Network Working Group D. Harrington
Request for Comments: 5590 Huawei Technologies (USA)
Updates: 3411, 3412, 3414, 3417 J. Schoenwaelder
Category: Standards Track Jacobs University Bremen
June 2009
Network Working Group D. Harrington
Request for Comments: 5590 Huawei Technologies (USA)
Updates: 3411, 3412, 3414, 3417 J. Schoenwaelder
Category: Standards Track Jacobs University Bremen
June 2009
Transport Subsystem for the Simple Network Management Protocol (SNMP)
简单网络管理协议（SNMP）的传输子系统
Status of This Memo
关于下段备忘
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.
本文件规定了互联网社区的互联网标准跟踪协议，并要求进行讨论和提出改进建议。有关本协议的标准化状态和状态，请参考当前版本的“互联网官方协议标准”（STD 1）。本备忘录的分发不受限制。
Copyright Notice
版权公告
Copyright (c) 2009 IETF Trust and the persons identified as the document authors. All rights reserved.
版权所有（c）2009 IETF信托基金和确定为文件作者的人员。版权所有。
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents in effect on the date of publication of this document (http://trustee.ietf.org/license-info). Please review these documents carefully, as they describe your rights and restrictions with respect to this document.
本文件受BCP 78和IETF信托在本文件出版之日生效的与IETF文件有关的法律规定的约束(http://trustee.ietf.org/license-info). 请仔细阅读这些文件，因为它们描述了您对本文件的权利和限制。
This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s) controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English.
本文件可能包含2008年11月10日之前发布或公开的IETF文件或IETF贡献中的材料。控制某些材料版权的人员可能未授予IETF信托允许在IETF标准流程之外修改此类材料的权利。在未从控制此类材料版权的人员处获得充分许可的情况下，不得在IETF标准流程之外修改本文件，也不得在IETF标准流程之外创建其衍生作品，除了将其格式化以RFC形式发布或将其翻译成英语以外的其他语言。
Abstract
摘要
This document defines a Transport Subsystem, extending the Simple Network Management Protocol (SNMP) architecture defined in RFC 3411. This document defines a subsystem to contain Transport Models that is comparable to other subsystems in the RFC 3411 architecture. As work is being done to expand the transports to include secure transports, such as the Secure Shell (SSH) Protocol and Transport Layer Security
本文档定义了传输子系统，扩展了RFC 3411中定义的简单网络管理协议（SNMP）体系结构。本文件定义了包含传输模型的子系统，该传输模型可与RFC 3411体系结构中的其他子系统进行比较。正在进行扩展传输以包括安全传输的工作，例如安全外壳（SSH）协议和传输层安全
(TLS), using a subsystem will enable consistent design and modularity of such Transport Models. This document identifies and describes some key aspects that need to be considered for any Transport Model for SNMP.
（TLS），使用子系统将实现此类传输模型的一致设计和模块化。本文档确定并描述了SNMP的任何传输模型都需要考虑的一些关键方面。
Table of Contents
目录
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. The Internet-Standard Management Framework . . . . . . . . 3
1.2. Conventions . . . . . . . . . . . . . . . . . . . . . . . 3
1.3. Where This Extension Fits . . . . . . . . . . . . . . . . 4
2. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Requirements of a Transport Model . . . . . . . . . . . . . . 7
3.1. Message Security Requirements . . . . . . . . . . . . . . 7
3.1.1. Security Protocol Requirements . . . . . . . . . . . . 7
3.2. SNMP Requirements . . . . . . . . . . . . . . . . . . . . 8
3.2.1. Architectural Modularity Requirements . . . . . . . . 8
3.2.2. Access Control Requirements . . . . . . . . . . . . . 11
3.2.3. Security Parameter Passing Requirements . . . . . . . 12
3.2.4. Separation of Authentication and Authorization . . . . 12
3.3. Session Requirements . . . . . . . . . . . . . . . . . . . 13
3.3.1. No SNMP Sessions . . . . . . . . . . . . . . . . . . . 13
3.3.2. Session Establishment Requirements . . . . . . . . . . 14
3.3.3. Session Maintenance Requirements . . . . . . . . . . . 15
3.3.4. Message Security versus Session Security . . . . . . . 15
4. Scenario Diagrams and the Transport Subsystem . . . . . . . . 16
5. Cached Information and References . . . . . . . . . . . . . . 17
5.1. securityStateReference . . . . . . . . . . . . . . . . . . 17
5.2. tmStateReference . . . . . . . . . . . . . . . . . . . . . 17
5.2.1. Transport Information . . . . . . . . . . . . . . . . 18
5.2.2. securityName . . . . . . . . . . . . . . . . . . . . . 19
5.2.3. securityLevel . . . . . . . . . . . . . . . . . . . . 20
5.2.4. Session Information . . . . . . . . . . . . . . . . . 20
6. Abstract Service Interfaces . . . . . . . . . . . . . . . . . 21
6.1. sendMessage ASI . . . . . . . . . . . . . . . . . . . . . 21
6.2. Changes to RFC 3411 Outgoing ASIs . . . . . . . . . . . . 22
6.2.1. Message Processing Subsystem Primitives . . . . . . . 22
6.2.2. Security Subsystem Primitives . . . . . . . . . . . . 23
6.3. The receiveMessage ASI . . . . . . . . . . . . . . . . . . 24
6.4. Changes to RFC 3411 Incoming ASIs . . . . . . . . . . . . 25
6.4.1. Message Processing Subsystem Primitive . . . . . . . . 25
6.4.2. Security Subsystem Primitive . . . . . . . . . . . . . 26
7. Security Considerations . . . . . . . . . . . . . . . . . . . 27
7.1. Coexistence, Security Parameters, and Access Control . . . 27
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 29
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 29
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 30
10.1. Normative References . . . . . . . . . . . . . . . . . . . 30
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. The Internet-Standard Management Framework . . . . . . . . 3
1.2. Conventions . . . . . . . . . . . . . . . . . . . . . . . 3
1.3. Where This Extension Fits . . . . . . . . . . . . . . . . 4
2. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Requirements of a Transport Model . . . . . . . . . . . . . . 7
3.1. Message Security Requirements . . . . . . . . . . . . . . 7
3.1.1. Security Protocol Requirements . . . . . . . . . . . . 7
3.2. SNMP Requirements . . . . . . . . . . . . . . . . . . . . 8
3.2.1. Architectural Modularity Requirements . . . . . . . . 8
3.2.2. Access Control Requirements . . . . . . . . . . . . . 11
3.2.3. Security Parameter Passing Requirements . . . . . . . 12
3.2.4. Separation of Authentication and Authorization . . . . 12
3.3. Session Requirements . . . . . . . . . . . . . . . . . . . 13
3.3.1. No SNMP Sessions . . . . . . . . . . . . . . . . . . . 13
3.3.2. Session Establishment Requirements . . . . . . . . . . 14
3.3.3. Session Maintenance Requirements . . . . . . . . . . . 15
3.3.4. Message Security versus Session Security . . . . . . . 15
4. Scenario Diagrams and the Transport Subsystem . . . . . . . . 16
5. Cached Information and References . . . . . . . . . . . . . . 17
5.1. securityStateReference . . . . . . . . . . . . . . . . . . 17
5.2. tmStateReference . . . . . . . . . . . . . . . . . . . . . 17
5.2.1. Transport Information . . . . . . . . . . . . . . . . 18
5.2.2. securityName . . . . . . . . . . . . . . . . . . . . . 19
5.2.3. securityLevel . . . . . . . . . . . . . . . . . . . . 20
5.2.4. Session Information . . . . . . . . . . . . . . . . . 20
6. Abstract Service Interfaces . . . . . . . . . . . . . . . . . 21
6.1. sendMessage ASI . . . . . . . . . . . . . . . . . . . . . 21
6.2. Changes to RFC 3411 Outgoing ASIs . . . . . . . . . . . . 22
6.2.1. Message Processing Subsystem Primitives . . . . . . . 22
6.2.2. Security Subsystem Primitives . . . . . . . . . . . . 23
6.3. The receiveMessage ASI . . . . . . . . . . . . . . . . . . 24
6.4. Changes to RFC 3411 Incoming ASIs . . . . . . . . . . . . 25
6.4.1. Message Processing Subsystem Primitive . . . . . . . . 25
6.4.2. Security Subsystem Primitive . . . . . . . . . . . . . 26
7. Security Considerations . . . . . . . . . . . . . . . . . . . 27
7.1. Coexistence, Security Parameters, and Access Control . . . 27
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 29
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 29
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 30
10.1. Normative References . . . . . . . . . . . . . . . . . . . 30
10.2. Informative References . . . . . . . . . . . . . . . . . . 30
Appendix A. Why tmStateReference? . . . . . . . . . . . . . . . . 32
A.1. Define an Abstract Service Interface . . . . . . . . . . . 32
A.2. Using an Encapsulating Header . . . . . . . . . . . . . . 32
A.3. Modifying Existing Fields in an SNMP Message . . . . . . . 32
A.4. Using a Cache . . . . . . . . . . . . . . . . . . . . . . 33
10.2. Informative References . . . . . . . . . . . . . . . . . . 30
Appendix A. Why tmStateReference? . . . . . . . . . . . . . . . . 32
A.1. Define an Abstract Service Interface . . . . . . . . . . . 32
A.2. Using an Encapsulating Header . . . . . . . . . . . . . . 32
A.3. Modifying Existing Fields in an SNMP Message . . . . . . . 32
A.4. Using a Cache . . . . . . . . . . . . . . . . . . . . . . 33
This document defines a Transport Subsystem, extending the Simple Network Management Protocol (SNMP) architecture defined in [RFC3411]. This document identifies and describes some key aspects that need to be considered for any Transport Model for SNMP.
本文件定义了传输子系统，扩展了[RFC3411]中定义的简单网络管理协议（SNMP）体系结构。本文档确定并描述了SNMP的任何传输模型都需要考虑的一些关键方面。
For a detailed overview of the documents that describe the current Internet-Standard Management Framework, please refer to Section 7 of RFC 3410 [RFC3410].
有关描述当前互联网标准管理框架的文件的详细概述，请参阅RFC 3410[RFC3410]第7节。
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 [RFC2119].
本文件中的关键词“必须”、“不得”、“要求”、“应”、“不应”、“应”、“不应”、“建议”、“可”和“可选”应按照RFC 2119[RFC2119]中所述进行解释。
Lowercase versions of the keywords should be read as in normal English. They will usually, but not always, be used in a context that relates to compatibility with the RFC 3411 architecture or the subsystem defined here but that might have no impact on on-the-wire compatibility. These terms are used as guidance for designers of proposed IETF models to make the designs compatible with RFC 3411 subsystems and Abstract Service Interfaces (ASIs). Implementers are free to implement differently. Some usages of these lowercase terms are simply normal English usage.
关键字的小写版本应该像普通英语一样阅读。它们通常（但不总是）用于与RFC 3411体系结构或此处定义的子系统的兼容性相关的上下文中，但可能不会影响导线兼容性。这些术语用作建议IETF模型设计者的指南，以使设计与RFC 3411子系统和抽象服务接口（ASI）兼容。实现者可以自由地以不同的方式实现。这些小写术语的一些用法只是普通的英语用法。
For consistency with SNMP-related specifications, this document favors terminology as defined in STD 62, rather than favoring terminology that is consistent with non-SNMP specifications that use different variations of the same terminology. This is consistent with the IESG decision to not require the SNMPv3 terminology be modified to match the usage of other non-SNMP specifications when SNMPv3 was advanced to Full Standard.
为了与SNMP相关规范保持一致，本文件支持STD 62中定义的术语，而不支持与使用相同术语不同变体的非SNMP规范保持一致的术语。这与IESG的决定是一致的，即当SNMPv3升级到完整标准时，不要求修改SNMPv3术语以匹配其他非SNMP规范的使用。
This document discusses an extension to the modular RFC 3411 architecture; this is not a protocol document. An architectural "MUST" is a really sharp constraint; to allow for the evolution of technology and to not unnecessarily constrain future models, often a
本文件讨论了模块化RFC 3411架构的扩展；这不是协议文件。建筑“必须”是一个非常尖锐的约束；为了允许技术的发展，并避免不必要地限制未来的模型，通常
"SHOULD" or a "should" is more appropriate than a "MUST" in an architecture. Future models MAY express tighter requirements for their own model-specific processing.
在体系结构中，“应该”或“应该”比“必须”更合适。未来的模型可能会对自己的模型特定处理提出更严格的要求。
It is expected that readers of this document will have read RFCs 3410 and 3411, and have a general understanding of the functionality defined in RFCs 3412-3418.
本文件的读者应已阅读RFCs 3410和3411，并对RFCs 3412-3418中定义的功能有大致了解。
The "Transport Subsystem" is an additional component for the SNMP Engine depicted in RFC 3411, Section 3.1.
“传输子系统”是RFC 3411第3.1节中描述的SNMP引擎的附加组件。
The following diagram depicts its place in the RFC 3411 architecture.
下图描述了其在RFC 3411体系结构中的位置。
+-------------------------------------------------------------------+
| SNMP entity |
| |
| +-------------------------------------------------------------+ |
| | SNMP engine (identified by snmpEngineID) | |
| | | |
| | +------------+ | |
| | | Transport | | |
| | | Subsystem | | |
| | +------------+ | |
| | | |
| | +------------+ +------------+ +-----------+ +-----------+ | |
| | | Dispatcher | | Message | | Security | | Access | | |
| | | | | Processing | | Subsystem | | Control | | |
| | | | | Subsystem | | | | Subsystem | | |
| | +------------+ +------------+ +-----------+ +-----------+ | |
| +-------------------------------------------------------------+ |
| |
| +-------------------------------------------------------------+ |
| | Application(s) | |
| | | |
| | +-------------+ +--------------+ +--------------+ | |
| | | Command | | Notification | | Proxy | | |
| | | Generator | | Receiver | | Forwarder | | |
| | +-------------+ +--------------+ +--------------+ | |
| | | |
| | +-------------+ +--------------+ +--------------+ | |
| | | Command | | Notification | | Other | | |
| | | Responder | | Originator | | | | |
| | +-------------+ +--------------+ +--------------+ | |
| +-------------------------------------------------------------+ |
| |
+-------------------------------------------------------------------+
+-------------------------------------------------------------------+
| SNMP entity |
| |
| +-------------------------------------------------------------+ |
| | SNMP engine (identified by snmpEngineID) | |
| | | |
| | +------------+ | |
| | | Transport | | |
| | | Subsystem | | |
| | +------------+ | |
| | | |
| | +------------+ +------------+ +-----------+ +-----------+ | |
| | | Dispatcher | | Message | | Security | | Access | | |
| | | | | Processing | | Subsystem | | Control | | |
| | | | | Subsystem | | | | Subsystem | | |
| | +------------+ +------------+ +-----------+ +-----------+ | |
| +-------------------------------------------------------------+ |
| |
| +-------------------------------------------------------------+ |
| | Application(s) | |
| | | |
| | +-------------+ +--------------+ +--------------+ | |
| | | Command | | Notification | | Proxy | | |
| | | Generator | | Receiver | | Forwarder | | |
| | +-------------+ +--------------+ +--------------+ | |
| | | |
| | +-------------+ +--------------+ +--------------+ | |
| | | Command | | Notification | | Other | | |
| | | Responder | | Originator | | | | |
| | +-------------+ +--------------+ +--------------+ | |
| +-------------------------------------------------------------+ |
| |
+-------------------------------------------------------------------+
The transport mappings defined in RFC 3417 do not provide lower-layer security functionality, and thus do not provide transport-specific security parameters. This document updates RFC 3411 and RFC 3417 by defining an architectural extension and modifying the ASIs that transport mappings (hereafter called "Transport Models") can use to pass transport-specific security parameters to other subsystems, including transport-specific security parameters that are translated into the transport-independent securityName and securityLevel parameters.
RFC 3417中定义的传输映射不提供较低层的安全功能，因此不提供特定于传输的安全参数。本文档通过定义体系结构扩展和修改ASIs更新了RFC 3411和RFC 3417，传输映射（以下称为“传输模型”）可用于将传输特定的安全参数传递给其他子系统，包括转换为与传输无关的securityName和securityLevel参数的传输特定安全参数。
The Transport Security Model [RFC5591] and the Secure Shell Transport Model [RFC5592] utilize the Transport Subsystem. The Transport Security Model is an alternative to the existing SNMPv1 Security Model [RFC3584], the SNMPv2c Security Model [RFC3584], and the User-based Security Model [RFC3414]. The Secure Shell Transport Model is an alternative to existing transport mappings as described in [RFC3417].
传输安全模型[RFC5591]和安全外壳传输模型[RFC5592]利用传输子系统。传输安全模型是现有SNMPv1安全模型[RFC3584]、SNMPv2c安全模型[RFC3584]和基于用户的安全模型[RFC3414]的替代方案。安全外壳传输模型是[RFC3417]中描述的现有传输映射的替代方案。
Just as there are multiple ways to secure one's home or business, in a continuum of alternatives, there are multiple ways to secure a network management protocol. Let's consider three general approaches.
正如有多种方法可以保护家庭或企业的安全一样，在一系列备选方案中，也有多种方法可以保护网络管理协议。让我们考虑三种一般方法。
In the first approach, an individual could sit on his front porch waiting for intruders. In the second approach, he could hire an employee, schedule the employee, position the employee to guard what he wants protected, hire a second guard to cover if the first gets sick, and so on. In the third approach, he could hire a security company, tell them what he wants protected, and leave the details to them. Considerations of hiring and training employees, positioning and scheduling the guards, arranging for cover, etc., are the responsibility of the security company. The individual therefore achieves the desired security, with significantly less effort on his part except for identifying requirements and verifying the quality of service being provided.
在第一种方法中，一个人可以坐在他的前廊上等待入侵者。在第二种方法中，他可以雇佣一名员工，安排员工时间，安排员工看守他想要保护的东西，如果第一名员工生病，雇佣第二名员工看守，等等。在第三种方法中，他可以雇佣一家保安公司，告诉他们他想要保护什么，然后把细节留给他们。雇佣和培训员工、安排和安排警卫、安排掩护等事项由安保公司负责。因此，除了确定需求和验证所提供的服务质量外，个人只需花费更少的努力即可实现所需的安全性。
The User-based Security Model (USM) as defined in [RFC3414] largely uses the first approach -- it provides its own security. It utilizes existing mechanisms (e.g., SHA), but provides all the coordination. USM provides for the authentication of a principal, message encryption, data integrity checking, timeliness checking, etc.
[RFC3414]中定义的基于用户的安全模型（USM）主要使用第一种方法——它提供自己的安全性。它利用现有机制（如SHA），但提供所有协调。USM提供主体身份验证、消息加密、数据完整性检查、及时性检查等。
USM was designed to be independent of other existing security infrastructures. USM therefore uses a separate principal and key management infrastructure. Operators have reported that deploying another principal and key management infrastructure in order to use
USM被设计成独立于其他现有的安全基础设施。因此，USM使用单独的主体和密钥管理基础架构。运营商报告称，为了使用
SNMPv3 is a deterrent to deploying SNMPv3. It is possible to use external mechanisms to handle the distribution of keys for use by USM. The more important issue is that operators wanted to leverage existing user management infrastructures that were not specific to SNMP.
SNMPv3是部署SNMPv3的威慑力量。可以使用外部机制来处理USM使用的密钥分发。更重要的问题是，运营商希望利用不特定于SNMP的现有用户管理基础架构。
A USM-compliant architecture might combine the authentication mechanism with an external mechanism, such as RADIUS [RFC2865], to provide the authentication service. Similarly, it might be possible to utilize an external protocol to encrypt a message, to check timeliness, to check data integrity, etc. However, this corresponds to the second approach -- requiring the coordination of a number of differently subcontracted services. Building solid security between the various services is difficult, and there is a significant potential for gaps in security.
符合USM的体系结构可以将身份验证机制与外部机制（如RADIUS[RFC2865]）相结合，以提供身份验证服务。类似地，可以利用外部协议加密消息、检查及时性、检查数据完整性等。但是，这与第二种方法相对应——需要协调许多不同的分包服务。在各种服务之间建立可靠的安全性是困难的，而且存在很大的潜在安全漏洞。
An alternative approach might be to utilize one or more lower-layer security mechanisms to provide the message-oriented security services required. These would include authentication of the sender, encryption, timeliness checking, and data integrity checking. This corresponds to the third approach described above. There are a number of IETF standards available or in development to address these problems through security layers at the transport layer or application layer, among them are TLS [RFC5246], Simple Authentication and Security Layer (SASL) [RFC4422], and SSH [RFC4251]
另一种方法可能是利用一个或多个较低层安全机制来提供所需的面向消息的安全服务。这些将包括发送方身份验证、加密、及时性检查和数据完整性检查。这对应于上述第三种方法。有许多IETF标准可用或正在开发中，通过传输层或应用层的安全层来解决这些问题，其中包括TLS[RFC5246]、简单认证和安全层（SASL）[RFC4422]和SSH[RFC4251]
From an operational perspective, it is highly desirable to use security mechanisms that can unify the administrative security management for SNMPv3, command line interfaces (CLIs), and other management interfaces. The use of security services provided by lower layers is the approach commonly used for the CLI, and is also the approach being proposed for other network management protocols, such as syslog [RFC5424] and NETCONF [RFC4741].
从操作角度来看，非常需要使用能够统一SNMPv3、命令行接口（CLI）和其他管理接口的管理安全管理的安全机制。使用较低层提供的安全服务是CLI常用的方法，也是其他网络管理协议（如syslog[RFC5424]和NETCONF[RFC4741]）建议的方法。
This document defines a Transport Subsystem extension to the RFC 3411 architecture that is based on the third approach. This extension specifies how other lower-layer protocols with common security infrastructures can be used underneath the SNMP protocol and the desired goal of unified administrative security can be met.
本文件定义了基于第三种方法的RFC 3411体系结构的传输子系统扩展。此扩展指定如何在SNMP协议下使用具有公共安全基础结构的其他较低层协议，并实现统一管理安全的预期目标。
This extension allows security to be provided by an external protocol connected to the SNMP engine through an SNMP Transport Model [RFC3417]. Such a Transport Model would then enable the use of existing security mechanisms, such as TLS [RFC5246] or SSH [RFC4251], within the RFC 3411 architecture.
此扩展允许通过SNMP传输模型[RFC3417]连接到SNMP引擎的外部协议提供安全性。这样的传输模型将允许在RFC 3411体系结构中使用现有的安全机制，如TLS[RFC5246]或SSH[RFC4251]。
There are a number of Internet security protocols and mechanisms that are in widespread use. Many of them try to provide a generic infrastructure to be used by many different application-layer protocols. The motivation behind the Transport Subsystem is to leverage these protocols where it seems useful.
有许多广泛使用的互联网安全协议和机制。他们中的许多人试图提供一个通用的基础设施，供许多不同的应用层协议使用。传输子系统背后的动机是在似乎有用的地方利用这些协议。
There are a number of challenges to be addressed to map the security provided by a secure transport into the SNMP architecture so that SNMP continues to provide interoperability with existing implementations. These challenges are described in detail in this document. For some key issues, design choices are described that might be made to provide a workable solution that meets operational requirements and fits into the SNMP architecture defined in [RFC3411].
要将安全传输提供的安全性映射到SNMP体系结构中，以便SNMP继续提供与现有实现的互操作性，需要解决许多难题。本文档详细描述了这些挑战。对于一些关键问题，描述了可能做出的设计选择，以提供满足操作要求并适合[RFC3411]中定义的SNMP体系结构的可行解决方案。
Transport security protocols SHOULD provide protection against the following message-oriented threats:
传输安全协议应针对以下面向消息的威胁提供保护：
1. modification of information
1. 修改资料
2. masquerade
2. 掩藏
3. message stream modification
3. 消息流修改
4. disclosure
4. 披露
These threats are described in Section 1.4 of [RFC3411]. The security requirements outlined there do not require protection against denial of service or traffic analysis; however, transport security protocols should not make those threats significantly worse.
[RFC3411]第1.4节描述了这些威胁。此处概述的安全要求不需要针对拒绝服务或流量分析提供保护；然而，传输安全协议不应使这些威胁显著恶化。
There are a number of standard protocols that could be proposed as possible solutions within the Transport Subsystem. Some factors should be considered when selecting a protocol.
在传输子系统中，有许多标准协议可以作为可能的解决方案提出。选择协议时应考虑一些因素。
Using a protocol in a manner for which it was not designed has numerous problems. The advertised security characteristics of a protocol might depend on it being used as designed; when used in other ways, it might not deliver the expected security characteristics. It is recommended that any proposed model include a description of the applicability of the Transport Model.
以非设计的方式使用协议存在许多问题。协议的公布安全特性可能取决于它是否按设计使用；当以其他方式使用时，它可能无法提供预期的安全特性。建议任何拟议模型包括对交通模型适用性的描述。
A Transport Model SHOULD NOT require modifications to the underlying protocol. Modifying the protocol might change its security characteristics in ways that could impact other existing usages. If a change is necessary, the change SHOULD be an extension that has no impact on the existing usages. Any Transport Model specification should include a description of potential impact on other usages of the protocol.
传输模型不应要求修改基础协议。修改协议可能会以可能影响其他现有用法的方式更改其安全特性。如果需要更改，那么更改应该是对现有用法没有影响的扩展。任何传输模型规范都应包括对协议其他用途的潜在影响的描述。
Since multiple Transport Models can exist simultaneously within the Transport Subsystem, Transport Models MUST be able to coexist with each other.
由于在传输子系统中可以同时存在多个传输模型，因此传输模型必须能够彼此共存。
SNMP version 3 (SNMPv3) is based on a modular architecture (defined in Section 3 of [RFC3411]) to allow the evolution of the SNMP protocol standards over time and to minimize the side effects between subsystems when changes are made.
SNMP版本3（SNMPv3）基于模块化体系结构（在[RFC3411]第3节中定义），以允许SNMP协议标准随时间演变，并在进行更改时将子系统之间的副作用降至最低。
The RFC 3411 architecture includes a Message Processing Subsystem for permitting different message versions to be handled by a single engine, a Security Subsystem for enabling different methods of providing security services, Applications to support different types of Application processors, and an Access Control Subsystem for allowing multiple approaches to access control. The RFC 3411 architecture does not include a subsystem for Transport Models, despite the fact there are multiple transport mappings already defined for SNMP [RFC3417]. This document describes a Transport Subsystem that is compatible with the RFC 3411 architecture. As work is being done to use secure transports such as SSH and TLS, using a subsystem will enable consistent design and modularity of such Transport Models.
RFC 3411体系结构包括一个允许单个引擎处理不同消息版本的消息处理子系统、一个支持提供安全服务的不同方法的安全子系统、支持不同类型应用处理器的应用程序、，以及用于允许多种访问控制方法的访问控制子系统。RFC 3411体系结构不包括传输模型的子系统，尽管已经为SNMP定义了多个传输映射[RFC3417]。本文档描述了与RFC 3411体系结构兼容的传输子系统。在使用SSH和TLS等安全传输的过程中，使用子系统将实现此类传输模型的一致性设计和模块化。
The design of this Transport Subsystem accepts the goals of the RFC 3411 architecture that are defined in Section 1.5 of [RFC3411]. This Transport Subsystem uses a modular design that permits Transport Models (which might or might not be security-aware) to be "plugged into" the RFC 3411 architecture. Such Transport Models would be independent of other modular SNMP components as much as possible. This design also permits Transport Models to be advanced through the standards process independently of other Transport Models.
该传输子系统的设计符合[RFC3411]第1.5节中定义的RFC 3411体系结构的目标。该传输子系统采用模块化设计，允许传输模型（可能具有安全意识，也可能不具有安全意识）“插入”RFC 3411体系结构。这种传输模型将尽可能独立于其他模块化SNMP组件。此设计还允许独立于其他运输模型，通过标准流程推进运输模型。
The following diagram depicts the SNMPv3 architecture, including the new Transport Subsystem defined in this document and a new Transport Security Model defined in [RFC5591].
下图描述了SNMPv3体系结构，包括本文档中定义的新传输子系统和[RFC5591]中定义的新传输安全模型。
+------------------------------+
| Network |
+------------------------------+
^ ^ ^
| | |
v v v
+-------------------------------------------------------------------+
| +--------------------------------------------------+ |
| | Transport Subsystem | |
| | +-----+ +-----+ +-----+ +-----+ +-------+ | |
| | | UDP | | TCP | | SSH | | TLS | . . . | other | | |
| | +-----+ +-----+ +-----+ +-----+ +-------+ | |
| +--------------------------------------------------+ |
| ^ |
| | |
| Dispatcher v |
| +-------------------+ +---------------------+ +----------------+ |
| | Transport | | Message Processing | | Security | |
| | Dispatch | | Subsystem | | Subsystem | |
| | | | +------------+ | | +------------+ | |
| | | | +->| v1MP |<--->| | USM | | |
| | | | | +------------+ | | +------------+ | |
| | | | | +------------+ | | +------------+ | |
| | | | +->| v2cMP |<--->| | Transport | | |
| | Message | | | +------------+ | | | Security | | |
| | Dispatch <--------->| +------------+ | | | Model | | |
| | | | +->| v3MP |<--->| +------------+ | |
| | | | | +------------+ | | +------------+ | |
| | PDU Dispatch | | | +------------+ | | | Other | | |
| +-------------------+ | +->| otherMP |<--->| | Model(s) | | |
| ^ | +------------+ | | +------------+ | |
| | +---------------------+ +----------------+ |
| v |
| +-------+-------------------------+---------------+ |
| ^ ^ ^ |
| | | | |
| v v v |
| +-------------+ +---------+ +--------------+ +-------------+ |
| | COMMAND | | ACCESS | | NOTIFICATION | | PROXY | |
| | RESPONDER |<->| CONTROL |<->| ORIGINATOR | | FORWARDER | |
| | Application | | | | Applications | | Application | |
| +-------------+ +---------+ +--------------+ +-------------+ |
| ^ ^ |
| | | |
| v v |
| +----------------------------------------------+ |
| | MIB instrumentation | SNMP entity |
+-------------------------------------------------------------------+
+------------------------------+
| Network |
+------------------------------+
^ ^ ^
| | |
v v v
+-------------------------------------------------------------------+
| +--------------------------------------------------+ |
| | Transport Subsystem | |
| | +-----+ +-----+ +-----+ +-----+ +-------+ | |
| | | UDP | | TCP | | SSH | | TLS | . . . | other | | |
| | +-----+ +-----+ +-----+ +-----+ +-------+ | |
| +--------------------------------------------------+ |
| ^ |
| | |
| Dispatcher v |
| +-------------------+ +---------------------+ +----------------+ |
| | Transport | | Message Processing | | Security | |
| | Dispatch | | Subsystem | | Subsystem | |
| | | | +------------+ | | +------------+ | |
| | | | +->| v1MP |<--->| | USM | | |
| | | | | +------------+ | | +------------+ | |
| | | | | +------------+ | | +------------+ | |
| | | | +->| v2cMP |<--->| | Transport | | |
| | Message | | | +------------+ | | | Security | | |
| | Dispatch <--------->| +------------+ | | | Model | | |
| | | | +->| v3MP |<--->| +------------+ | |
| | | | | +------------+ | | +------------+ | |
| | PDU Dispatch | | | +------------+ | | | Other | | |
| +-------------------+ | +->| otherMP |<--->| | Model(s) | | |
| ^ | +------------+ | | +------------+ | |
| | +---------------------+ +----------------+ |
| v |
| +-------+-------------------------+---------------+ |
| ^ ^ ^ |
| | | | |
| v v v |
| +-------------+ +---------+ +--------------+ +-------------+ |
| | COMMAND | | ACCESS | | NOTIFICATION | | PROXY | |
| | RESPONDER |<->| CONTROL |<->| ORIGINATOR | | FORWARDER | |
| | Application | | | | Applications | | Application | |
| +-------------+ +---------+ +--------------+ +-------------+ |
| ^ ^ |
| | | |
| v v |
| +----------------------------------------------+ |
| | MIB instrumentation | SNMP entity |
+-------------------------------------------------------------------+
The RFC 3411 architecture and the Security Subsystem assume that a Security Model is called by a Message Processing Model and will perform multiple security functions within the Security Subsystem. A Transport Model that supports a secure transport protocol might perform similar security functions within the Transport Subsystem, including the translation of transport-security parameters to/from Security-Model-independent parameters.
RFC 3411体系结构和安全子系统假定安全模型由消息处理模型调用，并将在安全子系统内执行多个安全功能。支持安全传输协议的传输模型可能在传输子系统内执行类似的安全功能，包括将传输安全参数转换为安全模型独立参数或从安全模型独立参数转换为安全参数。
To accommodate this, an implementation-specific cache of transport-specific information will be described (not shown), and the data flows on this path will be extended to pass Security-Model-independent values. This document amends some of the ASIs defined in RFC 3411; these changes are covered in Section 6 of this document.
为了适应这种情况，将描述特定于传输的信息的特定于实现的缓存（未显示），并且此路径上的数据流将被扩展以传递与安全模型无关的值。本文件修订了RFC 3411中定义的部分ASI；本文件第6节介绍了这些变更。
New Security Models might be defined that understand how to work with these modified ASIs and the transport-information cache. One such Security Model, the Transport Security Model, is defined in [RFC5591].
可能会定义新的安全模型，以了解如何使用这些修改后的ASI和传输信息缓存。[RFC5591]中定义了一个这样的安全模型，即传输安全模型。
The introduction of secure transports affects the responsibilities and order of processing within the RFC 3411 architecture. While the steps are the same, they might occur in a different order, and might be done by different subsystems. With the existing RFC 3411 architecture, security processing starts when the Message Processing Model decodes portions of the encoded message to extract parameters that identify which Security Model MUST handle the security-related tasks.
安全传输的引入会影响RFC 3411体系结构中的职责和处理顺序。虽然步骤相同，但它们可能以不同的顺序出现，并且可能由不同的子系统完成。在现有RFC 3411体系结构中，当消息处理模型解码编码消息的部分以提取识别哪个安全模型必须处理安全相关任务的参数时，安全处理开始。
A secure transport performs those security functions on the message, before the message is decoded. Some of these functions might then be repeated by the selected Security Model.
安全传输在消息解码之前对消息执行这些安全功能。选择的安全模型可能会重复其中一些功能。
A secure Transport Model will establish an authenticated and possibly encrypted tunnel between the Transport Models of two SNMP engines. After a transport-layer tunnel is established, then SNMP messages can be sent through the tunnel from one SNMP engine to the other. While the Community Security Models [RFC3584] and the User-based Security Model establish a security association for each SNMP message, newer Transport Models MAY support sending multiple SNMP messages through the same tunnel to amortize the costs of establishing a security association.
安全传输模型将在两个SNMP引擎的传输模型之间建立经过身份验证且可能加密的隧道。建立传输层隧道后，可以通过隧道将SNMP消息从一个SNMP引擎发送到另一个。虽然社区安全模型[RFC3584]和基于用户的安全模型为每个SNMP消息建立安全关联，但较新的传输模型可能支持通过同一隧道发送多个SNMP消息，以分摊建立安全关联的成本。
RFC 3411 made some design decisions related to the support of an Access Control Subsystem. These include establishing and passing in a model-independent manner the securityModel, securityName, and securityLevel parameters, and separating message authentication from data-access authorization.
RFC 3411做出了一些与访问控制子系统支持相关的设计决策。其中包括以独立于模型的方式建立和传递securityModel、securityName和securityLevel参数，以及将消息身份验证与数据访问授权分离。
SNMP data-access controls are expected to work on the basis of who can perform what operations on which subsets of data, and based on the security services that will be provided to secure the data in transit. The securityModel and securityLevel parameters establish the protections for transit -- whether authentication and privacy services will be or have been applied to the message. The securityName is a model-independent identifier of the security "principal".
SNMP数据访问控制应基于谁可以对哪些数据子集执行哪些操作，以及为保护传输中的数据而提供的安全服务。securityModel和securityLevel参数建立了对传输的保护——验证和隐私服务是否将或已经应用于消息。securityName是安全“主体”的独立于模型的标识符。
A Security Model plays a role in security that goes beyond protecting the message -- it provides a mapping between the Security-Model-specific principal for an incoming message to a Security-Model independent securityName that can be used for subsequent processing, such as for access control. The securityName is mapped from a mechanism-specific identity, and this mapping must be done for incoming messages by the Security Model before it passes securityName to the Message Processing Model via the processIncoming ASI.
安全模型在安全性中的作用不仅仅是保护消息——它提供了传入消息的特定于安全模型的主体到可用于后续处理（如访问控制）的独立于安全模型的securityName之间的映射。securityName是从特定于机制的标识映射而来的，在安全模型通过processIncoming ASI将securityName传递给消息处理模型之前，必须先对传入消息执行此映射。
A Security Model is also responsible to specify, via the securityLevel parameter, whether incoming messages have been authenticated and encrypted, and to ensure that outgoing messages are authenticated and encrypted based on the value of securityLevel.
安全模型还负责通过securityLevel参数指定传入消息是否经过身份验证和加密，并确保根据securityLevel的值对传出消息进行身份验证和加密。
A Transport Model MAY provide suggested values for securityName and securityLevel. A Security Model might have multiple sources for determining the principal and desired security services, and a particular Security Model might or might not utilize the values proposed by a Transport Model when deciding the value of securityName and securityLevel.
传输模型可以为securityName和securityLevel提供建议值。一个安全模型可能有多个源来确定主体和所需的安全服务，而一个特定的安全模型在决定securityName和securityLevel的值时可能会也可能不会利用传输模型提出的值。
Documents defining a new transport domain MUST define a prefix that MAY be prepended to all securityNames passed by the Security Model. The prefix MUST include one to four US-ASCII alpha-numeric characters, not including a ":" (US-ASCII 0x3a) character. If a prefix is used, a securityName is constructed by concatenating the prefix and a ":" (US-ASCII 0x3a) character, followed by a non-empty identity in an snmpAdminString-compatible format. The prefix can be used by SNMP Applications to distinguish "alice" authenticated by SSH
定义新传输域的文档必须定义前缀，该前缀可以在安全模型传递的所有SecurityName之前。前缀必须包括一到四个US-ASCII字母数字字符，不包括“：”（US-ASCII 0x3a）字符。如果使用前缀，则通过将前缀和“：”（US-ASCII 0x3a）字符连接起来，然后以SNMPAdministring兼容格式后跟非空标识来构造securityName。SNMP应用程序可以使用前缀来区分通过SSH认证的“alice”
from "alice" authenticated by TLS. Transport domains and their corresponding prefixes are coordinated via the IANA registry "SNMP Transport Domains".
来自TLS认证的“alice”。传输域及其相应前缀通过IANA注册表“SNMP传输域”进行协调。
A Message Processing Model might unpack SNMP-specific security parameters from an incoming message before calling a specific Security Model to handle the security-related processing of the message. When using a secure Transport Model, some security parameters might be extracted from the transport layer by the Transport Model before the message is passed to the Message Processing Subsystem.
消息处理模型可能会在调用特定的安全模型来处理消息的安全相关处理之前，从传入消息中解压缩SNMP特定的安全参数。当使用安全传输模型时，在将消息传递给消息处理子系统之前，传输模型可能会从传输层提取一些安全参数。
This document describes a cache mechanism (see Section 5) into which the Transport Model puts information about the transport and security parameters applied to a transport connection or an incoming message; a Security Model might extract that information from the cache. A tmStateReference is passed as an extra parameter in the ASIs between the Transport Subsystem and the Message Processing and Security Subsystems in order to identify the relevant cache. This approach of passing a model-independent reference is consistent with the securityStateReference cache already being passed around in the RFC 3411 ASIs.
本文档描述了一种缓存机制（见第5节），传输模型将有关应用于传输连接或传入消息的传输和安全参数的信息放入其中；安全模型可以从缓存中提取该信息。tmStateReference作为额外参数在传输子系统与消息处理和安全子系统之间的ASIs中传递，以识别相关缓存。这种传递独立于模型的引用的方法与RFC 3411 ASIs中已经传递的securityStateReference缓存一致。
The RFC 3411 architecture defines a separation of authentication and the authorization to access and/or modify MIB data. A set of model-independent parameters (securityModel, securityName, and securityLevel) are passed between the Security Subsystem, the Applications, and the Access Control Subsystem.
RFC 3411体系结构定义了身份验证和访问和/或修改MIB数据的授权的分离。在安全子系统、应用程序和访问控制子系统之间传递一组与模型无关的参数（securityModel、securityName和securityLevel）。
This separation was a deliberate decision of the SNMPv3 WG, in order to allow support for authentication protocols that do not provide data-access authorization capabilities, and in order to support data-access authorization schemes, such as the View-based access Control Model (VACM), that do not perform their own authentication.
这种分离是SNMPv3工作组的一项深思熟虑的决定，目的是支持不提供数据访问授权功能的身份验证协议，以及支持不执行自身身份验证的数据访问授权方案，如基于视图的访问控制模型（VACM）。
A Message Processing Model determines which Security Model is used, either based on the message version (e.g., SNMPv1 and SNMPv2c) or possibly by a value specified in the message (e.g., msgSecurityModel field in SNMPv3).
消息处理模型根据消息版本（例如，SNMPv1和SNMPv2c）或可能根据消息中指定的值（例如，SNMPv3中的msgSecurityModel字段）确定使用哪个安全模型。
The Security Model makes the decision which securityName and securityLevel values are passed as model-independent parameters to an Application, which then passes them via the isAccessAllowed ASI to the Access Control Subsystem.
安全模型决定将哪些securityName和securityLevel值作为独立于模型的参数传递给应用程序，然后应用程序通过isAccessAllowed ASI将它们传递给访问控制子系统。
An Access Control Model performs the mapping from the model-independent security parameters to a policy within the Access Control Model that is Access-Control-Model-dependent.
访问控制模型执行从独立于模型的安全参数到访问控制模型中依赖于访问控制模型的策略的映射。
A Transport Model does not know which Security Model will be used for an incoming message, and so cannot know how the securityName and securityLevel parameters will be determined. It can propose an authenticated identity (via the tmSecurityName field), but there is no guarantee that this value will be used by the Security Model. For example, non-transport-aware Security Models will typically determine the securityName (and securityLevel) based on the contents of the SNMP message itself. Such Security Models will simply not know that the tmStateReference cache exists.
传输模型不知道传入消息将使用哪个安全模型，因此不知道如何确定securityName和securityLevel参数。它可以提出一个经过身份验证的身份（通过tmSecurityName字段），但不能保证安全模型会使用该值。例如，非传输感知安全模型通常会根据SNMP消息本身的内容确定securityName（和securityLevel）。这样的安全模型根本不知道引用缓存是否存在。
Further, even if the Transport Model can influence the choice of securityName, it cannot directly determine the authorization allowed to this identity. If two different Transport Models each authenticate a transport principal that are then both mapped to the same securityName, then these two identities will typically be afforded exactly the same authorization by the Access Control Model.
此外，即使传输模型可以影响securityName的选择，它也不能直接确定允许此身份的授权。如果两个不同的传输模型分别对一个传输主体进行身份验证，然后两者都映射到相同的securityName，那么访问控制模型通常会为这两个身份提供完全相同的授权。
The only way for the Access Control Model to differentiate between identities based on the underlying Transport Model would be for such transport-authenticated identities to be mapped to distinct securityNames. How and if this is done is Security-Model-dependent.
访问控制模型根据底层传输模型区分身份的唯一方法是将此类经过传输身份验证的身份映射到不同的SecurityName。如何以及是否这样做取决于安全模型。
Some secure transports have a notion of sessions, while other secure transports provide channels or other session-like mechanisms. Throughout this document, the term "session" is used in a broad sense to cover transport sessions, transport channels, and other transport-layer, session-like mechanisms. Transport-layer sessions that can secure multiple SNMP messages within the lifetime of the session are considered desirable because the cost of authentication can be amortized over potentially many transactions. How a transport session is actually established, opened, closed, or maintained is specific to a particular Transport Model.
一些安全传输具有会话的概念，而其他安全传输提供通道或其他类似会话的机制。在本文档中，术语“会话”在广义上用于涵盖传输会话、传输通道和其他传输层类会话机制。可以在会话的生命周期内保护多个SNMP消息的传输层会话被认为是可取的，因为身份验证的成本可以分摊到潜在的许多事务中。传输会话的实际建立、打开、关闭或维护方式特定于特定的传输模型。
To reduce redundancy, this document describes aspects that are expected to be common to all Transport Model sessions.
为了减少冗余，本文档描述了所有传输模型会话所共有的方面。
The architecture defined in [RFC3411] and the Transport Subsystem defined in this document do not support SNMP sessions or include a session selector in the Abstract Service Interfaces.
[RFC3411]中定义的体系结构和本文档中定义的传输子系统不支持SNMP会话或在抽象服务接口中包含会话选择器。
The Transport Subsystem might support transport sessions. However, the Transport Subsystem does not have access to the pduType (i.e., the SNMP operation type), and so cannot select a given transport session for particular types of traffic.
传输子系统可能支持传输会话。但是，传输子系统无权访问pduType（即SNMP操作类型），因此无法为特定类型的流量选择给定的传输会话。
Certain parameters of the Abstract Service Interfaces might be used to guide the selection of an appropriate transport session to use for a given request by an Application.
抽象服务接口的某些参数可用于指导选择适当的传输会话以用于应用程序的给定请求。
The transportDomain and transportAddress identify the transport connection to a remote network node. Elements of the transport address (such as the port number) might be used by an Application to send a particular PDU type to a particular transport address. For example, the SNMP-TARGET-MIB and SNMP-NOTIFICATION-MIB [RFC3413] are used to configure notification originators with the destination port to which SNMPv2-Trap PDUs or Inform PDUs are to be sent, but the Transport Subsystem never looks inside the PDU.
transportDomain和transportAddress标识到远程网络节点的传输连接。应用程序可以使用传输地址的元素（例如端口号）将特定PDU类型发送到特定的传输地址。例如，SNMP-TARGET-MIB和SNMP-NOTIFICATION-MIB[RFC3413]用于使用SNMPv2陷阱PDU或通知PDU要发送到的目标端口配置通知发起人，但传输子系统从不查看PDU内部。
The securityName identifies which security principal to communicate with at that address (e.g., different Network Management System (NMS) applications), and the securityLevel might permit selection of different sets of security properties for different purposes (e.g., encrypted SET vs. non-encrypted GET operations).
securityName标识在该地址与哪个安全主体通信（例如，不同的网络管理系统（NMS）应用程序），securityLevel可能允许为不同目的选择不同的安全属性集（例如，加密集与非加密GET操作）。
However, because the handling of transport sessions is specific to each Transport Model, some Transport Models MAY restrict selecting a particular transport session. A user application might use a unique combination of transportDomain, transportAddress, securityModel, securityName, and securityLevel to try to force the selection of a given transport session. This usage is NOT RECOMMENDED because it is not guaranteed to be interoperable across implementations and across models.
但是，由于传输会话的处理特定于每个传输模型，因此某些传输模型可能会限制选择特定的传输会话。用户应用程序可能使用transportDomain、transportAddress、securityModel、securityName和securityLevel的唯一组合来强制选择给定的传输会话。不建议使用此用法，因为它不能保证跨实现和跨模型进行互操作。
Implementations SHOULD be able to maintain some reasonable number of concurrent transport sessions, and MAY provide non-standard internal mechanisms to select transport sessions.
实现应该能够维护一些合理数量的并发传输会话，并且可以提供非标准的内部机制来选择传输会话。
SNMP Applications provide the transportDomain, transportAddress, securityName, and securityLevel to be used to create a new session.
SNMP应用程序提供用于创建新会话的transportDomain、transportAddress、securityName和securityLevel。
If the Transport Model cannot provide at least the requested level of security, the Transport Model should discard the message and should notify the Dispatcher that establishing a session and sending the message failed. Similarly, if the session cannot be established, then the message should be discarded and the Dispatcher notified.
如果传输模型至少不能提供请求的安全级别，则传输模型应丢弃消息，并通知调度程序建立会话和发送消息失败。类似地，如果无法建立会话，则应丢弃消息并通知调度程序。
Transport session establishment might require provisioning authentication credentials at an engine, either statically or dynamically. How this is done is dependent on the Transport Model and the implementation.
传输会话建立可能需要在引擎上以静态或动态方式提供身份验证凭据。如何做到这一点取决于传输模型和实现。
A Transport Model can tear down sessions as needed. It might be necessary for some implementations to tear down sessions as the result of resource constraints, for example.
传输模型可以根据需要中断会话。例如，某些实现可能需要由于资源限制而中断会话。
The decision to tear down a session is implementation-dependent. How an implementation determines that an operation has completed is implementation-dependent. While it is possible to tear down each transport session after processing for each message has completed, this is not recommended for performance reasons.
中断会话的决定取决于实现。实现如何确定操作已完成取决于实现。虽然可以在每个消息的处理完成后中断每个传输会话，但出于性能原因，不建议这样做。
The elements of procedure describe when cached information can be discarded, and the timing of cache cleanup might have security implications, but cache memory management is an implementation issue.
过程的元素描述何时可以丢弃缓存的信息，缓存清理的时间可能会带来安全问题，但缓存内存管理是一个实现问题。
If a Transport Model defines MIB module objects to maintain session state information, then the Transport Model MUST define what happens to the objects when a related session is torn down, since this will impact the interoperability of the MIB module.
如果传输模型定义MIB模块对象以维护会话状态信息，则传输模型必须定义相关会话中断时对象发生的情况，因为这将影响MIB模块的互操作性。
A Transport Model session is associated with state information that is maintained for its lifetime. This state information allows for the application of various security services to multiple messages. Cryptographic keys associated with the transport session SHOULD be used to provide authentication, integrity checking, and encryption services, as needed, for data that is communicated during the session. The cryptographic protocols used to establish keys for a Transport Model session SHOULD ensure that fresh new session keys are generated for each session. This would ensure that a cross-session replay attack would be unsuccessful; that is, an attacker could not take a message observed on one session and successfully replay it on another session.
传输模型会话与在其生存期内维护的状态信息相关联。此状态信息允许对多条消息应用各种安全服务。与传输会话相关联的加密密钥应用于根据需要为会话期间通信的数据提供身份验证、完整性检查和加密服务。用于为传输模型会话建立密钥的加密协议应确保为每个会话生成新的会话密钥。这将确保跨会话重播攻击不成功；也就是说，攻击者无法获取在一个会话上观察到的消息并在另一个会话上成功重播该消息。
A good security protocol would also protect against replay attacks within a session; that is, an attacker could not take a message observed on a session and successfully replay it later in the same session. One approach would be to use sequence information within the protocol, allowing the participants to detect if messages were replayed or reordered within a session.
良好的安全协议还可以防止会话中的重播攻击；也就是说，攻击者无法获取会话中观察到的消息，并在同一会话中成功重播该消息。一种方法是在协议中使用序列信息，允许参与者检测消息是否在会话中被重放或重新排序。
If a secure transport session is closed between the time a request message is received and the corresponding response message is sent, then the response message SHOULD be discarded, even if a new session has been established. The SNMPv3 WG decided that this should be a "SHOULD" architecturally, and it is a Security-Model-specific decision whether to REQUIRE this. The architecture does not mandate this requirement in order to allow for future Security Models where this might make sense; however, not requiring this could lead to added complexity and security vulnerabilities, so most Security Models SHOULD require this.
如果在接收到请求消息和发送相应的响应消息之间关闭了安全传输会话，则即使已建立新会话，也应丢弃响应消息。SNMPv3工作组决定在架构上这应该是一个“应该”的决定，是否需要它是一个特定于安全模型的决定。该体系结构并不强制要求满足这一要求，以便在有意义的情况下考虑未来的安全模型；但是，不要求这样做可能会增加复杂性和安全漏洞，因此大多数安全模型都应该要求这样做。
SNMPv3 was designed to support multiple levels of security, selectable on a per-message basis by an SNMP Application, because, for example, there is not much value in using encryption for a command generator to poll for potentially non-sensitive performance data on thousands of interfaces every ten minutes; such encryption might add significant overhead to processing of the messages.
SNMPv3旨在支持多个级别的安全性，可由SNMP应用程序在每条消息的基础上进行选择，因为，例如，使用命令生成器加密每十分钟轮询数千个接口上的潜在非敏感性能数据没有多大价值；这种加密可能会给消息的处理增加大量开销。
Some Transport Models might support only specific authentication and encryption services, such as requiring all messages to be carried using both authentication and encryption, regardless of the security level requested by an SNMP Application. A Transport Model MAY upgrade the security level requested by a transport-aware Security Model, i.e., noAuthNoPriv and authNoPriv might be sent over an authenticated and encrypted session. A Transport Model MUST NOT downgrade the security level requested by a transport-aware Security Model, and SHOULD discard any message where this would occur. This is a SHOULD rather than a MUST only to permit the potential development of models that can perform error-handling in a manner that is less severe than discarding the message. However, any model that does not discard the message in this circumstance should have a clear justification for why not discarding will not create a security vulnerability.
有些传输模型可能只支持特定的身份验证和加密服务，例如要求所有消息都使用身份验证和加密进行传输，而不管SNMP应用程序请求的安全级别如何。传输模型可以升级传输感知安全模型所请求的安全级别，即noAuthNoPriv和authNoPriv可以通过经过认证和加密的会话发送。传输模型不得降低传输感知安全模型所请求的安全级别，并应丢弃任何可能发生这种情况的消息。这是一种应该而非必须的方式，只允许潜在的模型开发，这些模型可以以比丢弃消息更不严重的方式执行错误处理。但是，在这种情况下，任何不丢弃消息的模型都应该有明确的理由说明为什么不丢弃消息不会产生安全漏洞。
Sections 4.6.1 and 4.6.2 of RFC 3411 provide scenario diagrams to illustrate how an outgoing message is created and how an incoming message is processed. RFC 3411 does not define ASIs for the "Send SNMP Request Message to Network", "Receive SNMP Response Message from Network", "Receive SNMP Message from Network" and "Send SNMP message to Network" arrows in these diagrams.
RFC 3411第4.6.1节和第4.6.2节提供了场景图，以说明如何创建传出消息以及如何处理传入消息。RFC 3411没有为这些图中的“向网络发送SNMP请求消息”、“从网络接收SNMP响应消息”、“从网络接收SNMP消息”和“向网络发送SNMP消息”箭头定义ASI。
This document defines two ASIs corresponding to these arrows: a sendMessage ASI to send SNMP messages to the network and a receiveMessage ASI to receive SNMP messages from the network. These ASIs are used for all SNMP messages, regardless of pduType.
本文档定义了与这些箭头相对应的两个ASI：sendMessage ASI用于向网络发送SNMP消息，receiveMessage ASI用于从网络接收SNMP消息。这些ASI用于所有SNMP消息，而不考虑pduType。
When performing SNMP processing, there are two levels of state information that might need to be retained: the immediate state linking a request-response pair and a potentially longer-term state relating to transport and security.
在执行SNMP处理时，可能需要保留两个级别的状态信息：链接请求-响应对的即时状态和与传输和安全性相关的潜在长期状态。
The RFC 3411 architecture uses caches to maintain the short-term message state, and uses references in the ASIs to pass this information between subsystems.
RFC 3411体系结构使用缓存来维护短期消息状态，并使用ASIs中的引用在子系统之间传递此信息。
This document defines the requirements for a cache to handle additional short-term message state and longer-term transport state information, using a tmStateReference parameter to pass this information between subsystems.
本文档定义了高速缓存处理附加短期消息状态和长期传输状态信息的要求，使用tmStateReference参数在子系统之间传递该信息。
To simplify the elements of procedure, the release of state information is not always explicitly specified. As a general rule, if state information is available when a message being processed gets discarded, the state related to that message should also be discarded. If state information is available when a relationship between engines is severed, such as the closing of a transport session, the state information for that relationship should also be discarded.
为了简化过程的元素，并不总是明确指定状态信息的发布。作为一般规则，如果在丢弃正在处理的消息时状态信息可用，则也应丢弃与该消息相关的状态。如果引擎之间的关系断开时状态信息可用，例如关闭传输会话，则该关系的状态信息也应丢弃。
Since the contents of a cache are meaningful only within an implementation, and not on-the-wire, the format of the cache is implementation-specific.
由于缓存的内容仅在实现中有意义，而在线路上没有意义，因此缓存的格式是特定于实现的。
The securityStateReference parameter is defined in RFC 3411. Its primary purpose is to provide a mapping between a request and the corresponding response. This cache is not accessible to Transport Models, and an entry is typically only retained for the lifetime of a request-response pair of messages.
securityStateReference参数在RFC 3411中定义。其主要目的是提供请求和相应响应之间的映射。传输模型无法访问此缓存，条目通常仅在请求-响应消息对的生命周期内保留。
For each transport session, information about the transport security is stored in a tmState cache or datastore that is referenced by a tmStateReference. The tmStateReference parameter is used to pass model-specific and mechanism-specific parameters between the Transport Subsystem and transport-aware Security Models.
对于每个传输会话，有关传输安全性的信息存储在tmState缓存或由tmStateReference引用的数据存储中。tmStateReference参数用于在传输子系统和传输感知安全模型之间传递特定于模型和特定于机制的参数。
In general, when necessary, the tmState is populated by the Security Model for outgoing messages and by the Transport Model for incoming messages. However, in both cases, the model populating the tmState
通常，必要时，tmState由传出消息的安全模型和传入消息的传输模型填充。但是，在这两种情况下，填充tmState的模型
might have incomplete information, and the missing information might be populated by the other model when the information becomes available.
可能有不完整的信息，当信息可用时，丢失的信息可能由其他模型填充。
The tmState might contain both long-term and short-term information. The session information typically remains valid for the duration of the transport session, might be used for several messages, and might be stored in a local configuration datastore. Some information has a shorter lifespan, such as tmSameSecurity and tmRequestedSecurityLevel, which are associated with a specific message.
tmState可能包含长期和短期信息。会话信息通常在传输会话期间保持有效，可能用于多条消息，并且可能存储在本地配置数据存储中。某些信息的生命周期较短，例如与特定消息相关联的tmSameSecurity和tmRequestedSecurityLevel。
Since this cache is only used within an implementation, and not on-the-wire, the precise contents and format of the cache are implementation-dependent. For architectural modularity between Transport Models and transport-aware Security Models, a fully-defined tmState MUST conceptually include at least the following fields:
由于此缓存仅在实现中使用，而不是在线路上使用，因此缓存的精确内容和格式取决于实现。对于传输模型和传输感知安全模型之间的体系结构模块化，完整定义的tmState在概念上必须至少包括以下字段：
tmTransportDomain
tmTransportDomain
tmTransportAddress
tmTransportAddress
tmSecurityName
tmSecurityName
tmRequestedSecurityLevel
tmRequestedSecurityLevel
tmTransportSecurityLevel
tmTransportSecurityLevel
tmSameSecurity
TMSA安全
tmSessionID
tSessionID
The details of these fields are described in the following subsections.
这些字段的详细信息将在以下小节中描述。
Information about the source of an incoming SNMP message is passed up from the Transport Subsystem as far as the Message Processing Subsystem. However, these parameters are not included in the processIncomingMsg ASI defined in RFC 3411; hence, this information is not directly available to the Security Model.
有关传入SNMP消息源的信息从传输子系统传递到消息处理子系统。但是，这些参数不包括在RFC 3411中定义的processIncomingMsg ASI中；因此，该信息不能直接用于安全模型。
A transport-aware Security Model might wish to take account of the transport protocol and originating address when authenticating the request and setting up the authorization parameters. It is therefore
传输感知安全模型可能希望在验证请求和设置授权参数时考虑传输协议和原始地址。因此
necessary for the Transport Model to include this information in the tmStateReference cache so that it is accessible to the Security Model.
传输模型需要将此信息包含在引用缓存中，以便安全模型可以访问它。
o tmTransportDomain: the transport protocol (and hence the Transport Model) used to receive the incoming message.
o tmTransportDomain：用于接收传入消息的传输协议（以及传输模型）。
o tmTransportAddress: the source of the incoming message.
o tmTransportAddress：传入消息的源。
The ASIs used for processing an outgoing message all include explicit transportDomain and transportAddress parameters. The values within the securityStateReference cache might override these parameters for outgoing messages.
用于处理传出消息的ASI都包含显式transportDomain和transportAddress参数。securityStateReference缓存中的值可能会覆盖传出消息的这些参数。
There are actually three distinct "identities" that can be identified during the processing of an SNMP request over a secure transport:
在通过安全传输处理SNMP请求期间，实际上可以识别三个不同的“标识”：
o transport principal: the transport-authenticated identity on whose behalf the secure transport connection was (or should be) established. This value is transport-, mechanism-, and implementation-specific, and is only used within a given Transport Model.
o 传输主体：代表其建立（或应建立）安全传输连接的传输认证标识。此值是特定于传输、机制和实现的，并且仅在给定的传输模型中使用。
o tmSecurityName: a human-readable name (in snmpAdminString format) representing this transport identity. This value is transport-and implementation-specific, and is only used (directly) by the Transport and Security Models.
o tmSecurityName：表示此传输标识的人类可读名称（snmpAdminString格式）。此值是特定于传输和实现的，并且仅由传输和安全模型（直接）使用。
o securityName: a human-readable name (in snmpAdminString format) representing the SNMP principal in a model-independent manner. This value is used directly by SNMP Applications, the Access Control Subsystem, the Message Processing Subsystem, and the Security Subsystem.
o securityName：一个可读的名称（snmpAdminString格式），以独立于模型的方式表示SNMP主体。SNMP应用程序、访问控制子系统、消息处理子系统和安全子系统直接使用此值。
The transport principal might or might not be the same as the tmSecurityName. Similarly, the tmSecurityName might or might not be the same as the securityName as seen by the Application and Access Control Subsystems. In particular, a non-transport-aware Security Model will ignore tmSecurityName completely when determining the SNMP securityName.
传输主体可能与tmSecurityName相同，也可能不同。类似地，tmSecurityName可能与应用程序和访问控制子系统看到的securityName相同，也可能不同。特别是，非传输感知安全模型在确定SNMP securityName时将完全忽略tmSecurityName。
However, it is important that the mapping between the transport principal and the SNMP securityName (for transport-aware Security Models) is consistent and predictable in order to allow configuration of suitable access control and the establishment of transport connections.
但是，传输主体和SNMP securityName（对于传输感知安全模型）之间的映射必须一致且可预测，以便配置适当的访问控制和建立传输连接。
There are two distinct issues relating to security level as applied to secure transports. For clarity, these are handled by separate fields in the tmStateReference cache:
应用于安全传输的安全级别有两个不同的问题。为清楚起见，这些由tmStateReference缓存中的单独字段处理：
o tmTransportSecurityLevel: an indication from the Transport Model of the level of security offered by this session. The Security Model can use this to ensure that incoming messages were suitably protected before acting on them.
o tmTransportSecurityLevel：从传输模型中指示此会话提供的安全级别。安全模型可以使用它来确保传入消息在对其进行操作之前得到适当的保护。
o tmRequestedSecurityLevel: an indication from the Security Model of the level of security required to be provided by the transport protocol. The Transport Model can use this to ensure that outgoing messages will not be sent over an insufficiently secure session.
o tmRequestedSecurityLevel：从安全模型中指示传输协议需要提供的安全级别。传输模型可以使用它来确保传出消息不会通过安全性不足的会话发送。
For security reasons, if a secure transport session is closed between the time a request message is received and the corresponding response message is sent, then the response message SHOULD be discarded, even if a new session has been established. The SNMPv3 WG decided that this should be a "SHOULD" architecturally, and it is a Security-Model-specific decision whether to REQUIRE this.
出于安全原因，如果在收到请求消息和发送相应的响应消息之间关闭了安全传输会话，则即使已建立新会话，也应丢弃响应消息。SNMPv3工作组决定在架构上这应该是一个“应该”的决定，是否需要它是一个特定于安全模型的决定。
o tmSameSecurity: this flag is used by a transport-aware Security Model to indicate whether the Transport Model MUST enforce this restriction.
o tmSameSecurity：传输感知安全模型使用此标志指示传输模型是否必须强制执行此限制。
o tmSessionID: in order to verify whether the session has changed, the Transport Model must be able to compare the session used to receive the original request with the one to be used to send the response. This typically needs some form of session identifier. This value is only ever used by the Transport Model, so the format and interpretation of this field are model-specific and implementation-dependent.
o TMSSessionID：为了验证会话是否已更改，传输模型必须能够将用于接收原始请求的会话与用于发送响应的会话进行比较。这通常需要某种形式的会话标识符。此值仅由传输模型使用，因此此字段的格式和解释是特定于模型且依赖于实现的。
When processing an outgoing message, if tmSameSecurity is true, then the tmSessionID MUST match the current transport session; otherwise, the message MUST be discarded and the Dispatcher notified that sending the message failed.
处理传出消息时，如果tmSameSecurity为true，则TMSSessionID必须与当前传输会话匹配；否则，必须丢弃该消息，并通知调度程序发送该消息失败。
Abstract service interfaces have been defined by RFC 3411 to describe the conceptual data flows between the various subsystems within an SNMP entity and to help keep the subsystems independent of each other except for the common parameters.
RFC 3411定义了抽象服务接口，以描述SNMP实体内各子系统之间的概念数据流，并帮助保持子系统彼此独立（公共参数除外）。
This document introduces a couple of new ASIs to define the interface between the Transport and Dispatcher Subsystems; it also extends some of the ASIs defined in RFC 3411 to include transport-related information.
本文档介绍了两个新的ASI，用于定义传输子系统和调度子系统之间的接口；它还扩展了RFC 3411中定义的一些ASI，以包括与传输相关的信息。
This document follows the example of RFC 3411 regarding the release of state information and regarding error indications.
本文件遵循RFC 3411关于状态信息发布和错误指示的示例。
1) The release of state information is not always explicitly specified in a Transport Model. As a general rule, if state information is available when a message gets discarded, the message-state information should also be released, and if state information is available when a session is closed, the session-state information should also be released. Keeping sensitive security information longer than necessary might introduce potential vulnerabilities to an implementation.
1) 状态信息的发布并不总是在传输模型中明确指定。作为一般规则，如果消息被丢弃时状态信息可用，则还应释放消息状态信息，如果会话关闭时状态信息可用，则还应释放会话状态信息。将敏感安全信息保留的时间过长可能会给实现带来潜在的漏洞。
2)An error indication in statusInformation will typically include the Object Identifier (OID) and value for an incremented error counter. This might be accompanied by values for contextEngineID and contextName for this counter, a value for securityLevel, and the appropriate state reference if the information is available at the point where the error is detected.
2） statusInformation中的错误指示通常包括对象标识符（OID）和递增错误计数器的值。这可能伴随着此计数器的contextEngineID和contextName的值、securityLevel的值，以及适当的状态引用（如果在检测到错误时信息可用）。
The sendMessage ASI is used to pass a message from the Dispatcher to the appropriate Transport Model for sending. The sendMessageASI defined in this document replaces the text "Send SNMP Request Message to Network" that appears in the diagram in Section 4.6.1 of RFC 3411 and the text "Send SNMP Message to Network" that appears in Section 4.6.2 of RFC 3411.
sendMessage ASI用于将消息从调度器传递到适当的传输模型以进行发送。本文档中定义的sendMessageASI替换RFC 3411第4.6.1节图表中出现的文本“向网络发送SNMP请求消息”和RFC 3411第4.6.2节中出现的文本“向网络发送SNMP消息”。
If present and valid, the tmStateReference refers to a cache containing Transport-Model-specific parameters for the transport and transport security. How a tmStateReference is determined to be present and valid is implementation-dependent. How the information in the cache is used is Transport-Model-dependent and implementation-dependent.
如果存在且有效，tmStateReference引用包含传输和传输安全的传输模型特定参数的缓存。如何确定引用的存在和有效性取决于实现。缓存中信息的使用方式取决于传输模型和实现。
This might sound underspecified, but a Transport Model might be something like SNMP over UDP over IPv6, where no security is provided, so it might have no mechanisms for utilizing a tmStateReference cache.
这听起来可能不够具体，但传输模型可能类似于IPv6上UDP上的SNMP，其中没有提供安全性，因此可能没有利用tmStateReference缓存的机制。
statusInformation =
sendMessage(
IN destTransportDomain -- transport domain to be used
IN destTransportAddress -- transport address to be used
IN outgoingMessage -- the message to send
IN outgoingMessageLength -- its length
IN tmStateReference -- reference to transport state
)
statusInformation =
sendMessage(
IN destTransportDomain -- transport domain to be used
IN destTransportAddress -- transport address to be used
IN outgoingMessage -- the message to send
IN outgoingMessageLength -- its length
IN tmStateReference -- reference to transport state
)
Additional parameters have been added to the ASIs defined in RFC 3411 that are concerned with communication between the Dispatcher and Message Processing Subsystems, and between the Message Processing and Security Subsystems.
在RFC 3411中定义的ASIs中添加了其他参数，这些参数与调度器和消息处理子系统之间以及消息处理子系统和安全子系统之间的通信有关。
A tmStateReference parameter has been added as an OUT parameter to the prepareOutgoingMessage and prepareResponseMessage ASIs. This is passed from the Message Processing Subsystem to the Dispatcher, and from there to the Transport Subsystem.
tmStateReference参数已作为输出参数添加到prepareOutgoingMessage和prepareResponseMessage ASIs中。这将从消息处理子系统传递到调度程序，再从调度程序传递到传输子系统。
How or if the Message Processing Subsystem modifies or utilizes the contents of the cache is Message-Processing-Model specific.
消息处理子系统如何或是否修改或利用缓存的内容是特定于消息处理模型的。
statusInformation = -- success or errorIndication
prepareOutgoingMessage(
IN transportDomain -- transport domain to be used
IN transportAddress -- transport address to be used
IN messageProcessingModel -- typically, SNMP version
IN securityModel -- Security Model to use
IN securityName -- on behalf of this principal
IN securityLevel -- Level of Security requested
IN contextEngineID -- data from/at this entity
IN contextName -- data from/in this context
IN pduVersion -- the version of the PDU
IN PDU -- SNMP Protocol Data Unit
IN expectResponse -- TRUE or FALSE
IN sendPduHandle -- the handle for matching
incoming responses
statusInformation = -- success or errorIndication
prepareOutgoingMessage(
IN transportDomain -- transport domain to be used
IN transportAddress -- transport address to be used
IN messageProcessingModel -- typically, SNMP version
IN securityModel -- Security Model to use
IN securityName -- on behalf of this principal
IN securityLevel -- Level of Security requested
IN contextEngineID -- data from/at this entity
IN contextName -- data from/in this context
IN pduVersion -- the version of the PDU
IN PDU -- SNMP Protocol Data Unit
IN expectResponse -- TRUE or FALSE
IN sendPduHandle -- the handle for matching
incoming responses
OUT destTransportDomain -- destination transport domain
OUT destTransportAddress -- destination transport address
OUT outgoingMessage -- the message to send
OUT outgoingMessageLength -- its length
OUT tmStateReference -- (NEW) reference to transport state
)
OUT destTransportDomain -- destination transport domain
OUT destTransportAddress -- destination transport address
OUT outgoingMessage -- the message to send
OUT outgoingMessageLength -- its length
OUT tmStateReference -- (NEW) reference to transport state
)
statusInformation = -- success or errorIndication
prepareResponseMessage(
IN messageProcessingModel -- typically, SNMP version
IN securityModel -- Security Model to use
IN securityName -- on behalf of this principal
IN securityLevel -- Level of Security requested
IN contextEngineID -- data from/at this entity
IN contextName -- data from/in this context
IN pduVersion -- the version of the PDU
IN PDU -- SNMP Protocol Data Unit
IN maxSizeResponseScopedPDU -- maximum size able to accept
IN stateReference -- reference to state information
-- as presented with the request
IN statusInformation -- success or errorIndication
-- error counter OID/value if error
OUT destTransportDomain -- destination transport domain
OUT destTransportAddress -- destination transport address
OUT outgoingMessage -- the message to send
OUT outgoingMessageLength -- its length
OUT tmStateReference -- (NEW) reference to transport state
)
statusInformation = -- success or errorIndication
prepareResponseMessage(
IN messageProcessingModel -- typically, SNMP version
IN securityModel -- Security Model to use
IN securityName -- on behalf of this principal
IN securityLevel -- Level of Security requested
IN contextEngineID -- data from/at this entity
IN contextName -- data from/in this context
IN pduVersion -- the version of the PDU
IN PDU -- SNMP Protocol Data Unit
IN maxSizeResponseScopedPDU -- maximum size able to accept
IN stateReference -- reference to state information
-- as presented with the request
IN statusInformation -- success or errorIndication
-- error counter OID/value if error
OUT destTransportDomain -- destination transport domain
OUT destTransportAddress -- destination transport address
OUT outgoingMessage -- the message to send
OUT outgoingMessageLength -- its length
OUT tmStateReference -- (NEW) reference to transport state
)
transportDomain and transportAddress parameters have been added as IN parameters to the generateRequestMsg and generateResponseMsg ASIs, and a tmStateReference parameter has been added as an OUT parameter. The transportDomain and transportAddress parameters will have been passed into the Message Processing Subsystem from the Dispatcher and are passed on to the Security Subsystem. The tmStateReference parameter will be passed from the Security Subsystem back to the Message Processing Subsystem, and on to the Dispatcher and Transport Subsystems.
transportDomain和transportAddress参数已作为IN参数添加到generateRequestMsg和generateResponseMsg ASIs，tmStateReference参数已作为OUT参数添加。transportDomain和transportAddress参数将从调度器传递到消息处理子系统，并传递到安全子系统。tmStateReference参数将从安全子系统传回消息处理子系统，再传回调度程序和传输子系统。
If a cache exists for a session identifiable from the tmTransportDomain, tmTransportAddress, tmSecurityName, and requested securityLevel, then a transport-aware Security Model might create a tmStateReference parameter to this cache and pass that as an OUT parameter.
如果存在可从tmTransportDomain、tmTransportAddress、tmSecurityName和请求的securityLevel识别的会话的缓存，则传输感知安全模型可能会为此缓存创建一个tmStateReference参数，并将其作为输出参数传递。
statusInformation =
generateRequestMsg(
IN transportDomain -- (NEW) destination transport domain
IN transportAddress -- (NEW) destination transport address
IN messageProcessingModel -- typically, SNMP version
IN globalData -- message header, admin data
IN maxMessageSize -- of the sending SNMP entity
IN securityModel -- for the outgoing message
IN securityEngineID -- authoritative SNMP entity
IN securityName -- on behalf of this principal
IN securityLevel -- Level of Security requested
IN scopedPDU -- message (plaintext) payload
OUT securityParameters -- filled in by Security Module
OUT wholeMsg -- complete generated message
OUT wholeMsgLength -- length of generated message
OUT tmStateReference -- (NEW) reference to transport state
)
statusInformation =
generateRequestMsg(
IN transportDomain -- (NEW) destination transport domain
IN transportAddress -- (NEW) destination transport address
IN messageProcessingModel -- typically, SNMP version
IN globalData -- message header, admin data
IN maxMessageSize -- of the sending SNMP entity
IN securityModel -- for the outgoing message
IN securityEngineID -- authoritative SNMP entity
IN securityName -- on behalf of this principal
IN securityLevel -- Level of Security requested
IN scopedPDU -- message (plaintext) payload
OUT securityParameters -- filled in by Security Module
OUT wholeMsg -- complete generated message
OUT wholeMsgLength -- length of generated message
OUT tmStateReference -- (NEW) reference to transport state
)
statusInformation =
generateResponseMsg(
IN transportDomain -- (NEW) destination transport domain
IN transportAddress -- (NEW) destination transport address
IN messageProcessingModel -- Message Processing Model
IN globalData -- msgGlobalData
IN maxMessageSize -- from msgMaxSize
IN securityModel -- as determined by MPM
IN securityEngineID -- the value of snmpEngineID
IN securityName -- on behalf of this principal
IN securityLevel -- for the outgoing message
IN scopedPDU -- as provided by MPM
IN securityStateReference -- as provided by MPM
OUT securityParameters -- filled in by Security Module
OUT wholeMsg -- complete generated message
OUT wholeMsgLength -- length of generated message
OUT tmStateReference -- (NEW) reference to transport state
)
statusInformation =
generateResponseMsg(
IN transportDomain -- (NEW) destination transport domain
IN transportAddress -- (NEW) destination transport address
IN messageProcessingModel -- Message Processing Model
IN globalData -- msgGlobalData
IN maxMessageSize -- from msgMaxSize
IN securityModel -- as determined by MPM
IN securityEngineID -- the value of snmpEngineID
IN securityName -- on behalf of this principal
IN securityLevel -- for the outgoing message
IN scopedPDU -- as provided by MPM
IN securityStateReference -- as provided by MPM
OUT securityParameters -- filled in by Security Module
OUT wholeMsg -- complete generated message
OUT wholeMsgLength -- length of generated message
OUT tmStateReference -- (NEW) reference to transport state
)
The receiveMessage ASI is used to pass a message from the Transport Subsystem to the Dispatcher. The receiveMessage ASI replaces the text "Receive SNMP Response Message from Network" that appears in the diagram in Section 4.6.1 of RFC 3411 and the text "Receive SNMP Message from Network" from Section 4.6.2 of RFC3411.
receiveMessage ASI用于将消息从传输子系统传递给调度员。receiveMessage ASI替换RFC 3411第4.6.1节图表中出现的文本“从网络接收SNMP响应消息”，以及RFC3411第4.6.2节中的文本“从网络接收SNMP消息”。
When a message is received on a given transport session, if a cache does not already exist for that session, the Transport Model might create one, referenced by tmStateReference. The contents of this
当在给定的传输会话上接收到消息时，如果该会话尚未存在缓存，则传输模型可能会创建一个由tmstateference引用的缓存。本报告的内容
cache are discussed in Section 5. How this information is determined is implementation- and Transport-Model-specific.
缓存将在第5节中讨论。如何确定这些信息取决于具体的实现和传输模型。
"Might create one" might sound underspecified, but a Transport Model might be something like SNMP over UDP over IPv6, where transport security is not provided, so it might not create a cache.
“可能创建一个”听起来可能不够具体，但传输模型可能类似于IPv6上UDP上的SNMP，其中不提供传输安全性，因此可能不会创建缓存。
The Transport Model does not know the securityModel for an incoming message; this will be determined by the Message Processing Model in a Message-Processing-Model-dependent manner.
传输模型不知道传入消息的安全模型；这将由消息处理模型以依赖于消息处理模型的方式确定。
statusInformation =
receiveMessage(
IN transportDomain -- origin transport domain
IN transportAddress -- origin transport address
IN incomingMessage -- the message received
IN incomingMessageLength -- its length
IN tmStateReference -- reference to transport state
)
statusInformation =
receiveMessage(
IN transportDomain -- origin transport domain
IN transportAddress -- origin transport address
IN incomingMessage -- the message received
IN incomingMessageLength -- its length
IN tmStateReference -- reference to transport state
)
The tmStateReference parameter has also been added to some of the incoming ASIs defined in RFC 3411. How or if a Message Processing Model or Security Model uses tmStateReference is message-processing-and Security-Model-specific.
tmStateReference参数也已添加到RFC 3411中定义的一些传入ASI中。消息处理模型或安全模型如何或是否使用tmStateReference是特定于消息处理和安全模型的。
This might sound underspecified, but a Message Processing Model might have access to all the information from the cache and from the message. The Message Processing Model might determine that the USM Security Model is specified in an SNMPv3 message header; the USM Security Model has no need of values in the tmStateReference cache to authenticate and secure the SNMP message, but an Application might have specified to use a secure transport such as that provided by the SSH Transport Model to send the message to its destination.
这听起来可能不够具体，但消息处理模型可能可以访问缓存和消息中的所有信息。消息处理模型可以确定在SNMPv3消息头中指定USM安全模型；USM安全模型不需要tmStateReference缓存中的值来验证和保护SNMP消息，但应用程序可能已指定使用安全传输，如SSH传输模型提供的传输，以将消息发送到其目标。
The tmStateReference parameter of prepareDataElements is passed from the Dispatcher to the Message Processing Subsystem. How or if the Message Processing Subsystem modifies or utilizes the contents of the cache is Message-Processing-Model-specific.
prepareDataElements的tmStateReference参数从调度程序传递到消息处理子系统。消息处理子系统如何或是否修改或利用缓存的内容是特定于消息处理模型的。
result = -- SUCCESS or errorIndication
prepareDataElements(
IN transportDomain -- origin transport domain
IN transportAddress -- origin transport address
IN wholeMsg -- as received from the network
result = -- SUCCESS or errorIndication
prepareDataElements(
IN transportDomain -- origin transport domain
IN transportAddress -- origin transport address
IN wholeMsg -- as received from the network
IN wholeMsgLength -- as received from the network
IN tmStateReference -- (NEW) from the Transport Model
OUT messageProcessingModel -- typically, SNMP version
OUT securityModel -- Security Model to use
OUT securityName -- on behalf of this principal
OUT securityLevel -- Level of Security requested
OUT contextEngineID -- data from/at this entity
OUT contextName -- data from/in this context
OUT pduVersion -- the version of the PDU
OUT PDU -- SNMP Protocol Data Unit
OUT pduType -- SNMP PDU type
OUT sendPduHandle -- handle for matched request
OUT maxSizeResponseScopedPDU -- maximum size sender can accept
OUT statusInformation -- success or errorIndication
-- error counter OID/value if error
OUT stateReference -- reference to state information
-- to be used for possible Response
)
IN wholeMsgLength -- as received from the network
IN tmStateReference -- (NEW) from the Transport Model
OUT messageProcessingModel -- typically, SNMP version
OUT securityModel -- Security Model to use
OUT securityName -- on behalf of this principal
OUT securityLevel -- Level of Security requested
OUT contextEngineID -- data from/at this entity
OUT contextName -- data from/in this context
OUT pduVersion -- the version of the PDU
OUT PDU -- SNMP Protocol Data Unit
OUT pduType -- SNMP PDU type
OUT sendPduHandle -- handle for matched request
OUT maxSizeResponseScopedPDU -- maximum size sender can accept
OUT statusInformation -- success or errorIndication
-- error counter OID/value if error
OUT stateReference -- reference to state information
-- to be used for possible Response
)
The processIncomingMessage ASI passes tmStateReference from the Message Processing Subsystem to the Security Subsystem.
processIncomingMessage ASI将tmStateReference从消息处理子系统传递到安全子系统。
If tmStateReference is present and valid, an appropriate Security Model might utilize the information in the cache. How or if the Security Subsystem utilizes the information in the cache is Security-Model-specific.
如果tmStateReference存在且有效，则适当的安全模型可能会利用缓存中的信息。安全子系统如何或是否利用缓存中的信息是特定于安全模型的。
statusInformation = -- errorIndication or success
-- error counter OID/value if error
processIncomingMsg(
IN messageProcessingModel -- typically, SNMP version
IN maxMessageSize -- of the sending SNMP entity
IN securityParameters -- for the received message
IN securityModel -- for the received message
IN securityLevel -- Level of Security
IN wholeMsg -- as received on the wire
IN wholeMsgLength -- length as received on the wire
IN tmStateReference -- (NEW) from the Transport Model
OUT securityEngineID -- authoritative SNMP entity
OUT securityName -- identification of the principal
OUT scopedPDU, -- message (plaintext) payload
OUT maxSizeResponseScopedPDU -- maximum size sender can handle
OUT securityStateReference -- reference to security state
-- information, needed for response
)
statusInformation = -- errorIndication or success
-- error counter OID/value if error
processIncomingMsg(
IN messageProcessingModel -- typically, SNMP version
IN maxMessageSize -- of the sending SNMP entity
IN securityParameters -- for the received message
IN securityModel -- for the received message
IN securityLevel -- Level of Security
IN wholeMsg -- as received on the wire
IN wholeMsgLength -- length as received on the wire
IN tmStateReference -- (NEW) from the Transport Model
OUT securityEngineID -- authoritative SNMP entity
OUT securityName -- identification of the principal
OUT scopedPDU, -- message (plaintext) payload
OUT maxSizeResponseScopedPDU -- maximum size sender can handle
OUT securityStateReference -- reference to security state
-- information, needed for response
)
This document defines an architectural approach that permits SNMP to utilize transport-layer security services. Each proposed Transport Model should discuss the security considerations of that Transport Model.
本文档定义了允许SNMP利用传输层安全服务的体系结构方法。每个拟议的传输模型都应讨论该传输模型的安全考虑因素。
It is considered desirable by some industry segments that SNMP Transport Models utilize transport-layer security that addresses perfect forward secrecy at least for encryption keys. Perfect forward secrecy guarantees that compromise of long-term secret keys does not result in disclosure of past session keys. Each proposed Transport Model should include a discussion in its security considerations of whether perfect forward secrecy is appropriate for that Transport Model.
一些行业部门认为，SNMP传输模型利用传输层安全性是可取的，至少对于加密密钥而言，传输层安全性能够解决完美的前向保密性。完美的前向保密性保证了长期密钥的泄露不会导致过去会话密钥的泄露。每个提议的传输模型都应在其安全考虑中包括一个讨论，即完美前向保密性是否适用于该传输模型。
The denial-of-service characteristics of various Transport Models and security protocols will vary and should be evaluated when determining the applicability of a Transport Model to a particular deployment situation.
各种传输模型和安全协议的拒绝服务特性会有所不同，在确定传输模型对特定部署情况的适用性时，应对其进行评估。
Since the cache will contain security-related parameters, implementers SHOULD store this information (in memory or in persistent storage) in a manner to protect it from unauthorized disclosure and/or modification.
由于缓存将包含与安全相关的参数，所以实现者应该以保护信息不被未经授权的泄露和/或修改的方式存储该信息（在内存中或在持久存储中）。
Care must be taken to ensure that an SNMP engine is sending packets out over a transport using credentials that are legal for that engine to use on behalf of that user. Otherwise, an engine that has multiple transports open might be "tricked" into sending a message through the wrong transport.
必须注意确保SNMP引擎使用该引擎代表该用户合法使用的凭据通过传输发送数据包。否则，打开多个传输的引擎可能会被“欺骗”，通过错误的传输发送消息。
A Security Model might have multiple sources from which to define the securityName and securityLevel. The use of a secure Transport Model does not imply that the securityName and securityLevel chosen by the Security Model represent the transport-authenticated identity or the transport-provided security services. The securityModel, securityName, and securityLevel parameters are a related set, and an administrator should understand how the specified securityModel selects the corresponding securityName and securityLevel.
一个安全模型可能有多个源来定义securityName和securityLevel。使用安全传输模型并不意味着安全模型选择的securityName和securityLevel表示传输认证标识或传输提供的安全服务。securityModel、securityName和securityLevel参数是相关的集合，管理员应该了解指定的securityModel如何选择相应的securityName和securityLevel。
In the RFC 3411 architecture, the Message Processing Model makes the decision about which Security Model to use. The architectural change described by this document does not alter that.
在RFC3411体系结构中，消息处理模型决定使用哪个安全模型。本文档描述的体系结构更改不会改变这一点。
The architecture change described by this document does, however, allow SNMP to support two different approaches to security -- message-driven security and transport-driven security. With message-driven security, SNMP provides its own security and passes security parameters within the SNMP message; with transport-driven security, SNMP depends on an external entity to provide security during transport by "wrapping" the SNMP message.
但是，本文档描述的体系结构更改允许SNMP支持两种不同的安全方法—消息驱动安全和传输驱动安全。利用消息驱动的安全性，SNMP提供其自身的安全性，并在SNMP消息中传递安全参数；对于传输驱动的安全性，SNMP依靠外部实体通过“包装”SNMP消息在传输期间提供安全性。
Using a non-transport-aware Security Model with a secure Transport Model is NOT RECOMMENDED for the following reasons.
由于以下原因，不建议将非传输感知安全模型与安全传输模型一起使用。
Security Models defined before the Transport Security Model (i.e., SNMPv1, SNMPv2c, and USM) do not support transport-based security and only have access to the security parameters contained within the SNMP message. They do not know about the security parameters associated with a secure transport. As a result, the Access Control Subsystem bases its decisions on the security parameters extracted from the SNMP message, not on transport-based security parameters.
在传输安全模型（即SNMPv1、SNMPv2c和USM）之前定义的安全模型不支持基于传输的安全性，只能访问SNMP消息中包含的安全参数。他们不知道与安全传输相关的安全参数。因此，访问控制子系统的决策基于从SNMP消息中提取的安全参数，而不是基于传输的安全参数。
Implications of combining older Security Models with Secure Transport Models are known. The securityName used for access control decisions is based on the message-driven identity, which might be unauthenticated, and not on the transport-driven, authenticated identity:
已知将旧的安全模型与安全传输模型相结合的含义。用于访问控制决策的securityName基于消息驱动的标识，该标识可能未经身份验证，而不是基于传输驱动的身份验证：
o An SNMPv1 message will always be paired with an SNMPv1 Security Model (per RFC 3584), regardless of the transport mapping or Transport Model used, and access controls will be based on the unauthenticated community name.
o SNMPv1消息将始终与SNMPv1安全模型配对（根据RFC 3584），无论使用何种传输映射或传输模型，访问控制将基于未经验证的社区名称。
o An SNMPv2c message will always be paired with an SNMPv2c Security Model (per RFC 3584), regardless of the transport mapping or Transport Model used, and access controls will be based on the unauthenticated community name.
o 无论使用何种传输映射或传输模型，SNMPv2c消息将始终与SNMPv2c安全模型配对（根据RFC 3584），并且访问控制将基于未经验证的社区名称。
o An SNMPv3 message will always be paired with the securityModel specified in the msgSecurityParameters field of the message (per RFC 3412), regardless of the transport mapping or Transport Model used. If the SNMPv3 message specifies the User-based Security Model (USM) with noAuthNoPriv, then the access controls will be based on the unauthenticated USM user.
o 无论使用何种传输映射或传输模型，SNMPv3消息始终与消息的msgSecurityParameters字段中指定的securityModel配对（根据RFC 3412）。如果SNMPv3消息使用noAuthNoPriv指定基于用户的安全模型（USM），则访问控制将基于未经验证的USM用户。
o For outgoing messages, if a Secure Transport Model is selected in combination with a Security Model that does not populate a tmStateReference, the Secure Transport Model SHOULD detect the lack of a valid tmStateReference and fail.
o 对于传出消息，如果选择安全传输模型与未填充tmStateReference的安全模型相结合，则安全传输模型应检测到缺少有效的tmStateReference并失败。
In times of network stress, a Secure Transport Model might not work properly if its underlying security mechanisms (e.g., Network Time Protocol (NTP) or Authentication, Authorization, and Accounting (AAA) protocols or certificate authorities) are not reachable. The User-based Security Model was explicitly designed to not depend upon external network services, and provides its own security services. It is RECOMMENDED that operators provision authPriv USM as a fallback mechanism to supplement any Security Model or Transport Model that has external dependencies, so that secure SNMP communications can continue when the external network service is not available.
在网络压力下，如果无法访问安全传输模型的底层安全机制（例如，网络时间协议（NTP）或身份验证、授权和计费（AAA）协议或证书颁发机构），则安全传输模型可能无法正常工作。基于用户的安全模型被明确设计为不依赖于外部网络服务，并提供自己的安全服务。建议运营商将authPriv USM作为回退机制提供，以补充任何具有外部依赖性的安全模型或传输模型，以便在外部网络服务不可用时可以继续进行安全SNMP通信。
IANA has created a new registry in the Simple Network Management Protocol (SNMP) Number Spaces. The new registry is called "SNMP Transport Domains". This registry contains US-ASCII alpha-numeric strings of one to four characters to identify prefixes for corresponding SNMP transport domains. Each transport domain MUST have an OID assignment under snmpDomains [RFC2578]. Values are to be assigned via [RFC5226] "Specification Required".
IANA在简单网络管理协议（SNMP）编号空间中创建了一个新的注册表。新的注册表称为“SNMP传输域”。此注册表包含一到四个字符的US-ASCII字母数字字符串，用于标识相应SNMP传输域的前缀。每个传输域必须在snmpDomains[RFC2578]下具有OID分配。通过[RFC5226]“所需规格”分配值。
The registry has been populated with the following initial entries:
注册表已填充以下初始项：
Registry Name: SNMP Transport Domains Reference: [RFC2578] [RFC3417] [RFC5590] Registration Procedures: Specification Required Each domain is assigned a MIB-defined OID under snmpDomains
注册表名称：SNMP传输域参考：[RFC2578][RFC3417][RFC5590]注册过程：所需规范为每个域分配一个在snmpDomains下定义的MIB OID
Prefix snmpDomains Reference
------- ----------------------------- ---------
udp snmpUDPDomain [RFC3417] [RFC5590]
clns snmpCLNSDomain [RFC3417] [RFC5590]
cons snmpCONSDomain [RFC3417] [RFC5590]
ddp snmpDDPDomain [RFC3417] [RFC5590]
ipx snmpIPXDomain [RFC3417] [RFC5590]
prxy rfc1157Domain [RFC3417] [RFC5590]
Prefix snmpDomains Reference
------- ----------------------------- ---------
udp snmpUDPDomain [RFC3417] [RFC5590]
clns snmpCLNSDomain [RFC3417] [RFC5590]
cons snmpCONSDomain [RFC3417] [RFC5590]
ddp snmpDDPDomain [RFC3417] [RFC5590]
ipx snmpIPXDomain [RFC3417] [RFC5590]
prxy rfc1157Domain [RFC3417] [RFC5590]
The Integrated Security for SNMP WG would like to thank the following people for their contributions to the process.
SNMP集成安全工作组感谢以下人员对该过程的贡献。
The authors of submitted Security Model proposals: Chris Elliot, Wes Hardaker, David Harrington, Keith McCloghrie, Kaushik Narayan, David Perkins, Joseph Salowey, and Juergen Schoenwaelder.
提交的安全模型提案的作者：Chris Elliot、Wes Hardaker、David Harrington、Keith McCloghrie、Kaushik Narayan、David Perkins、Joseph Salowey和Juergen Schoenwaeld。
The members of the Protocol Evaluation Team: Uri Blumenthal, Lakshminath Dondeti, Randy Presuhn, and Eric Rescorla.
方案评估小组成员：Uri Blumenthal、Lakshminath Dondeti、Randy Presohn和Eric Rescorla。
WG members who performed detailed reviews: Wes Hardaker, Jeffrey Hutzelman, Tom Petch, Dave Shield, and Bert Wijnen.
进行详细审查的工作组成员：韦斯·哈达克、杰弗里·哈泽尔曼、汤姆·佩奇、戴夫·希尔德和伯特·维恩。
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2119]Bradner，S.，“RFC中用于表示需求水平的关键词”，BCP 14，RFC 2119，1997年3月。
[RFC2578] McCloghrie, K., Ed., Perkins, D., Ed., and J. Schoenwaelder, Ed., "Structure of Management Information Version 2 (SMIv2)", STD 58, RFC 2578, April 1999.
[RFC2578]McCloghrie，K.，Ed.，Perkins，D.，Ed.，和J.Schoenwaeld，Ed.“管理信息的结构版本2（SMIv2）”，STD 58，RFC 2578，1999年4月。
[RFC3411] Harrington, D., Presuhn, R., and B. Wijnen, "An Architecture for Describing Simple Network Management Protocol (SNMP) Management Frameworks", STD 62, RFC 3411, December 2002.
[RFC3411]Harrington，D.，Presohn，R.，和B.Wijnen，“描述简单网络管理协议（SNMP）管理框架的体系结构”，STD 62，RFC 3411，2002年12月。
[RFC3412] Case, J., Harrington, D., Presuhn, R., and B. Wijnen, "Message Processing and Dispatching for the Simple Network Management Protocol (SNMP)", STD 62, RFC 3412,
[RFC3412]Case，J.，Harrington，D.，Presohn，R.，和B.Wijnen，“简单网络管理协议（SNMP）的消息处理和调度”，STD 62，RFC 3412，
December 2002.
2002年12月。
[RFC3413] Levi, D., Meyer, P., and B. Stewart, "Simple Network Management Protocol (SNMP) Applications", STD 62, RFC 3413, December 2002.
[RFC3413]Levi，D.，Meyer，P.，和B.Stewart，“简单网络管理协议（SNMP）应用”，STD 62，RFC 3413，2002年12月。
[RFC3414] Blumenthal, U. and B. Wijnen, "User-based Security Model (USM) for version 3 of the Simple Network Management Protocol (SNMPv3)", STD 62, RFC 3414, December 2002.
[RFC3414]Blumenthal，U.和B.Wijnen，“简单网络管理协议（SNMPv3）版本3的基于用户的安全模型（USM）”，STD 62，RFC 3414，2002年12月。
[RFC3417] Presuhn, R., "Transport Mappings for the Simple Network Management Protocol (SNMP)", STD 62, RFC 3417, December 2002.
[RFC3417]Presohn，R.，“简单网络管理协议（SNMP）的传输映射”，STD 62，RFC 34172002年12月。
[RFC2865] Rigney, C., Willens, S., Rubens, A., and W. Simpson, "Remote Authentication Dial In User Service (RADIUS)", RFC 2865, June 2000.
[RFC2865]Rigney，C.，Willens，S.，Rubens，A.，和W.Simpson，“远程认证拨入用户服务（RADIUS）”，RFC 28652000年6月。
[RFC3410] Case, J., Mundy, R., Partain, D., and B. Stewart, "Introduction and Applicability Statements for Internet-Standard Management Framework", RFC 3410, December 2002.
[RFC3410]Case，J.，Mundy，R.，Partain，D.，和B.Stewart，“互联网标准管理框架的介绍和适用性声明”，RFC 34102002年12月。
[RFC3584] Frye, R., Levi, D., Routhier, S., and B. Wijnen, "Coexistence between Version 1, Version 2, and Version 3 of the Internet-standard Network Management Framework", BCP 74, RFC 3584, August 2003.
[RFC3584]Frye，R.，Levi，D.，Routhier，S.，和B.Wijnen，“互联网标准网络管理框架版本1，版本2和版本3之间的共存”，BCP 74，RFC 3584，2003年8月。
[RFC4251] Ylonen, T. and C. Lonvick, "The Secure Shell (SSH) Protocol Architecture", RFC 4251, January 2006.
[RFC4251]Ylonen，T.和C.Lonvick，“安全外壳（SSH）协议架构”，RFC 4251，2006年1月。
[RFC4422] Melnikov, A. and K. Zeilenga, "Simple Authentication and Security Layer (SASL)", RFC 4422, June 2006.
[RFC4422]Melnikov，A.和K.Zeilenga，“简单身份验证和安全层（SASL）”，RFC 4422，2006年6月。
[RFC4741] Enns, R., "NETCONF Configuration Protocol", RFC 4741, December 2006.
[RFC4741]Enns，R.，“网络配置协议”，RFC 47412006年12月。
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 5226, May 2008.
[RFC5226]Narten，T.和H.Alvestrand，“在RFCs中编写IANA注意事项部分的指南”，BCP 26，RFC 5226，2008年5月。
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security (TLS) Protocol Version 1.2", RFC 5246, August 2008.
[RFC5246]Dierks，T.和E.Rescorla，“传输层安全（TLS）协议版本1.2”，RFC 5246，2008年8月。
[RFC5424] Gerhards, R., "The Syslog Protocol", RFC 5424, March 2009.
[RFC5424]Gerhards，R.，“系统日志协议”，RFC 54242009年3月。
[RFC5591] Harrington, D. and W. Hardaker, "Transport Security Model for the Simple Network Management Protocol (SNMP)", RFC 5591, June 2009.
[RFC5591]Harrington，D.和W.Hardaker，“简单网络管理协议（SNMP）的传输安全模型”，RFC 55912009年6月。
[RFC5592] Harrington, D., Salowey, J., and W. Hardaker, "Secure Shell Transport Model for the Simple Network Management Protocol (SNMP)", RFC 5592, June 2009.
[RFC5592]Harrington，D.，Salowey，J.，和W.Hardaker，“简单网络管理协议（SNMP）的安全外壳传输模型”，RFC 55922009年6月。
Appendix A. Why tmStateReference?
附录A.为什么选择参考？
This appendix considers why a cache-based approach was selected for passing parameters.
本附录考虑了为什么选择基于缓存的方法来传递参数。
There are four approaches that could be used for passing information between the Transport Model and a Security Model.
有四种方法可用于在传输模型和安全模型之间传递信息。
1. One could define an ASI to supplement the existing ASIs.
1. 可以定义ASI来补充现有的ASI。
2. One could add a header to encapsulate the SNMP message.
2. 可以添加一个头来封装SNMP消息。
3. One could utilize fields already defined in the existing SNMPv3 message.
3. 可以利用现有SNMPv3消息中已经定义的字段。
4. One could pass the information in an implementation-specific cache or via a MIB module.
4. 可以在特定于实现的缓存中或通过MIB模块传递信息。
Abstract Service Interfaces (ASIs) are defined by a set of primitives that specify the services provided and the abstract data elements that are to be passed when the services are invoked. Defining additional ASIs to pass the security and transport information from the Transport Subsystem to the Security Subsystem has the advantage of being consistent with existing RFC 3411/3412 practice; it also helps to ensure that any Transport Model proposals pass the necessary data and do not cause side effects by creating model-specific dependencies between itself and models or subsystems other than those that are clearly defined by an ASI.
抽象服务接口（ASI）由一组原语定义，这些原语指定所提供的服务以及调用服务时要传递的抽象数据元素。定义额外的ASI以将安全和传输信息从传输子系统传递到安全子系统具有与现有RFC 3411/3412实践一致的优点；它还有助于确保任何交通模型提案都能传递必要的数据，并且不会因在其自身和模型或子系统（ASI明确定义的模型或子系统除外）之间创建特定于模型的依赖关系而产生副作用。
A header could encapsulate the SNMP message to pass necessary information from the Transport Model to the Dispatcher and then to a Message Processing Model. The message header would be included in the wholeMessage ASI parameter and would be removed by a corresponding Message Processing Model. This would imply the (one and only) Message Dispatcher would need to be modified to determine which SNMP message version was involved, and a new Message Processing Model would need to be developed that knew how to extract the header from the message and pass it to the Security Model.
报头可以封装SNMP消息，以便将必要的信息从传输模型传递给调度器，然后再传递给消息处理模型。消息头将包含在wholeMessage ASI参数中，并由相应的消息处理模型删除。这意味着（一个且唯一的）消息分派器需要修改以确定涉及哪个SNMP消息版本，并且需要开发一个新的消息处理模型，该模型知道如何从消息中提取头并将其传递给安全模型。
[RFC3412] defines the SNMPv3 message, which contains fields to pass security-related parameters. The Transport Subsystem could use these fields in an SNMPv3 message (or comparable fields in other message
[RFC3412]定义SNMPv3消息，该消息包含传递安全相关参数的字段。传输子系统可以在SNMPv3消息中使用这些字段（或在其他消息中使用类似字段）
formats) to pass information between Transport Models in different SNMP engines and to pass information between a Transport Model and a corresponding Message Processing Model.
格式）在不同SNMP引擎中的传输模型之间传递信息，并在传输模型和相应的消息处理模型之间传递信息。
If the fields in an incoming SNMPv3 message are changed by the Transport Model before passing it to the Security Model, then the Transport Model will need to decode the ASN.1 message, modify the fields, and re-encode the message in ASN.1 before passing the message on to the Message Dispatcher or to the transport layer. This would require an intimate knowledge of the message format and message versions in order for the Transport Model to know which fields could be modified. This would seriously violate the modularity of the architecture.
如果传入SNMPv3消息中的字段在传递给安全模型之前被传输模型更改，那么传输模型将需要解码ASN.1消息，修改字段，并在将消息传递给消息调度程序或传输层之前重新编码ASN.1中的消息。这需要对消息格式和消息版本有深入的了解，以便传输模型知道哪些字段可以修改。这将严重违反体系结构的模块化。
This document describes a cache into which the Transport Model (TM) puts information about the security applied to an incoming message; a Security Model can extract that information from the cache. Given that there might be multiple TM security caches, a tmStateReference is passed as an extra parameter in the ASIs between the Transport Subsystem and the Security Subsystem so that the Security Model knows which cache of information to consult.
本文档描述了一个缓存，传输模型（TM）将有关应用于传入消息的安全性的信息放入其中；安全模型可以从缓存中提取该信息。考虑到可能存在多个TM安全缓存，在传输子系统和安全子系统之间的ASIs中将tmStateReference作为额外参数传递，以便安全模型知道要查询的信息缓存。
This approach does create dependencies between a specific Transport Model and a corresponding specific Security Model. However, the approach of passing a model-independent reference to a model-dependent cache is consistent with the securityStateReference already being passed around in the RFC 3411 ASIs.
这种方法确实会在特定的传输模型和相应的特定安全模型之间创建依赖关系。但是，将独立于模型的引用传递给依赖于模型的缓存的方法与RFC 3411 ASIs中已经传递的securityStateReference是一致的。
Authors' Addresses
作者地址
David Harrington Huawei Technologies (USA) 1700 Alma Dr. Suite 100 Plano, TX 75075 USA
David Harrington Huawei Technologies（美国）1700 Alma Dr.Suite 100 Plano，TX 75075美国
Phone: +1 603 436 8634
EMail: ietfdbh@comcast.net
Phone: +1 603 436 8634
EMail: ietfdbh@comcast.net
Juergen Schoenwaelder Jacobs University Bremen Campus Ring 1 28725 Bremen Germany
德国不来梅大学校园环128725
Phone: +49 421 200-3587
EMail: j.schoenwaelder@jacobs-university.de
Phone: +49 421 200-3587
EMail: j.schoenwaelder@jacobs-university.de