rfc2592.txt

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Network Working Group                                            D. Levi
Request for Comments: 2592                               Nortel Networks
Category: Standards Track                               J. Schoenwaelder
                                                         TU Braunschweig
                                                                May 1999


                 Definitions of Managed Objects for the
                    Delegation of Management Scripts

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (1999).  All Rights Reserved.

Abstract

   This memo defines a portion of the Management Information Base (MIB)
   for use with network management protocols in the Internet community.
   In particular, it describes a set of managed objects that allow the
   delegation of management scripts to distributed managers.

Table of Contents

   1. Introduction .................................................   2
   2. The SNMP Management Framework ................................   2
   3. Overview .....................................................   3
   3.1 Terms ......................................................    4
   4. Requirements and Design Issues ..............................    5
   4.1 Script Languages ...........................................    5
   4.2 Script Transfer ............................................    6
   4.3 Script Execution ...........................................    7
   5. The Structure of the MIB .....................................   8
   5.1 The smLanguageGroup ........................................    9
   5.2 The smScriptGroup ..........................................    9
   5.3 The smCodeGroup ............................................   10
   5.4 The smLaunchGroup ..........................................   10
   5.5 The smRunGroup .............................................   11
   6 Definitions ..................................................   11
   7. Usage Examples ...............................................  41
   7.1 Pushing a script via SNMP ..................................   41



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   7.2 Pulling a script from a URL ................................   42
   7.3 Modifying an existing script ...............................   42
   7.4 Removing an existing script ................................   43
   7.5 Creating a launch button ...................................   43
   7.6 Launching a script .........................................   44
   7.7 Terminating a script .......................................   44
   7.8 Removing a launch button ...................................   45
   8. VACM Configuration Examples ..................................  45
   8.1 Sandbox for guests .........................................   45
   8.2 Sharing scripts ............................................   46
   8.3 Emergency scripts ..........................................   47
   9. IANA Considerations ..........................................  48
   10. Security Considerations .....................................  48
   11. Intellectual Property .......................................  49
   12.  Acknowledgments ............................................. 49
   13. References ..................................................  50
   14. Editors' Addresses ..........................................  52
   16. Full Copyright Statement ....................................  53

1.  Introduction

   This memo defines a portion of the Management Information Base (MIB)
   for use with network management protocols in the Internet community.
   In particular, it describes a set of managed objects that allow the
   delegation of management scripts to distributed managers.

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [21].

2.  The SNMP Management Framework

   The SNMP Management Framework presently consists of five major
   components:

      o   An overall architecture, described in RFC 2271 [1].

      o   Mechanisms for describing and naming objects and events for
          the purpose of management. The first version of this Structure
          of Management Information (SMI) is called SMIv1 and described
          in STD 16, RFC 1155 [2], STD 16, RFC 1212 [3] and RFC 1215
          [4]. The second version, called SMIv2, is described in STD 58,
          RFC 2578 [5], RFC 2579 [6] and RFC 2580 [7].








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      o   Message protocols for transferring management information. The
          first version of the SNMP message protocol is called SNMPv1
          and described in STD 15, RFC 1157 [8]. A second version of the
          SNMP message protocol, which is not an Internet standards
          track protocol, is called SNMPv2c and described in RFC 1901
          [9] and RFC 1906 [10]. The third version of the message
          protocol is called SNMPv3 and described in RFC 1906 [10], RFC
          2272 [11] and RFC 2274 [12].

      o   Protocol operations for accessing management information. The
          first set of protocol operations and associated PDU formats is
          described in STD 15, RFC 1157 [8]. A second set of protocol
          operations and associated PDU formats is described in RFC 1905
          [13].

      o   A set of fundamental applications described in RFC 2273 [14]
          and the view-based access control mechanism described in RFC
          2275 [15].

   Managed objects are accessed via a virtual information store, termed
   the Management Information Base or MIB.  Objects in the MIB are
   defined using the mechanisms defined in the SMI.

   MIB conforming to the SMIv1 can be produced through the appropriate
   translations. The resulting translated MIB must be semantically
   equivalent, except where objects or events are omitted because no
   translation is possible (use of Counter64). Some machine readable
   information in SMIv2 will be converted into textual descriptions in
   SMIv1 during the translation process. However, this loss of machine
   readable information is not considered to change the semantics of the
   MIB.

3.  Overview

   The Script MIB module defined in this memo can be used to delegate
   management functions to distributed managers. Management functions
   are defined as management scripts written in a management scripting
   language. This MIB makes no assumptions about the language itself and
   even allows distribution of compiled native code, if an
   implementation is able to execute native code under the control of
   this MIB.

   The Script MIB defines a standard interface for the delegation of
   management functions based on the Internet management framework. In
   particular, it provides the following capabilities:

   1.   Capabilities to transfer management scripts to a distributed
        manager.



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   2.   Capabilities for initiating, suspending, resuming and
        terminating management scripts.

   3.   Capabilities to transfer arguments for management scripts.

   4.   Capabilities to monitor and control running management scripts.

   5.   Capabilities to transfer the results produced by running
        management scripts.

   This memo does not address any additional topics like the generation
   of notifications or how to address remote agents from a Script MIB
   implementation.

3.1.  Terms

   This section defines the terms used throughout this memo.

   o    A `distributed manager' is a processing entity which is capable
        of performing network management functions. For the scope of
        this memo, a distributed manager is assumed to implement the
        Script MIB.

   o    A `higher-level manager', or just `manager', is a processing
        entity or human who initiates and controls the operations
        performed by one or more distributed managers.

   o    A `management script' is a set of instructions written in an
        executable language which implements a management function.

   o    A `management scripting language' is a language used to write
        management scripts. Note, the term scripting language does not
        imply that the language must have the characteristics of
        scripting languages (e.g. string orientation, interpretation,
        weak typing). The MIB defined in this memo also allows to
        control management scripts written in arbitrary compiled system
        programming languages.

   o    A `distributed manager' can be decomposed into an `SNMP entity'
        which implements the Script MIB defined in this memo and the
        `runtime system' that executes scripts. The Script MIB sees the
        runtime system as the managed resource which is controlled by
        the MIB.

        The runtime system can act as an SNMP application, according to
        the SNMP architecture defined in RFC 2271 [1]. For example, a
        runtime system which sends SNMP requests to other SNMP entities
        will act as a command generator application. The SNMP



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        applications in the runtime system may use the same SNMP engine
        which also serves the command responder application used to
        implement the Script MIB, but they are not required to do so.

   o    A `launch button' is the conceptual button used to start the
        execution of a management script. It assignes control parameters
        to a management script. In particular, it defines the ownership
        of the scripts started from a launch button. The ownership can
        be used by the language runtime system to enforce security
        profiles on a running management script.

4.  Requirements and Design Issues

   This section discusses some general requirements that have influenced
   the design of the Script MIB.

   o    The Script MIB must not make any assumptions about specific
        languages or runtime systems.

   o    The Script MIB must provide mechanisms that help to avoid new
        management problems (e.g. script version problems).

   o    The Script MIB must provide SNMP interfaces to all functions
        required to delegate management scripts. However, other
        protocols might be used in addition if they provide a
        significant improvement in terms of convenience for
        implementation or performance.

   o    The Script MIB must be organized so that access can be
        controlled effectively by using view-based access control [15].

   The following sections discuss some design issues in more detail.

4.1.  Script Languages

   The Script MIB defined in this memo makes no assumption about the
   script language. This MIB can therefore be used in combination with
   different languages (such as Tcl or Java) and/or different versions
   of the same language. No assumptions are made about the format in
   which management scripts are transferred.

   The Script MIB provides access to information about the language
   versions supported by a Script MIB implementation so that a manager
   can learn about the capabilities provided by an implementation.
   Languages and language versions are identified as follows:






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   1.   The language is identified by an object identifier. Object
        identifier for well-known languages will be registered by the
        Internet Assigned Numbers Authority (IANA). Enterprise specific
        languages can also be registered in the enterprise specific OID
        subtree.

   2.   A particular version of a language is identified by a language
        version number. The combination of a language object identifier
        and a language version is in most cases sufficient to decide
        whether a script can be executed or not.

   3.   Different implementations of the same language version might
        have differences due to ambiguities in the language definition
        or additional language features provided by an implementor. An
        additional object identifier value is provided which identifies
        the organization which provides the implementation of a
        language. This might be used by scripts that require a
        particular implementation of a language.

   4.   Finally, there might be different versions of a language
        implementation. A version number for the language implementation
        is provided so that the manager can also distinguish between
        different implementations from the same organization of a
        particular language version.

   The version numbers can either be used by a manager to select the
   language version required to execute a particular script or to select
   a script that fits the language versions supported by a particular
   Script MIB implementation.

   An additional table lists language extensions that provide features
   not provided by the core language. Language extensions are usually
   required to turn a general purpose language into a management
   language. In many cases, language extensions will come in the form of
   libraries that provide capabilities like sending SNMP requests to
   remote SNMP agents or accessing the local MIB instrumentation. Every
   extension is associated with a language and carries its own version
   numbers.

4.2.  Script Transfer

   There are two different ways to transfer management scripts to a
   distributed manager. The first approach requires that the manager
   pushes the script to the distributed manager. This is therefore
   called the `push model'. The second approach is the `pull model'