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rfc:rfc6353

Internet Engineering Task Force (IETF) W. Hardaker Request for Comments: 6353 SPARTA, Inc. Obsoletes: 5953 July 2011 Category: Standards Track ISSN: 2070-1721

         Transport Layer Security (TLS) Transport Model for
           the Simple Network Management Protocol (SNMP)

Abstract

 This document describes a Transport Model for the Simple Network
 Management Protocol (SNMP), that uses either the Transport Layer
 Security protocol or the Datagram Transport Layer Security (DTLS)
 protocol.  The TLS and DTLS protocols provide authentication and
 privacy services for SNMP applications.  This document describes how
 the TLS Transport Model (TLSTM) implements the needed features of an
 SNMP Transport Subsystem to make this protection possible in an
 interoperable way.
 This Transport Model is designed to meet the security and operational
 needs of network administrators.  It supports the sending of SNMP
 messages over TLS/TCP and DTLS/UDP.  The TLS mode can make use of
 TCP's improved support for larger packet sizes and the DTLS mode
 provides potentially superior operation in environments where a
 connectionless (e.g., UDP) transport is preferred.  Both TLS and DTLS
 integrate well into existing public keying infrastructures.
 This document also defines a portion of the Management Information
 Base (MIB) for use with network management protocols.  In particular,
 it defines objects for managing the TLS Transport Model for SNMP.

Status of This Memo

 This is an Internet Standards Track document.
 This document is a product of the Internet Engineering Task Force
 (IETF).  It represents the consensus of the IETF community.  It has
 received public review and has been approved for publication by the
 Internet Engineering Steering Group (IESG).  Further information on
 Internet Standards is available in Section 2 of RFC 5741.
 Information about the current status of this document, any errata,
 and how to provide feedback on it may be obtained at
 http://www.rfc-editor.org/info/rfc6353.

Hardaker Standards Track [Page 1] RFC 6353 TLS Transport Model for SNMP July 2011

Copyright Notice

 Copyright (c) 2011 IETF Trust and the persons identified as the
 document authors.  All rights reserved.
 This document is subject to BCP 78 and the IETF Trust's Legal
 Provisions Relating to IETF Documents
 (http://trustee.ietf.org/license-info) in effect on the date of
 publication of this document.  Please review these documents
 carefully, as they describe your rights and restrictions with respect
 to this document.  Code Components extracted from this document must
 include Simplified BSD License text as described in Section 4.e of
 the Trust Legal Provisions and are provided without warranty as
 described in the Simplified BSD License.
 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.

Table of Contents

 1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
   1.1.  Conventions  . . . . . . . . . . . . . . . . . . . . . . .  7
   1.2.  Changes Since RFC 5953 . . . . . . . . . . . . . . . . . .  8
 2.  The Transport Layer Security Protocol  . . . . . . . . . . . .  8
 3.  How the TLSTM Fits into the Transport Subsystem  . . . . . . .  8
   3.1.  Security Capabilities of This Model  . . . . . . . . . . . 11
     3.1.1.  Threats  . . . . . . . . . . . . . . . . . . . . . . . 11
     3.1.2.  Message Protection . . . . . . . . . . . . . . . . . . 12
     3.1.3.  (D)TLS Connections . . . . . . . . . . . . . . . . . . 13
   3.2.  Security Parameter Passing . . . . . . . . . . . . . . . . 14
   3.3.  Notifications and Proxy  . . . . . . . . . . . . . . . . . 14
 4.  Elements of the Model  . . . . . . . . . . . . . . . . . . . . 15
   4.1.  X.509 Certificates . . . . . . . . . . . . . . . . . . . . 15
     4.1.1.  Provisioning for the Certificate . . . . . . . . . . . 15
   4.2.  (D)TLS Usage . . . . . . . . . . . . . . . . . . . . . . . 17
   4.3.  SNMP Services  . . . . . . . . . . . . . . . . . . . . . . 18
     4.3.1.  SNMP Services for an Outgoing Message  . . . . . . . . 18
     4.3.2.  SNMP Services for an Incoming Message  . . . . . . . . 19

Hardaker Standards Track [Page 2] RFC 6353 TLS Transport Model for SNMP July 2011

   4.4.  Cached Information and References  . . . . . . . . . . . . 20
     4.4.1.  TLS Transport Model Cached Information . . . . . . . . 20
       4.4.1.1.  tmSecurityName . . . . . . . . . . . . . . . . . . 20
       4.4.1.2.  tmSessionID  . . . . . . . . . . . . . . . . . . . 21
       4.4.1.3.  Session State  . . . . . . . . . . . . . . . . . . 21
 5.  Elements of Procedure  . . . . . . . . . . . . . . . . . . . . 21
   5.1.  Procedures for an Incoming Message . . . . . . . . . . . . 21
     5.1.1.  DTLS over UDP Processing for Incoming Messages . . . . 22
     5.1.2.  Transport Processing for Incoming SNMP Messages  . . . 23
   5.2.  Procedures for an Outgoing SNMP Message  . . . . . . . . . 25
   5.3.  Establishing or Accepting a Session  . . . . . . . . . . . 26
     5.3.1.  Establishing a Session as a Client . . . . . . . . . . 26
     5.3.2.  Accepting a Session as a Server  . . . . . . . . . . . 28
   5.4.  Closing a Session  . . . . . . . . . . . . . . . . . . . . 29
 6.  MIB Module Overview  . . . . . . . . . . . . . . . . . . . . . 30
   6.1.  Structure of the MIB Module  . . . . . . . . . . . . . . . 30
   6.2.  Textual Conventions  . . . . . . . . . . . . . . . . . . . 30
   6.3.  Statistical Counters . . . . . . . . . . . . . . . . . . . 30
   6.4.  Configuration Tables . . . . . . . . . . . . . . . . . . . 30
     6.4.1.  Notifications  . . . . . . . . . . . . . . . . . . . . 31
   6.5.  Relationship to Other MIB Modules  . . . . . . . . . . . . 31
     6.5.1.  MIB Modules Required for IMPORTS . . . . . . . . . . . 31
 7.  MIB Module Definition  . . . . . . . . . . . . . . . . . . . . 31
 8.  Operational Considerations . . . . . . . . . . . . . . . . . . 54
   8.1.  Sessions . . . . . . . . . . . . . . . . . . . . . . . . . 54
   8.2.  Notification Receiver Credential Selection . . . . . . . . 54
   8.3.  contextEngineID Discovery  . . . . . . . . . . . . . . . . 55
   8.4.  Transport Considerations . . . . . . . . . . . . . . . . . 55
 9.  Security Considerations  . . . . . . . . . . . . . . . . . . . 55
   9.1.  Certificates, Authentication, and Authorization  . . . . . 55
   9.2.  (D)TLS Security Considerations . . . . . . . . . . . . . . 56
     9.2.1.  TLS Version Requirements . . . . . . . . . . . . . . . 56
     9.2.2.  Perfect Forward Secrecy  . . . . . . . . . . . . . . . 57
   9.3.  Use with SNMPv1/SNMPv2c Messages . . . . . . . . . . . . . 57
   9.4.  MIB Module Security  . . . . . . . . . . . . . . . . . . . 57
 10. IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 59
 11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 59
 12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 60
   12.1. Normative References . . . . . . . . . . . . . . . . . . . 60
   12.2. Informative References . . . . . . . . . . . . . . . . . . 61
 Appendix A.  Target and Notification Configuration Example . . . . 63
   A.1.  Configuring a Notification Originator  . . . . . . . . . . 63
   A.2.  Configuring TLSTM to Utilize a Simple Derivation of
         tmSecurityName . . . . . . . . . . . . . . . . . . . . . . 64
   A.3.  Configuring TLSTM to Utilize Table-Driven Certificate
         Mapping  . . . . . . . . . . . . . . . . . . . . . . . . . 64

Hardaker Standards Track [Page 3] RFC 6353 TLS Transport Model for SNMP July 2011

1. Introduction

 It is important to understand the modular SNMPv3 architecture as
 defined by [RFC3411] and enhanced by the Transport Subsystem
 [RFC5590].  It is also important to understand the terminology of the
 SNMPv3 architecture in order to understand where the Transport Model
 described in this document fits into the architecture and how it
 interacts with the other architecture subsystems.  For a detailed
 overview of the documents that describe the current Internet-Standard
 Management Framework, please refer to Section 7 of [RFC3410].
 This document describes a Transport Model that makes use of the
 Transport Layer Security (TLS) [RFC5246] and the Datagram Transport
 Layer Security (DTLS) Protocol [RFC4347], within a Transport
 Subsystem [RFC5590].  DTLS is the datagram variant of the Transport
 Layer Security (TLS) protocol [RFC5246].  The Transport Model in this
 document is referred to as the Transport Layer Security Transport
 Model (TLSTM).  TLS and DTLS take advantage of the X.509 public
 keying infrastructure [RFC5280].  While (D)TLS supports multiple
 authentication mechanisms, this document only discusses X.509
 certificate-based authentication.  Although other forms of
 authentication are possible, they are outside the scope of this
 specification.  This transport model is designed to meet the security
 and operational needs of network administrators, operating in both
 environments where a connectionless (e.g., UDP) transport is
 preferred and in environments where large quantities of data need to
 be sent (e.g., over a TCP-based stream).  Both TLS and DTLS integrate
 well into existing public keying infrastructures.  This document
 supports sending of SNMP messages over TLS/TCP and DTLS/UDP.
 This document also defines a portion of the Management Information
 Base (MIB) for use with network management protocols.  In particular,
 it defines objects for managing the TLS Transport Model for SNMP.
 Managed objects are accessed via a virtual information store, termed
 the Management Information Base or MIB.  MIB objects are generally
 accessed through the Simple Network Management Protocol (SNMP).
 Objects in the MIB are defined using the mechanisms defined in the
 Structure of Management Information (SMI).  This memo specifies a MIB
 module that is compliant to the SMIv2, which is described in STD 58:
 [RFC2578], [RFC2579], and [RFC2580].

Hardaker Standards Track [Page 4] RFC 6353 TLS Transport Model for SNMP July 2011

 The diagram shown below gives a conceptual overview of two SNMP
 entities communicating using the TLS Transport Model (shown as
 "TLSTM").  One entity contains a command responder and notification
 originator application, and the other a command generator and
 notification receiver application.  It should be understood that this
 particular mix of application types is an example only and other
 combinations are equally valid.
 Note: this diagram shows the Transport Security Model (TSM) being
 used as the security model that is defined in [RFC5591].

Hardaker Standards Track [Page 5] RFC 6353 TLS Transport Model for SNMP July 2011

+———————————————————————+ | Network | +———————————————————————+

   ^                     |            ^               |
   |Notifications        |Commands    |Commands       |Notifications

+—|———————|——-+ +–|—————|————–+ | | V | | | V | | +————+ +————+ | | +———–+ +———-+ | | | (D)TLS | | (D)TLS | | | | (D)TLS | | (D)TLS | | | | (Client) | | (Server) | | | | (Client) | | (Server) | | | +————+ +————+ | | +———–+ +———-+ | | ^ ^ | | ^ ^ | | | | | | | | | | +————-+ | | +————–+ | | +—–|————+ | | +—–|————+ | | | V | | | | V | | | | +——–+ | +—–+ | | | +——–+ | +—–+ | | | | TLS TM |←——–>|Cache| | | | | TLS TM |←——–>|Cache| | | | +——–+ | +—–+ | | | +——–+ | +—–+ | | |Transport Subsys. | ^ | | |Transport Subsys. | ^ | | +——————+ | | | +——————+ | | | ^ | | | ^ | | | | +–+ | | | +–+ | | v | | | V | | | +—–+ +——–+ +——-+ | | | +—–+ +——–+ +——-+ | | | | | |Message | |Securi.| | | | | | |Message | |Securi.| | | | |Disp.| |Proc. | |Subsys.| | | | |Disp.| |Proc. | |Subsys.| | | | | | |Subsys. | | | | | | | | |Subsys. | | | | | | | | | | | | | | | | | | | | | | | | | | | +—-+ | | +—+ | | | | | | | +—-+ | | +—+ | | | | | ←–>|v3MP|←→ |TSM|←-+ | | | ←–>|v3MP|←–>|TSM|←-+ | | | | | +—-+ | | +—+ | | | | | | +—-+ | | +—+ | | | | | | | | | | | | | | | | | | | +—–+ +——–+ +——-+ | | +—–+ +——–+ +——-+ | | ^ | | ^ | | | | | | | | +-+————+ | | +-+———-+ | | | | | | | | | | v v | | v V | | +————-+ +————-+ | | +————-+ +————-+ | | | COMMAND | | NOTIFICAT. | | | | COMMAND | | NOTIFICAT. | | | | RESPONDER | | ORIGINATOR | | | | GENERATOR | | RECEIVER | | | | application | | application | | | | application | | application | | | +————-+ +————-+ | | +————-+ +————-+ | | SNMP entity | | SNMP entity | +———————————+ +———————————+

Hardaker Standards Track [Page 6] RFC 6353 TLS Transport Model for SNMP July 2011

1.1. Conventions

 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.  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 a Full Standard.
 "Authentication" in this document typically refers to the English
 meaning of "serving to prove the authenticity of" the message, not
 data source authentication or peer identity authentication.
 The terms "manager" and "agent" are not used in this document
 because, in the [RFC3411] architecture, all SNMP entities have the
 capability of acting as manager, agent, or both depending on the SNMP
 application types supported in the implementation.  Where distinction
 is required, the application names of command generator, command
 responder, notification originator, notification receiver, and proxy
 forwarder are used.  See "SNMP Applications" [RFC3413] for further
 information.
 Large portions of this document simultaneously refer to both TLS and
 DTLS when discussing TLSTM components that function equally with
 either protocol.  "(D)TLS" is used in these places to indicate that
 the statement applies to either or both protocols as appropriate.
 When a distinction between the protocols is needed, they are referred
 to independently through the use of "TLS" or "DTLS".  The Transport
 Model, however, is named "TLS Transport Model" and refers not to the
 TLS or DTLS protocol but to the specification in this document, which
 includes support for both TLS and DTLS.
 Throughout this document, the terms "client" and "server" are used to
 refer to the two ends of the (D)TLS transport connection.  The client
 actively opens the (D)TLS connection, and the server passively
 listens for the incoming (D)TLS connection.  An SNMP entity may act
 as a (D)TLS client or server or both, depending on the SNMP
 applications supported.
 The User-Based Security Model (USM) [RFC3414] is a mandatory-to-
 implement Security Model in STD 62.  While (D)TLS and USM frequently
 refer to a user, the terminology preferred in RFC 3411 and in this
 memo is "principal".  A principal is the "who" on whose behalf
 services are provided or processing takes place.  A principal can be,
 among other things, an individual acting in a particular role; a set
 of individuals, with each acting in a particular role; an application
 or a set of applications, or a combination of these within an
 administrative domain.

Hardaker Standards Track [Page 7] RFC 6353 TLS Transport Model for SNMP July 2011

 Throughout this document, the term "session" is used to refer to a
 secure association between two TLS Transport Models that permits the
 transmission of one or more SNMP messages within the lifetime of the
 session.  The (D)TLS protocols also have an internal notion of a
 session and although these two concepts of a session are related,
 when the term "session" is used this document is referring to the
 TLSTM's specific session and not directly to the (D)TLS protocol's
 session.
 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 [RFC2119].

1.2. Changes Since RFC 5953

 This document obsoletes [RFC5953].
 Since the publication of RFC 5953, a few editorial errata have been
 noted.  These errata are posted on the RFC Editor web site.  These
 errors have been corrected in this document.
 This document updates the references to RFC 3490 (IDNA 2003) to
 [RFC5890] (IDNA 2008), because RFC 3490 was obsoleted by RFC 5890.
 References to RFC 1033 were replaced with references to [RFC1123].
 Added informative reference to 5953.
 Updated MIB dates and revision date.

2. The Transport Layer Security Protocol

 (D)TLS provides authentication, data message integrity, and privacy
 at the transport layer (see [RFC4347]).
 The primary goals of the TLS Transport Model are to provide privacy,
 peer identity authentication, and data integrity between two
 communicating SNMP entities.  The TLS and DTLS protocols provide a
 secure transport upon which the TLSTM is based.  Please refer to
 [RFC5246] and [RFC4347] for complete descriptions of the protocols.

3. How the TLSTM Fits into the Transport Subsystem

 A transport model is a component of the Transport Subsystem.  The TLS
 Transport Model thus fits between the underlying (D)TLS transport
 layer and the Message Dispatcher [RFC3411] component of the SNMP
 engine.

Hardaker Standards Track [Page 8] RFC 6353 TLS Transport Model for SNMP July 2011

 The TLS Transport Model will establish a session between itself and
 the TLS Transport Model of another SNMP engine.  The sending
 transport model passes unencrypted and unauthenticated messages from
 the Dispatcher to (D)TLS to be encrypted and authenticated, and the
 receiving transport model accepts decrypted and authenticated/
 integrity-checked incoming messages from (D)TLS and passes them to
 the Dispatcher.
 After a TLS Transport Model session is established, SNMP messages can
 conceptually be sent through the session from one SNMP message
 Dispatcher to another SNMP Message Dispatcher.  If multiple SNMP
 messages are needed to be passed between two SNMP applications they
 MAY be passed through the same session.  A TLSTM implementation
 engine MAY choose to close the session to conserve resources.
 The TLS Transport Model of an SNMP engine will perform the
 translation between (D)TLS-specific security parameters and SNMP-
 specific, model-independent parameters.

Hardaker Standards Track [Page 9] RFC 6353 TLS Transport Model for SNMP July 2011

 The diagram below depicts where the TLS Transport Model (shown as
 "(D)TLS TM") fits into the architecture described in RFC 3411 and the
 Transport Subsystem:
 +------------------------------+
 |    Network                   |
 +------------------------------+
    ^       ^              ^
    |       |              |
    v       v              v
 +-------------------------------------------------------------------+
 | +--------------------------------------------------+              |
 | |  Transport Subsystem                             |  +--------+  |
 | | +-----+ +-----+ +-------+             +-------+  |  |        |  |
 | | | UDP | | SSH | |(D)TLS |    . . .    | other |<--->| Cache  |  |
 | | |     | | TM  | | TM    |             |       |  |  |        |  |
 | | +-----+ +-----+ +-------+             +-------+  |  +--------+  |
 | +--------------------------------------------------+         ^    |
 |              ^                                               |    |
 |              |                                               |    |
 | 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          |

Hardaker Standards Track [Page 10] RFC 6353 TLS Transport Model for SNMP July 2011

 | +-------------+   +---------+   +--------------+  +-------------+ |
 | |   COMMAND   |   | ACCESS  |   | NOTIFICATION |  |    PROXY    | |
 | |  RESPONDER  |<->| CONTROL |<->|  ORIGINATOR  |  |  FORWARDER  | |
 | | application |   |         |   | applications |  | application | |
 | +-------------+   +---------+   +--------------+  +-------------+ |
 |      ^                                 ^                          |
 |      |                                 |                          |
 |      v                                 v                          |
 | +----------------------------------------------+                  |
 | |             MIB instrumentation              |      SNMP entity |
 +-------------------------------------------------------------------+

3.1. Security Capabilities of This Model

3.1.1. Threats

 The TLS Transport Model provides protection against the threats
 identified by the RFC 3411 architecture [RFC3411]:
 1.  Modification of Information - The modification threat is the
     danger that an unauthorized entity may alter in-transit SNMP
     messages generated on behalf of an authorized principal in such a
     way as to effect unauthorized management operations, including
     falsifying the value of an object.
     (D)TLS provides verification that the content of each received
     message has not been modified during its transmission through the
     network, data has not been altered or destroyed in an
     unauthorized manner, and data sequences have not been altered to
     an extent greater than can occur non-maliciously.
 2.  Masquerade - The masquerade threat is the danger that management
     operations unauthorized for a given principal may be attempted by
     assuming the identity of another principal that has the
     appropriate authorizations.
     The TLSTM verifies the identity of the (D)TLS server through the
     use of the (D)TLS protocol and X.509 certificates.  A TLS
     Transport Model implementation MUST support the authentication of
     both the server and the client.
 3.  Message stream modification - The re-ordering, delay, or replay
     of messages can and does occur through the natural operation of
     many connectionless transport services.  The message stream
     modification threat is the danger that messages may be
     maliciously re-ordered, delayed, or replayed to an extent that is
     greater than can occur through the natural operation of

Hardaker Standards Track [Page 11] RFC 6353 TLS Transport Model for SNMP July 2011

     connectionless transport services, in order to effect
     unauthorized management operations.
     (D)TLS provides replay protection with a Message Authentication
     Code (MAC) that includes a sequence number.  Since UDP provides
     no sequencing ability, DTLS uses a sliding window protocol with
     the sequence number used for replay protection (see [RFC4347]).
 4.  Disclosure - The disclosure threat is the danger of eavesdropping
     on the exchanges between SNMP engines.
     (D)TLS provides protection against the disclosure of information
     to unauthorized recipients or eavesdroppers by allowing for
     encryption of all traffic between SNMP engines.  A TLS Transport
     Model implementation MUST support message encryption to protect
     sensitive data from eavesdropping attacks.
 5.  Denial of Service - The RFC 3411 architecture [RFC3411] states
     that denial-of-service (DoS) attacks need not be addressed by an
     SNMP security protocol.  However, connectionless transports (like
     DTLS over UDP) are susceptible to a variety of DoS attacks
     because they are more vulnerable to spoofed IP addresses.  See
     Section 4.2 for details on how the cookie mechanism is used.
     Note, however, that this mechanism does not provide any defense
     against DoS attacks mounted from valid IP addresses.
 See Section 9 for more detail on the security considerations
 associated with the TLSTM and these security threats.

3.1.2. Message Protection

 The RFC 3411 architecture recognizes three levels of security:
 o  without authentication and without privacy (noAuthNoPriv)
 o  with authentication but without privacy (authNoPriv)
 o  with authentication and with privacy (authPriv)
 The TLS Transport Model determines from (D)TLS the identity of the
 authenticated principal, the transport type, and the transport
 address associated with an incoming message.  The TLS Transport Model
 provides the identity and destination type and address to (D)TLS for
 outgoing messages.
 When an application requests a session for a message, it also
 requests a security level for that session.  The TLS Transport Model
 MUST ensure that the (D)TLS connection provides security at least as

Hardaker Standards Track [Page 12] RFC 6353 TLS Transport Model for SNMP July 2011

 high as the requested level of security.  How the security level is
 translated into the algorithms used to provide data integrity and
 privacy is implementation dependent.  However, the NULL integrity and
 encryption algorithms MUST NOT be used to fulfill security level
 requests for authentication or privacy.  Implementations MAY choose
 to force (D)TLS to only allow cipher_suites that provide both
 authentication and privacy to guarantee this assertion.
 If a suitable interface between the TLS Transport Model and the
 (D)TLS Handshake Protocol is implemented to allow the selection of
 security-level-dependent algorithms (for example, a security level to
 cipher_suites mapping table), then different security levels may be
 utilized by the application.
 The authentication, integrity, and privacy algorithms used by the
 (D)TLS Protocols may vary over time as the science of cryptography
 continues to evolve and the development of (D)TLS continues over
 time.  Implementers are encouraged to plan for changes in operator
 trust of particular algorithms.  Implementations SHOULD offer
 configuration settings for mapping algorithms to SNMPv3 security
 levels.

3.1.3. (D)TLS Connections

 (D)TLS connections are opened by the TLS Transport Model during the
 elements of procedure for an outgoing SNMP message.  Since the sender
 of a message initiates the creation of a (D)TLS connection if needed,
 the (D)TLS connection will already exist for an incoming message.
 Implementations MAY choose to instantiate (D)TLS connections in
 anticipation of outgoing messages.  This approach might be useful to
 ensure that a (D)TLS connection to a given target can be established
 before it becomes important to send a message over the (D)TLS
 connection.  Of course, there is no guarantee that a pre-established
 session will still be valid when needed.
 DTLS connections, when used over UDP, are uniquely identified within
 the TLS Transport Model by the combination of transportDomain,
 transportAddress, tmSecurityName, and requestedSecurityLevel
 associated with each session.  Each unique combination of these
 parameters MUST have a locally chosen unique tlstmSessionID for each
 active session.  For further information, see Section 5.  TLS over
 TCP sessions, on the other hand, do not require a unique pairing of
 address and port attributes since their lower-layer protocols (TCP)
 already provide adequate session framing.  But they must still
 provide a unique tlstmSessionID for referencing the session.

Hardaker Standards Track [Page 13] RFC 6353 TLS Transport Model for SNMP July 2011

 The tlstmSessionID MUST NOT change during the entire duration of the
 session from the TLSTM's perspective, and MUST uniquely identify a
 single session.  As an implementation hint: note that the (D)TLS
 internal SessionID does not meet these requirements, since it can
 change over the life of the connection as seen by the TLSTM (for
 example, during renegotiation), and does not necessarily uniquely
 identify a TLSTM session (there can be multiple TLSTM sessions
 sharing the same D(TLS) internal SessionID).

3.2. Security Parameter Passing

 For the (D)TLS server-side, (D)TLS-specific security parameters
 (i.e., cipher_suites, X.509 certificate fields, IP addresses, and
 ports) are translated by the TLS Transport Model into security
 parameters for the TLS Transport Model and security model (e.g.,
 tmSecurityLevel, tmSecurityName, transportDomain, transportAddress).
 The transport-related and (D)TLS-security-related information,
 including the authenticated identity, are stored in a cache
 referenced by tmStateReference.
 For the (D)TLS client side, the TLS Transport Model takes input
 provided by the Dispatcher in the sendMessage() Abstract Service
 Interface (ASI) and input from the tmStateReference cache.  The
 (D)TLS Transport Model converts that information into suitable
 security parameters for (D)TLS and establishes sessions as needed.
 The elements of procedure in Section 5 discuss these concepts in much
 greater detail.

3.3. Notifications and Proxy

 (D)TLS connections may be initiated by (D)TLS clients on behalf of
 SNMP applications that initiate communications, such as command
 generators, notification originators, proxy forwarders.  Command
 generators are frequently operated by a human, but notification
 originators and proxy forwarders are usually unmanned automated
 processes.  The targets to whom notifications and proxied requests
 should be sent are typically determined and configured by a network
 administrator.
 The SNMP-TARGET-MIB module [RFC3413] contains objects for defining
 management targets, including transportDomain, transportAddress,
 securityName, securityModel, and securityLevel parameters, for
 notification originator, proxy forwarder, and SNMP-controllable
 command generator applications.  Transport domains and transport
 addresses are configured in the snmpTargetAddrTable, and the
 securityModel, securityName, and securityLevel parameters are
 configured in the snmpTargetParamsTable.  This document defines a MIB

Hardaker Standards Track [Page 14] RFC 6353 TLS Transport Model for SNMP July 2011

 module that extends the SNMP-TARGET-MIB's snmpTargetParamsTable to
 specify a (D)TLS client-side certificate to use for the connection.
 When configuring a (D)TLS target, the snmpTargetAddrTDomain and
 snmpTargetAddrTAddress parameters in snmpTargetAddrTable SHOULD be
 set to the snmpTLSTCPDomain or snmpDTLSUDPDomain object and an
 appropriate snmpTLSAddress value.  When used with the SNMPv3 message
 processing model, the snmpTargetParamsMPModel column of the
 snmpTargetParamsTable SHOULD be set to a value of 3.  The
 snmpTargetParamsSecurityName SHOULD be set to an appropriate
 securityName value, and the snmpTlstmParamsClientFingerprint
 parameter of the snmpTlstmParamsTable SHOULD be set to a value that
 refers to a locally held certificate (and the corresponding private
 key) to be used.  Other parameters, for example, cryptographic
 configuration such as which cipher_suites to use, must come from
 configuration mechanisms not defined in this document.
 The securityName defined in the snmpTargetParamsSecurityName column
 will be used by the access control model to authorize any
 notifications that need to be sent.

4. Elements of the Model

 This section contains definitions required to realize the (D)TLS
 Transport Model defined by this document.

4.1. X.509 Certificates

 (D)TLS can make use of X.509 certificates for authentication of both
 sides of the transport.  This section discusses the use of X.509
 certificates in the TLSTM.
 While (D)TLS supports multiple authentication mechanisms, this
 document only discusses X.509-certificate-based authentication; other
 forms of authentication are outside the scope of this specification.
 TLSTM implementations are REQUIRED to support X.509 certificates.

4.1.1. Provisioning for the Certificate

 Authentication using (D)TLS will require that SNMP entities have
 certificates, either signed by trusted Certification Authorities
 (CAs), or self signed.  Furthermore, SNMP entities will most commonly
 need to be provisioned with root certificates that represent the list
 of trusted CAs that an SNMP entity can use for certificate
 verification.  SNMP entities SHOULD also be provisioned with an X.509
 certificate revocation mechanism which can be used to verify that a
 certificate has not been revoked.  Trusted public keys from either CA
 certificates and/or self-signed certificates MUST be installed into

Hardaker Standards Track [Page 15] RFC 6353 TLS Transport Model for SNMP July 2011

 the server through a trusted out-of-band mechanism and their
 authenticity MUST be verified before access is granted.
 Having received a certificate from a connecting TLSTM client, the
 authenticated tmSecurityName of the principal is derived using the
 snmpTlstmCertToTSNTable.  This table allows mapping of incoming
 connections to tmSecurityNames through defined transformations.  The
 transformations defined in the SNMP-TLS-TM-MIB include:
 o  Mapping a certificate's subjectAltName or CommonName components to
    a tmSecurityName, or
 o  Mapping a certificate's fingerprint value to a directly specified
    tmSecurityName
 As an implementation hint: implementations may choose to discard any
 connections for which no potential snmpTlstmCertToTSNTable mapping
 exists before performing certificate verification to avoid expending
 computational resources associated with certificate verification.
 Deployments SHOULD map the "subjectAltName" component of X.509
 certificates to the TLSTM specific tmSecurityNames.  The
 authenticated identity can be obtained by the TLS Transport Model by
 extracting the subjectAltName(s) from the peer's certificate.  The
 receiving application will then have an appropriate tmSecurityName
 for use by other SNMPv3 components like an access control model.
 An example of this type of mapping setup can be found in Appendix A.
 This tmSecurityName may be later translated from a TLSTM specific
 tmSecurityName to an SNMP engine securityName by the security model.
 A security model, like the TSM security model [RFC5591], may perform
 an identity mapping or a more complex mapping to derive the
 securityName from the tmSecurityName offered by the TLS Transport
 Model.
 The standard View-Based Access Control Model (VACM) access control
 model constrains securityNames to be 32 octets or less in length.  A
 TLSTM generated tmSecurityName, possibly in combination with a
 messaging or security model that increases the length of the
 securityName, might cause the securityName length to exceed 32
 octets.  For example, a 32-octet tmSecurityName derived from an IPv6
 address, paired with a TSM prefix, will generate a 36-octet
 securityName.  Such a securityName will not be able to be used with
 standard VACM or TARGET MIB modules.  Operators should be careful to
 select algorithms and subjectAltNames to avoid this situation.

Hardaker Standards Track [Page 16] RFC 6353 TLS Transport Model for SNMP July 2011

 A pictorial view of the complete transformation process (using the
 TSM security model for the example) is shown below:
  +-------------+     +-------+                   +-----+
  | Certificate |     |       |                   |     |
  |    Path     |     | TLSTM |  tmSecurityName   | TSM |
  | Validation  | --> |       | ----------------->|     |
  +-------------+     +-------+                   +-----+
                                                      |
                                                      | securityName
                                                      V
                                                  +-------------+
                                                  | application |
                                                  +-------------+

4.2. (D)TLS Usage

 (D)TLS MUST negotiate a cipher_suite that uses X.509 certificates for
 authentication, and MUST authenticate both the client and the server.
 The mandatory-to-implement cipher_suite is specified in the TLS
 specification [RFC5246].
 TLSTM verifies the certificates when the connection is opened (see
 Section 5.3).  For this reason, TLS renegotiation with different
 certificates MUST NOT be done.  That is, implementations MUST either
 disable renegotiation completely (RECOMMENDED), or they MUST present
 the same certificate during renegotiation (and MUST verify that the
 other end presented the same certificate).
 For DTLS over UDP, each SNMP message MUST be placed in a single UDP
 datagram; it MAY be split to multiple DTLS records.  In other words,
 if a single datagram contains multiple DTLS application_data records,
 they are concatenated when received.  The TLSTM implementation SHOULD
 return an error if the SNMP message does not fit in the UDP datagram,
 and thus cannot be sent.
 For DTLS over UDP, the DTLS server implementation MUST support DTLS
 cookies ([RFC4347] already requires that clients support DTLS
 cookies).  Implementations are not required to perform the cookie
 exchange for every DTLS handshake; however, enabling it by default is
 RECOMMENDED.
 For DTLS, replay protection MUST be used.

Hardaker Standards Track [Page 17] RFC 6353 TLS Transport Model for SNMP July 2011

4.3. SNMP Services

 This section describes the services provided by the TLS Transport
 Model with their inputs and outputs.  The services are between the
 Transport Model and the Dispatcher.
 The services are described as primitives of an abstract service
 interface (ASI) and the inputs and outputs are described as abstract
 data elements as they are passed in these abstract service
 primitives.

4.3.1. SNMP Services for an Outgoing Message

 The Dispatcher passes the information to the TLS Transport Model
 using the ASI defined in the Transport Subsystem:
    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
     )
 The abstract data elements returned from or passed as parameters into
 the abstract service primitives are as follows:
 statusInformation:  An indication of whether the sending of the
    message was successful.  If not, it is an indication of the
    problem.
 destTransportDomain:  The transport domain for the associated
    destTransportAddress.  The Transport Model uses this parameter to
    determine the transport type of the associated
    destTransportAddress.  This document specifies the
    snmpTLSTCPDomain and the snmpDTLSUDPDomain transport domains.
 destTransportAddress:  The transport address of the destination TLS
    Transport Model in a format specified by the SnmpTLSAddress
    TEXTUAL-CONVENTION.
 outgoingMessage:  The outgoing message to send to (D)TLS for
    encapsulation and transmission.
 outgoingMessageLength:  The length of the outgoingMessage.

Hardaker Standards Track [Page 18] RFC 6353 TLS Transport Model for SNMP July 2011

 tmStateReference:  A reference used to pass model-specific and
    mechanism-specific parameters between the Transport Subsystem and
    transport-aware Security Models.

4.3.2. SNMP Services for an Incoming Message

 The TLS Transport Model processes the received message from the
 network using the (D)TLS service and then passes it to the Dispatcher
 using the following ASI:
    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 abstract data elements returned from or passed as parameters into
 the abstract service primitives are as follows:
 statusInformation:  An indication of whether the passing of the
    message was successful.  If not, it is an indication of the
    problem.
 transportDomain:  The transport domain for the associated
    transportAddress.  This document specifies the snmpTLSTCPDomain
    and the snmpDTLSUDPDomain transport domains.
 transportAddress:  The transport address of the source of the
    received message in a format specified by the SnmpTLSAddress
    TEXTUAL-CONVENTION.
 incomingMessage:  The whole SNMP message after being processed by
    (D)TLS.
 incomingMessageLength:  The length of the incomingMessage.
 tmStateReference:  A reference used to pass model-specific and
    mechanism-specific parameters between the Transport Subsystem and
    transport-aware Security Models.

Hardaker Standards Track [Page 19] RFC 6353 TLS Transport Model for SNMP July 2011

4.4. Cached Information and References

 When performing SNMP processing, there are two levels of state
 information that may need to be retained: the immediate state linking
 a request-response pair, and potentially longer-term state relating
 to transport and security.  "Transport Subsystem for the Simple
 Network Management Protocol (SNMP)" [RFC5590] defines general
 requirements for caches and references.

4.4.1. TLS Transport Model Cached Information

 The TLS Transport Model has specific responsibilities regarding the
 cached information.  See the Elements of Procedure in Section 5 for
 detailed processing instructions on the use of the tmStateReference
 fields by the TLS Transport Model.

4.4.1.1. tmSecurityName

 The tmSecurityName MUST be a human-readable name (in snmpAdminString
 format) representing the identity that has been set according to the
 procedures in Section 5.  The tmSecurityName MUST be constant for all
 traffic passing through a single TLSTM session.  Messages MUST NOT be
 sent through an existing (D)TLS connection that was established using
 a different tmSecurityName.
 On the (D)TLS server side of a connection, the tmSecurityName is
 derived using the procedures described in Section 5.3.2 and the SNMP-
 TLS-TM-MIB's snmpTlstmCertToTSNTable DESCRIPTION clause.
 On the (D)TLS client side of a connection, the tmSecurityName is
 presented to the TLS Transport Model by the security model through
 the tmStateReference.  This tmSecurityName is typically a copy of or
 is derived from the securityName that was passed by application
 (possibly because of configuration specified in the SNMP-TARGET-MIB).
 The Security Model likely derived the tmSecurityName from the
 securityName presented to the Security Model by the application
 (possibly because of configuration specified in the SNMP-TARGET-MIB).
 Transport-Model-aware security models derive tmSecurityName from a
 securityName, possibly configured in MIB modules for notifications
 and access controls.  Transport Models SHOULD use predictable
 tmSecurityNames so operators will know what to use when configuring
 MIB modules that use securityNames derived from tmSecurityNames.  The
 TLSTM generates predictable tmSecurityNames based on the
 configuration found in the SNMP-TLS-TM-MIB's snmpTlstmCertToTSNTable
 and relies on the network operators to have configured this table
 appropriately.

Hardaker Standards Track [Page 20] RFC 6353 TLS Transport Model for SNMP July 2011

4.4.1.2. tmSessionID

 The tmSessionID MUST be recorded per message at the time of receipt.
 When tmSameSecurity is set, the recorded tmSessionID can be used to
 determine whether the (D)TLS connection available for sending a
 corresponding outgoing message is the same (D)TLS connection as was
 used when receiving the incoming message (e.g., a response to a
 request).

4.4.1.3. Session State

 The per-session state that is referenced by tmStateReference may be
 saved across multiple messages in a Local Configuration Datastore.
 Additional session/connection state information might also be stored
 in a Local Configuration Datastore.

5. Elements of Procedure

 Abstract service interfaces have been defined by [RFC3411] and
 further augmented by [RFC5590] to describe the conceptual data flows
 between the various subsystems within an SNMP entity.  The TLSTM uses
 some of these conceptual data flows when communicating between
 subsystems.
 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 gets discarded, the
 message-state information should also be released.  If state
 information is available when a session is closed, the session state
 information should also be released.  Sensitive information, like
 cryptographic keys, should be overwritten appropriately prior to
 being released.
 An error indication in statusInformation will typically include the
 Object Identifier (OID) and value for an incremented error counter.
 This may be accompanied by the requested securityLevel and the
 tmStateReference.  Per-message context information is not accessible
 to Transport Models, so for the returned counter OID and value,
 contextEngine would be set to the local value of snmpEngineID and
 contextName to the default context for error counters.

5.1. Procedures for an Incoming Message

 This section describes the procedures followed by the (D)TLS
 Transport Model when it receives a (D)TLS protected packet.  The
 required functionality is broken into two different sections.

Hardaker Standards Track [Page 21] RFC 6353 TLS Transport Model for SNMP July 2011

 Section 5.1.1 describes the processing required for de-multiplexing
 multiple DTLS connections, which is specifically needed for DTLS over
 UDP sessions.  It is assumed that TLS protocol implementations
 already provide appropriate message demultiplexing.
 Section 5.1.2 describes the transport processing required once the
 (D)TLS processing has been completed.  This will be needed for all
 (D)TLS-based connections.

5.1.1. DTLS over UDP Processing for Incoming Messages

 Demultiplexing of incoming packets into separate DTLS sessions MUST
 be implemented.  For connection-oriented transport protocols, such as
 TCP, the transport protocol takes care of demultiplexing incoming
 packets to the right connection.  For DTLS over UDP, this
 demultiplexing will either need to be done within the DTLS
 implementation, if supported, or by the TLSTM implementation.
 Like TCP, DTLS over UDP uses the four-tuple <source IP, destination
 IP, source port, destination port> for identifying the connection
 (and relevant DTLS connection state).  This means that when
 establishing a new session, implementations MUST use a different UDP
 source port number for each active connection to a remote destination
 IP-address/port-number combination to ensure the remote entity can
 disambiguate between multiple connections.
 If demultiplexing received UDP datagrams to DTLS connection state is
 done by the TLSTM implementation (instead of the DTLS
 implementation), the steps below describe one possible method to
 accomplish this.
 The important output results from the steps in this process are the
 remote transport address, incomingMessage, incomingMessageLength, and
 the tlstmSessionID.
 1)  The TLS Transport Model examines the raw UDP message, in an
     implementation-dependent manner.
 2)  The TLS Transport Model queries the Local Configuration Datastore
     (LCD) (see [RFC3411], Section 3.4.2) using the transport
     parameters (source and destination IP addresses and ports) to
     determine if a session already exists.
     2a)  If a matching entry in the LCD does not exist, then the UDP
          packet is passed to the DTLS implementation for processing.
          If the DTLS implementation decides to continue with the
          connection and allocate state for it, it returns a new DTLS
          connection handle (an implementation dependent detail).  In

Hardaker Standards Track [Page 22] RFC 6353 TLS Transport Model for SNMP July 2011

          this case, TLSTM selects a new tlstmSessionId, and caches
          this and the DTLS connection handle as a new entry in the
          LCD (indexed by the transport parameters).  If the DTLS
          implementation returns an error or does not allocate
          connection state (which can happen with the stateless cookie
          exchange), processing stops.
     2b)  If a session does exist in the LCD, then its DTLS connection
          handle (an implementation dependent detail) and its
          tlstmSessionId is extracted from the LCD.  The UDP packet
          and the connection handle are passed to the DTLS
          implementation.  If the DTLS implementation returns success
          but does not return an incomingMessage and an
          incomingMessageLength, then processing stops (this is the
          case when the UDP datagram contained DTLS handshake
          messages, for example).  If the DTLS implementation returns
          an error, then processing stops.
 3)  Retrieve the incomingMessage and an incomingMessageLength from
     DTLS.  These results and the tlstmSessionID are used below in
     Section 5.1.2 to complete the processing of the incoming message.

5.1.2. Transport Processing for Incoming SNMP Messages

 The procedures in this section describe how the TLS Transport Model
 should process messages that have already been properly extracted
 from the (D)TLS stream.  Note that care must be taken when processing
 messages originating from either TLS or DTLS to ensure they're
 complete and single.  For example, multiple SNMP messages can be
 passed through a single DTLS message and partial SNMP messages may be
 received from a TLS stream.  These steps describe the processing of a
 singular SNMP message after it has been delivered from the (D)TLS
 stream.
 1)  Determine the tlstmSessionID for the incoming message.  The
     tlstmSessionID MUST be a unique session identifier for this
     (D)TLS connection.  The contents and format of this identifier
     are implementation dependent as long as it is unique to the
     session.  A session identifier MUST NOT be reused until all
     references to it are no longer in use.  The tmSessionID is equal
     to the tlstmSessionID discussed in Section 5.1.1. tmSessionID
     refers to the session identifier when stored in the
     tmStateReference and tlstmSessionID refers to the session
     identifier when stored in the LCD.  They MUST always be equal
     when processing a given session's traffic.

Hardaker Standards Track [Page 23] RFC 6353 TLS Transport Model for SNMP July 2011

     If this is the first message received through this session, and
     the session does not have an assigned tlstmSessionID yet, then
     the snmpTlstmSessionAccepts counter is incremented and a
     tlstmSessionID for the session is created.  This will only happen
     on the server side of a connection because a client would have
     already assigned a tlstmSessionID during the openSession()
     invocation.  Implementations may have performed the procedures
     described in Section 5.3.2 prior to this point or they may
     perform them now, but the procedures described in Section 5.3.2
     MUST be performed before continuing beyond this point.
 2)  Create a tmStateReference cache for the subsequent reference and
     assign the following values within it:
     tmTransportDomain  = snmpTLSTCPDomain or snmpDTLSUDPDomain as
        appropriate.
     tmTransportAddress  = The address from which the message
        originated.
     tmSecurityLevel  = The derived tmSecurityLevel for the session,
        as discussed in Sections 3.1.2 and 5.3.
     tmSecurityName  = The derived tmSecurityName for the session as
        discussed in Section 5.3.  This value MUST be constant during
        the lifetime of the session.
     tmSessionID  = The tlstmSessionID described in step 1 above.
 3)  The incomingMessage and incomingMessageLength are assigned values
     from the (D)TLS processing.
 4)  The TLS Transport Model passes the transportDomain,
     transportAddress, incomingMessage, and incomingMessageLength to
     the Dispatcher using the receiveMessage ASI:
    statusInformation =
    receiveMessage(
    IN   transportDomain     -- snmpTLSTCPDomain or snmpDTLSUDPDomain,
    IN   transportAddress    -- address for the received message
    IN   incomingMessage        -- the whole SNMP message from (D)TLS
    IN   incomingMessageLength  -- the length of the SNMP message
    IN   tmStateReference    -- transport info
     )

Hardaker Standards Track [Page 24] RFC 6353 TLS Transport Model for SNMP July 2011

5.2. Procedures for an Outgoing SNMP Message

 The Dispatcher sends a message to the TLS Transport Model using the
 following ASI:
    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              -- transport info
    )
 This section describes the procedure followed by the TLS Transport
 Model whenever it is requested through this ASI to send a message.
 1)  If tmStateReference does not refer to a cache containing values
     for tmTransportDomain, tmTransportAddress, tmSecurityName,
     tmRequestedSecurityLevel, and tmSameSecurity, then increment the
     snmpTlstmSessionInvalidCaches counter, discard the message, and
     return the error indication in the statusInformation.  Processing
     of this message stops.
 2)  Extract the tmSessionID, tmTransportDomain, tmTransportAddress,
     tmSecurityName, tmRequestedSecurityLevel, and tmSameSecurity
     values from the tmStateReference.  Note: the tmSessionID value
     may be undefined if no session exists yet over which the message
     can be sent.
 3)  If tmSameSecurity is true and tmSessionID is either undefined or
     refers to a session that is no longer open, then increment the
     snmpTlstmSessionNoSessions counter, discard the message, and
     return the error indication in the statusInformation.  Processing
     of this message stops.
 4)  If tmSameSecurity is false and tmSessionID refers to a session
     that is no longer available, then an implementation SHOULD open a
     new session, using the openSession() ASI (described in greater
     detail in step 5b).  Instead of opening a new session an
     implementation MAY return an snmpTlstmSessionNoSessions error to
     the calling module and stop the processing of the message.
 5)  If tmSessionID is undefined, then use tmTransportDomain,
     tmTransportAddress, tmSecurityName, and tmRequestedSecurityLevel
     to see if there is a corresponding entry in the LCD suitable to
     send the message over.

Hardaker Standards Track [Page 25] RFC 6353 TLS Transport Model for SNMP July 2011

     5a)  If there is a corresponding LCD entry, then this session
          will be used to send the message.
     5b)  If there is no corresponding LCD entry, then open a session
          using the openSession() ASI (discussed further in
          Section 5.3.1).  Implementations MAY wish to offer message
          buffering to prevent redundant openSession() calls for the
          same cache entry.  If an error is returned from
          openSession(), then discard the message, discard the
          tmStateReference, increment the snmpTlstmSessionOpenErrors,
          return an error indication to the calling module, and stop
          the processing of the message.
 6)  Using either the session indicated by the tmSessionID (if there
     was one) or the session resulting from a previous step (4 or 5),
     pass the outgoingMessage to (D)TLS for encapsulation and
     transmission.

5.3. Establishing or Accepting a Session

 Establishing a (D)TLS connection as either a client or a server
 requires slightly different processing.  The following two sections
 describe the necessary processing steps.

5.3.1. Establishing a Session as a Client

 The TLS Transport Model provides the following primitive for use by a
 client to establish a new (D)TLS connection:
 statusInformation =           -- errorIndication or success
 openSession(
 IN   tmStateReference         -- transport information to be used
 OUT  tmStateReference         -- transport information to be used
 IN   maxMessageSize           -- of the sending SNMP entity
 )
 The following describes the procedure to follow when establishing an
 SNMP over a (D)TLS connection between SNMP engines for exchanging
 SNMP messages.  This process is followed by any SNMP client's engine
 when establishing a session for subsequent use.
 This procedure MAY be done automatically for an SNMP application that
 initiates a transaction, such as a command generator, a notification
 originator, or a proxy forwarder.
 1)  The snmpTlstmSessionOpens counter is incremented.

Hardaker Standards Track [Page 26] RFC 6353 TLS Transport Model for SNMP July 2011

 2)  The client selects the appropriate certificate and cipher_suites
     for the key agreement based on the tmSecurityName and the
     tmRequestedSecurityLevel for the session.  For sessions being
     established as a result of an SNMP-TARGET-MIB based operation,
     the certificate will potentially have been identified via the
     snmpTlstmParamsTable mapping and the cipher_suites will have to
     be taken from a system-wide or implementation-specific
     configuration.  If no row in the snmpTlstmParamsTable exists,
     then implementations MAY choose to establish the connection using
     a default client certificate available to the application.
     Otherwise, the certificate and appropriate cipher_suites will
     need to be passed to the openSession() ASI as supplemental
     information or configured through an implementation-dependent
     mechanism.  It is also implementation-dependent and possibly
     policy-dependent how tmRequestedSecurityLevel will be used to
     influence the security capabilities provided by the (D)TLS
     connection.  However this is done, the security capabilities
     provided by (D)TLS MUST be at least as high as the level of
     security indicated by the tmRequestedSecurityLevel parameter.
     The actual security level of the session is reported in the
     tmStateReference cache as tmSecurityLevel.  For (D)TLS to provide
     strong authentication, each principal acting as a command
     generator SHOULD have its own certificate.
 3)  Using the destTransportDomain and destTransportAddress values,
     the client will initiate the (D)TLS handshake protocol to
     establish session keys for message integrity and encryption.
     If the attempt to establish a session is unsuccessful, then
     snmpTlstmSessionOpenErrors is incremented, an error indication is
     returned, and processing stops.  If the session failed to open
     because the presented server certificate was unknown or invalid,
     then the snmpTlstmSessionUnknownServerCertificate or
     snmpTlstmSessionInvalidServerCertificates MUST be incremented and
     an snmpTlstmServerCertificateUnknown or
     snmpTlstmServerInvalidCertificate notification SHOULD be sent as
     appropriate.  Reasons for server certificate invalidation
     include, but are not limited to, cryptographic validation
     failures and an unexpected presented certificate identity.
 4)  The (D)TLS client MUST then verify that the (D)TLS server's
     presented certificate is the expected certificate.  The (D)TLS
     client MUST NOT transmit SNMP messages until the server
     certificate has been authenticated, the client certificate has
     been transmitted, and the TLS connection has been fully
     established.

Hardaker Standards Track [Page 27] RFC 6353 TLS Transport Model for SNMP July 2011

     If the connection is being established from a configuration based
     on SNMP-TARGET-MIB configuration, then the snmpTlstmAddrTable
     DESCRIPTION clause describes how the verification is done (using
     either a certificate fingerprint, or an identity authenticated
     via certification path validation).
     If the connection is being established for reasons other than
     configuration found in the SNMP-TARGET-MIB, then configuration
     and procedures outside the scope of this document should be
     followed.  Configuration mechanisms SHOULD be similar in nature
     to those defined in the snmpTlstmAddrTable to ensure consistency
     across management configuration systems.  For example, a command-
     line tool for generating SNMP GETs might support specifying
     either the server's certificate fingerprint or the expected host
     name as a command-line argument.
 5)  (D)TLS provides assurance that the authenticated identity has
     been signed by a trusted configured Certification Authority.  If
     verification of the server's certificate fails in any way (for
     example, because of failures in cryptographic verification or the
     presented identity did not match the expected named entity), then
     the session establishment MUST fail, and the
     snmpTlstmSessionInvalidServerCertificates object is incremented.
     If the session cannot be opened for any reason at all, including
     cryptographic verification failures and snmpTlstmCertToTSNTable
     lookup failures, then the snmpTlstmSessionOpenErrors counter is
     incremented and processing stops.
 6)  The TLSTM-specific session identifier (tlstmSessionID) is set in
     the tmSessionID of the tmStateReference passed to the TLS
     Transport Model to indicate that the session has been established
     successfully and to point to a specific (D)TLS connection for
     future use.  The tlstmSessionID is also stored in the LCD for
     later lookup during processing of incoming messages
     (Section 5.1.2).

5.3.2. Accepting a Session as a Server

 A (D)TLS server should accept new session connections from any client
 for which it is able to verify the client's credentials.  This is
 done by authenticating the client's presented certificate through a
 certificate path validation process (e.g., [RFC5280]) or through
 certificate fingerprint verification using fingerprints configured in
 the snmpTlstmCertToTSNTable.  Afterward, the server will determine
 the identity of the remote entity using the following procedures.

Hardaker Standards Track [Page 28] RFC 6353 TLS Transport Model for SNMP July 2011

 The (D)TLS server identifies the authenticated identity from the
 (D)TLS client's principal certificate using configuration information
 from the snmpTlstmCertToTSNTable mapping table.  The (D)TLS server
 MUST request and expect a certificate from the client and MUST NOT
 accept SNMP messages over the (D)TLS connection until the client has
 sent a certificate and it has been authenticated.  The resulting
 derived tmSecurityName is recorded in the tmStateReference cache as
 tmSecurityName.  The details of the lookup process are fully
 described in the DESCRIPTION clause of the snmpTlstmCertToTSNTable
 MIB object.  If any verification fails in any way (for example,
 because of failures in cryptographic verification or because of the
 lack of an appropriate row in the snmpTlstmCertToTSNTable), then the
 session establishment MUST fail, and the
 snmpTlstmSessionInvalidClientCertificates object is incremented.  If
 the session cannot be opened for any reason at all, including
 cryptographic verification failures, then the
 snmpTlstmSessionOpenErrors counter is incremented and processing
 stops.
 Servers that wish to support multiple principals at a particular port
 SHOULD make use of a (D)TLS extension that allows server-side
 principal selection like the Server Name Indication extension defined
 in Section 3.1 of [RFC4366].  Supporting this will allow, for
 example, sending notifications to a specific principal at a given TCP
 or UDP port.

5.4. Closing a Session

 The TLS Transport Model provides the following primitive to close a
 session:
 statusInformation =
 closeSession(
 IN  tmSessionID        -- session ID of the session to be closed
 )
 The following describes the procedure to follow to close a session
 between a client and server.  This process is followed by any SNMP
 engine closing the corresponding SNMP session.
 1)  Increment either the snmpTlstmSessionClientCloses or the
     snmpTlstmSessionServerCloses counter as appropriate.
 2)  Look up the session using the tmSessionID.
 3)  If there is no open session associated with the tmSessionID, then
     closeSession processing is completed.

Hardaker Standards Track [Page 29] RFC 6353 TLS Transport Model for SNMP July 2011

 4)  Have (D)TLS close the specified connection.  This MUST include
     sending a close_notify TLS Alert to inform the other side that
     session cleanup may be performed.

6. MIB Module Overview

 This MIB module provides management of the TLS Transport Model.  It
 defines needed textual conventions, statistical counters,
 notifications, and configuration infrastructure necessary for session
 establishment.  Example usage of the configuration tables can be
 found in Appendix A.

6.1. Structure of the MIB Module

 Objects in this MIB module are arranged into subtrees.  Each subtree
 is organized as a set of related objects.  The overall structure and
 assignment of objects to their subtrees, and the intended purpose of
 each subtree, is shown below.

6.2. Textual Conventions

 Generic and Common Textual Conventions used in this module can be
 found summarized at http://www.ops.ietf.org/mib-common-tcs.html.
 This module defines the following new Textual Conventions:
 o  A new TransportAddress format for describing (D)TLS connection
    addressing requirements.
 o  A certificate fingerprint allowing MIB module objects to
    generically refer to a stored X.509 certificate using a
    cryptographic hash as a reference pointer.

6.3. Statistical Counters

 The SNMP-TLS-TM-MIB defines counters that provide network management
 stations with information about session usage and potential errors
 that a device may be experiencing.

6.4. Configuration Tables

 The SNMP-TLS-TM-MIB defines configuration tables that an
 administrator can use for configuring a device for sending and
 receiving SNMP messages over (D)TLS.  In particular, there are MIB
 tables that extend the SNMP-TARGET-MIB for configuring (D)TLS
 certificate usage and a MIB table for mapping incoming (D)TLS client
 certificates to SNMPv3 tmSecurityNames.

Hardaker Standards Track [Page 30] RFC 6353 TLS Transport Model for SNMP July 2011

6.4.1. Notifications

 The SNMP-TLS-TM-MIB defines notifications to alert management
 stations when a (D)TLS connection fails because a server's presented
 certificate did not meet an expected value
 (snmpTlstmServerCertificateUnknown) or because cryptographic
 validation failed (snmpTlstmServerInvalidCertificate).

6.5. Relationship to Other MIB Modules

 Some management objects defined in other MIB modules are applicable
 to an entity implementing the TLS Transport Model.  In particular, it
 is assumed that an entity implementing the SNMP-TLS-TM-MIB will
 implement the SNMPv2-MIB [RFC3418], the SNMP-FRAMEWORK-MIB [RFC3411],
 the SNMP-TARGET-MIB [RFC3413], the SNMP-NOTIFICATION-MIB [RFC3413],
 and the SNMP-VIEW-BASED-ACM-MIB [RFC3415].
 The SNMP-TLS-TM-MIB module contained in this document is for managing
 TLS Transport Model information.

6.5.1. MIB Modules Required for IMPORTS

 The SNMP-TLS-TM-MIB module imports items from SNMPv2-SMI [RFC2578],
 SNMPv2-TC [RFC2579], SNMP-FRAMEWORK-MIB [RFC3411], SNMP-TARGET-MIB
 [RFC3413], and SNMPv2-CONF [RFC2580].

7. MIB Module Definition

SNMP-TLS-TM-MIB DEFINITIONS ::= BEGIN

IMPORTS

  MODULE-IDENTITY, OBJECT-TYPE,
  OBJECT-IDENTITY, mib-2, snmpDomains,
  Counter32, Unsigned32, Gauge32, NOTIFICATION-TYPE
    FROM SNMPv2-SMI                 -- RFC 2578 or any update thereof
  TEXTUAL-CONVENTION, TimeStamp, RowStatus, StorageType,
  AutonomousType
    FROM SNMPv2-TC                  -- RFC 2579 or any update thereof
  MODULE-COMPLIANCE, OBJECT-GROUP, NOTIFICATION-GROUP
    FROM SNMPv2-CONF                -- RFC 2580 or any update thereof
  SnmpAdminString
    FROM SNMP-FRAMEWORK-MIB         -- RFC 3411 or any update thereof
  snmpTargetParamsName, snmpTargetAddrName
    FROM SNMP-TARGET-MIB            -- RFC 3413 or any update thereof
  ;

snmpTlstmMIB MODULE-IDENTITY

  LAST-UPDATED "201107190000Z"

Hardaker Standards Track [Page 31] RFC 6353 TLS Transport Model for SNMP July 2011

  ORGANIZATION "ISMS Working Group"
  CONTACT-INFO "WG-EMail:   isms@lists.ietf.org
                Subscribe:  isms-request@lists.ietf.org
                Chairs:
                   Juergen Schoenwaelder
                   Jacobs University Bremen
                   Campus Ring 1
                   28725 Bremen
                   Germany
                   +49 421 200-3587
                   j.schoenwaelder@jacobs-university.de
                   Russ Mundy
                   SPARTA, Inc.
                   7110 Samuel Morse Drive
                   Columbia, MD  21046
                   USA
                Editor:
                   Wes Hardaker
                   SPARTA, Inc.
                   P.O. Box 382
                   Davis, CA  95617
                   USA
                   ietf@hardakers.net
                "
  DESCRIPTION  "
      The TLS Transport Model MIB
      Copyright (c) 2010-2011 IETF Trust and the persons identified
      as authors of the code.  All rights reserved.
      Redistribution and use in source and binary forms, with or
      without modification, is permitted pursuant to, and subject
      to the license terms contained in, the Simplified BSD License
      set forth in Section 4.c of the IETF Trust's Legal Provisions
      Relating to IETF Documents
      (http://trustee.ietf.org/license-info)."
     REVISION     "201107190000Z"
     DESCRIPTION  "This version of this MIB module is part of
                   RFC 6353; see the RFC itself for full legal
                   notices.  The only change was to introduce
                   new wording to reflect require changes for
                   IDNA addresses in the SnmpTLSAddress TC."

Hardaker Standards Track [Page 32] RFC 6353 TLS Transport Model for SNMP July 2011

     REVISION     "201005070000Z"
     DESCRIPTION  "This version of this MIB module is part of
                   RFC 5953; see the RFC itself for full legal
                   notices."
  ::= { mib-2 198 }

– subtrees of the SNMP-TLS-TM-MIB –

snmpTlstmNotifications OBJECT IDENTIFIER ::= { snmpTlstmMIB 0 } snmpTlstmIdentities OBJECT IDENTIFIER ::= { snmpTlstmMIB 1 } snmpTlstmObjects OBJECT IDENTIFIER ::= { snmpTlstmMIB 2 } snmpTlstmConformance OBJECT IDENTIFIER ::= { snmpTlstmMIB 3 }

– snmpTlstmObjects - Objects –

snmpTLSTCPDomain OBJECT-IDENTITY

  STATUS      current
  DESCRIPTION
      "The SNMP over TLS via TCP transport domain.  The
      corresponding transport address is of type SnmpTLSAddress.
      The securityName prefix to be associated with the
      snmpTLSTCPDomain is 'tls'.  This prefix may be used by
      security models or other components to identify which secure
      transport infrastructure authenticated a securityName."
  REFERENCE
    "RFC 2579: Textual Conventions for SMIv2"
  ::= { snmpDomains 8 }

snmpDTLSUDPDomain OBJECT-IDENTITY

  STATUS      current
  DESCRIPTION
      "The SNMP over DTLS via UDP transport domain.  The
      corresponding transport address is of type SnmpTLSAddress.
      The securityName prefix to be associated with the
      snmpDTLSUDPDomain is 'dtls'.  This prefix may be used by
      security models or other components to identify which secure
      transport infrastructure authenticated a securityName."
  REFERENCE
    "RFC 2579: Textual Conventions for SMIv2"
  ::= { snmpDomains 9 }

Hardaker Standards Track [Page 33] RFC 6353 TLS Transport Model for SNMP July 2011

SnmpTLSAddress ::= TEXTUAL-CONVENTION

  DISPLAY-HINT "1a"
  STATUS       current
  DESCRIPTION
      "Represents an IPv4 address, an IPv6 address, or a
       US-ASCII-encoded hostname and port number.
      An IPv4 address must be in dotted decimal format followed by a
      colon ':' (US-ASCII character 0x3A) and a decimal port number
      in US-ASCII.
      An IPv6 address must be a colon-separated format (as described
      in RFC 5952), surrounded by square brackets ('[', US-ASCII
      character 0x5B, and ']', US-ASCII character 0x5D), followed by
      a colon ':' (US-ASCII character 0x3A) and a decimal port number
      in US-ASCII.
      A hostname is always in US-ASCII (as per RFC 1123);
      internationalized hostnames are encoded as A-labels as specified
      in  RFC 5890.  The hostname is followed by a
      colon ':' (US-ASCII character 0x3A) and a decimal port number
      in US-ASCII.  The name SHOULD be fully qualified whenever
      possible.
      Values of this textual convention may not be directly usable
      as transport-layer addressing information, and may require
      run-time resolution.  As such, applications that write them
      must be prepared for handling errors if such values are not
      supported, or cannot be resolved (if resolution occurs at the
      time of the management operation).
      The DESCRIPTION clause of TransportAddress objects that may
      have SnmpTLSAddress values must fully describe how (and
      when) such names are to be resolved to IP addresses and vice
      versa.
      This textual convention SHOULD NOT be used directly in object
      definitions since it restricts addresses to a specific
      format.  However, if it is used, it MAY be used either on its
      own or in conjunction with TransportAddressType or
      TransportDomain as a pair.
      When this textual convention is used as a syntax of an index
      object, there may be issues with the limit of 128
      sub-identifiers specified in SMIv2 (STD 58).  It is RECOMMENDED
      that all MIB documents using this textual convention make
      explicit any limitations on index component lengths that
      management software must observe.  This may be done either by

Hardaker Standards Track [Page 34] RFC 6353 TLS Transport Model for SNMP July 2011

      including SIZE constraints on the index components or by
      specifying applicable constraints in the conceptual row
      DESCRIPTION clause or in the surrounding documentation."
  REFERENCE
    "RFC 1123: Requirements for Internet Hosts - Application and
               Support
     RFC 5890: Internationalized Domain Names for Applications (IDNA):
               Definitions and Document Framework
     RFC 5952: A Recommendation for IPv6 Address Text Representation
    "
  SYNTAX       OCTET STRING (SIZE (1..255))

SnmpTLSFingerprint ::= TEXTUAL-CONVENTION

  DISPLAY-HINT "1x:1x"
  STATUS       current
  DESCRIPTION
     "A fingerprint value that can be used to uniquely reference
     other data of potentially arbitrary length.
     An SnmpTLSFingerprint value is composed of a 1-octet hashing
     algorithm identifier followed by the fingerprint value.  The
     octet value encoded is taken from the IANA TLS HashAlgorithm
     Registry (RFC 5246).  The remaining octets are filled using the
     results of the hashing algorithm.
     This TEXTUAL-CONVENTION allows for a zero-length (blank)
     SnmpTLSFingerprint value for use in tables where the
     fingerprint value may be optional.  MIB definitions or
     implementations may refuse to accept a zero-length value as
     appropriate."
     REFERENCE "RFC 5246: The Transport Layer
                Security (TLS) Protocol Version 1.2
                http://www.iana.org/assignments/tls-parameters/
     "
  SYNTAX OCTET STRING (SIZE (0..255))

– Identities for use in the snmpTlstmCertToTSNTable

snmpTlstmCertToTSNMIdentities OBJECT IDENTIFIER

  ::= { snmpTlstmIdentities 1 }

snmpTlstmCertSpecified OBJECT-IDENTITY

  STATUS        current
  DESCRIPTION  "Directly specifies the tmSecurityName to be used for
                this certificate.  The value of the tmSecurityName
                to use is specified in the snmpTlstmCertToTSNData
                column.  The snmpTlstmCertToTSNData column must
                contain a non-zero length SnmpAdminString compliant

Hardaker Standards Track [Page 35] RFC 6353 TLS Transport Model for SNMP July 2011

                value or the mapping described in this row must be
                considered a failure."
  ::= { snmpTlstmCertToTSNMIdentities 1 }

snmpTlstmCertSANRFC822Name OBJECT-IDENTITY

  STATUS        current
  DESCRIPTION  "Maps a subjectAltName's rfc822Name to a
                tmSecurityName.  The local part of the rfc822Name is
                passed unaltered but the host-part of the name must
                be passed in lowercase.  This mapping results in a
                1:1 correspondence between equivalent subjectAltName
                rfc822Name values and tmSecurityName values except
                that the host-part of the name MUST be passed in
                lowercase.
                Example rfc822Name Field:  FooBar@Example.COM
                is mapped to tmSecurityName: FooBar@example.com."
  ::= { snmpTlstmCertToTSNMIdentities 2 }

snmpTlstmCertSANDNSName OBJECT-IDENTITY

  STATUS        current
  DESCRIPTION  "Maps a subjectAltName's dNSName to a
                tmSecurityName after first converting it to all
                lowercase (RFC 5280 does not specify converting to
                lowercase so this involves an extra step).  This
                mapping results in a 1:1 correspondence between
                subjectAltName dNSName values and the tmSecurityName
                values."
  REFERENCE "RFC 5280 - Internet X.509 Public Key Infrastructure
                       Certificate and Certificate Revocation
                       List (CRL) Profile."
  ::= { snmpTlstmCertToTSNMIdentities 3 }

snmpTlstmCertSANIpAddress OBJECT-IDENTITY

  STATUS        current
  DESCRIPTION  "Maps a subjectAltName's iPAddress to a
                tmSecurityName by transforming the binary encoded
                address as follows:
                1) for IPv4, the value is converted into a
                   decimal-dotted quad address (e.g., '192.0.2.1').
                2) for IPv6 addresses, the value is converted into a
                   32-character all lowercase hexadecimal string
                   without any colon separators.

Hardaker Standards Track [Page 36] RFC 6353 TLS Transport Model for SNMP July 2011

                This mapping results in a 1:1 correspondence between
                subjectAltName iPAddress values and the
                tmSecurityName values.
                The resulting length of an encoded IPv6 address is
                the maximum length supported by the View-Based
                Access Control Model (VACM).  Using both the
                Transport Security Model's support for transport
                prefixes (see the SNMP-TSM-MIB's
                snmpTsmConfigurationUsePrefix object for details)
                will result in securityName lengths that exceed what
                VACM can handle."
  ::= { snmpTlstmCertToTSNMIdentities 4 }

snmpTlstmCertSANAny OBJECT-IDENTITY

  STATUS        current
  DESCRIPTION  "Maps any of the following fields using the
                corresponding mapping algorithms:
                |------------+----------------------------|
                | Type       | Algorithm                  |
                |------------+----------------------------|
                | rfc822Name | snmpTlstmCertSANRFC822Name |
                | dNSName    | snmpTlstmCertSANDNSName    |
                | iPAddress  | snmpTlstmCertSANIpAddress  |
                |------------+----------------------------|
                The first matching subjectAltName value found in the
                certificate of the above types MUST be used when
                deriving the tmSecurityName.  The mapping algorithm
                specified in the 'Algorithm' column MUST be used to
                derive the tmSecurityName.
                This mapping results in a 1:1 correspondence between
                subjectAltName values and tmSecurityName values.  The
                three sub-mapping algorithms produced by this
                combined algorithm cannot produce conflicting
                results between themselves."
  ::= { snmpTlstmCertToTSNMIdentities 5 }

snmpTlstmCertCommonName OBJECT-IDENTITY

  STATUS        current
  DESCRIPTION  "Maps a certificate's CommonName to a tmSecurityName
                after converting it to a UTF-8 encoding.  The usage
                of CommonNames is deprecated and users are
                encouraged to use subjectAltName mapping methods
                instead.  This mapping results in a 1:1

Hardaker Standards Track [Page 37] RFC 6353 TLS Transport Model for SNMP July 2011

                correspondence between certificate CommonName values
                and tmSecurityName values."
  ::= { snmpTlstmCertToTSNMIdentities 6 }

– The snmpTlstmSession Group

snmpTlstmSession OBJECT IDENTIFIER ::= { snmpTlstmObjects 1 }

snmpTlstmSessionOpens OBJECT-TYPE

  SYNTAX       Counter32
  MAX-ACCESS   read-only
  STATUS       current
  DESCRIPTION
     "The number of times an openSession() request has been executed
     as a (D)TLS client, regardless of whether it succeeded or
     failed."
  ::= { snmpTlstmSession 1 }

snmpTlstmSessionClientCloses OBJECT-TYPE

  SYNTAX       Counter32
  MAX-ACCESS   read-only
  STATUS       current
  DESCRIPTION
      "The number of times a closeSession() request has been
      executed as a (D)TLS client, regardless of whether it
      succeeded or failed."
  ::= { snmpTlstmSession 2 }

snmpTlstmSessionOpenErrors OBJECT-TYPE

  SYNTAX       Counter32
  MAX-ACCESS   read-only
  STATUS       current
  DESCRIPTION
      "The number of times an openSession() request failed to open a
      session as a (D)TLS client, for any reason."
  ::= { snmpTlstmSession 3 }

snmpTlstmSessionAccepts OBJECT-TYPE

  SYNTAX       Counter32
  MAX-ACCESS   read-only
  STATUS       current
  DESCRIPTION
     "The number of times a (D)TLS server has accepted a new
     connection from a client and has received at least one SNMP
     message through it."
  ::= { snmpTlstmSession 4 }

Hardaker Standards Track [Page 38] RFC 6353 TLS Transport Model for SNMP July 2011

snmpTlstmSessionServerCloses OBJECT-TYPE

  SYNTAX       Counter32
  MAX-ACCESS   read-only
  STATUS       current
  DESCRIPTION
      "The number of times a closeSession() request has been
      executed as a (D)TLS server, regardless of whether it
      succeeded or failed."
  ::= { snmpTlstmSession 5 }

snmpTlstmSessionNoSessions OBJECT-TYPE

  SYNTAX       Counter32
  MAX-ACCESS   read-only
  STATUS       current
  DESCRIPTION
      "The number of times an outgoing message was dropped because
      the session associated with the passed tmStateReference was no
      longer (or was never) available."
  ::= { snmpTlstmSession 6 }

snmpTlstmSessionInvalidClientCertificates OBJECT-TYPE

  SYNTAX       Counter32
  MAX-ACCESS   read-only
  STATUS       current
  DESCRIPTION
      "The number of times an incoming session was not established
      on a (D)TLS server because the presented client certificate
      was invalid.  Reasons for invalidation include, but are not
      limited to, cryptographic validation failures or lack of a
      suitable mapping row in the snmpTlstmCertToTSNTable."
  ::= { snmpTlstmSession 7 }

snmpTlstmSessionUnknownServerCertificate OBJECT-TYPE

  SYNTAX       Counter32
  MAX-ACCESS   read-only
  STATUS       current
  DESCRIPTION
      "The number of times an outgoing session was not established
       on a (D)TLS client because the server certificate presented
       by an SNMP over (D)TLS server was invalid because no
       configured fingerprint or Certification Authority (CA) was
       acceptable to validate it.
       This may result because there was no entry in the
       snmpTlstmAddrTable or because no path could be found to a
       known CA."
  ::= { snmpTlstmSession 8 }

Hardaker Standards Track [Page 39] RFC 6353 TLS Transport Model for SNMP July 2011

snmpTlstmSessionInvalidServerCertificates OBJECT-TYPE

  SYNTAX       Counter32
  MAX-ACCESS   read-only
  STATUS       current
  DESCRIPTION
      "The number of times an outgoing session was not established
       on a (D)TLS client because the server certificate presented
       by an SNMP over (D)TLS server could not be validated even if
       the fingerprint or expected validation path was known.  That
       is, a cryptographic validation error occurred during
       certificate validation processing.
      Reasons for invalidation include, but are not
      limited to, cryptographic validation failures."
  ::= { snmpTlstmSession 9 }

snmpTlstmSessionInvalidCaches OBJECT-TYPE

  SYNTAX       Counter32
  MAX-ACCESS   read-only
  STATUS       current
  DESCRIPTION
      "The number of outgoing messages dropped because the
      tmStateReference referred to an invalid cache."
  ::= { snmpTlstmSession 10 }

– Configuration Objects

snmpTlstmConfig OBJECT IDENTIFIER ::= { snmpTlstmObjects 2 }

– Certificate mapping

snmpTlstmCertificateMapping OBJECT IDENTIFIER ::= { snmpTlstmConfig 1 }

snmpTlstmCertToTSNCount OBJECT-TYPE

  SYNTAX      Gauge32
  MAX-ACCESS  read-only
  STATUS      current
  DESCRIPTION
      "A count of the number of entries in the
      snmpTlstmCertToTSNTable."
  ::= { snmpTlstmCertificateMapping 1 }

snmpTlstmCertToTSNTableLastChanged OBJECT-TYPE

  SYNTAX      TimeStamp
  MAX-ACCESS  read-only
  STATUS      current

Hardaker Standards Track [Page 40] RFC 6353 TLS Transport Model for SNMP July 2011

  DESCRIPTION
      "The value of sysUpTime.0 when the snmpTlstmCertToTSNTable was
      last modified through any means, or 0 if it has not been
      modified since the command responder was started."
  ::= { snmpTlstmCertificateMapping 2 }

snmpTlstmCertToTSNTable OBJECT-TYPE

  SYNTAX      SEQUENCE OF SnmpTlstmCertToTSNEntry
  MAX-ACCESS  not-accessible
  STATUS      current
  DESCRIPTION
      "This table is used by a (D)TLS server to map the (D)TLS
      client's presented X.509 certificate to a tmSecurityName.
      On an incoming (D)TLS/SNMP connection, the client's presented
      certificate must either be validated based on an established
      trust anchor, or it must directly match a fingerprint in this
      table.  This table does not provide any mechanisms for
      configuring the trust anchors; the transfer of any needed
      trusted certificates for path validation is expected to occur
      through an out-of-band transfer.
      Once the certificate has been found acceptable (either by path
      validation or directly matching a fingerprint in this table),
      this table is consulted to determine the appropriate
      tmSecurityName to identify with the remote connection.  This
      is done by considering each active row from this table in
      prioritized order according to its snmpTlstmCertToTSNID value.
      Each row's snmpTlstmCertToTSNFingerprint value determines
      whether the row is a match for the incoming connection:
          1) If the row's snmpTlstmCertToTSNFingerprint value
             identifies the presented certificate, then consider the
             row as a successful match.
          2) If the row's snmpTlstmCertToTSNFingerprint value
             identifies a locally held copy of a trusted CA
             certificate and that CA certificate was used to
             validate the path to the presented certificate, then
             consider the row as a successful match.
      Once a matching row has been found, the
      snmpTlstmCertToTSNMapType value can be used to determine how
      the tmSecurityName to associate with the session should be
      determined.  See the snmpTlstmCertToTSNMapType column's
      DESCRIPTION for details on determining the tmSecurityName
      value.  If it is impossible to determine a tmSecurityName from
      the row's data combined with the data presented in the

Hardaker Standards Track [Page 41] RFC 6353 TLS Transport Model for SNMP July 2011

      certificate, then additional rows MUST be searched looking for
      another potential match.  If a resulting tmSecurityName mapped
      from a given row is not compatible with the needed
      requirements of a tmSecurityName (e.g., VACM imposes a
      32-octet-maximum length and the certificate derived
      securityName could be longer), then it must be considered an
      invalid match and additional rows MUST be searched looking for
      another potential match.
      If no matching and valid row can be found, the connection MUST
      be closed and SNMP messages MUST NOT be accepted over it.
      Missing values of snmpTlstmCertToTSNID are acceptable and
      implementations should continue to the next highest numbered
      row.  It is recommended that administrators skip index values
      to leave room for the insertion of future rows (for example,
      use values of 10 and 20 when creating initial rows).
      Users are encouraged to make use of certificates with
      subjectAltName fields that can be used as tmSecurityNames so
      that a single root CA certificate can allow all child
      certificate's subjectAltName to map directly to a
      tmSecurityName via a 1:1 transformation.  However, this table
      is flexible to allow for situations where existing deployed
      certificate infrastructures do not provide adequate
      subjectAltName values for use as tmSecurityNames.
      Certificates may also be mapped to tmSecurityNames using the
      CommonName portion of the Subject field.  However, the usage
      of the CommonName field is deprecated and thus this usage is
      NOT RECOMMENDED.  Direct mapping from each individual
      certificate fingerprint to a tmSecurityName is also possible
      but requires one entry in the table per tmSecurityName and
      requires more management operations to completely configure a
      device."
  ::= { snmpTlstmCertificateMapping 3 }

snmpTlstmCertToTSNEntry OBJECT-TYPE

  SYNTAX      SnmpTlstmCertToTSNEntry
  MAX-ACCESS  not-accessible
  STATUS      current
  DESCRIPTION
      "A row in the snmpTlstmCertToTSNTable that specifies a mapping
      for an incoming (D)TLS certificate to a tmSecurityName to use
      for a connection."
  INDEX   { snmpTlstmCertToTSNID }
  ::= { snmpTlstmCertToTSNTable 1 }

Hardaker Standards Track [Page 42] RFC 6353 TLS Transport Model for SNMP July 2011

SnmpTlstmCertToTSNEntry ::= SEQUENCE {

  snmpTlstmCertToTSNID           Unsigned32,
  snmpTlstmCertToTSNFingerprint  SnmpTLSFingerprint,
  snmpTlstmCertToTSNMapType      AutonomousType,
  snmpTlstmCertToTSNData         OCTET STRING,
  snmpTlstmCertToTSNStorageType  StorageType,
  snmpTlstmCertToTSNRowStatus    RowStatus

}

snmpTlstmCertToTSNID OBJECT-TYPE

  SYNTAX      Unsigned32 (1..4294967295)
  MAX-ACCESS  not-accessible
  STATUS      current
  DESCRIPTION
      "A unique, prioritized index for the given entry.  Lower
      numbers indicate a higher priority."
  ::= { snmpTlstmCertToTSNEntry 1 }

snmpTlstmCertToTSNFingerprint OBJECT-TYPE

  SYNTAX      SnmpTLSFingerprint (SIZE(1..255))
  MAX-ACCESS  read-create
  STATUS      current
  DESCRIPTION
      "A cryptographic hash of an X.509 certificate.  The results of
      a successful matching fingerprint to either the trusted CA in
      the certificate validation path or to the certificate itself
      is dictated by the snmpTlstmCertToTSNMapType column."
  ::= { snmpTlstmCertToTSNEntry 2 }

snmpTlstmCertToTSNMapType OBJECT-TYPE

  SYNTAX      AutonomousType
  MAX-ACCESS  read-create
  STATUS      current
  DESCRIPTION
      "Specifies the mapping type for deriving a tmSecurityName from
      a certificate.  Details for mapping of a particular type SHALL
      be specified in the DESCRIPTION clause of the OBJECT-IDENTITY
      that describes the mapping.  If a mapping succeeds it will
      return a tmSecurityName for use by the TLSTM model and
      processing stops.
      If the resulting mapped value is not compatible with the
      needed requirements of a tmSecurityName (e.g., VACM imposes a
      32-octet-maximum length and the certificate derived
      securityName could be longer), then future rows MUST be
      searched for additional snmpTlstmCertToTSNFingerprint matches
      to look for a mapping that succeeds.

Hardaker Standards Track [Page 43] RFC 6353 TLS Transport Model for SNMP July 2011

      Suitable values for assigning to this object that are defined
      within the SNMP-TLS-TM-MIB can be found in the
      snmpTlstmCertToTSNMIdentities portion of the MIB tree."
  DEFVAL { snmpTlstmCertSpecified }
  ::= { snmpTlstmCertToTSNEntry 3 }

snmpTlstmCertToTSNData OBJECT-TYPE

  SYNTAX      OCTET STRING (SIZE(0..1024))
  MAX-ACCESS  read-create
  STATUS      current
  DESCRIPTION
      "Auxiliary data used as optional configuration information for
      a given mapping specified by the snmpTlstmCertToTSNMapType
      column.  Only some mapping systems will make use of this
      column.  The value in this column MUST be ignored for any
      mapping type that does not require data present in this
      column."
  DEFVAL { "" }
  ::= { snmpTlstmCertToTSNEntry 4 }

snmpTlstmCertToTSNStorageType OBJECT-TYPE

  SYNTAX       StorageType
  MAX-ACCESS   read-create
  STATUS       current
  DESCRIPTION
      "The storage type for this conceptual row.  Conceptual rows
      having the value 'permanent' need not allow write-access to
      any columnar objects in the row."
  DEFVAL      { nonVolatile }
  ::= { snmpTlstmCertToTSNEntry 5 }

snmpTlstmCertToTSNRowStatus OBJECT-TYPE

  SYNTAX      RowStatus
  MAX-ACCESS  read-create
  STATUS      current
  DESCRIPTION
      "The status of this conceptual row.  This object may be used
      to create or remove rows from this table.
      To create a row in this table, an administrator must set this
      object to either createAndGo(4) or createAndWait(5).
      Until instances of all corresponding columns are appropriately
      configured, the value of the corresponding instance of the
      snmpTlstmParamsRowStatus column is notReady(3).
      In particular, a newly created row cannot be made active until
      the corresponding snmpTlstmCertToTSNFingerprint,

Hardaker Standards Track [Page 44] RFC 6353 TLS Transport Model for SNMP July 2011

      snmpTlstmCertToTSNMapType, and snmpTlstmCertToTSNData columns
      have been set.
      The following objects may not be modified while the
      value of this object is active(1):
          - snmpTlstmCertToTSNFingerprint
          - snmpTlstmCertToTSNMapType
          - snmpTlstmCertToTSNData
      An attempt to set these objects while the value of
      snmpTlstmParamsRowStatus is active(1) will result in
      an inconsistentValue error."
  ::= { snmpTlstmCertToTSNEntry 6 }

– Maps tmSecurityNames to certificates for use by the SNMP-TARGET-MIB

snmpTlstmParamsCount OBJECT-TYPE

  SYNTAX      Gauge32
  MAX-ACCESS  read-only
  STATUS      current
  DESCRIPTION
      "A count of the number of entries in the snmpTlstmParamsTable."
  ::= { snmpTlstmCertificateMapping 4 }

snmpTlstmParamsTableLastChanged OBJECT-TYPE

  SYNTAX      TimeStamp
  MAX-ACCESS  read-only
  STATUS      current
  DESCRIPTION
      "The value of sysUpTime.0 when the snmpTlstmParamsTable
      was last modified through any means, or 0 if it has not been
      modified since the command responder was started."
  ::= { snmpTlstmCertificateMapping 5 }

snmpTlstmParamsTable OBJECT-TYPE

  SYNTAX      SEQUENCE OF SnmpTlstmParamsEntry
  MAX-ACCESS  not-accessible
  STATUS      current
  DESCRIPTION
      "This table is used by a (D)TLS client when a (D)TLS
      connection is being set up using an entry in the
      SNMP-TARGET-MIB.  It extends the SNMP-TARGET-MIB's
      snmpTargetParamsTable with a fingerprint of a certificate to
      use when establishing such a (D)TLS connection."
  ::= { snmpTlstmCertificateMapping 6 }

snmpTlstmParamsEntry OBJECT-TYPE

  SYNTAX      SnmpTlstmParamsEntry
  MAX-ACCESS  not-accessible

Hardaker Standards Track [Page 45] RFC 6353 TLS Transport Model for SNMP July 2011

  STATUS      current
  DESCRIPTION
      "A conceptual row containing a fingerprint hash of a locally
      held certificate for a given snmpTargetParamsEntry.  The
      values in this row should be ignored if the connection that
      needs to be established, as indicated by the SNMP-TARGET-MIB
      infrastructure, is not a certificate and (D)TLS based
      connection.  The connection SHOULD NOT be established if the
      certificate fingerprint stored in this entry does not point to
      a valid locally held certificate or if it points to an
      unusable certificate (such as might happen when the
      certificate's expiration date has been reached)."
  INDEX    { IMPLIED snmpTargetParamsName }
  ::= { snmpTlstmParamsTable 1 }

SnmpTlstmParamsEntry ::= SEQUENCE {

  snmpTlstmParamsClientFingerprint SnmpTLSFingerprint,
  snmpTlstmParamsStorageType       StorageType,
  snmpTlstmParamsRowStatus         RowStatus

}

snmpTlstmParamsClientFingerprint OBJECT-TYPE

  SYNTAX      SnmpTLSFingerprint
  MAX-ACCESS  read-create
  STATUS      current
  DESCRIPTION
      "This object stores the hash of the public portion of a
      locally held X.509 certificate.  The X.509 certificate, its
      public key, and the corresponding private key will be used
      when initiating a (D)TLS connection as a (D)TLS client."
  ::= { snmpTlstmParamsEntry 1 }

snmpTlstmParamsStorageType OBJECT-TYPE

  SYNTAX       StorageType
  MAX-ACCESS   read-create
  STATUS       current
  DESCRIPTION
      "The storage type for this conceptual row.  Conceptual rows
      having the value 'permanent' need not allow write-access to
      any columnar objects in the row."
  DEFVAL      { nonVolatile }
  ::= { snmpTlstmParamsEntry 2 }

snmpTlstmParamsRowStatus OBJECT-TYPE

  SYNTAX      RowStatus
  MAX-ACCESS  read-create
  STATUS      current
  DESCRIPTION

Hardaker Standards Track [Page 46] RFC 6353 TLS Transport Model for SNMP July 2011

      "The status of this conceptual row.  This object may be used
      to create or remove rows from this table.
      To create a row in this table, an administrator must set this
      object to either createAndGo(4) or createAndWait(5).
      Until instances of all corresponding columns are appropriately
      configured, the value of the corresponding instance of the
      snmpTlstmParamsRowStatus column is notReady(3).
      In particular, a newly created row cannot be made active until
      the corresponding snmpTlstmParamsClientFingerprint column has
      been set.
      The snmpTlstmParamsClientFingerprint object may not be modified
      while the value of this object is active(1).
      An attempt to set these objects while the value of
      snmpTlstmParamsRowStatus is active(1) will result in
      an inconsistentValue error."
  ::= { snmpTlstmParamsEntry 3 }

snmpTlstmAddrCount OBJECT-TYPE

  SYNTAX      Gauge32
  MAX-ACCESS  read-only
  STATUS      current
  DESCRIPTION
      "A count of the number of entries in the snmpTlstmAddrTable."
  ::= { snmpTlstmCertificateMapping 7 }

snmpTlstmAddrTableLastChanged OBJECT-TYPE

  SYNTAX      TimeStamp
  MAX-ACCESS  read-only
  STATUS      current
  DESCRIPTION
      "The value of sysUpTime.0 when the snmpTlstmAddrTable
      was last modified through any means, or 0 if it has not been
      modified since the command responder was started."
  ::= { snmpTlstmCertificateMapping 8 }

snmpTlstmAddrTable OBJECT-TYPE

  SYNTAX      SEQUENCE OF SnmpTlstmAddrEntry
  MAX-ACCESS  not-accessible
  STATUS      current
  DESCRIPTION
      "This table is used by a (D)TLS client when a (D)TLS
      connection is being set up using an entry in the
      SNMP-TARGET-MIB.  It extends the SNMP-TARGET-MIB's

Hardaker Standards Track [Page 47] RFC 6353 TLS Transport Model for SNMP July 2011

      snmpTargetAddrTable so that the client can verify that the
      correct server has been reached.  This verification can use
      either a certificate fingerprint, or an identity
      authenticated via certification path validation.
      If there is an active row in this table corresponding to the
      entry in the SNMP-TARGET-MIB that was used to establish the
      connection, and the row's snmpTlstmAddrServerFingerprint
      column has non-empty value, then the server's presented
      certificate is compared with the
      snmpTlstmAddrServerFingerprint value (and the
      snmpTlstmAddrServerIdentity column is ignored).  If the
      fingerprint matches, the verification has succeeded.  If the
      fingerprint does not match, then the connection MUST be
      closed.
      If the server's presented certificate has passed
      certification path validation [RFC5280] to a configured
      trust anchor, and an active row exists with a zero-length
      snmpTlstmAddrServerFingerprint value, then the
      snmpTlstmAddrServerIdentity column contains the expected
      host name.  This expected host name is then compared against
      the server's certificate as follows:
  1. Implementations MUST support matching the expected host

name against a dNSName in the subjectAltName extension

        field and MAY support checking the name against the
        CommonName portion of the subject distinguished name.
  1. The '*' (ASCII 0x2a) wildcard character is allowed in the

dNSName of the subjectAltName extension (and in common

        name, if used to store the host name), but only as the
        left-most (least significant) DNS label in that value.
        This wildcard matches any left-most DNS label in the
        server name.  That is, the subject *.example.com matches
        the server names a.example.com and b.example.com, but does
        not match example.com or a.b.example.com.  Implementations
        MUST support wildcards in certificates as specified above,
        but MAY provide a configuration option to disable them.
  1. If the locally configured name is an internationalized

domain name, conforming implementations MUST convert it to

        the ASCII Compatible Encoding (ACE) format for performing
        comparisons, as specified in Section 7 of [RFC5280].
      If the expected host name fails these conditions then the
      connection MUST be closed.

Hardaker Standards Track [Page 48] RFC 6353 TLS Transport Model for SNMP July 2011

      If there is no row in this table corresponding to the entry
      in the SNMP-TARGET-MIB and the server can be authorized by
      another, implementation-dependent means, then the connection
      MAY still proceed."
  ::= { snmpTlstmCertificateMapping 9 }

snmpTlstmAddrEntry OBJECT-TYPE

  SYNTAX      SnmpTlstmAddrEntry
  MAX-ACCESS  not-accessible
  STATUS      current
  DESCRIPTION
      "A conceptual row containing a copy of a certificate's
      fingerprint for a given snmpTargetAddrEntry.  The values in
      this row should be ignored if the connection that needs to be
      established, as indicated by the SNMP-TARGET-MIB
      infrastructure, is not a (D)TLS based connection.  If an
      snmpTlstmAddrEntry exists for a given snmpTargetAddrEntry, then
      the presented server certificate MUST match or the connection
      MUST NOT be established.  If a row in this table does not
      exist to match an snmpTargetAddrEntry row, then the connection
      SHOULD still proceed if some other certificate validation path
      algorithm (e.g., RFC 5280) can be used."
  INDEX    { IMPLIED snmpTargetAddrName }
  ::= { snmpTlstmAddrTable 1 }

SnmpTlstmAddrEntry ::= SEQUENCE {

  snmpTlstmAddrServerFingerprint    SnmpTLSFingerprint,
  snmpTlstmAddrServerIdentity       SnmpAdminString,
  snmpTlstmAddrStorageType          StorageType,
  snmpTlstmAddrRowStatus            RowStatus

}

snmpTlstmAddrServerFingerprint OBJECT-TYPE

  SYNTAX      SnmpTLSFingerprint
  MAX-ACCESS  read-create
  STATUS      current
  DESCRIPTION
      "A cryptographic hash of a public X.509 certificate.  This
      object should store the hash of the public X.509 certificate
      that the remote server should present during the (D)TLS
      connection setup.  The fingerprint of the presented
      certificate and this hash value MUST match exactly or the
      connection MUST NOT be established."
  DEFVAL { "" }
  ::= { snmpTlstmAddrEntry 1 }

Hardaker Standards Track [Page 49] RFC 6353 TLS Transport Model for SNMP July 2011

snmpTlstmAddrServerIdentity OBJECT-TYPE

  SYNTAX      SnmpAdminString
  MAX-ACCESS  read-create
  STATUS      current
  DESCRIPTION
      "The reference identity to check against the identity
      presented by the remote system."
  DEFVAL { "" }
  ::= { snmpTlstmAddrEntry 2 }

snmpTlstmAddrStorageType OBJECT-TYPE

  SYNTAX       StorageType
  MAX-ACCESS   read-create
  STATUS       current
  DESCRIPTION
      "The storage type for this conceptual row.  Conceptual rows
      having the value 'permanent' need not allow write-access to
      any columnar objects in the row."
  DEFVAL      { nonVolatile }
  ::= { snmpTlstmAddrEntry 3 }

snmpTlstmAddrRowStatus OBJECT-TYPE

  SYNTAX      RowStatus
  MAX-ACCESS  read-create
  STATUS      current
  DESCRIPTION
      "The status of this conceptual row.  This object may be used
      to create or remove rows from this table.
      To create a row in this table, an administrator must set this
      object to either createAndGo(4) or createAndWait(5).
      Until instances of all corresponding columns are
      appropriately configured, the value of the
      corresponding instance of the snmpTlstmAddrRowStatus
      column is notReady(3).
      In particular, a newly created row cannot be made active until
      the corresponding snmpTlstmAddrServerFingerprint column has been
      set.
      Rows MUST NOT be active if the snmpTlstmAddrServerFingerprint
      column is blank and the snmpTlstmAddrServerIdentity is set to
      '*' since this would insecurely accept any presented
      certificate.

Hardaker Standards Track [Page 50] RFC 6353 TLS Transport Model for SNMP July 2011

      The snmpTlstmAddrServerFingerprint object may not be modified
      while the value of this object is active(1).
      An attempt to set these objects while the value of
      snmpTlstmAddrRowStatus is active(1) will result in
      an inconsistentValue error."
  ::= { snmpTlstmAddrEntry 4 }

– snmpTlstmNotifications - Notifications Information –

snmpTlstmServerCertificateUnknown NOTIFICATION-TYPE

  OBJECTS { snmpTlstmSessionUnknownServerCertificate }
  STATUS  current
  DESCRIPTION
      "Notification that the server certificate presented by an SNMP
       over (D)TLS server was invalid because no configured
       fingerprint or CA was acceptable to validate it.  This may be
       because there was no entry in the snmpTlstmAddrTable or
       because no path could be found to known Certification
       Authority.
       To avoid notification loops, this notification MUST NOT be
       sent to servers that themselves have triggered the
       notification."
  ::= { snmpTlstmNotifications 1 }

snmpTlstmServerInvalidCertificate NOTIFICATION-TYPE

  OBJECTS { snmpTlstmAddrServerFingerprint,
            snmpTlstmSessionInvalidServerCertificates}
  STATUS  current
  DESCRIPTION
      "Notification that the server certificate presented by an SNMP
       over (D)TLS server could not be validated even if the
       fingerprint or expected validation path was known.  That is, a
       cryptographic validation error occurred during certificate
       validation processing.
       To avoid notification loops, this notification MUST NOT be
       sent to servers that themselves have triggered the
       notification."
  ::= { snmpTlstmNotifications 2 }

– snmpTlstmCompliances - Conformance Information –

Hardaker Standards Track [Page 51] RFC 6353 TLS Transport Model for SNMP July 2011

snmpTlstmCompliances OBJECT IDENTIFIER ::= { snmpTlstmConformance 1 }

snmpTlstmGroups OBJECT IDENTIFIER ::= { snmpTlstmConformance 2 }

– Compliance statements –

snmpTlstmCompliance MODULE-COMPLIANCE

  STATUS      current
  DESCRIPTION
      "The compliance statement for SNMP engines that support the
      SNMP-TLS-TM-MIB"
  MODULE
      MANDATORY-GROUPS { snmpTlstmStatsGroup,
                         snmpTlstmIncomingGroup,
                         snmpTlstmOutgoingGroup,
                         snmpTlstmNotificationGroup }
  ::= { snmpTlstmCompliances 1 }

– Units of conformance – snmpTlstmStatsGroup OBJECT-GROUP

  OBJECTS {
      snmpTlstmSessionOpens,
      snmpTlstmSessionClientCloses,
      snmpTlstmSessionOpenErrors,
      snmpTlstmSessionAccepts,
      snmpTlstmSessionServerCloses,
      snmpTlstmSessionNoSessions,
      snmpTlstmSessionInvalidClientCertificates,
      snmpTlstmSessionUnknownServerCertificate,
      snmpTlstmSessionInvalidServerCertificates,
      snmpTlstmSessionInvalidCaches
  }
  STATUS      current
  DESCRIPTION
      "A collection of objects for maintaining
      statistical information of an SNMP engine that
      implements the SNMP TLS Transport Model."
  ::= { snmpTlstmGroups 1 }

snmpTlstmIncomingGroup OBJECT-GROUP

  OBJECTS {
      snmpTlstmCertToTSNCount,
      snmpTlstmCertToTSNTableLastChanged,
      snmpTlstmCertToTSNFingerprint,

Hardaker Standards Track [Page 52] RFC 6353 TLS Transport Model for SNMP July 2011

      snmpTlstmCertToTSNMapType,
      snmpTlstmCertToTSNData,
      snmpTlstmCertToTSNStorageType,
      snmpTlstmCertToTSNRowStatus
  }
  STATUS      current
  DESCRIPTION
      "A collection of objects for maintaining
      incoming connection certificate mappings to
      tmSecurityNames of an SNMP engine that implements the
      SNMP TLS Transport Model."
  ::= { snmpTlstmGroups 2 }

snmpTlstmOutgoingGroup OBJECT-GROUP

  OBJECTS {
      snmpTlstmParamsCount,
      snmpTlstmParamsTableLastChanged,
      snmpTlstmParamsClientFingerprint,
      snmpTlstmParamsStorageType,
      snmpTlstmParamsRowStatus,
      snmpTlstmAddrCount,
      snmpTlstmAddrTableLastChanged,
      snmpTlstmAddrServerFingerprint,
      snmpTlstmAddrServerIdentity,
      snmpTlstmAddrStorageType,
      snmpTlstmAddrRowStatus
  }
  STATUS      current
  DESCRIPTION
      "A collection of objects for maintaining
      outgoing connection certificates to use when opening
      connections as a result of SNMP-TARGET-MIB settings."
  ::= { snmpTlstmGroups 3 }

snmpTlstmNotificationGroup NOTIFICATION-GROUP

  NOTIFICATIONS {
      snmpTlstmServerCertificateUnknown,
      snmpTlstmServerInvalidCertificate
  }
  STATUS current
  DESCRIPTION
      "Notifications"
  ::= { snmpTlstmGroups 4 }

END

Hardaker Standards Track [Page 53] RFC 6353 TLS Transport Model for SNMP July 2011

8. Operational Considerations

 This section discusses various operational aspects of deploying
 TLSTM.

8.1. Sessions

 A session is discussed throughout this document as meaning a security
 association between two TLSTM instances.  State information for the
 sessions are maintained in each TLSTM implementation and this
 information is created and destroyed as sessions are opened and
 closed.  A "broken" session (one side up and one side down) can
 result if one side of a session is brought down abruptly (i.e.,
 reboot, power outage, etc.).  Whenever possible, implementations
 SHOULD provide graceful session termination through the use of TLS
 disconnect messages.  Implementations SHOULD also have a system in
 place for detecting "broken" sessions through the use of heartbeats
 [HEARTBEAT] or other detection mechanisms.
 Implementations SHOULD limit the lifetime of established sessions
 depending on the algorithms used for generation of the master session
 secret, the privacy and integrity algorithms used to protect
 messages, the environment of the session, the amount of data
 transferred, and the sensitivity of the data.

8.2. Notification Receiver Credential Selection

 When an SNMP engine needs to establish an outgoing session for
 notifications, the snmpTargetParamsTable includes an entry for the
 snmpTargetParamsSecurityName of the target.  Servers that wish to
 support multiple principals at a particular port SHOULD make use of
 the Server Name Indication extension defined in Section 3.1 of
 [RFC4366].  Without the Server Name Indication the receiving SNMP
 engine (server) will not know which (D)TLS certificate to offer to
 the client so that the tmSecurityName identity-authentication will be
 successful.
 Another solution is to maintain a one-to-one mapping between
 certificates and incoming ports for notification receivers.  This can
 be handled at the notification originator by configuring the
 snmpTargetAddrTable (snmpTargetAddrTDomain and
 snmpTargetAddrTAddress) and requiring the receiving SNMP engine to
 monitor multiple incoming static ports based on which principals are
 capable of receiving notifications.
 Implementations MAY also choose to designate a single Notification
 Receiver Principal to receive all incoming notifications or select an

Hardaker Standards Track [Page 54] RFC 6353 TLS Transport Model for SNMP July 2011

 implementation specific method of selecting a server certificate to
 present to clients.

8.3. contextEngineID Discovery

 SNMPv3 requires that an application know the identifier
 (snmpEngineID) of the remote SNMP protocol engine in order to
 retrieve or manipulate objects maintained on the remote SNMP entity.
 [RFC5343] introduces a well-known localEngineID and a discovery
 mechanism that can be used to learn the snmpEngineID of a remote SNMP
 protocol engine.  Implementations are RECOMMENDED to support and use
 the contextEngineID discovery mechanism defined in [RFC5343].

8.4. Transport Considerations

 This document defines how SNMP messages can be transmitted over the
 TLS- and DTLS-based protocols.  Each of these protocols is
 additionally based on other transports (TCP and UDP).  These two base
 protocols also have operational considerations that must be taken
 into consideration when selecting a (D)TLS-based protocol to use such
 as its performance in degraded or limited networks.  It is beyond the
 scope of this document to summarize the characteristics of these
 transport mechanisms.  Please refer to the base protocol documents
 for details on messaging considerations with respect to MTU size,
 fragmentation, performance in lossy networks, etc.

9. Security Considerations

 This document describes a transport model that permits SNMP to
 utilize (D)TLS security services.  The security threats and how the
 (D)TLS transport model mitigates these threats are covered in detail
 throughout this document.  Security considerations for DTLS are
 covered in [RFC4347] and security considerations for TLS are
 described in Section 11 and Appendices D, E, and F of TLS 1.2
 [RFC5246].  When run over a connectionless transport such as UDP,
 DTLS is more vulnerable to denial-of-service attacks from spoofed IP
 addresses; see Section 4.2 for details how the cookie exchange is
 used to address this issue.

9.1. Certificates, Authentication, and Authorization

 Implementations are responsible for providing a security certificate
 installation and configuration mechanism.  Implementations SHOULD
 support certificate revocation lists.
 (D)TLS provides for authentication of the identity of both the (D)TLS
 server and the (D)TLS client.  Access to MIB objects for the

Hardaker Standards Track [Page 55] RFC 6353 TLS Transport Model for SNMP July 2011

 authenticated principal MUST be enforced by an access control
 subsystem (e.g., the VACM).
 Authentication of the command generator principal's identity is
 important for use with the SNMP access control subsystem to ensure
 that only authorized principals have access to potentially sensitive
 data.  The authenticated identity of the command generator
 principal's certificate is mapped to an SNMP model-independent
 securityName for use with SNMP access control.
 The (D)TLS handshake only provides assurance that the certificate of
 the authenticated identity has been signed by a configured accepted
 Certification Authority.  (D)TLS has no way to further authorize or
 reject access based on the authenticated identity.  An Access Control
 Model (such as the VACM) provides access control and authorization of
 a command generator's requests to a command responder and a
 notification receiver's authorization to receive Notifications from a
 notification originator.  However, to avoid man-in-the-middle
 attacks, both ends of the (D)TLS-based connection MUST check the
 certificate presented by the other side against what was expected.
 For example, command generators must check that the command responder
 presented and authenticated itself with an X.509 certificate that was
 expected.  Not doing so would allow an impostor, at a minimum, to
 present false data, receive sensitive information, and/or provide a
 false belief that configuration was actually received and acted upon.
 Authenticating and verifying the identity of the (D)TLS server and
 the (D)TLS client for all operations ensures the authenticity of the
 SNMP engine that provides MIB data.
 The instructions found in the DESCRIPTION clause of the
 snmpTlstmCertToTSNTable object must be followed exactly.  It is also
 important that the rows of the table be searched in prioritized order
 starting with the row containing the lowest numbered
 snmpTlstmCertToTSNID value.

9.2. (D)TLS Security Considerations

 This section discusses security considerations specific to the usage
 of (D)TLS.

9.2.1. TLS Version Requirements

 Implementations of TLS typically support multiple versions of the
 Transport Layer Security protocol as well as the older Secure Sockets
 Layer (SSL) protocol.  Because of known security vulnerabilities,
 TLSTM clients and servers MUST NOT request, offer, or use SSL 2.0.
 See Appendix E.2 of [RFC5246] for further details.

Hardaker Standards Track [Page 56] RFC 6353 TLS Transport Model for SNMP July 2011

9.2.2. Perfect Forward Secrecy

 The use of Perfect Forward Secrecy is RECOMMENDED and can be provided
 by (D)TLS with appropriately selected cipher_suites, as discussed in
 Appendix F of [RFC5246].

9.3. Use with SNMPv1/SNMPv2c Messages

 The SNMPv1 and SNMPv2c message processing described in [RFC3584] (BCP
 74) always selects the SNMPv1 or SNMPv2c Security Models,
 respectively.  Both of these and the User-based Security Model
 typically used with SNMPv3 derive the securityName and securityLevel
 from the SNMP message received, even when the message was received
 over a secure transport.  Access control decisions are therefore made
 based on the contents of the SNMP message, rather than using the
 authenticated identity and securityLevel provided by the TLS
 Transport Model.  It is RECOMMENDED that only SNMPv3 messages using
 the Transport Security Model (TSM) or another secure-transport aware
 security model be sent over the TLSTM transport.
 Using a non-transport-aware Security Model with a secure Transport
 Model is NOT RECOMMENDED.  See [RFC5590], Section 7.1 for additional
 details on the coexistence of security-aware transports and non-
 transport-aware security models.

9.4. MIB Module Security

 There are a number of management objects defined in this MIB module
 with a MAX-ACCESS clause of read-write and/or read-create.  Such
 objects may be considered sensitive or vulnerable in some network
 environments.  The support for SET operations in a non-secure
 environment without proper protection can have a negative effect on
 network operations.  These are the tables and objects and their
 sensitivity/vulnerability:
 o  The snmpTlstmParamsTable can be used to change the outgoing X.509
    certificate used to establish a (D)TLS connection.  Modifications
    to objects in this table need to be adequately authenticated since
    modifying the values in this table will have profound impacts to
    the security of outbound connections from the device.  Since
    knowledge of authorization rules and certificate usage mechanisms
    may be considered sensitive, protection from disclosure of the
    SNMP traffic via encryption is also highly recommended.
 o  The snmpTlstmAddrTable can be used to change the expectations of
    the certificates presented by a remote (D)TLS server.
    Modifications to objects in this table need to be adequately
    authenticated since modifying the values in this table will have

Hardaker Standards Track [Page 57] RFC 6353 TLS Transport Model for SNMP July 2011

    profound impacts to the security of outbound connections from the
    device.  Since knowledge of authorization rules and certificate
    usage mechanisms may be considered sensitive, protection from
    disclosure of the SNMP traffic via encryption is also highly
    recommended.
 o  The snmpTlstmCertToTSNTable is used to specify the mapping of
    incoming X.509 certificates to tmSecurityNames, which eventually
    get mapped to an SNMPv3 securityName.  Modifications to objects in
    this table need to be adequately authenticated since modifying the
    values in this table will have profound impacts to the security of
    incoming connections to the device.  Since knowledge of
    authorization rules and certificate usage mechanisms may be
    considered sensitive, protection from disclosure of the SNMP
    traffic via encryption is also highly recommended.  When this
    table contains a significant number of rows it may affect the
    system performance when accepting new (D)TLS connections.
 Some of the readable objects in this MIB module (i.e., objects with a
 MAX-ACCESS other than not-accessible) may be considered sensitive or
 vulnerable in some network environments.  It is thus important to
 control even GET and/or NOTIFY access to these objects and possibly
 to even encrypt the values of these objects when sending them over
 the network via SNMP.  These are the tables and objects and their
 sensitivity/vulnerability:
 o  This MIB contains a collection of counters that monitor the (D)TLS
    connections being established with a device.  Since knowledge of
    connection and certificate usage mechanisms may be considered
    sensitive, protection from disclosure of the SNMP traffic via
    encryption is highly recommended.
 SNMP versions prior to SNMPv3 did not include adequate security.
 Even if the network itself is secure (for example, by using IPsec),
 even then, there is no control as to who on the secure network is
 allowed to access and GET/SET (read/change/create/delete) the objects
 in this MIB module.
 It is RECOMMENDED that implementers consider the security features as
 provided by the SNMPv3 framework (see [RFC3410], Section 8),
 including full support for the SNMPv3 cryptographic mechanisms (for
 authentication and privacy).
 Further, deployment of SNMP versions prior to SNMPv3 is NOT
 RECOMMENDED.  Instead, it is RECOMMENDED to deploy SNMPv3 and to
 enable cryptographic security.  It is then a customer/operator
 responsibility to ensure that the SNMP entity giving access to an
 instance of this MIB module is properly configured to give access to

Hardaker Standards Track [Page 58] RFC 6353 TLS Transport Model for SNMP July 2011

 the objects only to those principals (users) that have legitimate
 rights to indeed GET or SET (change/create/delete) them.

10. IANA Considerations

 IANA has assigned:
 1.  Two TCP/UDP port numbers from the "Registered Ports" range of the
     Port Numbers registry, with the following keywords:
   Keyword         Decimal      Description       References
   -------         -------      -----------       ----------
   snmptls         10161/tcp    SNMP-TLS          [RFC6353]
   snmpdtls        10161/udp    SNMP-DTLS         [RFC6353]
   snmptls-trap    10162/tcp    SNMP-Trap-TLS     [RFC6353]
   snmpdtls-trap   10162/udp    SNMP-Trap-DTLS    [RFC6353]
 These are the default ports for receipt of SNMP command messages
 (snmptls and snmpdtls) and SNMP notification messages (snmptls-trap
 and snmpdtls-trap) over a TLS Transport Model as defined in this
 document.
 2.  An SMI number (8) under snmpDomains for the snmpTLSTCPDomain
     object identifier
 3.  An SMI number (9) under snmpDomains for the snmpDTLSUDPDomain
     object identifier
 4.  An SMI number (198) under mib-2, for the MIB module in this
     document
 5.  "tls" as the corresponding prefix for the snmpTLSTCPDomain in the
     SNMP Transport Domains registry
 6.  "dtls" as the corresponding prefix for the snmpDTLSUDPDomain in
     the SNMP Transport Domains registry

11. Acknowledgements

 This document closely follows and copies the Secure Shell Transport
 Model for SNMP documented by David Harrington and Joseph Salowey in
 [RFC5592].
 This document was reviewed by the following people who helped provide
 useful comments (in alphabetical order): Andy Donati, Pasi Eronen,
 David Harrington, Jeffrey Hutzelman, Alan Luchuk, Michael Peck, Tom
 Petch, Randy Presuhn, Ray Purvis, Peter Saint-Andre, Joseph Salowey,
 Juergen Schoenwaelder, Dave Shield, and Robert Story.

Hardaker Standards Track [Page 59] RFC 6353 TLS Transport Model for SNMP July 2011

 This work was supported in part by the United States Department of
 Defense.  Large portions of this document are based on work by
 General Dynamics C4 Systems and the following individuals: Brian
 Baril, Kim Bryant, Dana Deluca, Dan Hanson, Tim Huemiller, John
 Holzhauer, Colin Hoogeboom, Dave Kornbau, Chris Knaian, Dan Knaul,
 Charles Limoges, Steve Moccaldi, Gerardo Orlando, and Brandon Yip.

12. References

12.1. Normative References

 [RFC1123]    Braden, R., "Requirements for Internet Hosts -
              Application and Support", STD 3, RFC 1123, October 1989.
 [RFC2119]    Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.
 [RFC2578]    McCloghrie, K., Ed., Perkins, D., Ed., and J.
              Schoenwaelder, Ed., "Structure of Management Information
              Version 2 (SMIv2)", STD 58, RFC 2578, April 1999.
 [RFC2579]    McCloghrie, K., Ed., Perkins, D., Ed., and J.
              Schoenwaelder, Ed., "Textual Conventions for SMIv2",
              STD 58, RFC 2579, April 1999.
 [RFC2580]    McCloghrie, K., Perkins, D., and J. Schoenwaelder,
              "Conformance Statements for SMIv2", STD 58, RFC 2580,
              April 1999.
 [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.
 [RFC3413]    Levi, D., Meyer, P., and B. Stewart, "Simple Network
              Management Protocol (SNMP) Applications", STD 62,
              RFC 3413, December 2002.
 [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.
 [RFC3415]    Wijnen, B., Presuhn, R., and K. McCloghrie, "View-based
              Access Control Model (VACM) for the Simple Network
              Management Protocol (SNMP)", STD 62, RFC 3415,
              December 2002.

Hardaker Standards Track [Page 60] RFC 6353 TLS Transport Model for SNMP July 2011

 [RFC3418]    Presuhn, R., "Management Information Base (MIB) for the
              Simple Network Management Protocol (SNMP)", STD 62,
              RFC 3418, December 2002.
 [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.
 [RFC4347]    Rescorla, E. and N. Modadugu, "Datagram Transport Layer
              Security", RFC 4347, April 2006.
 [RFC4366]    Blake-Wilson, S., Nystrom, M., Hopwood, D., Mikkelsen,
              J., and T. Wright, "Transport Layer Security (TLS)
              Extensions", RFC 4366, April 2006.
 [RFC5246]    Dierks, T. and E. Rescorla, "The Transport Layer
              Security (TLS) Protocol Version 1.2", RFC 5246,
              August 2008.
 [RFC5280]    Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
              Housley, R., and W. Polk, "Internet X.509 Public Key
              Infrastructure Certificate and Certificate Revocation
              List (CRL) Profile", RFC 5280, May 2008.
 [RFC5590]    Harrington, D. and J. Schoenwaelder, "Transport
              Subsystem for the Simple Network Management Protocol
              (SNMP)", RFC 5590, June 2009.
 [RFC5591]    Harrington, D. and W. Hardaker, "Transport Security
              Model for the Simple Network Management Protocol
              (SNMP)", RFC 5591, June 2009.
 [RFC5952]    Kawamura, S. and M. Kawashima, "A Recommendation for
              IPv6 Address Text Representation", RFC 5952,
              August 2010.

12.2. Informative References

 [HEARTBEAT]  Seggelmann, R., Tuexen, M., and M. Williams, "Transport
              Layer Security (TLS) and Datagram Transport Layer
              Security (DTLS) Heartbeat Extension", Work in Progress,
              July 2011.
 [RFC3410]    Case, J., Mundy, R., Partain, D., and B. Stewart,
              "Introduction and Applicability Statements for Internet-
              Standard Management Framework", RFC 3410, December 2002.

Hardaker Standards Track [Page 61] RFC 6353 TLS Transport Model for SNMP July 2011

 [RFC5343]    Schoenwaelder, J., "Simple Network Management Protocol
              (SNMP) Context EngineID Discovery", RFC 5343,
              September 2008.
 [RFC5592]    Harrington, D., Salowey, J., and W. Hardaker, "Secure
              Shell Transport Model for the Simple Network Management
              Protocol (SNMP)", RFC 5592, June 2009.
 [RFC5890]    Klensin, J., "Internationalized Domain Names for
              Applications (IDNA): Definitions and Document
              Framework", RFC 5890, August 2010.
 [RFC5953]    Hardaker, W., "Transport Layer Security (TLS) Transport
              Model for the Simple Network Management Protocol
              (SNMP)", RFC 5953, August 2010.

Hardaker Standards Track [Page 62] RFC 6353 TLS Transport Model for SNMP July 2011

Appendix A. Target and Notification Configuration Example

 The following sections describe example configuration for the SNMP-
 TLS-TM-MIB, the SNMP-TARGET-MIB, the NOTIFICATION-MIB, and the SNMP-
 VIEW-BASED-ACM-MIB.

A.1. Configuring a Notification Originator

 The following row adds the "Joe Cool" user to the "administrators"
 group:
     vacmSecurityModel              = 4 (TSM)
     vacmSecurityName               = "Joe Cool"
     vacmGroupName                  = "administrators"
     vacmSecurityToGroupStorageType = 3 (nonVolatile)
     vacmSecurityToGroupStatus      = 4 (createAndGo)
 The following row configures the snmpTlstmAddrTable to use
 certificate path validation and to require the remote notification
 receiver to present a certificate for the "server.example.org"
 identity.
     snmpTargetAddrName             =  "toNRAddr"
     snmpTlstmAddrServerFingerprint =  ""
     snmpTlstmAddrServerIdentity    =  "server.example.org"
     snmpTlstmAddrStorageType       =  3         (nonVolatile)
     snmpTlstmAddrRowStatus         =  4         (createAndGo)
 The following row configures the snmpTargetAddrTable to send
 notifications using TLS/TCP to the snmptls-trap port at 192.0.2.1:
     snmpTargetAddrName              = "toNRAddr"
     snmpTargetAddrTDomain           = snmpTLSTCPDomain
     snmpTargetAddrTAddress          = "192.0.2.1:10162"
     snmpTargetAddrTimeout           = 1500
     snmpTargetAddrRetryCount        = 3
     snmpTargetAddrTagList           = "toNRTag"
     snmpTargetAddrParams            = "toNR"     (MUST match below)
     snmpTargetAddrStorageType       = 3          (nonVolatile)
     snmpTargetAddrRowStatus         = 4          (createAndGo)

Hardaker Standards Track [Page 63] RFC 6353 TLS Transport Model for SNMP July 2011

 The following row configures the snmpTargetParamsTable to send the
 notifications to "Joe Cool", using authPriv SNMPv3 notifications
 through the TransportSecurityModel [RFC5591]:
     snmpTargetParamsName            = "toNR"     (must match above)
     snmpTargetParamsMPModel         = 3 (SNMPv3)
     snmpTargetParamsSecurityModel   = 4 (TransportSecurityModel)
     snmpTargetParamsSecurityName    = "Joe Cool"
     snmpTargetParamsSecurityLevel   = 3          (authPriv)
     snmpTargetParamsStorageType     = 3          (nonVolatile)
     snmpTargetParamsRowStatus       = 4          (createAndGo)

A.2. Configuring TLSTM to Utilize a Simple Derivation of tmSecurityName

 The following row configures the snmpTlstmCertToTSNTable to map a
 validated client certificate, referenced by the client's public X.509
 hash fingerprint, to a tmSecurityName using the subjectAltName
 component of the certificate.
     snmpTlstmCertToTSNID          = 1
                                     (chosen by ordering preference)
     snmpTlstmCertToTSNFingerprint = HASH (appropriate fingerprint)
     snmpTlstmCertToTSNMapType     = snmpTlstmCertSANAny
     snmpTlstmCertToTSNData        = ""  (not used)
     snmpTlstmCertToTSNStorageType = 3   (nonVolatile)
     snmpTlstmCertToTSNRowStatus   = 4   (createAndGo)
 This type of configuration should only be used when the naming
 conventions of the (possibly multiple) Certification Authorities are
 well understood, so two different principals cannot inadvertently be
 identified by the same derived tmSecurityName.

A.3. Configuring TLSTM to Utilize Table-Driven Certificate Mapping

 The following row configures the snmpTlstmCertToTSNTable to map a
 validated client certificate, referenced by the client's public X.509
 hash fingerprint, to the directly specified tmSecurityName of "Joe
 Cool".
     snmpTlstmCertToTSNID           = 2
                                      (chosen by ordering preference)
     snmpTlstmCertToTSNFingerprint  = HASH (appropriate fingerprint)
     snmpTlstmCertToTSNMapType      = snmpTlstmCertSpecified
     snmpTlstmCertToTSNSecurityName = "Joe Cool"
     snmpTlstmCertToTSNStorageType  = 3  (nonVolatile)
     snmpTlstmCertToTSNRowStatus    = 4  (createAndGo)

Hardaker Standards Track [Page 64] RFC 6353 TLS Transport Model for SNMP July 2011

Author's Address

 Wes Hardaker
 SPARTA, Inc.
 P.O. Box 382
 Davis, CA  95617
 USA
 Phone: +1 530 792 1913
 EMail: ietf@hardakers.net

Hardaker Standards Track [Page 65]

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