Network Working Group D. Crocker
Request for Comments: 1775 Brandenburg Consulting
Category: Informational March 1995

To Be "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.

Abstract

The Internet permits different levels of Access for consumers and
providers of service. The nature of those differences is quite
important in the capabilities They afford. Hence, it is appropriate
to provide terminology that distinguishes among the range, so that
the Internet community can gain some clarity when distinguishing
whether a user (or an organization) is "on" the Internet. This
document suggests four terms, for distinguishing the major classes of
access.

1. INTRODUCTION

The Internet is many things to many people. It began as a technology
and has grown into a global service. With the growth has come
increased complexity in details of the technology and service,
resulting in confusion when trying to determine whether a given user
is "on" the Internet. Who is on the Internet? What capabilities do
they have? This note is an attempt to aid Internet consumers and
providers in determining the basic types of end-user access that
distinguish critical differences in Internet attachment.

The list was developed primarily for the perspective of users, rather
than for the technical community. The definitions in this list take
the perspective that users are primarily interested in application
services. A curious implication is that some of the definitions do
not rely on the direct use of the underlying Internet connectivity
protocols, TCP/IP. For many technical discussions, therefore, these
terms will not be appropriate.

2. LABELS FOR INTERNET ACCESS

The following definitions move from "most" to "least" Internet
access, from the perspective of the user (consumer). The first term
is primarily applicable to Internet service providers. The remaining
terms are primarily applicable to consumers of Internet service.

FULL ACCESS

This is a permanent (full-time) Internet attachment running
TCP/IP, primarily appropriate for allowing the Internet community
to access application servers, operated by Internet service
providers. Machines with Full access are directly visible to
others attached to the Internet, such as through the Internet
Protocol's ICMP Echo (ping) facility. The core of the Internet
comprises those machines with Full access.

CLIENT ACCESS

The user runs applications that employ Internet application
protocols directly on their own computer platform, but might not
be running underlying Internet protocols (TCP/IP), might not have
full-time access, such as through dial-up, or might have
constrained access, such as through a firewall. When active,
Client users might be visible to the general Internet, but such
visibility cannot be predicted. For example, this means that most
Client access users will not be detected during an empirical
probing of systems "on" the Internet at any given moment, such as
through the ICMP Echo facility.

MEDIATED ACCESS

The user runs no Internet applications on their own platform. An
Internet service provider runs applications that use Internet
protocols on the provider's platform, for the user. User has
simplified access to the provider, such as dial-up terminal
connectivity. For Mediated access, the user is on the Internet,
but their computer platform is not. Instead, it is the computer
of the mediating service (provider) which is on the Internet.

MESSAGING ACCESS

The user has no Internet access, except through electronic mail
and through netnews, such as Usenet or a bulletin board service.
Since messaging services can be used as a high-latency -- i.e.,
slow -- transport service, the use of this level of access for
mail-enabled services can be quite powerful, though not
interactive.

3. SAMPLE USAGE

The test of a nomenclature is, of course, its application to real-
life situations. Two simple cases involve home users. If a user
accesses the Internet by running a terminal program on their PC and
then dials up a public service which provides the Internet
applications, then that user has Mediated Internet access. The
public service has Client or Full access, but the user does not. On
the other hand, users who access via SLIP or PPP are running Internet
applications on their own PCs and they have Client Internet access.

Many corporations now have a full-time link to the Internet. The
link is based on TCP/IP and usually has a number of Internet servers
running, for email exchange and for making public corporate data
available to the rest of the world, such as through the World Wide
Web and Gopher. Clearly, the corporation is "on" the Internet, with
Full Internet access.

What about a user in that corporation? Many corporations today
separate their internal internet from the public Internet via a
firewall. If a user from the internal internet has a desktop
computer and reaches out to the Internet, through the firewall, by
running any Internet applications, such as a Web browser, then that
user has Client Internet access.

Some corporations will not allow this, instead requiring all software
which touches the public Internet to be run on specially-administered
machines which are part of the corporation's firewall suite of
services. Hence, users must make a terminal connection to the
special machines, from there running the Internet applications. Such
users have Mediated Internet access, the same as home users who dial
up a public service.

4. SECURITY CONSIDERATIONS

This specification does NOT, itself, provide or define any security-
related mechanisms. However it does describe scenarios with
different security implications for users and providers. Readers of
this discussion are cautioned to consider those implications when
choosing a service.

5. ACKNOWLEDGMENTS

Development of these definitions was spurred by many public and
private discussions in which confusion over Internet access reigned.
Convergence on an initial set of three terms was the result of
discussion on the Big-Internet mailing list, particularly from
comments made by Alan Barret, Howard Berkowitz, Noel Chiappa, Steve

Goldstein, Iain Hanson, Gary Malkin, Bob McKisson, Tim O'Reilly, Dave
Piscitello and Bill Simpson. Eventually, the need for a fourth
category became evident and was discussed further with the
participants on the list. This does not mean that any of them
necessarily endorses the terms and definitions provided, merely that
their notes assisted my thinking on the topic. After the initial
round of public discussion, Smoot Carl-Mitchell and John Quarterman
of Texas Internet Consulting developed terminology for similar
categories and served to prompt modification of this set, described,
here, to distinguish between provider and consumer forms of access
and emphasize the role of Full access in defining the Internet core.

6. Security Considerations

Security issues are not discussed in this memo.

7. Author's Address

David H. Crocker
Brandenburg Consulting
675 Spruce Dr.
Sunnyvale, CA 94086 USA

Phone: +1 408 246 8253
Fax: +1 408 249 6205