draft-ietf-isms-dtls-tm-08.txt   draft-ietf-isms-dtls-tm-09.txt 
ISMS W. Hardaker ISMS W. Hardaker
Internet-Draft Sparta, Inc. Internet-Draft Sparta, Inc.
Intended status: Standards Track February 2, 2010 Intended status: Standards Track March 6, 2010
Expires: August 6, 2010 Expires: September 7, 2010
Transport Layer Security (TLS) Transport Model for SNMP Transport Layer Security (TLS) Transport Model for SNMP
draft-ietf-isms-dtls-tm-08.txt draft-ietf-isms-dtls-tm-09.txt
Abstract Abstract
This document describes a Transport Model for the Simple Network This document describes a Transport Model for the Simple Network
Management Protocol (SNMP), that uses either the Transport Layer Management Protocol (SNMP), that uses either the Transport Layer
Security protocol or the Datagram Transport Layer Security (DTLS) Security protocol or the Datagram Transport Layer Security (DTLS)
protocol. The TLS and DTLS protocols provide authentication and protocol. The TLS and DTLS protocols provide authentication and
privacy services for SNMP applications. This document describes how privacy services for SNMP applications. This document describes how
the TLS Transport Model (TLSTM) implements the needed features of a the TLS Transport Model (TLSTM) implements the needed features of a
SNMP Transport Subsystem to make this protection possible in an SNMP Transport Subsystem to make this protection possible in an
interoperable way. interoperable way.
This transport model is designed to meet the security and operational This transport model is designed to meet the security and operational
needs of network administrators. It supports sending of SNMP needs of network administrators. It supports sending of SNMP
messages over TLS/TCP, DTLS/UDP and DTLS/SCTP. The TLS mode can make messages over TLS/TCP and DTLS/UDP. The TLS mode can make use of
use of TCP's improved support for larger packet sizes and the DTLS TCP's improved support for larger packet sizes and the DTLS mode
mode provides potentially superior operation in environments where a provides potentially superior operation in environments where a
connectionless (e.g. UDP or SCTP) transport is preferred. Both TLS connectionless (e.g. UDP) transport is preferred. Both TLS and DTLS
and DTLS integrate well into existing public keying infrastructures. integrate well into existing public keying infrastructures.
This document also defines a portion of the Management Information This document also defines a portion of the Management Information
Base (MIB) for use with network management protocols. In particular Base (MIB) for use with network management protocols. In particular
it defines objects for managing the TLS Transport Model for SNMP. it defines objects for managing the TLS Transport Model for SNMP.
Status of this Memo Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
This Internet-Draft will expire on August 6, 2010. This Internet-Draft will expire on September 7, 2010.
Copyright Notice Copyright Notice
Copyright (c) 2010 IETF Trust and the persons identified as the Copyright (c) 2010 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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Without obtaining an adequate license from the person(s) controlling Without obtaining an adequate license from the person(s) controlling
the copyright in such materials, this document may not be modified the copyright in such materials, this document may not be modified
outside the IETF Standards Process, and derivative works of it may outside the IETF Standards Process, and derivative works of it may
not be created outside the IETF Standards Process, except to format not be created outside the IETF Standards Process, except to format
it for publication as an RFC or to translate it into languages other it for publication as an RFC or to translate it into languages other
than English. than English.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.1. Conventions . . . . . . . . . . . . . . . . . . . . . . . 7 1.1. Conventions . . . . . . . . . . . . . . . . . . . . . . . 8
2. The Transport Layer Security Protocol . . . . . . . . . . . . 8 2. The Transport Layer Security Protocol . . . . . . . . . . . . 9
3. How the TLSTM fits into the Transport Subsystem . . . . . . . 8 3. How the TLSTM fits into the Transport Subsystem . . . . . . . 9
3.1. Security Capabilities of this Model . . . . . . . . . . . 10 3.1. Security Capabilities of this Model . . . . . . . . . . . 11
3.1.1. Threats . . . . . . . . . . . . . . . . . . . . . . . 10 3.1.1. Threats . . . . . . . . . . . . . . . . . . . . . . . 11
3.1.2. Message Protection . . . . . . . . . . . . . . . . . . 12 3.1.2. Message Protection . . . . . . . . . . . . . . . . . . 12
3.1.3. (D)TLS Sessions . . . . . . . . . . . . . . . . . . . 12 3.1.3. (D)TLS Connections . . . . . . . . . . . . . . . . . . 13
3.2. Security Parameter Passing . . . . . . . . . . . . . . . . 13 3.2. Security Parameter Passing . . . . . . . . . . . . . . . . 14
3.3. Notifications and Proxy . . . . . . . . . . . . . . . . . 14 3.3. Notifications and Proxy . . . . . . . . . . . . . . . . . 14
4. Elements of the Model . . . . . . . . . . . . . . . . . . . . 14 4. Elements of the Model . . . . . . . . . . . . . . . . . . . . 15
4.1. X.509 Certificates . . . . . . . . . . . . . . . . . . . . 15 4.1. X.509 Certificates . . . . . . . . . . . . . . . . . . . . 15
4.1.1. Provisioning for the Certificate . . . . . . . . . . . 15 4.1.1. Provisioning for the Certificate . . . . . . . . . . . 15
4.2. Messages . . . . . . . . . . . . . . . . . . . . . . . . . 16 4.2. (D)TLS Usage . . . . . . . . . . . . . . . . . . . . . . . 17
4.3. SNMP Services . . . . . . . . . . . . . . . . . . . . . . 16 4.3. SNMP Services . . . . . . . . . . . . . . . . . . . . . . 17
4.3.1. SNMP Services for an Outgoing Message . . . . . . . . 17 4.3.1. SNMP Services for an Outgoing Message . . . . . . . . 18
4.3.2. SNMP Services for an Incoming Message . . . . . . . . 17 4.3.2. SNMP Services for an Incoming Message . . . . . . . . 18
4.4. Cached Information and References . . . . . . . . . . . . 18 4.4. Cached Information and References . . . . . . . . . . . . 19
4.4.1. TLS Transport Model Cached Information . . . . . . . . 18 4.4.1. TLS Transport Model Cached Information . . . . . . . . 19
4.4.1.1. tmSecurityName . . . . . . . . . . . . . . . . . . 19 4.4.1.1. tmSecurityName . . . . . . . . . . . . . . . . . . 20
4.4.1.2. tmSessionID . . . . . . . . . . . . . . . . . . . 19 4.4.1.2. tmSessionID . . . . . . . . . . . . . . . . . . . 20
4.4.1.3. Session State . . . . . . . . . . . . . . . . . . 19 4.4.1.3. Session State . . . . . . . . . . . . . . . . . . 20
5. Elements of Procedure . . . . . . . . . . . . . . . . . . . . 19 5. Elements of Procedure . . . . . . . . . . . . . . . . . . . . 20
5.1. Procedures for an Incoming Message . . . . . . . . . . . . 20 5.1. Procedures for an Incoming Message . . . . . . . . . . . . 21
5.1.1. DTLS Processing for Incoming Messages . . . . . . . . 20 5.1.1. DTLS over UDP Processing for Incoming Messages . . . . 21
5.1.2. Transport Processing for Incoming SNMP Messages . . . 22 5.1.2. Transport Processing for Incoming SNMP Messages . . . 23
5.2. Procedures for an Outgoing SNMP Message . . . . . . . . . 23 5.2. Procedures for an Outgoing SNMP Message . . . . . . . . . 24
5.3. Establishing or Accepting a Session . . . . . . . . . . . 25 5.3. Establishing or Accepting a Session . . . . . . . . . . . 25
5.3.1. Establishing a Session as a Client . . . . . . . . . . 25 5.3.1. Establishing a Session as a Client . . . . . . . . . . 26
5.3.2. Accepting a Session as a Server . . . . . . . . . . . 27 5.3.2. Accepting a Session as a Server . . . . . . . . . . . 28
5.4. Closing a Session . . . . . . . . . . . . . . . . . . . . 28 5.4. Closing a Session . . . . . . . . . . . . . . . . . . . . 29
6. MIB Module Overview . . . . . . . . . . . . . . . . . . . . . 28 6. MIB Module Overview . . . . . . . . . . . . . . . . . . . . . 29
6.1. Structure of the MIB Module . . . . . . . . . . . . . . . 28 6.1. Structure of the MIB Module . . . . . . . . . . . . . . . 29
6.2. Textual Conventions . . . . . . . . . . . . . . . . . . . 29 6.2. Textual Conventions . . . . . . . . . . . . . . . . . . . 29
6.3. Statistical Counters . . . . . . . . . . . . . . . . . . . 29 6.3. Statistical Counters . . . . . . . . . . . . . . . . . . . 30
6.4. Configuration Tables . . . . . . . . . . . . . . . . . . . 29 6.4. Configuration Tables . . . . . . . . . . . . . . . . . . . 30
6.4.1. Notifications . . . . . . . . . . . . . . . . . . . . 29 6.4.1. Notifications . . . . . . . . . . . . . . . . . . . . 30
6.5. Relationship to Other MIB Modules . . . . . . . . . . . . 29 6.5. Relationship to Other MIB Modules . . . . . . . . . . . . 30
6.5.1. MIB Modules Required for IMPORTS . . . . . . . . . . . 30 6.5.1. MIB Modules Required for IMPORTS . . . . . . . . . . . 30
7. MIB Module Definition . . . . . . . . . . . . . . . . . . . . 30 7. MIB Module Definition . . . . . . . . . . . . . . . . . . . . 31
8. Operational Considerations . . . . . . . . . . . . . . . . . . 51 8. Operational Considerations . . . . . . . . . . . . . . . . . . 52
8.1. Sessions . . . . . . . . . . . . . . . . . . . . . . . . . 52 8.1. Sessions . . . . . . . . . . . . . . . . . . . . . . . . . 52
8.2. Notification Receiver Credential Selection . . . . . . . . 52 8.2. Notification Receiver Credential Selection . . . . . . . . 53
8.3. contextEngineID Discovery . . . . . . . . . . . . . . . . 53 8.3. contextEngineID Discovery . . . . . . . . . . . . . . . . 53
8.4. Transport Considerations . . . . . . . . . . . . . . . . . 53 8.4. Transport Considerations . . . . . . . . . . . . . . . . . 54
9. Security Considerations . . . . . . . . . . . . . . . . . . . 53 9. Security Considerations . . . . . . . . . . . . . . . . . . . 54
9.1. Certificates, Authentication, and Authorization . . . . . 53 9.1. Certificates, Authentication, and Authorization . . . . . 54
9.2. Use with SNMPv1/SNMPv2c Messages . . . . . . . . . . . . . 54 9.2. Use with SNMPv1/SNMPv2c Messages . . . . . . . . . . . . . 55
9.3. MIB Module Security . . . . . . . . . . . . . . . . . . . 55 9.3. MIB Module Security . . . . . . . . . . . . . . . . . . . 55
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 56 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 57
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 57 11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 57
12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 58 12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 58
12.1. Normative References . . . . . . . . . . . . . . . . . . . 58 12.1. Normative References . . . . . . . . . . . . . . . . . . . 58
12.2. Informative References . . . . . . . . . . . . . . . . . . 59 12.2. Informative References . . . . . . . . . . . . . . . . . . 59
Appendix A. (D)TLS Overview . . . . . . . . . . . . . . . . . . . 60 Appendix A. Target and Notification Configuration Example . . . . 60
A.1. The (D)TLS Record Protocol . . . . . . . . . . . . . . . . 60 A.1. Configuring the Notification Originator . . . . . . . . . 60
A.2. The (D)TLS Handshake Protocol . . . . . . . . . . . . . . 61 A.2. Configuring the Command Responder . . . . . . . . . . . . 62
Appendix B. PKIX Certificate Infrastructure . . . . . . . . . . . 62 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 63
Appendix C. Target and Notification Configuration Example . . . . 63
C.1. Configuring the Notification Originator . . . . . . . . . 64
C.2. Configuring the Command Responder . . . . . . . . . . . . 64
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 65
1. Introduction 1. Introduction
It is important to understand the modular SNMPv3 architecture as It is important to understand the modular SNMPv3 architecture as
defined by [RFC3411] and enhanced by the Transport Subsystem defined by [RFC3411] and enhanced by the Transport Subsystem
[RFC5590]. It is also important to understand the terminology of the [RFC5590]. It is also important to understand the terminology of the
SNMPv3 architecture in order to understand where the Transport Model SNMPv3 architecture in order to understand where the Transport Model
described in this document fits into the architecture and how it described in this document fits into the architecture and how it
interacts with the other architecture subsystems. For a detailed interacts with the other architecture subsystems. For a detailed
overview of the documents that describe the current Internet-Standard overview of the documents that describe the current Internet-Standard
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subsystem [RFC5590]. DTLS is the datagram variant of the Transport subsystem [RFC5590]. DTLS is the datagram variant of the Transport
Layer Security (TLS) protocol [RFC5246]. The Transport Model in this Layer Security (TLS) protocol [RFC5246]. The Transport Model in this
document is referred to as the Transport Layer Security Transport document is referred to as the Transport Layer Security Transport
Model (TLSTM). TLS and DTLS take advantage of the X.509 public Model (TLSTM). TLS and DTLS take advantage of the X.509 public
keying infrastructure [RFC5280]. While (D)TLS supports multiple keying infrastructure [RFC5280]. While (D)TLS supports multiple
authentication mechanisms, this document only discusses X.509 authentication mechanisms, this document only discusses X.509
certificate based authentication. Although other forms of certificate based authentication. Although other forms of
authentication are possible they are outside the scope of this authentication are possible they are outside the scope of this
specification. This transport model is designed to meet the security specification. This transport model is designed to meet the security
and operational needs of network administrators, operating in both and operational needs of network administrators, operating in both
environments where a connectionless (e.g. UDP or SCTP) transport is environments where a connectionless (e.g. UDP) transport is
preferred and in environments where large quantities of data need to 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 be sent (e.g. over a TCP based stream). Both TLS and DTLS integrate
well into existing public keying infrastructures. This document well into existing public keying infrastructures. This document
supports sending of SNMP messages over TLS/TCP, DTLS/UDP and DTLS/ supports sending of SNMP messages over TLS/TCP and DTLS/UDP.
SCTP.
This document also defines a portion of the Management Information This document also defines a portion of the Management Information
Base (MIB) for use with network management protocols. In particular Base (MIB) for use with network management protocols. In particular
it defines objects for managing the TLS Transport Model for SNMP. it defines objects for managing the TLS Transport Model for SNMP.
Managed objects are accessed via a virtual information store, termed Managed objects are accessed via a virtual information store, termed
the Management Information Base or MIB. MIB objects are generally the Management Information Base or MIB. MIB objects are generally
accessed through the Simple Network Management Protocol (SNMP). accessed through the Simple Network Management Protocol (SNMP).
Objects in the MIB are defined using the mechanisms defined in the Objects in the MIB are defined using the mechanisms defined in the
Structure of Management Information (SMI). This memo specifies a MIB Structure of Management Information (SMI). This memo specifies a MIB
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contains a command responder and notification originator application, contains a command responder and notification originator application,
and the other a command generator and notification responder and the other a command generator and notification responder
application. It should be understood that this particular mix of application. It should be understood that this particular mix of
application types is an example only and other combinations are application types is an example only and other combinations are
equally valid. Note: this diagram shows the Transport Security Model equally valid. Note: this diagram shows the Transport Security Model
(TSM) being used as the security model which is defined in [RFC5591]. (TSM) being used as the security model which is defined in [RFC5591].
+---------------------------------------------------------------------+ +---------------------------------------------------------------------+
| Network | | Network |
+---------------------------------------------------------------------+ +---------------------------------------------------------------------+
^ | ^ | ^ | ^ |
|Notifications |Commands |Commands |Notifications |Notifications |Commands |Commands |Notifications
+---|---------------------|--------+ +--|---------------|-------------+ +---|---------------------|-------+ +--|---------------|--------------+
| | V | | | V | | | V | | | V |
| +------------+ +------------+ | | +-----------+ +----------+ | | +------------+ +------------+ | | +-----------+ +----------+ |
| | (D)TLS | | (D)TLS | | | | (D)TLS | | (D)TLS | | | | (D)TLS | | (D)TLS | | | | (D)TLS | | (D)TLS | |
| | Service | | Service | | | | Service | | Service | | | | (Client) | | (Server) | | | | (Client) | | (Server) | |
| | (Client) | | (Server) | | | | (Client) | | (Server)| | | +------------+ +------------+ | | +-----------+ +----------+ |
| +------------+ +------------+ | | +-----------+ +----------+ | | ^ ^ | | ^ ^ |
| ^ ^ | | ^ ^ | | | | | | | | |
| | | | | | | | | +-------------+ | | +--------------+ |
| +-------------+ | | +--------------+ | | +-----|------------+ | | +-----|------------+ |
| +-----|--------------+ | | +-----|-----------+ | | | V | | | | V | |
| | V | +-------+ | | | V | +--------+ | | | +--------+ | +-----+ | | | +--------+ | +-----+ |
| | +--------+ | | | | | | +--------+ | | | | | | | TLS TM |<--------->|Cache| | | | | TLS TM |<--------->|Cache| |
| | | TLS TM |---------->| Cache | | | | | TLS TM | <---->| Cache | | | | +--------+ | +-----+ | | | +--------+ | +-----+ |
| | | | | | | | | | | | | | | | | |Transport Subsys. | ^ | | |Transport Subsys. | ^ |
| | +--------+ | +-------+ | | | +--------+ | +--------+ | | +------------------+ | | | +------------------+ | |
| |Transport Subsystem | ^ | | |Transport Sub. | ^ | | ^ | | | ^ | |
| +--------------------+ | | | +-----------------+ | | | | +--+ | | | +--+ |
| ^ +----+ | | ^ | | | v | | | V | |
| | | | | | | | | +-----+ +--------+ +-------+ | | | +-----+ +--------+ +-------+ | |
| v | | | V | | | | | |Message | |Securi.| | | | | | |Message | |Securi.| | |
| +-------+ +----------+ +-----+ | | | +-----+ +------+ +-----+ | | | |Disp.| |Proc. | |Subsys.| | | | |Disp.| |Proc. | |Subsys.| | |
| | | |Message | |Sec. | | | | | | | MP | |Sec. | | | | | | |Subsys. | | | | | | | | |Subsys. | | | | |
| | Disp. | |Processing| |Sub- | | | | |Disp.| | Sub- | |Sub- | | | | | | | | | | | | | | | | | | | | |
| | | |Subsystem | |sys. | | | | | | |system| |sys. | | | | | | | +----+ | | +---+ | | | | | | | +----+ | | +---+ | | |
| | | | | | | | | | | | | | | | | | | | <--->|v3MP|<--> |TSM|<--+ | | | <--->|v3MP|<--->|TSM|<--+ |
| | | | | |+---+| | | | | | | | |+---+| | | | | | | +----+ | | +---+ | | | | | | +----+ | | +---+ | |
| | | | +-----+ | || || | | | | | |+----+| || || | | | | | | | | | | | | | | | | | |
| | <--->|v3MP |<--->|TSM|<-+ | | | <-->|v3MP|<->|TSM|<-+ | | +-----+ +--------+ +-------+ | | +-----+ +--------+ +-------+ |
| | | | +-----+ | || || | | | | |+----+| || || | | ^ | | ^ |
| +-------+ | | |+---+| | | +-----+ | | |+---+| | | | | | | |
| ^ | | | | | | ^ | | | | | | +-+------------+ | | +-+----------+ |
| | +----------+ +-----+ | | | +------+ +-----+ | | | | | | | | |
| +-+------------+ | | +-+----------+ | | v v | | v V |
| ^ ^ | | | ^ | | +-------------+ +-------------+ | | +-------------+ +-------------+ |
| | | | | | | | | | COMMAND | | NOTIFICAT. | | | | COMMAND | | NOTIFICAT. | |
| v v | | v V | | | RESPONDER | | ORIGINATOR | | | | GENERATOR | | RECEIVER | |
| +-------------+ +--------------+ | | +-----------+ +--------------+ | | | application | | application | | | | application | | application | |
| | COMMAND | | NOTIFICATION | | | | COMMAND | | NOTIFICATION | | | +-------------+ +-------------+ | | +-------------+ +-------------+ |
| | RESPONDER | | ORIGINATOR | | | | GENERATOR | | RECEIVER | | | SNMP entity | | SNMP entity |
| | application | | application | | | |application| | application | | +---------------------------------+ +---------------------------------+
| +-------------+ +--------------+ | | +-----------+ +--------------+ |
| SNMP entity | | SNMP entity |
+----------------------------------+ +--------------------------------+
1.1. Conventions 1.1. Conventions
For consistency with SNMP-related specifications, this document For consistency with SNMP-related specifications, this document
favors terminology as defined in STD 62, rather than favoring favors terminology as defined in STD 62, rather than favoring
terminology that is consistent with non-SNMP specifications. This is terminology that is consistent with non-SNMP specifications. This is
consistent with the IESG decision to not require the SNMPv3 consistent with the IESG decision to not require the SNMPv3
terminology be modified to match the usage of other non-SNMP terminology be modified to match the usage of other non-SNMP
specifications when SNMPv3 was advanced to Full Standard. specifications when SNMPv3 was advanced to Full Standard.
skipping to change at page 8, line 17 skipping to change at page 9, line 10
among other things, an individual acting in a particular role; a set among other things, an individual acting in a particular role; a set
of individuals, with each acting in a particular role; an application of individuals, with each acting in a particular role; an application
or a set of applications, or a combination of these within an or a set of applications, or a combination of these within an
administrative domain. administrative domain.
Throughout this document, the term "session" is used to refer to a Throughout this document, the term "session" is used to refer to a
secure association between two TLS Transport Models that permits the secure association between two TLS Transport Models that permits the
transmission of one or more SNMP messages within the lifetime of 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. The (D)TLS protocols also have an internal notion of a
session and although these two concepts of a session are related, session and although these two concepts of a session are related,
this document (unless otherwise specified) is referring to TLSTM's when the term "session" is used this document is referring to the
specific session and not directly to the (D)TLS protocol's session. TLSTM's specific session and not directly to the (D)TLS protocol's
session.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
2. The Transport Layer Security Protocol 2. The Transport Layer Security Protocol
(D)TLS provides authentication, data message integrity, and privacy (D)TLS provides authentication, data message integrity, and privacy
at the transport layer. (See [RFC4347]) at the transport layer. (See [RFC4347])
The primary goals of the TLS Transport Model are to provide privacy, The primary goals of the TLS Transport Model are to provide privacy,
peer identity authentication and data integrity between two peer identity authentication and data integrity between two
communicating SNMP entities. The TLS and DTLS protocols provide a communicating SNMP entities. The TLS and DTLS protocols provide a
secure transport upon which the TLSTM is based. An overview of secure transport upon which the TLSTM is based. Please refer to
(D)TLS can be found in section Appendix A. Please refer to [RFC5246] [RFC5246] and [RFC4347] for complete descriptions of the protocols.
and [RFC4347] for complete descriptions of the protocols.
3. How the TLSTM fits into the Transport Subsystem 3. How the TLSTM fits into the Transport Subsystem
A transport model is a component of the Transport Subsystem. The TLS A transport model is a component of the Transport Subsystem. The TLS
Transport Model thus fits between the underlying (D)TLS transport Transport Model thus fits between the underlying (D)TLS transport
layer and the Message Dispatcher [RFC3411] component of the SNMP layer and the Message Dispatcher [RFC3411] component of the SNMP
engine and the Transport Subsystem. engine and the Transport Subsystem.
The TLS Transport Model will establish a session between itself and The TLS Transport Model will establish a session between itself and
the TLS Transport Model of another SNMP engine. The sending the TLS Transport Model of another SNMP engine. The sending
skipping to change at page 9, line 10 skipping to change at page 9, line 49
the Dispatcher to (D)TLS to be encrypted and authenticated, and the the Dispatcher to (D)TLS to be encrypted and authenticated, and the
receiving transport model accepts decrypted and authenticated/ receiving transport model accepts decrypted and authenticated/
integrity-checked incoming messages from (D)TLS and passes them to integrity-checked incoming messages from (D)TLS and passes them to
the Dispatcher. the Dispatcher.
After a TLS Transport Model session is established, SNMP messages can After a TLS Transport Model session is established, SNMP messages can
conceptually be sent through the session from one SNMP message conceptually be sent through the session from one SNMP message
Dispatcher to another SNMP Message Dispatcher. If multiple SNMP Dispatcher to another SNMP Message Dispatcher. If multiple SNMP
messages are needed to be passed between two SNMP applications they messages are needed to be passed between two SNMP applications they
MAY be passed through the same session. A TLSTM implementation MAY be passed through the same session. A TLSTM implementation
engine MAY choose to close a (D)TLS session to conserve resources. engine MAY choose to close the session to conserve resources.
The TLS Transport Model of an SNMP engine will perform the The TLS Transport Model of an SNMP engine will perform the
translation between (D)TLS-specific security parameters and SNMP- translation between (D)TLS-specific security parameters and SNMP-
specific, model-independent parameters. specific, model-independent parameters.
The diagram below depicts where the TLS Transport Model fits into the The diagram below depicts where the TLS Transport Model fits into the
architecture described in RFC3411 and the Transport Subsystem: architecture described in RFC3411 and the Transport Subsystem:
+------------------------------+ +------------------------------+
| Network | | Network |
skipping to change at page 10, line 46 skipping to change at page 11, line 39
network, data has not been altered or destroyed in an network, data has not been altered or destroyed in an
unauthorized manner, and data sequences have not been altered to unauthorized manner, and data sequences have not been altered to
an extent greater than can occur non-maliciously. an extent greater than can occur non-maliciously.
2. Masquerade - The masquerade threat is the danger that management 2. Masquerade - The masquerade threat is the danger that management
operations unauthorized for a given principal may be attempted by operations unauthorized for a given principal may be attempted by
assuming the identity of another principal that has the assuming the identity of another principal that has the
appropriate authorizations. appropriate authorizations.
The TLSTM verifies of the identity of the (D)TLS server through The TLSTM verifies of the identity of the (D)TLS server through
the use of the (D)TLS protocol and X.509 certificates. The TLS the use of the (D)TLS protocol and X.509 certificates. A TLS
Transport Model MUST support authentication of both the server Transport Model implementation MUST support authentication of
and the client. both the server and the client.
3. Message stream modification - The re-ordering, delay or replay of 3. Message stream modification - The re-ordering, delay or replay of
messages can and does occur through the natural operation of many messages can and does occur through the natural operation of many
connectionless transport services. The message stream connectionless transport services. The message stream
modification threat is the danger that messages may be modification threat is the danger that messages may be
maliciously re-ordered, delayed or replayed to an extent which is maliciously re-ordered, delayed or replayed to an extent which is
greater than can occur through the natural operation of greater than can occur through the natural operation of
connectionless transport services, in order to effect connectionless transport services, in order to effect
unauthorized management operations. unauthorized management operations.
(D)TLS provides replay protection with a MAC that includes a (D)TLS provides replay protection with a MAC that includes a
sequence number. Since UDP provides no sequencing ability, DTLS sequence number. Since UDP provides no sequencing ability, DTLS
uses a sliding window protocol with the sequence number used for uses a sliding window protocol with the sequence number used for
replay protection (see [RFC4347]). replay protection (see [RFC4347]).
4. Disclosure - The disclosure threat is the danger of eavesdropping 4. Disclosure - The disclosure threat is the danger of eavesdropping
on the exchanges between SNMP engines. on the exchanges between SNMP engines.
(D)TLS provides protection against the disclosure of information (D)TLS provides protection against the disclosure of information
to unauthorized recipients or eavesdroppers by allowing for to unauthorized recipients or eavesdroppers by allowing for
encryption of all traffic between SNMP engines. The TLS encryption of all traffic between SNMP engines. A TLS Transport
Transport Model SHOULD support the message encryption to protect Model implementation SHOULD support the message encryption to
sensitive data from eavesdropping attacks. protect sensitive data from eavesdropping attacks.
5. Denial of Service - the RFC 3411 architecture [RFC3411] states 5. Denial of Service - the RFC 3411 architecture [RFC3411] states
that denial of service (DoS) attacks need not be addressed by an that denial of service (DoS) attacks need not be addressed by an
SNMP security protocol. However, datagram-based security SNMP security protocol. However, connectionless transports (like
protocols like DTLS are susceptible to a variety of denial of DTLS over UDP) are susceptible to a variety of denial of service
service attacks because they are more vulnerable to spoofed attacks because they are more vulnerable to spoofed IP addresses.
messages. See Section 4.2 for details how the cookie mechanism is used.
Note, however, that this mechanism does not provide any defense
In order to counter these attacks, DTLS borrows the stateless against denial of service attacks mounted from valid IP
cookie technique used by Photuris [RFC2522] and IKEv2 [RFC4306] addresses.
and is described fully in section 4.2.1 of [RFC4347]. This
mechanism, though, does not provide any defense against denial of
service attacks mounted from valid IP addresses. DTLS Transport
Model server implementations MUST support DTLS cookies.
Implementations are not required to perform the stateless cookie
exchange for every DTLS handshake, but in environments where an
overload on server side resources is detectable by the
implementation it is RECOMMENDED that the cookie exchange is
utilized by the implementation.
See Section 9 for more detail on the security considerations See Section 9 for more detail on the security considerations
associated with the TLSTM and these security threats. associated with the TLSTM and these security threats.
3.1.2. Message Protection 3.1.2. Message Protection
The RFC 3411 architecture recognizes three levels of security: The RFC 3411 architecture recognizes three levels of security:
o without authentication and without privacy (noAuthNoPriv) o without authentication and without privacy (noAuthNoPriv)
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o with authentication and with privacy (authPriv) o with authentication and with privacy (authPriv)
The TLS Transport Model determines from (D)TLS the identity of the The TLS Transport Model determines from (D)TLS the identity of the
authenticated principal, the transport type and the transport address authenticated principal, the transport type and the transport address
associated with an incoming message. The TLS Transport Model associated with an incoming message. The TLS Transport Model
provides the identity and destination type and address to (D)TLS for provides the identity and destination type and address to (D)TLS for
outgoing messages. outgoing messages.
When an application requests a session for a message it also requests When an application requests a session for a message it also requests
a security level for that session. The TLS Transport Model MUST a security level for that session. The TLS Transport Model MUST
ensure that the (D)TLS session provides security at least as high as ensure that the (D)TLS connection provides security at least as high
the requested level of security. How the security level is as the requested level of security. How the security level is
translated into the algorithms used to provide data integrity and translated into the algorithms used to provide data integrity and
privacy is implementation-dependent. However, the NULL integrity and privacy is implementation-dependent. However, the NULL integrity and
encryption algorithms MUST NOT be used to fulfill security level encryption algorithms MUST NOT be used to fulfill security level
requests for authentication or privacy. Implementations MAY choose requests for authentication or privacy. Implementations MAY choose
to force (D)TLS to only allow cipher_suites that provide both to force (D)TLS to only allow cipher_suites that provide both
authentication and privacy to guarantee this assertion. authentication and privacy to guarantee this assertion.
If a suitable interface between the TLS Transport Model and the If a suitable interface between the TLS Transport Model and the
(D)TLS Handshake Protocol is implemented to allow the selection of (D)TLS Handshake Protocol is implemented to allow the selection of
security level dependent algorithms (for example a security level to security level dependent algorithms (for example a security level to
skipping to change at page 12, line 46 skipping to change at page 13, line 24
utilized by the application. utilized by the application.
The authentication, integrity and privacy algorithms used by the The authentication, integrity and privacy algorithms used by the
(D)TLS Protocols may vary over time as the science of cryptography (D)TLS Protocols may vary over time as the science of cryptography
continues to evolve and the development of (D)TLS continues over continues to evolve and the development of (D)TLS continues over
time. Implementers are encouraged to plan for changes in operator time. Implementers are encouraged to plan for changes in operator
trust of particular algorithms. Implementations should offer trust of particular algorithms. Implementations should offer
configuration settings for mapping algorithms to SNMPv3 security configuration settings for mapping algorithms to SNMPv3 security
levels. levels.
3.1.3. (D)TLS Sessions 3.1.3. (D)TLS Connections
(D)TLS sessions are opened by the TLS Transport Model during the (D)TLS connections are opened by the TLS Transport Model during the
elements of procedure for an outgoing SNMP message. Since the sender elements of procedure for an outgoing SNMP message. Since the sender
of a message initiates the creation of a (D)TLS session if needed, of a message initiates the creation of a (D)TLS connection if needed,
the (D)TLS session will already exist for an incoming message. the (D)TLS connection will already exist for an incoming message.
Implementations MAY choose to instantiate (D)TLS sessions in Implementations MAY choose to instantiate (D)TLS connections in
anticipation of outgoing messages. This approach might be useful to anticipation of outgoing messages. This approach might be useful to
ensure that a (D)TLS session to a given target can be established 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 before it becomes important to send a message over the (D)TLS
session. Of course, there is no guarantee that a pre-established connection. Of course, there is no guarantee that a pre-established
session will still be valid when needed. session will still be valid when needed.
DTLS sessions, when used over UDP, are uniquely identified within the DTLS connections, when used over UDP, are uniquely identified within
TLS Transport Model by the combination of transportDomain, the TLS Transport Model by the combination of transportDomain,
transportAddress, tmSecurityName, and requestedSecurityLevel transportAddress, tmSecurityName, and requestedSecurityLevel
associated with each session. Each unique combination of these associated with each session. Each unique combination of these
parameters MUST have a locally-chosen unique tlstmSessionID for each parameters MUST have a locally-chosen unique tlstmSessionID for each
active session. For further information see Section 5. TLS over TCP active session. For further information see Section 5. TLS over TCP
and DTLS over SCTP sessions, on the other hand, do not require a sessions, on the other hand, do not require a unique pairing of
unique pairing of address and port attributes since their lower layer address and port attributes since their lower layer protocols (TCP)
protocols (TCP and SCTP) already provide adequate session framing. already provide adequate session framing. But they must still
But they must still provide a unique tlstmSessionID for referencing provide a unique tlstmSessionID for referencing the session.
the session.
As an implementation hint: although the tlstmSessionID may be the
same as the (D)TLS internal SessionID caution must be exercised since
the (D)TLS internal SessionID may change over the life of the
connection as seen by the TLSTM (for example during renegotiation).
The tlstmSessionID identifier MUST NOT change during the entire The tlstmSessionID identifier MUST NOT change during the entire
duration of the session from the TLSTM's perspective even if the TLS duration of the session from the TLSTM's perspective, and MUST
internal session identifier does change. 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 idenfify a TLSTM session (there can be multiple TLSTM
sessions sharing the same D(TLS) internal SessionID).
3.2. Security Parameter Passing 3.2. Security Parameter Passing
For the (D)TLS server-side, (D)TLS-specific security parameters For the (D)TLS server-side, (D)TLS-specific security parameters
(i.e., cipher_suites, X.509 certificate fields, IP address and port) (i.e., cipher_suites, X.509 certificate fields, IP address and port)
are translated by the TLS Transport Model into security parameters are translated by the TLS Transport Model into security parameters
for the TLS Transport Model and security model (e.g., for the TLS Transport Model and security model (e.g.,
tmSecurityLevel, tmSecurityName, transportDomain, transportAddress). tmSecurityLevel, tmSecurityName, transportDomain, transportAddress).
The transport-related and (D)TLS-security-related information, The transport-related and (D)TLS-security-related information,
including the authenticated identity, are stored in a cache including the authenticated identity, are stored in a cache
skipping to change at page 14, line 7 skipping to change at page 14, line 32
provided by the Dispatcher in the sendMessage() Abstract Service provided by the Dispatcher in the sendMessage() Abstract Service
Interface (ASI) and input from the tmStateReference cache. The Interface (ASI) and input from the tmStateReference cache. The
(D)TLS Transport Model converts that information into suitable (D)TLS Transport Model converts that information into suitable
security parameters for (D)TLS and establishes sessions as needed. security parameters for (D)TLS and establishes sessions as needed.
The elements of procedure in Section 5 discuss these concepts in much The elements of procedure in Section 5 discuss these concepts in much
greater detail. greater detail.
3.3. Notifications and Proxy 3.3. Notifications and Proxy
(D)TLS sessions may be initiated by (D)TLS clients on behalf of SNMP (D)TLS connections may be initiated by (D)TLS clients on behalf of
appplications that initiate communications, such as command SNMP appplications that initiate communications, such as command
generators, notification originators, proxy forwarders. Command generators, notification originators, proxy forwarders. Command
generators are frequently operated by a human, but notification generators are frequently operated by a human, but notification
originators and proxy forwarders are usually unmanned automated originators and proxy forwarders are usually unmanned automated
processes. The targets to whom notifications and proxied requests processes. The targets to whom notifications and proxied requests
should be sent is typically determined and configured by a network should be sent is typically determined and configured by a network
administrator. administrator.
The SNMP-TARGET-MIB module [RFC3413] contains objects for defining The SNMP-TARGET-MIB module [RFC3413] contains objects for defining
management targets, including transportDomain, transportAddress, management targets, including transportDomain, transportAddress,
securityName, securityModel, and securityLevel parameters, for securityName, securityModel, and securityLevel parameters, for
notification originator, proxy forwarder, and SNMP-controllable notification originator, proxy forwarder, and SNMP-controllable
command generator applications. Transport domains and transport command generator applications. Transport domains and transport
addresses are configured in the snmpTargetAddrTable, and the addresses are configured in the snmpTargetAddrTable, and the
securityModel, securityName, and securityLevel parameters are securityModel, securityName, and securityLevel parameters are
configured in the snmpTargetParamsTable. This document defines a MIB configured in the snmpTargetParamsTable. This document defines a MIB
module that extends the SNMP-TARGET-MIB's snmpTargetParamsTable to module that extends the SNMP-TARGET-MIB's snmpTargetParamsTable to
specify a (D)TLS client-side certificate to use for the connection. specify a (D)TLS client-side certificate to use for the connection.
When configuring a (D)TLS target, the snmpTargetAddrTDomain and When configuring a (D)TLS target, the snmpTargetAddrTDomain and
snmpTargetAddrTAddress parameters in snmpTargetAddrTable should be snmpTargetAddrTAddress parameters in snmpTargetAddrTable should be
set to the snmpTLSTCPDomain, snmpDTLSUDPDomain, or snmpDTLSSCTPDomain set to the snmpTLSTCPDomain or snmpDTLSUDPDomain object and an
object and an appropriate snmpTLSAddress value. When used with the appropriate snmpTLSAddress value. When used with the SNMPv3 message
SNMPv3 message processing model, the snmpTargetParamsMPModel column processing model, the snmpTargetParamsMPModel column of the
of the snmpTargetParamsTable should be set to a value of 3. The snmpTargetParamsTable should be set to a value of 3. The
snmpTargetParamsSecurityName should be set to an appropriate snmpTargetParamsSecurityName should be set to an appropriate
securityName value and the tlstmParamsClientFingerprint parameter of securityName value and the tlstmParamsClientFingerprint parameter of
the tlstmParamsTable should be set a value that refers to a locally the tlstmParamsTable should be set a value that refers to a locally
held certificate to be used. Other parameters, for example held certificate (and the corresponding private key) to be used.
cryptographic configuration such as which cipher suites to use, must Other parameters, for example cryptographic configuration such as
come from configuration mechanisms not defined in this document. which cipher suites to use, must come from configuration mechanisms
not defined in this document.
The securityName defined in the snmpTargetParamsSecurityName column The securityName defined in the snmpTargetParamsSecurityName column
will be used by the access control model to authorize any will be used by the access control model to authorize any
notifications that need to be sent. notifications that need to be sent.
4. Elements of the Model 4. Elements of the Model
This section contains definitions required to realize the (D)TLS This section contains definitions required to realize the (D)TLS
Transport Model defined by this document. Transport Model defined by this document.
4.1. X.509 Certificates 4.1. X.509 Certificates
(D)TLS can make use of X.509 certificates for authentication of both (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 sides of the transport. This section discusses the use of X.509
certificates in the TLSTM. A brief overview of X.509 certificate certificates in the TLSTM.
infrastructure can be found in Appendix B.
While (D)TLS supports multiple authentication mechanisms, this While (D)TLS supports multiple authentication mechanisms, this
document only discusses X.509 certificate based authentication. document only discusses X.509 certificate based authentication; Other
Although other forms of authentication are possible they are outside forms of authentication are are outside the scope of this
the scope of this specification. TLSTM implementations are REQUIRED specification. TLSTM implementations are REQUIRED to support X.509
to support X.509 certificates. certificates.
4.1.1. Provisioning for the Certificate 4.1.1. Provisioning for the Certificate
Authentication using (D)TLS will require that SNMP entities are Authentication using (D)TLS will require that SNMP entities have
provisioned with certificates, which are signed by trusted certificates, either signed by trusted certification authorities, or
certificate authorities (possibly the certificate itself). self-signed. Furthermore, SNMP entities will most commonly need to
Furthermore, SNMP entities will most commonly need to be provisioned be provisioned with root certificates which represent the list of
with root certificates which represent the list of trusted trusted certificate authorities that an SNMP entity can use for
certificate authorities that an SNMP entity can use for certificate certificate verification. SNMP entities SHOULD also be provisioned
verification. SNMP entities SHOULD also be provisioned with a X.509 with a X.509 certificate revocation mechanism which can be used to
certificate revocation mechanism which can be used to verify that a verify that a certificate has not been revoked. Trusted public keys
certificate has not been revoked. Trusted public keys from either CA from either CA certificates and/or self-signed certificates, MUST be
certificates and/or self-signed certificates, MUST be installed into installed into the server through a trusted out of band mechanism and
the server through a trusted out of band mechanism and their their authenticity MUST be verified before access is granted.
authenticity MUST be verified before access is granted.
Having received a certificate from a connecting TLSTM client, the Having received a certificate from a connecting TLSTM client, the
authenticated tmSecurityName of the principal is derived using the authenticated tmSecurityName of the principal is derived using the
tlstmCertToTSNTable. This table allows mapping of incoming tlstmCertToTSNTable. This table allows mapping of incoming
connections to tmSecurityNames through defined transformations. The connections to tmSecurityNames through defined transformations. The
transformations defined in the TLSTM-MIB include: transformations defined in the TLSTM-MIB include:
o Mapping a certificate's subjectAltName or CommonName components to o Mapping a certificate's subjectAltName or CommonName components to
a tmSecurityName, or a tmSecurityName, or
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computational resources associated with certificate verification. computational resources associated with certificate verification.
Enterprise configurations are encouraged to map a "subjectAltName" Enterprise configurations are encouraged to map a "subjectAltName"
component of the X.509 certificate to the TLSTM specific component of the X.509 certificate to the TLSTM specific
tmSecurityName. The authenticated identity can be obtained by the tmSecurityName. The authenticated identity can be obtained by the
TLS Transport Model by extracting the subjectAltName(s) from the TLS Transport Model by extracting the subjectAltName(s) from the
peer's certificate. The receiving application will then have an peer's certificate. The receiving application will then have an
appropriate tmSecurityName for use by other SNMPv3 components like an appropriate tmSecurityName for use by other SNMPv3 components like an
access control model. access control model.
An example of this type of mapping setup can be found in Appendix C. An example of this type of mapping setup can be found in Appendix A.
This tmSecurityName may be later translated from a TLSTM specific This tmSecurityName may be later translated from a TLSTM specific
tmSecurityName to a SNMP engine securityName by the security model. tmSecurityName to a SNMP engine securityName by the security model.
A security model, like the TSM security model [RFC5591], may perform A security model, like the TSM security model [RFC5591], may perform
an identity mapping or a more complex mapping to derive the an identity mapping or a more complex mapping to derive the
securityName from the tmSecurityName offered by the TLS Transport securityName from the tmSecurityName offered by the TLS Transport
Model. Model.
A pictorial view of the complete transformation process (using the A pictorial view of the complete transformation process (using the
TSM security model for the example) is shown below: TSM security model for the example) is shown below:
+-------------+ +-------+ +-----+ +-------------+ +-------+ +-----+
| Certificate | | | | | | Certificate | | | | |
| Path | | TLSTM | tmpSecurityName | TSM | | Path | | TLSTM | tmSecurityName | TSM |
| Validation | --> | | ----------------->| | | Validation | --> | | ----------------->| |
+-------------+ +-------+ +-----+ +-------------+ +-------+ +-----+
| |
| securityName | securityName
V V
+-------------+ +-------------+
| application | | application |
+-------------+ +-------------+
4.2. Messages 4.2. (D)TLS Usage
As stated in Section 4.1.1 of [RFC4347], each DTLS record must fit (D)TLS MUST negotiate a cipher suite that uses X.509 certificates for
within a single DTLS datagram. The TLSTM SHOULD prohibit SNMP authentication, and MUST authenticate both the client and the server.
messages from being sent that exceeds the maximum DTLS message size. The mandatory-to-implement cipher suite is specified in the TLS
The TLSTM implementation SHOULD return an error when the DTLS message specification [RFC5246].
size would be exceeded and the message won't be sent.
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 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.
4.3. SNMP Services 4.3. SNMP Services
This section describes the services provided by the TLS Transport This section describes the services provided by the TLS Transport
Model with their inputs and outputs. The services are between the Model with their inputs and outputs. The services are between the
Transport Model and the Dispatcher. Transport Model and the Dispatcher.
The services are described as primitives of an abstract service The services are described as primitives of an abstract service
interface (ASI) and the inputs and outputs are described as abstract interface (ASI) and the inputs and outputs are described as abstract
data elements as they are passed in these abstract service data elements as they are passed in these abstract service
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The abstract data elements returned from or passed as parameters into The abstract data elements returned from or passed as parameters into
the abstract service primitives are as follows: the abstract service primitives are as follows:
statusInformation: An indication of whether the sending of the statusInformation: An indication of whether the sending of the
message was successful. If not, it is an indication of the message was successful. If not, it is an indication of the
problem. problem.
destTransportDomain: The transport domain for the associated destTransportDomain: The transport domain for the associated
destTransportAddress. The Transport Model uses this parameter to destTransportAddress. The Transport Model uses this parameter to
determine the transport type of the associated determine the transport type of the associated
destTransportAddress. This document specifies the snmpTLSDomain, destTransportAddress. This document specifies the
the snmpDTLSUDPDomain and the snmpDTLSSCTPDomain transport snmpTLSTCPDomain and the snmpDTLSUDPDomain transport domains.
domains.
destTransportAddress: The transport address of the destination TLS destTransportAddress: The transport address of the destination TLS
Transport Model in a format specified by the SnmpTLSAddress Transport Model in a format specified by the SnmpTLSAddress
TEXTUAL-CONVENTION. TEXTUAL-CONVENTION.
outgoingMessage: The outgoing message to send to (D)TLS for outgoingMessage: The outgoing message to send to (D)TLS for
encapsulation and transmission. encapsulation and transmission.
outgoingMessageLength: The length of the outgoingMessage field. outgoingMessageLength: The length of the outgoingMessage field.
skipping to change at page 18, line 22 skipping to change at page 19, line 22
) )
The abstract data elements returned from or passed as parameters into The abstract data elements returned from or passed as parameters into
the abstract service primitives are as follows: the abstract service primitives are as follows:
statusInformation: An indication of whether the passing of the statusInformation: An indication of whether the passing of the
message was successful. If not, it is an indication of the message was successful. If not, it is an indication of the
problem. problem.
transportDomain: The transport domain for the associated transportDomain: The transport domain for the associated
transportAddress. This document specifies the snmpTLSDomain, the transportAddress. This document specifies the snmpTLSTCPDomain
snmpDTLSUDPDomain and the snmpDTLSSCTPDomain transport domains. and the snmpDTLSUDPDomain transport domains.
transportAddress: The transport address of the source of the transportAddress: The transport address of the source of the
received message in a format specified by the SnmpTLSAddress received message in a format specified by the SnmpTLSAddress
TEXTUAL-CONVENTION. TEXTUAL-CONVENTION.
incomingMessage: The whole SNMP message after being processed by incomingMessage: The whole SNMP message after being processed by
(D)TLS and the (D)TLS transport layer data has been removed. (D)TLS and the (D)TLS transport layer data has been removed.
incomingMessageLength: The length of the incomingMessage field. incomingMessageLength: The length of the incomingMessage field.
skipping to change at page 19, line 11 skipping to change at page 20, line 11
cached information. See the Elements of Procedure in Section 5 for cached information. See the Elements of Procedure in Section 5 for
detailed processing instructions on the use of the tmStateReference detailed processing instructions on the use of the tmStateReference
fields by the TLS Transport Model. fields by the TLS Transport Model.
4.4.1.1. tmSecurityName 4.4.1.1. tmSecurityName
The tmSecurityName MUST be a human-readable name (in snmpAdminString The tmSecurityName MUST be a human-readable name (in snmpAdminString
format) representing the identity that has been set according to the format) representing the identity that has been set according to the
procedures in Section 5. The tmSecurityName MUST be constant for all procedures in Section 5. The tmSecurityName MUST be constant for all
traffic passing through an TLSTM session. Messages MUST NOT be sent traffic passing through an TLSTM session. Messages MUST NOT be sent
through an existing (D)TLS session that was established using a through an existing (D)TLS connection that was established using a
different tmSecurityName. different tmSecurityName.
On the (D)TLS server side of a connection the tmSecurityName is On the (D)TLS server side of a connection the tmSecurityName is
derived using the procedures described in Section 5.3.2 and the derived using the procedures described in Section 5.3.2 and the
TLSTM-MIB's tlstmCertToTSNTable DESCRIPTION clause. TLSTM-MIB's tlstmCertToTSNTable DESCRIPTION clause.
On the (D)TLS client side of a connection the tmSecurityName is On the (D)TLS client side of a connection the tmSecurityName is
presented to the TLS Transport Model by the application (possibly presented to the TLS Transport Model by the application (possibly
because of configuration specified in the SNMP-TARGET-MIB). because of configuration specified in the SNMP-TARGET-MIB).
The securityName MAY be derived from the tmSecurityName by a Security The securityName MAY be derived from the tmSecurityName by a Security
Model and MAY be used to configure notifications and access controls Model and MAY be used to configure notifications and access controls
in MIB modules. Transport Models SHOULD generate a predictable in MIB modules. Transport Models SHOULD generate a predictable
tmSecurityName so operators will know what to use when configuring tmSecurityName so operators will know what to use when configuring
MIB modules that use securityNames derived from tmSecurityNames. MIB modules that use securityNames derived from tmSecurityNames. The
TLSTM generates predictable tmSecurityNames based on the
configuration found in the TLSTM-MIB's tlstmCertToTSNTable and relies
on the network operators to have configured this table appropriately.
4.4.1.2. tmSessionID 4.4.1.2. tmSessionID
The tmSessionID MUST be recorded per message at the time of receipt. The tmSessionID MUST be recorded per message at the time of receipt.
When tmSameSecurity is set, the recorded tmSessionID can be used to When tmSameSecurity is set, the recorded tmSessionID can be used to
determine whether the (D)TLS session available for sending a determine whether the (D)TLS connection available for sending a
corresponding outgoing message is the same (D)TLS session as was used corresponding outgoing message is the same (D)TLS connection as was
when receiving the incoming message (e.g., a response to a request). used when receiving the incoming message (e.g., a response to a
request).
4.4.1.3. Session State 4.4.1.3. Session State
The per-session state that is referenced by tmStateReference may be The per-session state that is referenced by tmStateReference may be
saved across multiple messages in a Local Configuration Datastore. saved across multiple messages in a Local Configuration Datastore.
Additional session/connection state information might also be stored Additional session/connection state information might also be stored
in a Local Configuration Datastore. in a Local Configuration Datastore.
5. Elements of Procedure 5. Elements of Procedure
skipping to change at page 20, line 27 skipping to change at page 21, line 31
contextEngine would be set to the local value of snmpEngineID and contextEngine would be set to the local value of snmpEngineID and
contextName to the default context for error counters. contextName to the default context for error counters.
5.1. Procedures for an Incoming Message 5.1. Procedures for an Incoming Message
This section describes the procedures followed by the (D)TLS This section describes the procedures followed by the (D)TLS
Transport Model when it receives a (D)TLS protected packet. The Transport Model when it receives a (D)TLS protected packet. The
required functionality is broken into two different sections. required functionality is broken into two different sections.
Section 5.1.1 describes the processing required for de-multiplexing Section 5.1.1 describes the processing required for de-multiplexing
multiple DTLS sessions, which is specifically needed for DTLS over multiple DTLS connections, which is specifically needed for DTLS over
UDP sessions. It is assumed that TLS and DTLS/SCP protocol UDP sessions. It is assumed that TLS protocol implementations
implementations already provide appropriate message demultiplexing. already provide appropriate message demultiplexing.
Section 5.1.2describes the transport processing required once the 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 processing has been completed. This will be needed for all
(D)TLS-based sessions. (D)TLS-based connections.
5.1.1. DTLS Processing for Incoming Messages 5.1.1. DTLS over UDP Processing for Incoming Messages
DTLS over UDP is significantly different in terms of session handling For connection-oriented transport protocols, such as TCP, the
than when TLS or DTLS is run over session based streaming protocols transport protocol takes care of demultiplexing incoming packets to
like TCP or SCTP. Specifically, the DTLS protocol, when run over the right connection. Depending on the DTLS implementation, for DTLS
UDP, does not have a session identifier that allows implementations over UDP, this demultiplexing may need to be done by the TLSTM
to determine through which session a packet arrived. It is critical, implementation.
however, that implementations are always able to derive a
tlstmSessionID from any session demultiplexing process. When Like TCP, DTLS over UDP uses the four-tuple <source IP, destination
establishing a new session implementations MUST use a different UDP 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 source port number for each active connection to a remote destination
IP-address/port-number combination to ensure the remote entity can IP-address/port-number combination to ensure the remote entity can
easily disambiguate between multiple sessions from a host to the same disambiguate between multiple connections.
port on a server.
A process for demultiplexing multiple DTLS sessions arriving over UDP If demultiplexing received UDP datagrams to DTLS connection state is
must be incorporated into the procedures for processing an incoming done by the TLSTM implementation (instead of the DTLS
message. The steps in this section describe one possible method to implementation), the steps below describe one possible method to
accomplish this, although any implementation-dependent method should accomplish this.
be suitable as long as the results are deterministic. The important
output results from the steps in this process are the
transportDomain, the transportAddress, the wholeMessage, the
wholeMessageLength, and a unique implementation-dependent session
identifier (tlstmSessionID).
This demultiplexing procedure assumes that upon session establishment The important output results from the steps in this process are the
an entry in a local transport mapping table is created in the remote transport address, incomingMessage, incomingMessageLength, and
Transport Model's Local Configuration Datastore (LCD). The transport the tlstmSessionID.
mapping table's entry should map a unique combination of the remote
address, remote port number, local address and local port number to
an implementation-dependent tlstmSessionID.
1) The TLS Transport Model examines the raw UDP message, in an 1) The TLS Transport Model examines the raw UDP message, in an
implementation-dependent manner. implementation-dependent manner.
2) The TLS Transport Model queries the LCD using the transport 2) The TLS Transport Model queries the LCD using the transport
parameters (source and destination addresses and ports) to parameters (source and destination IP addresses and ports) to
determine if a session already exists. determine if a session already exists.
If a matching entry in the LCD does not exist then the message is 2a) f a matching entry in the LCD does not exist, then the UDP
passed to DTLS for processing without a corresponding packet is passed to the DTLS implementation for processing.
tlstmSessionID. The incoming packet may result in a new session If the DTLS implementation decides to continue with the
being established if the receiving entity is acting as a DTLS connection and allocate state for it, it returns a new DTLS
server. If DTLS returns success then stop processing of this connection handle (an implementation dependent detail). In
message. If DTLS returns an error then increment the this case, TLSTM selects a new tlstmSessionId, and caches
snmpTlstmSessionNoSessions counter and stop processing the this and the DTLS connection handle as a new entry in the
message. LCD (indexed by the transport parameters). If the DTLS
implementation returns an error or does not allocate
Note that an entry would already exist if the client and server's connection state (which can happen with the stateless cookie
session establishment procedures had been successfully completed exchange), processing stops.
previously (as described both above and in Section 5.3) even if
no message had yet been sent through the newly established
session. An entry may not exist, however, if a message not
intended the SNMP entity was routed to it by mistake. An entry
might also be missing because of a "broken" session (see
operational considerations).
3) Retrieve the tlstmSessionID from the LCD.
4) The UDP packet and the tlstmSessionID are passed to DTLS for 2b) If a session does exist in the LCD then its DTLS connection
integrity checking and decryption. If processing does not return handle (an implementation dependent detail) and its
an incomingMessage and an incomingMessageLength then processing tlstmSessionId is extracted from the LCD. The UDP packet
stops. and the connection handle is 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.
5) Retrieve the incomingMessage and an incomingMessageLength from 3) Retrieve the incomingMessage and an incomingMessageLength from
DTLS. These results and the tlstmSessionID are used below in DTLS. These results and the tlstmSessionID are used below in
Section 5.1.2 to complete the processing of the incoming message. Section 5.1.2 to complete the processing of the incoming message.
5.1.2. Transport Processing for Incoming SNMP Messages 5.1.2. Transport Processing for Incoming SNMP Messages
The procedures in this section describe how the TLS Transport Model The procedures in this section describe how the TLS Transport Model
should process messages that have already been properly extracted should process messages that have already been properly extracted
from the (D)TLS stream. Note that care must be taken when processing from the (D)TLS stream. Note that care must be taken when processing
messages originating from either TLS or DTLS to ensure they're messages originating from either TLS or DTLS to ensure they're
complete and single. For example, multiple SNMP messages can be complete and single. For example, multiple SNMP messages can be
skipping to change at page 22, line 47 skipping to change at page 23, line 43
on the server side of a connection because a client would have on the server side of a connection because a client would have
already assigned a tlstmSessionID during the openSession() already assigned a tlstmSessionID during the openSession()
invocation. Implementations may have performed the procedures invocation. Implementations may have performed the procedures
described in Section 5.3.2 prior to this point or they may 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 perform them now, but the procedures described in Section 5.3.2
MUST be performed before continuing beyond this point. MUST be performed before continuing beyond this point.
2) Create a tmStateReference cache for the subsequent reference and 2) Create a tmStateReference cache for the subsequent reference and
assign the following values within it: assign the following values within it:
tmTransportDomain = snmpTLSTCPDomain, snmpDTLSUDPDomain or tmTransportDomain = snmpTLSTCPDomain or snmpDTLSUDPDomain as
snmpDTLSSCTPDomain as appropriate. appropriate.
tmTransportAddress = The address the message originated from. tmTransportAddress = The address the message originated from.
tmSecurityLevel = The derived tmSecurityLevel for the session, tmSecurityLevel = The derived tmSecurityLevel for the session,
as discussed in Section 3.1.2 and Section 5.3. as discussed in Section 3.1.2 and Section 5.3.
tmSecurityName = The derived tmSecurityName for the session as tmSecurityName = The derived tmSecurityName for the session as
discussed in Section 5.3. This value MUST be constant during discussed in Section 5.3. This value MUST be constant during
the lifetime of the (D)TLS session. the lifetime of the session.
tmSessionID = The tlstmSessionID described in step 1 above. tmSessionID = The tlstmSessionID described in step 1 above.
3) The incomingMessage and incomingMessageLength are assigned values 3) The incomingMessage and incomingMessageLength are assigned values
from the (D)TLS processing. from the (D)TLS processing.
4) The TLS Transport Model passes the transportDomain, 4) The TLS Transport Model passes the transportDomain,
transportAddress, incomingMessage, and incomingMessageLength to transportAddress, incomingMessage, and incomingMessageLength to
the Dispatcher using the receiveMessage ASI: the Dispatcher using the receiveMessage ASI:
statusInformation = statusInformation =
receiveMessage( receiveMessage(
IN transportDomain -- snmpTLSTCPDomain, snmpDTLSUDPDomain, IN transportDomain -- snmpTLSTCPDomain or snmpDTLSUDPDomain,
-- or snmpDTLSSCTPDomain IN transportAddress -- address for the received message
IN transportAddress -- address for the received message IN incomingMessage -- the whole SNMP message from (D)TLS
IN incomingMessage -- the whole SNMP message from (D)TLS IN incomingMessageLength -- the length of the SNMP message
IN incomingMessageLength -- the length of the SNMP message IN tmStateReference -- transport info
IN tmStateReference -- transport info )
)
5.2. Procedures for an Outgoing SNMP Message 5.2. Procedures for an Outgoing SNMP Message
The Dispatcher sends a message to the TLS Transport Model using the The Dispatcher sends a message to the TLS Transport Model using the
following ASI: following ASI:
statusInformation = statusInformation =
sendMessage( sendMessage(
IN destTransportDomain -- transport domain to be used IN destTransportDomain -- transport domain to be used
IN destTransportAddress -- transport address to be used IN destTransportAddress -- transport address to be used
skipping to change at page 25, line 12 skipping to change at page 25, line 49
return an error indication to the calling module and stop return an error indication to the calling module and stop
processing of the message. processing of the message.
6) Using either the session indicated by the tmSessionID if there 6) Using either the session indicated by the tmSessionID if there
was one or the session resulting from a previous step (4 or 5), was one or the session resulting from a previous step (4 or 5),
pass the outgoingMessage to (D)TLS for encapsulation and pass the outgoingMessage to (D)TLS for encapsulation and
transmission. transmission.
5.3. Establishing or Accepting a Session 5.3. Establishing or Accepting a Session
Establishing a (D)TLS session as either a client or a server requires Establishing a (D)TLS connection as either a client or a server
slightly different processing. The following two sections describe requires slightly different processing. The following two sections
the necessary processing steps. describe the necessary processing steps.
5.3.1. Establishing a Session as a Client 5.3.1. Establishing a Session as a Client
The TLS Transport Model provides the following primitive for use by a The TLS Transport Model provides the following primitive for use by a
client to establish a new (D)TLS session: client to establish a new (D)TLS connection:
statusInformation = -- errorIndication or success statusInformation = -- errorIndication or success
openSession( openSession(
IN tmStateReference -- transport information to be used IN tmStateReference -- transport information to be used
OUT tmStateReference -- transport information to be used OUT tmStateReference -- transport information to be used
IN maxMessageSize -- of the sending SNMP entity IN maxMessageSize -- of the sending SNMP entity
) )
The following describes the procedure to follow when establishing a The following describes the procedure to follow when establishing a
SNMP over (D)TLS session between SNMP engines for exchanging SNMP SNMP over (D)TLS connection between SNMP engines for exchanging SNMP
messages. This process is followed by any SNMP client's engine when messages. This process is followed by any SNMP client's engine when
establishing a session for subsequent use. establishing a session for subsequent use.
This MAY be done automatically for an SNMP application that initiates This MAY be done automatically for an SNMP application that initiates
a transaction, such as a command generator, a notification a transaction, such as a command generator, a notification
originator, or a proxy forwarder. originator, or a proxy forwarder.
1) The snmpTlstmSessionOpens counter is incremented. 1) The snmpTlstmSessionOpens counter is incremented.
2) The client selects the appropriate certificate and cipher_suites 2) The client selects the appropriate certificate and cipher_suites
for the key agreement based on the tmSecurityName and the for the key agreement based on the tmSecurityName and the
tmRequestedSecurityLevel for the session. For sessions being tmRequestedSecurityLevel for the session. For sessions being
established as a result of a SNMP-TARGET-MIB based operation, the established as a result of a SNMP-TARGET-MIB based operation, the
certificate will potentially have been identified via the certificate will potentially have been identified via the
tlstmParamsTable mapping and the cipher_suites will have to be tlstmParamsTable mapping and the cipher_suites will have to be
taken from system-wide or implementation-specific configuration. taken from system-wide or implementation-specific configuration.
Otherwise, the certificate and appropriate cipher_suites will If no row in the tlstmParamsTable exists then implementations MAY
need to be passed to the openSession() ASI as supplemental choose to establish the connection using a default client
information or configured through an implementation-dependent certificate available to the application. Otherwise, the
mechanism. It is also implementation-dependent and possibly certificate and appropriate cipher_suites will need to be passed
policy-dependent how tmRequestedSecurityLevel will be used to to the openSession() ASI as supplemental information or
influence the security capabilities provided by the (D)TLS configured through an implementation-dependent mechanism. It is
session. However this is done, the security capabilities also implementation-dependent and possibly policy-dependent how
provided by (D)TLS MUST be at least as high as the level of tmRequestedSecurityLevel will be used to influence the security
security indicated by the tmRequestedSecurityLevel parameter. capabilities provided by the (D)TLS connection. However this is
The actual security level of the session is reported in the done, the security capabilities provided by (D)TLS MUST be at
tmStateReference cache as tmSecurityLevel. For (D)TLS to provide least as high as the level of security indicated by the
strong authentication, each principal acting as a command tmRequestedSecurityLevel parameter. The actual security level of
generator SHOULD have its own certificate. 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, 3) Using the destTransportDomain and destTransportAddress values,
the client will initiate the (D)TLS handshake protocol to the client will initiate the (D)TLS handshake protocol to
establish session keys for message integrity and encryption. establish session keys for message integrity and encryption.
If the attempt to establish a session is unsuccessful, then If the attempt to establish a session is unsuccessful, then
snmpTlstmSessionOpenErrors is incremented, an error indication is snmpTlstmSessionOpenErrors is incremented, an error indication is
returned, and processing stops. If the session failed to open returned, and processing stops. If the session failed to open
because the presented server certificate was unknown or invalid because the presented server certificate was unknown or invalid
then the snmpTlstmSessionUnknownServerCertificate or then the snmpTlstmSessionUnknownServerCertificate or
skipping to change at page 26, line 35 skipping to change at page 27, line 28
cryptographic validation failures and an unexpected presented cryptographic validation failures and an unexpected presented
certificate identity. certificate identity.
4) The (D)TLS client MUST then verify that the (D)TLS server's 4) The (D)TLS client MUST then verify that the (D)TLS server's
presented certificate is the expected certificate. The (D)TLS presented certificate is the expected certificate. The (D)TLS
client MUST NOT transmit SNMP messages until the server client MUST NOT transmit SNMP messages until the server
certificate has been authenticated and the client certificate has certificate has been authenticated and the client certificate has
been transmitted. been transmitted.
If the connection is being established from configuration based If the connection is being established from configuration based
on SNMP-TARGET-MIB configuration then the procedures in the on SNMP-TARGET-MIB configuration, then the tlstmAddrTable
tlstmAddrTable DESCRIPTION clause should be followed to determine DESCRIPTION clause describes how the verification is done (using
if the presented identity matches the expectations of the either a certificate fingerprint, or an identity authenticated
configuration. Validation procedures (like the path validation via certification path validation).
procedures defined in [RFC5280] or through the use of
fingerprints as defined by the tlstmAddrServerIdentity column)
MUST be followed. If a server identity name has been configured
in the tlstmAddrServerIdentity column then this reference
identity must be compared against the presented identity (for
example using procedures described in
[I-D.saintandre-tls-server-id-check]).
If the connection is being established for reasons other than If the connection is being established for reasons other than
configuration found in the SNMP-TARGET-MIB then configuration and configuration found in the SNMP-TARGET-MIB then configuration and
procedures outside the scope of this document should be followed. procedures outside the scope of this document should be followed.
Configuration mechanisms SHOULD be similar in nature to those
defined in the tlstmAddrTable 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 5) (D)TLS provides assurance that the authenticated identity has
been signed by a trusted configured certificate authority. If been signed by a trusted configured certification authority. If
verification of the server's certificate fails in any way (for verification of the server's certificate fails in any way (for
example because of failures in cryptographic verification or the example because of failures in cryptographic verification or the
presented identity did not match the expected named entity) then presented identity did not match the expected named entity) then
the session establishment MUST fail, the the session establishment MUST fail, the
snmpTlstmSessionInvalidServerCertificates object is incremented. snmpTlstmSessionInvalidServerCertificates object is incremented.
If the session can not be opened for any reason at all, including If the session can not be opened for any reason at all, including
cryptographic verification failures, then the cryptographic verification failures, then the
snmpTlstmSessionOpenErrors counter is incremented and processing snmpTlstmSessionOpenErrors counter is incremented and processing
stops. stops.
6) The TLSTM-specific session identifier (tlstmSessionID) is set in 6) The TLSTM-specific session identifier (tlstmSessionID) is set in
the tmSessionID of the tmStateReference passed to the TLS the tmSessionID of the tmStateReference passed to the TLS
Transport Model to indicate that the session has been established Transport Model to indicate that the session has been established
successfully and to point to a specific (D)TLS session for future successfully and to point to a specific (D)TLS connection for
use. The tlstmSessionID is also stored in the LCD for later future use. The tlstmSessionID is also stored in the LCD for
lookup during processing of incoming messages (Section 5.1.2). later lookup during processing of incoming messages
(Section 5.1.2).
5.3.2. Accepting a Session as a Server 5.3.2. Accepting a Session as a Server
A (D)TLS server should accept new session connections from any client A (D)TLS server should accept new session connections from any client
that it is able to verify the client's credentials for. This is done that it is able to verify the client's credentials for. This is done
by authenticating the client's presented certificate through a by authenticating the client's presented certificate through a
certificate path validation process (e.g. [RFC5280]) or through certificate path validation process (e.g. [RFC5280]) or through
certificate fingerprint verification using fingerprints configure in certificate fingerprint verification using fingerprints configure in
the tlstmCertToTSNTable. Afterward the server will determine the the tlstmCertToTSNTable. Afterward the server will determine the
identity of the remote entity using the following procedures. identity of the remote entity using the following procedures.
The (D)TLS server identifies the authenticated identity from the The (D)TLS server identifies the authenticated identity from the
(D)TLS client's principal certificate using configuration information (D)TLS client's principal certificate using configuration information
from the tlstmCertToTSNTable mapping table. The (D)TLS server MUST from the tlstmCertToTSNTable mapping table. The (D)TLS server MUST
request and expect a certificate from the client and MUST NOT accept request and expect a certificate from the client and MUST NOT accept
SNMP messages over the (D)TLS session until the client has sent a SNMP messages over the (D)TLS connection until the client has sent a
certificate and it has been authenticated. The resulting derived certificate and it has been authenticated. The resulting derived
tmSecurityName is recorded in the tmStateReference cache as tmSecurityName is recorded in the tmStateReference cache as
tmSecurityName. The details of the lookup process are fully tmSecurityName. The details of the lookup process are fully
described in the DESCRIPTION clause of the tlstmCertToTSNTable MIB described in the DESCRIPTION clause of the tlstmCertToTSNTable MIB
object. If any verification fails in any way (for example because of object. If any verification fails in any way (for example because of
failures in cryptographic verification or because of the lack of an failures in cryptographic verification or because of the lack of an
appropriate row in the tlstmCertToTSNTable) then the session appropriate row in the tlstmCertToTSNTable) then the session
establishment MUST fail, the establishment MUST fail, the
snmpTlstmSessionInvalidClientCertificates object is incremented. If snmpTlstmSessionInvalidClientCertificates object is incremented. If
the session can not be opened for any reason at all, including the session can not be opened for any reason at all, including
cryptographic verification failures, then the cryptographic verification failures, then the
snmpTlstmSessionOpenErrors counter is incremented and processing snmpTlstmSessionOpenErrors counter is incremented and processing
stops. stops.
Servers that wish to support multiple principals at a particular port Servers that wish to support multiple principals at a particular port
SHOULD make use of a (D)TLS extension that allows server-side SHOULD make use of a (D)TLS extension that allows server-side
principal selection like the Server Name Indication extension defined principal selection like the Server Name Indication extension defined
in Section 3.1 of [RFC4366]. Supporting this will allow, for in Section 3.1 of [RFC4366]. Supporting this will allow, for
example, sending notifications to a specific principal at a given example, sending notifications to a specific principal at a given TCP
TCP, UDP or SCTP port. or UDP port.
5.4. Closing a Session 5.4. Closing a Session
The TLS Transport Model provides the following primitive to close a The TLS Transport Model provides the following primitive to close a
session: session:
statusInformation = statusInformation =
closeSession( closeSession(
IN tmSessionID -- session ID of the session to be closed IN tmSessionID -- session ID of the session to be closed
) )
skipping to change at page 28, line 34 skipping to change at page 29, line 27
engine closing the corresponding SNMP session. engine closing the corresponding SNMP session.
1) Increment either the snmpTlstmSessionClientCloses or the 1) Increment either the snmpTlstmSessionClientCloses or the
snmpTlstmSessionServerCloses counter as appropriate. snmpTlstmSessionServerCloses counter as appropriate.
2) Look up the session using the tmSessionID. 2) Look up the session using the tmSessionID.
3) If there is no open session associated with the tmSessionID, then 3) If there is no open session associated with the tmSessionID, then
closeSession processing is completed. closeSession processing is completed.
4) Have (D)TLS close the specified session. This SHOULD include 4) Have (D)TLS close the specified connection. This SHOULD include
sending a close_notify TLS Alert to inform the other side that sending a close_notify TLS Alert to inform the other side that
session cleanup may be performed. session cleanup may be performed.
6. MIB Module Overview 6. MIB Module Overview
This MIB module provides management of the TLS Transport Model. It This MIB module provides management of the TLS Transport Model. It
defines needed textual conventions, statistical counters, defines needed textual conventions, statistical counters,
notifications and configuration infrastructure necessary for session notifications and configuration infrastructure necessary for session
establishment. Example usage of the configuration tables can be establishment. Example usage of the configuration tables can be
found in Appendix C. found in Appendix A.
6.1. Structure of the MIB Module 6.1. Structure of the MIB Module
Objects in this MIB module are arranged into subtrees. Each subtree Objects in this MIB module are arranged into subtrees. Each subtree
is organized as a set of related objects. The overall structure and is organized as a set of related objects. The overall structure and
assignment of objects to their subtrees, and the intended purpose of assignment of objects to their subtrees, and the intended purpose of
each subtree, is shown below. each subtree, is shown below.
6.2. Textual Conventions 6.2. Textual Conventions
skipping to change at page 29, line 22 skipping to change at page 30, line 15
o A new TransportAddress format for describing (D)TLS connection o A new TransportAddress format for describing (D)TLS connection
addressing requirements. addressing requirements.
o A certificate fingerprint allowing MIB module objects to o A certificate fingerprint allowing MIB module objects to
generically refer to a stored X.509 certificate using a generically refer to a stored X.509 certificate using a
cryptographic hash as a reference pointer. cryptographic hash as a reference pointer.
6.3. Statistical Counters 6.3. Statistical Counters
The TLSTM-MIB defines some counters that can provide network managers The TLSTM-MIB defines some counters that can provide network
with information about (D)TLS session usage and potential errors that management stations with information about session usage and
a MIB-instrumented device may be experiencing. potential errors that a MIB-instrumented device may be experiencing.
6.4. Configuration Tables 6.4. Configuration Tables
The TLSTM-MIB defines configuration tables that a manager can use for The TLSTM-MIB defines configuration tables that an administrator can
configuring a MIB-instrumented device for sending and receiving SNMP use for configuring a MIB-instrumented device for sending and
messages over (D)TLS. In particular, there are MIB tables that receiving SNMP messages over (D)TLS. In particular, there are MIB
extend the SNMP-TARGET-MIB for configuring (D)TLS certificate usage tables that extend the SNMP-TARGET-MIB for configuring (D)TLS
and a MIB table for mapping incoming (D)TLS client certificates to certificate usage and a MIB table for mapping incoming (D)TLS client
SNMPv3 securityNames. certificates to SNMPv3 securityNames.
6.4.1. Notifications 6.4.1. Notifications
The TLSTM-MIB defines notifications to alert management stations when The TLSTM-MIB defines notifications to alert management stations when
a (D)TLS connection fails because a server's presented certificate a (D)TLS connection fails because a server's presented certificate
did not meet an expected value (tlstmServerCertificateUnknown) or did not meet an expected value (tlstmServerCertificateUnknown) or
because cryptographic validation failed because cryptographic validation failed
(tlstmServerInvalidCertificate). (tlstmServerInvalidCertificate).
6.5. Relationship to Other MIB Modules 6.5. Relationship to Other MIB Modules
skipping to change at page 30, line 35 skipping to change at page 31, line 28
FROM SNMPv2-TC FROM SNMPv2-TC
MODULE-COMPLIANCE, OBJECT-GROUP, NOTIFICATION-GROUP MODULE-COMPLIANCE, OBJECT-GROUP, NOTIFICATION-GROUP
FROM SNMPv2-CONF FROM SNMPv2-CONF
SnmpAdminString SnmpAdminString
FROM SNMP-FRAMEWORK-MIB FROM SNMP-FRAMEWORK-MIB
snmpTargetParamsName, snmpTargetAddrName snmpTargetParamsName, snmpTargetAddrName
FROM SNMP-TARGET-MIB FROM SNMP-TARGET-MIB
; ;
tlstmMIB MODULE-IDENTITY tlstmMIB MODULE-IDENTITY
LAST-UPDATED "201002020000Z" LAST-UPDATED "201003060000Z"
ORGANIZATION "ISMS Working Group" ORGANIZATION "ISMS Working Group"
CONTACT-INFO "WG-EMail: isms@lists.ietf.org CONTACT-INFO "WG-EMail: isms@lists.ietf.org
Subscribe: isms-request@lists.ietf.org Subscribe: isms-request@lists.ietf.org
Chairs: Chairs:
Juergen Schoenwaelder Juergen Schoenwaelder
Jacobs University Bremen Jacobs University Bremen
Campus Ring 1 Campus Ring 1
28725 Bremen 28725 Bremen
Germany Germany
skipping to change at page 31, line 37 skipping to change at page 32, line 30
set forth in Section 4.c of the IETF Trust's Legal Provisions set forth in Section 4.c of the IETF Trust's Legal Provisions
Relating to IETF Documents Relating to IETF Documents
(http://trustee.ietf.org/license-info). (http://trustee.ietf.org/license-info).
This version of this MIB module is part of RFC XXXX; This version of this MIB module is part of RFC XXXX;
see the RFC itself for full legal notices." see the RFC itself for full legal notices."
-- NOTE to RFC editor: replace XXXX with actual RFC number -- NOTE to RFC editor: replace XXXX with actual RFC number
-- for this document and remove this note -- for this document and remove this note
REVISION "201002020000Z" REVISION "201003060000Z"
DESCRIPTION "The initial version, published in RFC XXXX." DESCRIPTION "The initial version, published in RFC XXXX."
-- NOTE to RFC editor: replace XXXX with actual RFC number -- NOTE to RFC editor: replace XXXX with actual RFC number
-- for this document and remove this note -- for this document and remove this note
::= { snmpModules xxxx } ::= { snmpModules xxxx }
-- RFC Ed.: replace xxxx with IANA-assigned number and -- RFC Ed.: replace xxxx with IANA-assigned number and
-- remove this note -- remove this note
-- ************************************************ -- ************************************************
-- subtrees of the TLSTM-MIB -- subtrees of the TLSTM-MIB
skipping to change at page 32, line 13 skipping to change at page 33, line 6
tlstmObjects OBJECT IDENTIFIER ::= { tlstmMIB 2 } tlstmObjects OBJECT IDENTIFIER ::= { tlstmMIB 2 }
tlstmConformance OBJECT IDENTIFIER ::= { tlstmMIB 3 } tlstmConformance OBJECT IDENTIFIER ::= { tlstmMIB 3 }
-- ************************************************ -- ************************************************
-- tlstmObjects - Objects -- tlstmObjects - Objects
-- ************************************************ -- ************************************************
snmpTLSTCPDomain OBJECT-IDENTITY snmpTLSTCPDomain OBJECT-IDENTITY
STATUS current STATUS current
DESCRIPTION DESCRIPTION
"The SNMP over TLS transport domain. The corresponding "The SNMP over TLS transport domain. The corresponding
transport address is of type SnmpTLSAddress. transport address is of type SnmpTLSAddress.
The securityName prefix to be associated with the The securityName prefix to be associated with the
snmpTLSTCPDomain is 'tls'. This prefix may be used by snmpTLSTCPDomain is 'tls'. This prefix may be used by
security models or other components to identify which secure security models or other components to identify which secure
transport infrastructure authenticated a securityName." transport infrastructure authenticated a securityName."
::= { snmpDomains xx } ::= { snmpDomains xx }
-- RFC Ed.: replace xx with IANA-assigned number and -- RFC Ed.: replace xx with IANA-assigned number and
-- remove this note -- remove this note
-- RFC Ed.: replace 'tls' with the actual IANA assigned prefix string -- RFC Ed.: replace 'tls' with the actual IANA assigned prefix string
-- if 'tls' is not assigned to this document. -- if 'tls' is not assigned to this document.
snmpDTLSUDPDomain OBJECT-IDENTITY snmpDTLSUDPDomain OBJECT-IDENTITY
STATUS current STATUS current
DESCRIPTION DESCRIPTION
"The SNMP over DTLS/UDP transport domain. The corresponding "The SNMP over DTLS/UDP transport domain. The corresponding
transport address is of type SnmpTLSAddress. transport address is of type SnmpTLSAddress.
The securityName prefix to be associated with the The securityName prefix to be associated with the
snmpDTLSUDPDomain is 'dudp'. This prefix may be used by snmpDTLSUDPDomain is 'dudp'. This prefix may be used by
security models or other components to identify which secure security models or other components to identify which secure
transport infrastructure authenticated a securityName." transport infrastructure authenticated a securityName."
::= { snmpDomains yy } ::= { snmpDomains yy }
-- RFC Ed.: replace yy with IANA-assigned number and -- RFC Ed.: replace yy with IANA-assigned number and
-- remove this note -- remove this note
-- RFC Ed.: replace 'dudp' with the actual IANA assigned prefix string -- RFC Ed.: replace 'dudp' with the actual IANA assigned prefix string
-- if 'dudp' is not assigned to this document. -- if 'dudp' is not assigned to this document.
snmpDTLSSCTPDomain OBJECT-IDENTITY
STATUS current
DESCRIPTION
"The SNMP over DTLS/SCTP transport domain. The corresponding
transport address is of type SnmpTLSAddress.
The securityName prefix to be associated with the
snmpDTLSSCTPDomain is 'dsct'. This prefix may be used by
security models or other components to identify which secure
transport infrastructure authenticated a securityName."
::= { snmpDomains zz }
SnmpTLSAddress ::= TEXTUAL-CONVENTION SnmpTLSAddress ::= TEXTUAL-CONVENTION
DISPLAY-HINT "1a" DISPLAY-HINT "1a"
STATUS current STATUS current
DESCRIPTION DESCRIPTION
"Represents a IPv4 address, an IPv6 address or an US-ASCII "Represents a IPv4 address, an IPv6 address or an US-ASCII
encoded hostname and port number. encoded hostname and port number.
An IPv4 address must be in dotted decimal format followed by a An IPv4 address must be in dotted decimal format followed by a
colon ':' (US-ASCII character 0x3A) and a decimal port number colon ':' (US-ASCII character 0x3A) and a decimal port number
in US-ASCII. in US-ASCII.
skipping to change at page 33, line 46 skipping to change at page 34, line 20
A hostname is always in US-ASCII (as per RFC1033); A hostname is always in US-ASCII (as per RFC1033);
internationalized hostnames are encoded in US-ASCII as internationalized hostnames are encoded in US-ASCII as
specified in RFC 3490. The hostname is followed by a colon specified in RFC 3490. The hostname is followed by a colon
':' (US-ASCII character 0x3A) and a decimal port number in ':' (US-ASCII character 0x3A) and a decimal port number in
US-ASCII. The name SHOULD be fully qualified whenever US-ASCII. The name SHOULD be fully qualified whenever
possible. possible.
Values of this textual convention may not be directly usable Values of this textual convention may not be directly usable
as transport-layer addressing information, and may require as transport-layer addressing information, and may require
run-time resolution. As such, applications that write them run-time resolution. As such, applications that write them
must be prepared for handling errors if such values are not must be prepared for handling errors if such values are not
supported, or cannot be resolved (if resolution occurs at the supported, or cannot be resolved (if resolution occurs at the
time of the management operation). time of the management operation).
The DESCRIPTION clause of TransportAddress objects that may The DESCRIPTION clause of TransportAddress objects that may
have SnmpTLSAddress values must fully describe how (and have SnmpTLSAddress values must fully describe how (and
when) such names are to be resolved to IP addresses and vice when) such names are to be resolved to IP addresses and vice
versa. versa.
This textual convention SHOULD NOT be used directly in object This textual convention SHOULD NOT be used directly in object
definitions since it restricts addresses to a specific definitions since it restricts addresses to a specific
format. However, if it is used, it MAY be used either on its format. However, if it is used, it MAY be used either on its
own or in conjunction with TransportAddressType or own or in conjunction with TransportAddressType or
TransportDomain as a pair. TransportDomain as a pair.
When this textual convention is used as a syntax of an index When this textual convention is used as a syntax of an index
object, there may be issues with the limit of 128 object, there may be issues with the limit of 128
sub-identifiers specified in SMIv2 (STD 58). It is RECOMMENDED sub-identifiers specified in SMIv2 (STD 58). It is RECOMMENDED
that all MIB documents using this textual convention make that all MIB documents using this textual convention make
explicit any limitations on index component lengths that explicit any limitations on index component lengths that
management software must observe. This may be done either by management software must observe. This may be done either by
including SIZE constraints on the index components or by including SIZE constraints on the index components or by
specifying applicable constraints in the conceptual row specifying applicable constraints in the conceptual row
DESCRIPTION clause or in the surrounding documentation." DESCRIPTION clause or in the surrounding documentation."
REFERENCE REFERENCE
"RFC 1033: DOMAIN ADMINISTRATORS OPERATIONS GUIDE "RFC 1033: DOMAIN ADMINISTRATORS OPERATIONS GUIDE
RFC 3490: Internationalizing Domain Names in Applications RFC 3490: Internationalizing Domain Names in Applications
RFC 3986: Uniform Resource Identifier (URI): Generic Syntax RFC 3986: Uniform Resource Identifier (URI): Generic Syntax
skipping to change at page 35, line 37 skipping to change at page 36, line 8
passed unaltered but the host-part of the name must passed unaltered but the host-part of the name must
be passed in lower case. be passed in lower case.
Example rfc822Name Field: FooBar@Example.COM Example rfc822Name Field: FooBar@Example.COM
is mapped to tmSecurityName: FooBar@example.com" is mapped to tmSecurityName: FooBar@example.com"
::= { tlstmCertToTSNMIdentities 2 } ::= { tlstmCertToTSNMIdentities 2 }
tlstmCertSANDNSName OBJECT-IDENTITY tlstmCertSANDNSName OBJECT-IDENTITY
STATUS current STATUS current
DESCRIPTION "Maps a subjectAltName's dNSName to a DESCRIPTION "Maps a subjectAltName's dNSName to a
tmSecurityName by directly passing the value without tmSecurityName after first converting it to all
any transformations." lower case."
::= { tlstmCertToTSNMIdentities 3 } ::= { tlstmCertToTSNMIdentities 3 }
tlstmCertSANIpAddress OBJECT-IDENTITY tlstmCertSANIpAddress OBJECT-IDENTITY
STATUS current STATUS current
DESCRIPTION "Maps a subjectAltName's iPAddress to a DESCRIPTION "Maps a subjectAltName's iPAddress to a
tmSecurityName by transforming the binary encoded tmSecurityName by transforming the binary encoded
address as follows: address as follows:
1) for IPv4 the value is converted into a decimal 1) for IPv4 the value is converted into a decimal
dotted quad address (e.g. '192.0.2.1') dotted quad address (e.g. '192.0.2.1')
2) for IPv6 addresses the value is converted into a 2) for IPv6 addresses the value is converted into a
32-character hexadecimal string without any colon 32-character all lowercase hexadecimal string
separators. without any colon separators.
Note that the resulting length is the maximum Note that the resulting length is the maximum
length supported by the View-Based Access Control length supported by the View-Based Access Control
Model (VACM). Note that using both the Transport Model (VACM). Note that using both the Transport
Security Model's support for transport prefixes Security Model's support for transport prefixes
(see the SNMP-TSM-MIB's (see the SNMP-TSM-MIB's
snmpTsmConfigurationUsePrefix object for details) snmpTsmConfigurationUsePrefix object for details)
will result in securityName lengths that exceed will result in securityName lengths that exceed
what VACM can handle." what VACM can handle."
::= { tlstmCertToTSNMIdentities 4 } ::= { tlstmCertToTSNMIdentities 4 }
skipping to change at page 36, line 36 skipping to change at page 37, line 7
| iPAddress | tlstmCertSANIpAddress | | iPAddress | tlstmCertSANIpAddress |
|------------+------------------------| |------------+------------------------|
The first matching subjectAltName value found in the The first matching subjectAltName value found in the
certificate of the above types MUST be used when certificate of the above types MUST be used when
deriving the tmSecurityName." deriving the tmSecurityName."
::= { tlstmCertToTSNMIdentities 5 } ::= { tlstmCertToTSNMIdentities 5 }
tlstmCertCommonName OBJECT-IDENTITY tlstmCertCommonName OBJECT-IDENTITY
STATUS current STATUS current
DESCRIPTION "Maps a certificate's CommonName to a
tmSecurityName by directly passing the value without DESCRIPTION "Maps a certificate's CommonName to a tmSecurityName
any transformations." after converting it to a UTF-8 encoding."
::= { tlstmCertToTSNMIdentities 6 } ::= { tlstmCertToTSNMIdentities 6 }
-- The snmpTlstmSession Group -- The snmpTlstmSession Group
snmpTlstmSession OBJECT IDENTIFIER ::= { tlstmObjects 1 } snmpTlstmSession OBJECT IDENTIFIER ::= { tlstmObjects 1 }
snmpTlstmSessionOpens OBJECT-TYPE snmpTlstmSessionOpens OBJECT-TYPE
SYNTAX Counter32 SYNTAX Counter32
MAX-ACCESS read-only MAX-ACCESS read-only
STATUS current STATUS current
skipping to change at page 37, line 31 skipping to change at page 37, line 50
DESCRIPTION DESCRIPTION
"The number of times an openSession() request failed to open a "The number of times an openSession() request failed to open a
session as a (D)TLS client, for any reason." session as a (D)TLS client, for any reason."
::= { snmpTlstmSession 3 } ::= { snmpTlstmSession 3 }
snmpTlstmSessionAccepts OBJECT-TYPE snmpTlstmSessionAccepts OBJECT-TYPE
SYNTAX Counter32 SYNTAX Counter32
MAX-ACCESS read-only MAX-ACCESS read-only
STATUS current STATUS current
DESCRIPTION DESCRIPTION
"The number of times a server has accepted a (D)TLS session and "The number of times a (D)TLS server has accepted a new
at least one SNMP message has been accepted through it." connection from a client and has received at least one SNMP
message through it."
::= { snmpTlstmSession 4 } ::= { snmpTlstmSession 4 }
snmpTlstmSessionServerCloses OBJECT-TYPE snmpTlstmSessionServerCloses OBJECT-TYPE
SYNTAX Counter32 SYNTAX Counter32
MAX-ACCESS read-only MAX-ACCESS read-only
STATUS current STATUS current
DESCRIPTION DESCRIPTION
"The number of times a closeSession() request has been "The number of times a closeSession() request has been
executed as an (D)TLS server, regardless of whether it executed as an (D)TLS server, regardless of whether it
succeeded or failed." succeeded or failed."
skipping to change at page 38, line 30 skipping to change at page 38, line 50
SYNTAX Counter32 SYNTAX Counter32
MAX-ACCESS read-only MAX-ACCESS read-only
STATUS current STATUS current
DESCRIPTION DESCRIPTION
"The number of times an outgoing session was not established "The number of times an outgoing session was not established
on an (D)TLS client because the server certificate presented on an (D)TLS client because the server certificate presented
by a SNMP over (D)TLS server was invalid because no by a SNMP over (D)TLS server was invalid because no
configured fingerprint or CA was acceptable to validate it. configured fingerprint or CA was acceptable to validate it.
This may result because there was no entry in the This may result because there was no entry in the
tlstmAddrTable or because no path could be found to a known tlstmAddrTable or because no path could be found to a known
certificate authority." certification authority."
::= { snmpTlstmSession 8 } ::= { snmpTlstmSession 8 }
snmpTlstmSessionInvalidServerCertificates OBJECT-TYPE snmpTlstmSessionInvalidServerCertificates OBJECT-TYPE
SYNTAX Counter32 SYNTAX Counter32
MAX-ACCESS read-only MAX-ACCESS read-only
STATUS current STATUS current
DESCRIPTION DESCRIPTION
"The number of times an outgoing session was not established "The number of times an outgoing session was not established
on an (D)TLS client because the server certificate presented on an (D)TLS client because the server certificate presented
by an SNMP over (D)TLS server could not be validated even if by an SNMP over (D)TLS server could not be validated even if
skipping to change at page 42, line 46 skipping to change at page 43, line 17
value in this column MUST be ignored for any mapping type that value in this column MUST be ignored for any mapping type that
does not require data present in this column." does not require data present in this column."
DEFVAL { "" } DEFVAL { "" }
::= { tlstmCertToTSNEntry 4 } ::= { tlstmCertToTSNEntry 4 }
tlstmCertToTSNStorageType OBJECT-TYPE tlstmCertToTSNStorageType OBJECT-TYPE
SYNTAX StorageType SYNTAX StorageType
MAX-ACCESS read-create MAX-ACCESS read-create
STATUS current STATUS current
DESCRIPTION DESCRIPTION
"The storage type for this conceptual row. Conceptual rows "The storage type for this conceptual row. Conceptual rows
having the value 'permanent' need not allow write-access to having the value 'permanent' need not allow write-access to
any columnar objects in the row." any columnar objects in the row."
DEFVAL { nonVolatile } DEFVAL { nonVolatile }
::= { tlstmCertToTSNEntry 5 } ::= { tlstmCertToTSNEntry 5 }
tlstmCertToTSNRowStatus OBJECT-TYPE tlstmCertToTSNRowStatus OBJECT-TYPE
SYNTAX RowStatus SYNTAX RowStatus
MAX-ACCESS read-create MAX-ACCESS read-create
STATUS current STATUS current
DESCRIPTION DESCRIPTION
"The status of this conceptual row. This object may be used "The status of this conceptual row. This object may be used
to create or remove rows from this table. to create or remove rows from this table.
To create a row in this table, a manager must set this object To create a row in this table, an administrator must set this
to either createAndGo(4) or createAndWait(5). object to either createAndGo(4) or createAndWait(5).
Until instances of all corresponding columns are appropriately Until instances of all corresponding columns are appropriately
configured, the value of the corresponding instance of the configured, the value of the corresponding instance of the
tlstmParamsRowStatus column is 'notReady'. tlstmParamsRowStatus column is 'notReady'.
In particular, a newly created row cannot be made active until In particular, a newly created row cannot be made active until
the corresponding tlstmCertToTSNFingerprint, the corresponding tlstmCertToTSNFingerprint,
tlstmCertToTSNMapType, and tlstmCertToTSNData columns have been tlstmCertToTSNMapType, and tlstmCertToTSNData columns have been
set. set.
skipping to change at page 44, line 4 skipping to change at page 44, line 23
::= { tlstmCertificateMapping 4 } ::= { tlstmCertificateMapping 4 }
tlstmParamsTableLastChanged OBJECT-TYPE tlstmParamsTableLastChanged OBJECT-TYPE
SYNTAX TimeStamp SYNTAX TimeStamp
MAX-ACCESS read-only MAX-ACCESS read-only
STATUS current STATUS current
DESCRIPTION DESCRIPTION
"The value of sysUpTime.0 when the tlstmParamsTable "The value of sysUpTime.0 when the tlstmParamsTable
was last modified through any means, or 0 if it has not been was last modified through any means, or 0 if it has not been
modified since the command responder was started." modified since the command responder was started."
::= { tlstmCertificateMapping 5 } ::= { tlstmCertificateMapping 5 }
tlstmParamsTable OBJECT-TYPE tlstmParamsTable OBJECT-TYPE
SYNTAX SEQUENCE OF TlstmParamsEntry SYNTAX SEQUENCE OF TlstmParamsEntry
MAX-ACCESS not-accessible MAX-ACCESS not-accessible
STATUS current STATUS current
DESCRIPTION DESCRIPTION
"This table is used by a (D)TLS client when a (D)TLS session is "This table is used by a (D)TLS client when a (D)TLS
being set up using an entry in the SNMP-TARGET-MIB. It connection is being set up using an entry in the
extends the SNMP-TARGET-MIB's snmpTargetParamsTable with a SNMP-TARGET-MIB. It extends the SNMP-TARGET-MIB's
fingerprint of a certificate to use when establishing such a snmpTargetParamsTable with a fingerprint of a certificate to
(D)TLS connection." use when establishing such a (D)TLS connection."
::= { tlstmCertificateMapping 6 } ::= { tlstmCertificateMapping 6 }
tlstmParamsEntry OBJECT-TYPE tlstmParamsEntry OBJECT-TYPE
SYNTAX TlstmParamsEntry SYNTAX TlstmParamsEntry
MAX-ACCESS not-accessible MAX-ACCESS not-accessible
STATUS current STATUS current
DESCRIPTION DESCRIPTION
"A conceptual row containing a fingerprint hash of a locally "A conceptual row containing a fingerprint hash of a locally
held certificate for a given snmpTargetParamsEntry. The held certificate for a given snmpTargetParamsEntry. The
values in this row should be ignored if the connection that values in this row should be ignored if the connection that
skipping to change at page 44, line 49 skipping to change at page 45, line 18
tlstmParamsStorageType StorageType, tlstmParamsStorageType StorageType,
tlstmParamsRowStatus RowStatus tlstmParamsRowStatus RowStatus
} }
tlstmParamsClientFingerprint OBJECT-TYPE tlstmParamsClientFingerprint OBJECT-TYPE
SYNTAX Fingerprint SYNTAX Fingerprint
MAX-ACCESS read-create MAX-ACCESS read-create
STATUS current STATUS current
DESCRIPTION DESCRIPTION
"A cryptographic hash of a X.509 certificate. This object "A cryptographic hash of a X.509 certificate. This object
should store the hash of a locally held X.509 certificate that should store the hash of a locally held X.509 certificate (and
should be used when initiating a (D)TLS connection as a (D)TLS the corresponding private key) that should be used when
client." initiating a (D)TLS connection as a (D)TLS client."
::= { tlstmParamsEntry 1 } ::= { tlstmParamsEntry 1 }
tlstmParamsStorageType OBJECT-TYPE tlstmParamsStorageType OBJECT-TYPE
SYNTAX StorageType SYNTAX StorageType
MAX-ACCESS read-create MAX-ACCESS read-create
STATUS current STATUS current
DESCRIPTION DESCRIPTION
"The storage type for this conceptual row. Conceptual rows "The storage type for this conceptual row. Conceptual rows
having the value 'permanent' need not allow write-access to having the value 'permanent' need not allow write-access to
any columnar objects in the row." any columnar objects in the row."
skipping to change at page 45, line 24 skipping to change at page 45, line 42
::= { tlstmParamsEntry 2 } ::= { tlstmParamsEntry 2 }
tlstmParamsRowStatus OBJECT-TYPE tlstmParamsRowStatus OBJECT-TYPE
SYNTAX RowStatus SYNTAX RowStatus
MAX-ACCESS read-create MAX-ACCESS read-create
STATUS current STATUS current
DESCRIPTION DESCRIPTION
"The status of this conceptual row. This object may be used "The status of this conceptual row. This object may be used
to create or remove rows from this table. to create or remove rows from this table.
To create a row in this table, a manager must set this object To create a row in this table, an administrator must set this
to either createAndGo(4) or createAndWait(5). object to either createAndGo(4) or createAndWait(5).
Until instances of all corresponding columns are appropriately Until instances of all corresponding columns are appropriately
configured, the value of the corresponding instance of the configured, the value of the corresponding instance of the
tlstmParamsRowStatus column is 'notReady'. tlstmParamsRowStatus column is 'notReady'.
In particular, a newly created row cannot be made active until In particular, a newly created row cannot be made active until
the corresponding tlstmParamsClientFingerprint column has the corresponding tlstmParamsClientFingerprint column has
been set. been set.
The tlstmParamsClientFingerprint object may not be modified The tlstmParamsClientFingerprint object may not be modified
skipping to change at page 46, line 18 skipping to change at page 46, line 37
"The value of sysUpTime.0 when the tlstmAddrTable "The value of sysUpTime.0 when the tlstmAddrTable
was last modified through any means, or 0 if it has not been was last modified through any means, or 0 if it has not been
modified since the command responder was started." modified since the command responder was started."
::= { tlstmCertificateMapping 8 } ::= { tlstmCertificateMapping 8 }
tlstmAddrTable OBJECT-TYPE tlstmAddrTable OBJECT-TYPE
SYNTAX SEQUENCE OF TlstmAddrEntry SYNTAX SEQUENCE OF TlstmAddrEntry
MAX-ACCESS not-accessible MAX-ACCESS not-accessible
STATUS current STATUS current
DESCRIPTION DESCRIPTION
"This table is used by a (D)TLS client when a (D)TLS session "This table is used by a (D)TLS client when a (D)TLS
is being set up using an entry in the SNMP-TARGET-MIB. It connection is being set up using an entry in the
extends the SNMP-TARGET-MIB's snmpTargetAddrTable so that the SNMP-TARGET-MIB. It extends the SNMP-TARGET-MIB's
client can validate the certificate that the server presents. 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 a row in this table corresponding to the entry in If there is an active row in this table corresponding to the
the SNMP-TARGET-MIB that was used to establish the session entry in the SNMP-TARGET-MIB that was used to establish the
(and that row is active), then the fingerprint of the server's connection, and the row's tlstmAddrServerFingerprint column
presented certificate is compared with the value of the has non-empty value, then the server's presented certificate
tlstmAddrServerFingerprint column. If fingerprint does not is compared with the tlstmAddrServerFingerprint value (and
match, then the connection MUST NOT be established. the tlstmAddrServerIdentity 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 row exists with a zero-length If the server's presented certificate has passed
tlstmAddrServerFingerprint value and the certificate can be certification path validation [RFC5280] to a configured
validated through another certificate validation path (such as trust anchor, and an active row exists with a zero-length
the path validation procedures defined in [RFC5280]) then the tlstmAddrServerFingerprint value, then the
server's presented identity should be checked against the tlstmAddrServerIdentity column contains the expected host
value of the tlstmAddrServerIdentity column. If the server's name. This expected host name is then compared against the
identity does not match the reference identity found in the server's certificate as follows:
tlstmAddrServerIdentity column then the connection MUST NOT be
established.
A tlstmAddrServerIdentity may contain a single ASCII '*' - Implementations MUST support matching the expected host
character (ASCII code 0x2a) to match any server's identity if name against a dNSName in the subjectAltName extension field
the tlstmAddrServerFingerprint column is not blank. A row and SHOULD support checking the name against the common name
MUST NOT contain both a blank tlstmAddrServerFingerprint portion of the subject distinguished name.
column and a '*' in the tlstmAddrServerIdentity column since
this would insecurely accept any presented certificate.
If there is no row in this table corresponding to an entry in - The '*' (ASCII 0x2a) wildcard character is allowed in the
the SNMP-TARGET-MIB and another certificate validation path dNSName of the subjectAltName extension (and in common name,
algorithm (such as the path validation procedures defined in if used to store the host name), but only as the left-most
[RFC5280]) can be used, then the connection SHOULD still (least significant) DNS label in that value. This wildcard
proceed." 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.
- 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.
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."
::= { tlstmCertificateMapping 9 } ::= { tlstmCertificateMapping 9 }
tlstmAddrEntry OBJECT-TYPE tlstmAddrEntry OBJECT-TYPE
SYNTAX TlstmAddrEntry SYNTAX TlstmAddrEntry
MAX-ACCESS not-accessible MAX-ACCESS not-accessible
STATUS current STATUS current
DESCRIPTION DESCRIPTION
"A conceptual row containing a copy of a certificate's "A conceptual row containing a copy of a certificate's
fingerprint for a given snmpTargetAddrEntry. The values in fingerprint for a given snmpTargetAddrEntry. The values in
skipping to change at page 48, line 4 skipping to change at page 48, line 44
connection MUST NOT be established." connection MUST NOT be established."
DEFVAL { "" } DEFVAL { "" }
::= { tlstmAddrEntry 1 } ::= { tlstmAddrEntry 1 }
tlstmAddrServerIdentity OBJECT-TYPE tlstmAddrServerIdentity OBJECT-TYPE
SYNTAX SnmpAdminString SYNTAX SnmpAdminString
MAX-ACCESS read-create MAX-ACCESS read-create
STATUS current STATUS current
DESCRIPTION DESCRIPTION
"The reference identity to check against the identity "The reference identity to check against the identity
presented by the remote system. A single ASCII '*' character presented by the remote system."
(ASCII code 0x2a) may be used as a wildcard string and will DEFVAL { "" }
match any presented server identity."
REFERENCE "draft-saintandre-tls-server-id-check"
DEFVAL { "*" }
::= { tlstmAddrEntry 2 } ::= { tlstmAddrEntry 2 }
tlstmAddrStorageType OBJECT-TYPE tlstmAddrStorageType OBJECT-TYPE
SYNTAX StorageType SYNTAX StorageType
MAX-ACCESS read-create MAX-ACCESS read-create
STATUS current STATUS current
DESCRIPTION DESCRIPTION
"The storage type for this conceptual row. Conceptual rows "The storage type for this conceptual row. Conceptual rows
having the value 'permanent' need not allow write-access to having the value 'permanent' need not allow write-access to
any columnar objects in the row." any columnar objects in the row."
DEFVAL { nonVolatile } DEFVAL { nonVolatile }
::= { tlstmAddrEntry 3 } ::= { tlstmAddrEntry 3 }
tlstmAddrRowStatus OBJECT-TYPE tlstmAddrRowStatus OBJECT-TYPE
SYNTAX RowStatus SYNTAX RowStatus
MAX-ACCESS read-create MAX-ACCESS read-create
STATUS current STATUS current
DESCRIPTION DESCRIPTION
"The status of this conceptual row. This object may be used "The status of this conceptual row. This object may be used
to create or remove rows from this table. to create or remove rows from this table.
To create a row in this table, a manager must To create a row in this table, an administrator must set this
set this object to either createAndGo(4) or object to either createAndGo(4) or createAndWait(5).
createAndWait(5).
Until instances of all corresponding columns are Until instances of all corresponding columns are
appropriately configured, the value of the appropriately configured, the value of the
corresponding instance of the tlstmAddrRowStatus corresponding instance of the tlstmAddrRowStatus
column is 'notReady'. column is 'notReady'.
In particular, a newly created row cannot be made active until In particular, a newly created row cannot be made active until
the corresponding tlstmAddrServerFingerprint column has been the corresponding tlstmAddrServerFingerprint column has been
set. set.
skipping to change at page 52, line 8 skipping to change at page 52, line 46
END END
8. Operational Considerations 8. Operational Considerations
This section discusses various operational aspects of deploying This section discusses various operational aspects of deploying
TLSTM. TLSTM.
8.1. Sessions 8.1. Sessions
A session is discussed throughout this document as meaning a security A session is discussed throughout this document as meaning a security
association between the (D)TLS client and the (D)TLS server. State association between two TLSTM instances. State information for the
information for the sessions are maintained in each TLSTM sessions are maintained in each TLSTM implementation and this
implementation and this information is created and destroyed as information is created and destroyed as sessions are opened and
sessions are opened and closed. A "broken" session (one side up and closed. A "broken" session (one side up and one side down) can
one side down) can result if one side of a session is brought down result if one side of a session is brought down abruptly (i.e.,
abruptly (i.e., reboot, power outage, etc.). Whenever possible, reboot, power outage, etc.). Whenever possible, implementations
implementations SHOULD provide graceful session termination through SHOULD provide graceful session termination through the use of
the use of disconnect messages. Implementations SHOULD also have a disconnect messages. Implementations SHOULD also have a system in
system in place for detecting "broken" sessions through the use of place for detecting "broken" sessions through the use of heartbeats
heartbeats [I-D.seggelmann-tls-dtls-heartbeat] or other detection [I-D.seggelmann-tls-dtls-heartbeat] or other detection mechanisms.
mechanisms.
Implementations SHOULD limit the lifetime of established sessions Implementations SHOULD limit the lifetime of established sessions
depending on the algorithms used for generation of the master session depending on the algorithms used for generation of the master session
secret, the privacy and integrity algorithms used to protect secret, the privacy and integrity algorithms used to protect
messages, the environment of the session, the amount of data messages, the environment of the session, the amount of data
transferred, and the sensitivity of the data. transferred, and the sensitivity of the data.
8.2. Notification Receiver Credential Selection 8.2. Notification Receiver Credential Selection
When an SNMP engine needs to establish an outgoing session for When an SNMP engine needs to establish an outgoing session for
skipping to change at page 53, line 22 skipping to change at page 54, line 9
generators to discover a suitable default contextEngineID. generators to discover a suitable default contextEngineID.
Implementations should consider offering another engineID discovery Implementations should consider offering another engineID discovery
mechanism to continue providing Command Generators with a suitable mechanism to continue providing Command Generators with a suitable
contextEngineID mechanism. A recommended discovery solution is contextEngineID mechanism. A recommended discovery solution is
documented in [RFC5343]. documented in [RFC5343].
8.4. Transport Considerations 8.4. Transport Considerations
This document defines how SNMP messages can be transmitted over the This document defines how SNMP messages can be transmitted over the
TLS and DTLS based protocols. Each of these protocols are TLS and DTLS based protocols. Each of these protocols are
additionally based on other transports (TCP, UDP and SCTP). These additionally based on other transports (TCP and UDP). These three
three protocols also have operational considerations that must be protocols also have operational considerations that must be taken
taken into consideration when selecting a (D)TLS based protocol to into consideration when selecting a (D)TLS based protocol to use such
use such as its performance in degraded or limited networks. It is as its performance in degraded or limited networks. It is beyond the
beyond the scope of this document to summarize the characteristics of scope of this document to summarize the characteristics of these
these transport mechanisms. Please refer to the base protocol transport mechanisms. Please refer to the base protocol documents
documents for details on messaging considerations with respect to MTU for details on messaging considerations with respect to MTU size,
size, fragmentation, performance in lossy-networks, etc. fragmentation, performance in lossy-networks, etc.
9. Security Considerations 9. Security Considerations
This document describes a transport model that permits SNMP to This document describes a transport model that permits SNMP to
utilize (D)TLS security services. The security threats and how the utilize (D)TLS security services. The security threats and how the
(D)TLS transport model mitigates these threats are covered in detail (D)TLS transport model mitigates these threats are covered in detail
throughout this document. Security considerations for DTLS are throughout this document. Security considerations for DTLS are
covered in [RFC4347] and security considerations for TLS are covered in [RFC4347] and security considerations for TLS are
described in Section 11 and Appendices D, E, and F of TLS 1.2 described in Section 11 and Appendices D, E, and F of TLS 1.2
[RFC5246]. DTLS adds to the security considerations of TLS only [RFC5246]. When run over UDP, DTLS is more vulnerable to denial of
because it is more vulnerable to denial of service attacks. A random service attacks from spoofed IP addresses; see Section 4.2 for
cookie exchange was added to the handshake to prevent anonymous details how the cookie exchange is used to address this issue.
denial of service attacks. RFC 4347 recommends that the cookie
exchange is utilized for all handshakes. It is also RECOMMENDED by
this specification that users enable this cookie exchange.
9.1. Certificates, Authentication, and Authorization 9.1. Certificates, Authentication, and Authorization
Implementations are responsible for providing a security certificate Implementations are responsible for providing a security certificate
installation and configuration mechanism. Implementations SHOULD installation and configuration mechanism. Implementations SHOULD
support certificate revocation lists. support certificate revocation lists.
(D)TLS provides for authentication of the identity of both the (D)TLS (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 server and the (D)TLS client. Access to MIB objects for the
authenticated principal MUST be enforced by an access control authenticated principal MUST be enforced by an access control
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Authentication of the command generator principal's identity is Authentication of the command generator principal's identity is
important for use with the SNMP access control subsystem to ensure important for use with the SNMP access control subsystem to ensure
that only authorized principals have access to potentially sensitive that only authorized principals have access to potentially sensitive
data. The authenticated identity of the command generator data. The authenticated identity of the command generator
principal's certificate is mapped to an SNMP model-independent principal's certificate is mapped to an SNMP model-independent
securityName for use with SNMP access control. securityName for use with SNMP access control.
The (D)TLS handshake only provides assurance that the certificate of The (D)TLS handshake only provides assurance that the certificate of
the authenticated identity has been signed by an configured accepted the authenticated identity has been signed by an configured accepted
Certificate Authority. (D)TLS has no way to further authorize or certification authority. (D)TLS has no way to further authorize or
reject access based on the authenticated identity. An Access Control reject access based on the authenticated identity. An Access Control
Model (such as the VACM) provides access control and authorization of Model (such as the VACM) provides access control and authorization of
a command generator's requests to a command responder and a a command generator's requests to a command responder and a
notification responder's authorization to receive Notifications from notification responder's authorization to receive Notifications from
a notification originator. However to avoid man-in-the-middle a notification originator. However to avoid man-in-the-middle
attacks both ends of the (D)TLS based connection MUST check the attacks both ends of the (D)TLS based connection MUST check the
certificate presented by the other side against what was expected. certificate presented by the other side against what was expected.
For example, command generators must check that the command responder For example, command generators must check that the command responder
presented and authenticated itself with a X.509 certificate that was presented and authenticated itself with a X.509 certificate that was
expected. Not doing so would allow an impostor, at a minimum, to expected. Not doing so would allow an impostor, at a minimum, to
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enable cryptographic security. It is then a customer/operator enable cryptographic security. It is then a customer/operator
responsibility to ensure that the SNMP entity giving access to an responsibility to ensure that the SNMP entity giving access to an
instance of this MIB module is properly configured to give access to instance of this MIB module is properly configured to give access to
the objects only to those principals (users) that have legitimate the objects only to those principals (users) that have legitimate
rights to indeed GET or SET (change/create/delete) them. rights to indeed GET or SET (change/create/delete) them.
10. IANA Considerations 10. IANA Considerations
IANA is requested to assign: IANA is requested to assign:
1. a TCP port number above 1023 in the 1. Two TCP/UDP port numbers from the "Registered Ports" range of the
http://www.iana.org/assignments/port-numbers registry which will Port Numbers registry, with keywords "snmptls" and "snmptls-
be the default port for receipt of SNMP command messages over a trap". These are the default ports for receipt of SNMP command
TLS Transport Model as defined in this document, messages (snmptls) and SNMP notification messages (snmptls-trap)
over a TLS Transport Model as defined in this document.
2. a TCP port number above 1023 in the
http://www.iana.org/assignments/port-numbers registry which will
be the default port for receipt of SNMP notification messages
over a TLS Transport Model as defined in this document,
3. a UDP port number above 1023 in the
http://www.iana.org/assignments/port-numbers registry which will
be the default port for receipt of SNMP command messages over a
DTLS/UDP connection as defined in this document,
4. a UDP port number above 1023 in the
http://www.iana.org/assignments/port-numbers registry which will
be the default port for receipt of SNMP notification messages
over a DTLS/UDP connection as defined in this document,
5. a SCTP port number above 1023 in the
http://www.iana.org/assignments/port-numbers registry which will
be the default port for receipt of SNMP command messages over a
DTLS/SCTP connection as defined in this document,
6. a SCTP port number above 1023 in the
http://www.iana.org/assignments/port-numbers registry which will
be the default port for receipt of SNMP notification messages
over a DTLS/SCTP connection as defined in this document,
7. an SMI number under snmpDomains for the snmpTLSTCPDomain object
identifier,
8. an SMI number under snmpDomains for the snmpDTLSUDPDomain object
identifier,
9. an SMI number under snmpDomains for the snmpDTLSSCTPDomain
object identifier,
10. a SMI number under snmpModules, for the MIB module in this
document,
11. "tls" as the corresponding prefix for the snmpTLSTCPDomain in 2. an SMI number under snmpDomains for the snmpTLSTCPDomain object
the SNMP Transport Model registry, identifier,
12. "dudp" as the corresponding prefix for the snmpDTLSUDPDomain in 3. an SMI number under snmpDomains for the snmpDTLSUDPDomain object
the SNMP Transport Model registry, identifier,
13. "dsct" as the corresponding prefix for the snmpDTLSSCTPDomain in 4. a SMI number under snmpModules, for the MIB module in this
the SNMP Transport Model registry; document,
If possible, IANA is requested to use matching port numbers for all 5. "tls" as the corresponding prefix for the snmpTLSTCPDomain in the
assignments for SNMP Commands being sent over TLS, DTLS/UDP, DTLS/ SNMP Transport Model registry,
SCTP.
If possible, IANA is requested to use matching port numbers for all 6. "dudp" as the corresponding prefix for the snmpDTLSUDPDomain in
assignments for SNMP Notifications being sent over TLS, DTLS/UDP, the SNMP Transport Model registry,
DTLS/SCTP.
Editor's note: this section should be replaced with appropriate Editor's note: this section should be replaced with appropriate
descriptive assignment text after IANA assignments are made and prior descriptive assignment text after IANA assignments are made and prior
to publication. to publication.
11. Acknowledgements 11. Acknowledgements
This document closely follows and copies the Secure Shell Transport This document closely follows and copies the Secure Shell Transport
Model for SNMP defined by David Harrington and Joseph Salowey in Model for SNMP defined by David Harrington and Joseph Salowey in
[RFC5292]. [RFC5292].
This document was reviewed by the following people who helped provide This document was reviewed by the following people who helped provide
useful comments (in alphabetical order): Andy Donati, Pasi Eronen, useful comments (in alphabetical order): Andy Donati, Pasi Eronen,
David Harrington, Jeffrey Hutzelman, Alan Luchuk, Tom Petch, Randy David Harrington, Jeffrey Hutzelman, Alan Luchuk, Tom Petch, Randy
Presuhn, Ray Purvis, Joseph Salowey, Jurgen Schonwalder, Dave Shield, Presuhn, Ray Purvis, Joseph Salowey, Jurgen Schonwalder, Dave Shield,
Robert Story. Robert Story.
This work was supported in part by the United States Department of This work was supported in part by the United States Department of
Defense. Large portions of this document are based on work by Defense. Large portions of this document are based on work by
skipping to change at page 59, line 40 skipping to change at page 59, line 35
[RFC5590] Harrington, D. and J. Schoenwaelder, "Transport Subsystem [RFC5590] Harrington, D. and J. Schoenwaelder, "Transport Subsystem
for the Simple Network Management Protocol (SNMP)", for the Simple Network Management Protocol (SNMP)",
RFC 5590, June 2009. RFC 5590, June 2009.
[RFC5591] Harrington, D. and W. Hardaker, "Transport Security Model [RFC5591] Harrington, D. and W. Hardaker, "Transport Security Model
for the Simple Network Management Protocol (SNMP)", for the Simple Network Management Protocol (SNMP)",
RFC 5591, June 2009. RFC 5591, June 2009.
12.2. Informative References 12.2. Informative References
[RFC2522] Karn, P. and W. Simpson, "Photuris: Session-Key Management
Protocol", RFC 2522, March 1999.
[RFC3410] Case, J., Mundy, R., Partain, D., and B. Stewart, [RFC3410] Case, J., Mundy, R., Partain, D., and B. Stewart,
"Introduction and Applicability Statements for Internet- "Introduction and Applicability Statements for Internet-
Standard Management Framework", RFC 3410, December 2002. Standard Management Framework", RFC 3410, December 2002.
[RFC4306] Kaufman, C., "Internet Key Exchange (IKEv2) Protocol",
RFC 4306, December 2005.
[RFC4366] Blake-Wilson, S., Nystrom, M., Hopwood, D., Mikkelsen, J., [RFC4366] Blake-Wilson, S., Nystrom, M., Hopwood, D., Mikkelsen, J.,
and T. Wright, "Transport Layer Security (TLS) and T. Wright, "Transport Layer Security (TLS)
Extensions", RFC 4366, April 2006. Extensions", RFC 4366, April 2006.
[RFC5292] Chen, E. and S. Sangli, "Address-Prefix-Based Outbound [RFC5292] Chen, E. and S. Sangli, "Address-Prefix-Based Outbound
Route Filter for BGP-4", RFC 5292, August 2008. Route Filter for BGP-4", RFC 5292, August 2008.
[RFC5343] Schoenwaelder, J., "Simple Network Management Protocol [RFC5343] Schoenwaelder, J., "Simple Network Management Protocol
(SNMP) Context EngineID Discovery", RFC 5343, (SNMP) Context EngineID Discovery", RFC 5343,
September 2008. September 2008.
[I-D.saintandre-tls-server-id-check]
Saint-Andre, P., Zeilenga, K., Hodges, J., and B. Morgan,
"Best Practices for Checking of Server Identities in the
Context of Transport Layer Security (TLS)".
[I-D.seggelmann-tls-dtls-heartbeat] [I-D.seggelmann-tls-dtls-heartbeat]
Seggelmann, R., Tuexen, M., and M. Williams, "Transport Seggelmann, R., Tuexen, M., and M. Williams, "Transport
Layer Security and Datagram Transport Layer Security Layer Security and Datagram Transport Layer Security
Heartbeat Extension". Heartbeat Extension".
[AES] National Institute of Standards, "Specification for the Appendix A. Target and Notification Configuration Example
Advanced Encryption Standard (AES)".
[DES] National Institute of Standards, "American National
Standard for Information Systems-Data Link Encryption".
[DSS] National Institute of Standards, "Digital Signature
Standard".
[RSA] Rivest, R., Shamir, A., and L. Adleman, "A Method for
Obtaining Digital Signatures and Public-Key
Cryptosystems".
[X509] , ITU., "INFORMATION TECHNOLOGY OPEN SYSTEMS
INTERCONNECTION THE DIRECTORY: PUBLIC-KEY AND ATTRIBUTE
CERTIFICATE FRAMEWORKS".
Appendix A. (D)TLS Overview
The (D)TLS protocol is composed of two layers: the (D)TLS Record
Protocol and the (D)TLS Handshake Protocol. The following
subsections provide an overview of these two layers. Please refer to
[RFC4347] for a complete description of the protocol.
A.1. The (D)TLS Record Protocol
At the lowest layer, layered on top of the transport control protocol
or a datagram transport protocol (e.g. UDP or SCTP) is the (D)TLS
Record Protocol.
The (D)TLS Record Protocol provides security that has three basic
properties:
o The session can be confidential. Symmetric cryptography is used
for data encryption (e.g., [AES], [DES] etc.). The keys for this
symmetric encryption are generated uniquely for each session and
are based on a secret negotiated by another protocol (such as the
(D)TLS Handshake Protocol). The Record Protocol can also be used
without encryption.
o Messages can have data integrity. Message transport includes a
message integrity check using a keyed MAC. Secure hash functions
(e.g., SHA, MD5, etc.) are used for MAC computations. The Record
Protocol can operate without a MAC, but is generally only used in
this mode while another protocol is using the Record Protocol as a
transport for negotiating security parameters.
o Messages are protected against replay. (D)TLS uses explicit
sequence numbers and integrity checks. DTLS uses a sliding window
to protect against replay of messages within a session.
(D)TLS also provides protection against replay of entire sessions.
In a properly-implemented keying material exchange, both sides will
generate new random numbers for each exchange. This results in
different encryption and integrity keys for every session.
A.2. The (D)TLS Handshake Protocol
The (D)TLS Record Protocol is used for encapsulation of various
higher-level protocols. One such encapsulated protocol, the (D)TLS
Handshake Protocol, allows the server and client to authenticate each
other and to negotiate an integrity algorithm, an encryption
algorithm and cryptographic keys before the application protocol
transmits or receives its first octet of data. Only the (D)TLS
client can initiate the handshake protocol. The (D)TLS Handshake
Protocol provides security that has four basic properties:
o The peer's identity can be authenticated using asymmetric (public
key) cryptography (e.g., RSA [RSA], DSS [DSS], etc.). This
authentication can be made optional, but is generally required by
at least one of the peers.
(D)TLS supports three authentication modes: authentication of both
the server and the client, server authentication with an
unauthenticated client, and total anonymity. For authentication
of both entities, each entity provides a valid certificate chain
leading to an acceptable certificate authority. Each entity is
responsible for verifying that the other's certificate is valid
and has not expired or been revoked. See
[I-D.saintandre-tls-server-id-check] for further details on
standardized processing when checking server certificate
identities.
o The negotiation of a shared secret is secure: the negotiated
secret is unavailable to eavesdroppers, and for any authenticated
handshake the secret cannot be obtained, even by an attacker who
can place himself in the middle of the session.
o The negotiation is not vulnerable to malicious modification: it is
infeasible for an attacker to modify negotiation communication
without being detected by the parties to the communication.
o DTLS uses a stateless cookie exchange to protect against anonymous
denial of service attacks and has retransmission timers, sequence
numbers, and counters to handle message loss, reordering, and
fragmentation.
Appendix B. PKIX Certificate Infrastructure
Users of a public key from a PKIX / X.509 certificate can be be
confident that the associated private key is owned by the correct
remote subject (person or system) with which an encryption or digital
signature mechanism will be used. This confidence is obtained
through the use of public key certificates, which are data structures
that bind public key values to subjects. The binding is asserted by
having a trusted CA digitally sign each certificate. The CA may base
this assertion upon technical means (i.e., proof of possession
through a challenge-response protocol), presentation of the private
key, or on an assertion by the subject. A certificate has a limited
valid lifetime which is indicated in its signed contents. Because a
certificate's signature and timeliness can be independently checked
by a certificate-using client, certificates can be distributed via
untrusted communications and server systems, and can be cached in
unsecured storage in certificate-using systems.
ITU-T X.509 (formerly CCITT X.509) or ISO/IEC/ITU 9594-8 [X509],
which was first published in 1988 as part of the X.500 Directory
recommendations, defines a standard certificate format which is a
certificate which binds a subject (principal) to a public key value.
This was later further expanded and documented in [RFC5280].
A X.509 certificate is a sequence of three required fields:
tbsCertificate: The tbsCertificate field contains the names of the
subject and issuer, a public key associated with the subject, a
validity period, and other associated information. This field may
also contain extension components.
signatureAlgorithm: The signatureAlgorithm field contains the
identifier for the cryptographic algorithm used by the certificate
authority (CA) to sign this certificate.
signatureValue: The signatureValue field contains a digital
signature computed by the CA upon the ASN.1 DER encoded
tbsCertificate field. The ASN.1 DER encoded tbsCertificate is
used as the input to the signature function. This signature value
is then ASN.1 DER encoded as a BIT STRING and included in the
Certificate's signature field. By generating this signature, the
CA certifies the validity of the information in the tbsCertificate
field. In particular, the CA certifies the binding between the
public key material and the subject of the certificate.
The basic X.509 authentication procedure is as follows: A system is
initialized with a number of root certificates that contain the
public keys of a number of trusted CAs. When a system receives a
X.509 certificate, signed by one of those CAs, the certificate has to
be verified. It first checks the signatureValue field by using the
public key of the corresponding trusted CA. Then it compares the
digest of the received certificate with a digest of the
tbsCertificate field. If they match, then the subject in the
tbsCertificate field is authenticated.
Appendix C. Target and Notification Configuration Example
Configuring the SNMP-TARGET-MIB and NOTIFICATION-MIB along with Configuring the SNMP-TARGET-MIB and NOTIFICATION-MIB along with
access control settings for the SNMP-VIEW-BASED-ACM-MIB can be a access control settings for the SNMP-VIEW-BASED-ACM-MIB can be a
daunting task without an example to follow. The following section daunting task without an example to follow. The following section
describes an example of what pieces must be in place to accomplish describes an example of what pieces must be in place to accomplish
this configuration. this configuration.
The isAccessAllowed() ASI requires configuration to exist in the The isAccessAllowed() ASI requires configuration to exist in the
following SNMP-VIEW-BASED-ACM-MIB tables: following SNMP-VIEW-BASED-ACM-MIB tables:
skipping to change at page 64, line 22 skipping to change at page 60, line 42
vacmSecurityToGroupStatus = 4 (createAndGo) vacmSecurityToGroupStatus = 4 (createAndGo)
This example will assume that the "administrators" group has been This example will assume that the "administrators" group has been
given proper permissions via rows in the vacmAccessTable and given proper permissions via rows in the vacmAccessTable and
vacmViewTreeFamilyTable. vacmViewTreeFamilyTable.
Depending on whether this VACM configuration is for a Command Depending on whether this VACM configuration is for a Command
Responder or a command generator the security name "blueberry" will Responder or a command generator the security name "blueberry" will
come from a few different locations. come from a few different locations.
C.1. Configuring the Notification Originator A.1. Configuring the Notification Originator
For notification originators performing authorization checks, the For notification originators performing authorization checks, the
server's certificate must be verified against the expected server's certificate must be verified against the expected
certificate before proceeding to send the notification. The expected certificate before proceeding to send the notification. The expected
certificate from the server may be listed in the tlstmAddrTable or certificate from the server may be listed in the tlstmAddrTable or
may be determined through other X.509 path validation mechanisms. may be determined through other X.509 path validation mechanisms.
The securityName to use for VACM authorization checks is set by the The securityName to use for VACM authorization checks is set by the
SNMP-TARGET-MIB's snmpTargetParamsSecurityName column. SNMP-TARGET-MIB's snmpTargetParamsSecurityName column.
The certificate that the notification originator should present to The certificate that the notification originator should present to
the server is taken from the tlstmParamsClientFingerprint column from the server is taken from the tlstmParamsClientFingerprint column from
the appropriate entry in the tlstmParamsTable table. the appropriate entry in the tlstmParamsTable table. (Or else a
default certificate may be used if available.)
C.2. Configuring the Command Responder To configure a notification originator to open a TLS over TCP
connection to a notification receiver it must be configured so the
server's presented certificate can be verified against the expected
certificate before proceeding to send the notification. This is done
by configuring the tlstmAddrTable accordingly. For example, if the
verification is done via certification path validation (to a trust
anchor configured in implementation dependent manner), then the table
entries could look like:
snmpTargetAddrTable row:
snmpTargetAddrName = "toNRAddr"
snmpTargetAddrTDomain = snmpTLSTCPDomain
snmpTargetAddrTAddress = "192.0.2.1:XXXTLSTCPTRAPPORT"
snmpTargetAddrTimeout = 1500
snmpTargetAddrRetryCount = 3
snmpTargetAddrTagList = "toNRTag"
snmpTargetAddrParams = "toNR" (MUST match below)
snmpTargetAddrStorageType = 3 (nonVolatile)
snmpTargetAddrColumnStatus = 4 (createAndGo)
snmpTargetParamsTable row:
snmpTargetParamsName = toNR
snmpTargetParamsMPModel = SNMPv3
snmpTargetParamsSecurityModel = 4 (TransportSecurityModel)
snmpTargetParamsSecurityName = "blueberry"
snmpTargetParamsSecurityLevel = 3 (authPriv)
snmpTargetParamsStorageType = 3 (nonVolatile)
snmpTargetParamsRowStatus = 4 (createAndGo0
tlstmAddrTable row:
snmpTargetAddrName = "toNRAddr"
tlstmAddrServerFingerprint = ""
tlstmAddrServerIdentity = "server.example.org"
tlstmAddrStorageType = 3 (nonVolatile)
tlstmAddrRowStatus = 4 (createAndGo)
Editor's note: replace the string "XXXTLSTCPTRAPPORT" above with the
appropriately assigned "snmptls-trap" port.
A.2. Configuring the Command Responder
For command responder applications, the vacmSecurityName "blueberry" For command responder applications, the vacmSecurityName "blueberry"
value is a value that derived from an incoming (D)TLS session. The value is a value that derived from an incoming (D)TLS connection.
mapping from a recevied (D)TLS client certificate to a tmSecurityName The mapping from a recevied (D)TLS client certificate to a
is done with the tlstmCertToTSNTable. The certificates must be tmSecurityName is done with the tlstmCertToTSNTable. The
loaded into the device so that a tlstmCertToTSNEntry may refer to it. certificates must be loaded into the device so that a
As an example, consider the following entry which will provide a tlstmCertToTSNEntry may refer to it. As an example, consider the
mapping from a client's public X.509's hash fingerprint directly to following entry which will provide a mapping from a client's public
the "blueberry" tmSecurityName: X.509's hash fingerprint directly to the "blueberry" tmSecurityName:
tlstmCertToTSNID = 1 (chosen by ordering preference) tlstmCertToTSNID = 1 (chosen by ordering preference)
tlstmCertToTSNFingerprint = HASH (appropriate fingerprint) tlstmCertToTSNFingerprint = HASH (appropriate fingerprint)
tlstmCertToTSNMapType = 1 (specified) tlstmCertToTSNMapType = tlstmCertSpecified
tlstmCertToTSNSecurityName = "blueberry" tlstmCertToTSNSecurityName = "blueberry"
tlstmCertToTSNStorageType = 3 (nonVolatile) tlstmCertToTSNStorageType = 3 (nonVolatile)
tlstmCertToTSNRowStatus = 4 (createAndGo) tlstmCertToTSNRowStatus = 4 (createAndGo)
The above is an example of how to map a particular certificate to a The above is an example of how to map a particular certificate to a
particular tmSecurityName. It is recommended, however, that users particular tmSecurityName. It is recommended, however, that users
make use of direct subjectAltName or CommonName mappings where make use of direct subjectAltName or CommonName mappings where
possible as it provides a more scalable approach to certificate possible as it provides a more scalable approach to certificate
management. This entry provides an example of using a subjectAltName management. This entry provides an example of using a subjectAltName
mapping: mapping:
tlstmCertToTSNID = 1 (chosen by ordering preference) tlstmCertToTSNID = 1 (chosen by ordering preference)
tlstmCertToTSNFingerprint = HASH (appropriate fingerprint) tlstmCertToTSNFingerprint = HASH (appropriate fingerprint)
tlstmCertToTSNMapType = 2 (bySubjectAltName) tlstmCertToTSNMapType = tlstmCertSANAny
tlstmCertToTSNSANType = 1 (any) tlstmCertToTSNData = "" (not used)
tlstmCertToTSNStorageType = 3 (nonVolatile) tlstmCertToTSNStorageType = 3 (nonVolatile)
tlstmCertToTSNRowStatus = 4 (createAndGo) tlstmCertToTSNRowStatus = 4 (createAndGo)
The above entry indicates the subjectAltName field for certificates The above entry indicates the subjectAltName field for certificates
created by an issuing certificate with a corresponding fingerprint created by an issuing certificate with a corresponding fingerprint
will be trusted to always produce common names that are directly one- will be trusted to always produce common names that are directly one-
to-one mappable into tmSecurityNames. This type of configuration to-one mappable into tmSecurityNames. This type of configuration
should only be used when the certificate authorities naming should only be used when the certificate authorities naming
conventions are carefully controlled. conventions are carefully controlled.
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