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

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.

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.

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.

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

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

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

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.

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.

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.

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.

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.

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,

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

 
 
 
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