RFC 340 UNKNOWN TELNET · PROTOCOL DESIGN · SECURITY

Proposed Telnet Changes

Arguments for keeping data type codes and password masking in Telnet.

On rfc-editor.org ↗
PUBLISHED
May 1972
AUTHORS
T.C. O'Sullivan
STREAM
Legacy
CONTEXT
Response to RFC 328 proposal
FEATURES DISCUSSED
Data Types and Hide Your Input
DOI
10.17487/RFC0340

RFC text

Original text · RFC Editor View on rfc-editor.org ↗
Network Working Group                                Tom O'Sullivan
Request for Comments:  340                           Raytheon Company
NIC          9933                                    Sudbury, Mass.
Categories:  Telnet
References:  RFC 328                                 15 May 1972


                        PROPOSED TELNET CHANGES

   The proposed change to the TELNET protocol calling for one standard
protocol and dropping the idea of minimum implementation seems
reasonable at this time.

   I suggest that both Data Types and Hide Your Input be kept for the
following reasons:

   Data Types:

The objection stating that switching out of ASCII results in an
irreversible change and loss of control can be met by requiring other
codes to provide to a return to ASCII.  Each other code may have its
own return code, however, it may not always be employed.  Other codes
are important for alphanumeric terminals that have special devices
attached.  Several potential cases can be cited:

   1.  Cal comp plotter attached to a teletype has logic permitting a
       program to turn the plotter on and off.  When operating I believe
       it uses an 8 bit code which could conflict with Telnet signals.

   2.  Numerically controlled machines, either controlled from a user
       terminal or code prepared by a HOST computer to be punched on the
       paper tape punch at a teletype way require the use of an arbitrary
       8 bit code.

   3.  Experiments controlled from alphanumeric terminal or sensor data
       collected through a cal-comp like connection may require the use
       of a full 8 bit code.

In these cases a transparent data type with a provision for a return
to ASCII mode seems desirable.

Hide Your Input:

As more and more use of data base systems in the network is
considered, the need for and importance of using access keys,
passwords, etc. grows.  The fact that it is difficult to select the
length of input to be hidden is not a persuasive argument.  Potential
solutions seem to exist, e.g. the protocol could provide for accepting
length statements from the user program, data base system, operating
system, etc. and in default of this, use a default length representing
the server system expected optimum length.



       [ This RFC was put into machine readable form for entry ]
       [ into the online RFC archives by BBN Corp. under the   ]
       [ direction of Alex McKenzie.                   12/96   ]

AI ELI5

On this page
PROBLEMA proposal suggested simplifying Telnet by dropping the Data Types feature and the Hide Your Input feature. Some argue this would remove important capabilities.
MECHANISMThis RFC supports keeping both features: Data Types allow switches to special 8-bit codes needed by attached devices like plotters and machine tools; Hide Your Input lets password entry be masked.
WHY THEY MATTERBoth features provide necessary support for specialized hardware and security, and can be improved with return codes and protocol enhancements.

§1Introduction

This RFC is a response to RFC 328, which proposed simplifying Telnet. Tom O'Sullivan agrees with the general direction but argues for keeping two features: Data Types and Hide Your Input (password masking). Removing these features would lose capabilities needed by specialized equipment and security-sensitive applications.

In Telnet discussions, someone suggested removing two optional features. This person says those two features are still useful.

§2Data Types

Data Types allow Telnet to switch out of ASCII mode to handle arbitrary 8-bit codes. This is essential for terminals with attached specialized equipment. Examples include Calcomp plotters, numerically controlled machines, and sensor experiments. Each non-ASCII mode should provide a return code to ASCII. Data Types serve real use cases on the ARPANET.

Some terminals have special gadgets plugged in (like a drawing machine or a drill controller) that use 8-bit codes the ASCII alphabet does not have. Telnet needs to handle this, and each gadget mode should have a way to get back to normal letters.

§3Hide Your Input

Hide Your Input (password masking) masks characters as they are entered, so passwords and access keys do not appear on the console. With more network database systems coming online and requiring passwords, this feature becomes more important, not less.

The concern that it is hard to select the masking length can be solved by letting the server program specify how many characters to mask, with a reasonable default. Passwords and secrets are critical to network security, so this feature should stay.

When you type a password, you want it hidden so nobody watching can see it. Network databases will need this more and more, so the feature is worth improving, not removing.

§4References