NIST Special Publication 500-205 Computer Systems Guidelines for the Evaluation Technology of Virtual Terminal U.S. DEPARTMENT OF COMMERCE Technology Administration Implementations National Institute of Standards and Technology Carol A. Edgar or 1f.rLl''V STAND 5 TECH R Nisr I c NIST A11103 illPM^ PUBLICATIONS QC 100 .U57 20'= The National Institute of Standards and Technology was established in 1 988 by Congress to "assist industry in the development of technology . needed to improve product quality, to modernize manufacturing processes, to ensure product reliability . and to facilitate rapid commercialization . of products based on new scientific discoveries." NIST, originally founded as the National Bureau of Standards in 1901, works to strengthen U.S. industry's competitiveness; advance science and engineering; and improve public health, safety, and the environment. 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CO 80303. ^Some elements at Boulder, CO 80303. NIST Special Publication 500-205 '^^J^, Guidelines for the Evaluation of Virtual Terminal Implementations Carol A. Edgar Systems and Network Architecture Division Computer Systems Laboratory National Institute of Standards and Technology Gaithersburg, MD 20899 This work is a contribution of the National Institute of standards and Technology, and it is not subject to copyright Partial funding for this docunnent was provided by the Internal Revenue Service November 1992 U.S. DEPARTMENT OF COMMERCE Barbara Hackman Franklin, Secretary TECHNOLOGY ADMINISTRATION Robert M. White, Under Secretary for Technology NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY John W. Lyons, Director Reports on Computer Systems Technology The National Institute of Standards and Technology (NIST) has a unique responsibility for computer systenns technology within the Federal government. NIST's Computer Systems Laboratory (CSL) devel- ops standards and guidelines, provides technical assistance, and conducts research for computers and related telecommunications systems to achieve more effective utilization of Federal information technol- ogy resources. CSL's responsibilities include development of technical, management, physical, and ad- ministrative standards and guidelines for the cost-effective security and privacy of sensitive unclassified information processed in Federal computers. CSL assists agencies in developing security plans and In improving computer security awareness training. This Special Publication 500 series reports CSL re- search and guidelines to Federal agencies as well as to organizations in industry, government, and academia. National Institute of Standards and Technology Special Publication 500-205 Natl. Inst. Stand. Technol. Spec. Publ. 500-205, 47 pages (Nov. 1992) CODEN: NSPUE2 U.S. GOVERNMENT PRINTING OFFICE WASHINGTON: 1992 For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402 Contents List of Figures v Disclaimer v 1 Introduction 1 1.1 Scope 1 1.2 Overview 2 1.3 Acknowledgments 2 2 Virtual Terminal Overview S 2.1 The Need for a Virtual Terminal Service 3 2.2 Achieving the Virtual TermineJ Goal 3 3 Virtual Terminal Tutorial 5 3.1 Definitions 6 3.1.1 The Virtual Terminal 6 3.1.2 Virtual Terminal Environment 7 3.1.3 Conceptual Commimications Area 7 3.2 Virtual Terminal Objects 7 3.2.1 Display Objects 8 3.2.2 Control Objects 10 3.2.3 Device Objects 10 3.3 Virtual Terminal Communication Modes 10 3.4 VirtueJ Terminal Service Facilities 11 3.4.1 Establishment 11 3.4.2 Data Transfer 12 3.4.3 Termination 14 3.4.4 Negotiation 14 3.4.4.1 Switch Profile Negotiation 15 3.4.4.2 Multiple Interaction Negotiation 15 3.4.4.3 No Negotiation 15 3.4.5 Delivery Control 15 3.4.6 Access Right Mainagement 16 3.4.7 Interrupt 17 3.5 Repertoires 17 iii 4 Virtual Terminal Profiles 19 4.1 A-Mode Default Profile 20 4.2 Generalized Telnet Profile 20 4.3 X.SProfUe 21 4.4 Tremsparent Profile 22 4.5 S-Mode Defatdt Profile 22 4.6 Forms Profile 23 4.7 Paged Profile 23 5 Industry/ Government Open Systems Specification Requirements 25 6 Evaluation Guidelines 27 6.1 Csindidate Implementations 27 6.2 Functional Evaluation Guidelines 27 6.2.1 Virtual Terminal Roles 28 6.2.2 Network Type 28 6.2.3 Functional Units 29 6.2.4 Implementation Profiles 30 6.2.5 Profile Option Support 30 6.2.6 User Interface 30 6.2.7 Application Gateways 31 6.2.8 Application Integration 31 6.2.9 Administrative Functions 32 6.2.9.1 Administration Functions 32 6.2.9.2 Debug Capabilities 33 6.2.9.3 Access Control 33 6.2.10 Underlying Open Systems Interconnection Layers 33 6.2.11 Conformance and Interoperability Testing and Registration 34 6.2.12 Heirdware Requirements 35 6.2.13 Software Requirements 35 6.2.14 Documentation 35 6.3 Other Guidelines 36 7 Virtual Terminal Products 37 Appendix A Virtual Terminal and X Windows 41 Appendix B Abbreviations 45 Appendix C Glossary 47 References 49 iv List of Figures 3.1 The Mapping of the Virtual Terinin«il Protocol to the Open Systems Interconnection Reference Model 5 3.2 Virtual Terminal Model 6 3.3 Virtual Terminal Communication 7 3.4 Conceptual Communications Area Components 8 3.5 Display Object 9 3.6 Asynchronous Mode Commtmication Flow 11 3.7 Synchronous Mode Communication Flow 12 4.1 Virtual Terminal Profiles 19 6.1 Initiator/Responder Relationship 29 A.l X Windows to OSI Mapping 42 A.2 Xll Client/Server Relationship 43 Disclaimer Certain commercial products axe identified in this report. Such identification does not imply recommendation or endorsement by the Nationeil Institute of Standards and Technology, nor does it imply that the equipment identified is necessarily the best available for the purpose. V Chapter 1 Introduction The Government Open Systems Interconnection Profile (GOSIP) [11] mjindates that Federfil agen- cies requiring remote terminal access capability procure products conforming to the International Organization for Standardization Open Systems Interconnection Basic Class Virtual Terminal Ser- vice and Protocol [14, 15]. The Federal government is cooperating with the commercial sector to produce ein Industry/Government Open Systems Specification (IGOSS) [13] which will be referenced by the next version of the Government Open Systems Interconnection Protocol. The IGOSS will expand the tjrpes of terminals which can use the OSI VirtucJ Terminal protocol. This document, Guidelines for the Evaluation of Virtual Terminal Implementations, advances the goals of the GOSIP by assisting a user in determining which VirtueJ Terminal (VT) imple- mentation, among severed candidates, best meets the functional requirements of that user. This document is one in a series of evaluation guidelines for Open Systems Interconnection (OSI) ap- plications. Evaluation guidelines for Message Hsindling Systems (MHS) implementations [26] and File Transfer, Access, and Mzinagement (FTAM) implementations [18] have preceded this one, and evaluation guidelines for other OSI applications, such as Directory Services, wiU foUow. The Eveduation Guidelines section of this document