Internet-Draft Updates to the TLSTM for SNMP May 2022
Vaughn Expires 17 November 2022 [Page]
Workgroup:
Internet Engineering Task Force
Internet-Draft:
draft-ietf-opsawg-tlstm-update-04
Updates:
6353 (if approved)
Published:
Intended Status:
Standards Track
Expires:
Author:
K. Vaughn, Ed.
Trevilon LLC

Updates to the TLS Transport Model for SNMP

Abstract

This document updates the TLS Transport Model (TLSTM), as defined in RFC 6353, to reflect changes necessary to support Transport Layer Security Version 1.3 (TLS 1.3) and Datagram Transport Layer Security Version 1.3 (DTLS 1.3), which are jointly known as "(D)TLS 1.3". This document is compatible with (D)TLS 1.2 and is intended to be compatible with future versions of SNMP and (D)TLS.

This document updates the SNMP-TLS-TM-MIB as defined in RFC 6353.

Status of This Memo

This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.

Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at https://datatracker.ietf.org/drafts/current/.

Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress."

This Internet-Draft will expire on 17 November 2022.

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Table of Contents

1. Introduction

This document updates and clarifies how the rules of [RFC6353] apply when using Transport Layer Security (TLS) or Datagram Transport Layer Security (DTLS) versions later than 1.2. This document jointly refers to these two protocols as "(D)TLS". The update also incorporates the [RFC8996] update, which prohibits the use of TLS versions prior to TLS 1.2. Although the text of this document specifically references SNMPv3 and (D)TLS 1.3, this document may be applicable to future versions of these protocols and is backwards compatible with (D)TLS 1.2.

1.1. Conventions

Within this document the terms "TLS", "DTLS", and "(D)TLS" apply to all versions of the indicated protocols. The term "SNMP" means "SMNPv3" unless a specific version number is indicated. Specific version numbers are used when the text needs to emphasize version numbers.

For consistency with SNMP-related specifications, this document favors terminology as defined in [STD62], rather than favoring terminology that is consistent with non-SNMP specifications. This is consistent with the IESG decision to not require the SNMP terminology be modified to match the usage of other non-SNMP specifications when SNMP was advanced to a Full Standard. "Authentication" in this document typically refers to the English meaning of "serving to prove the authenticity of" the message, not data source authentication or peer identity authentication. The terms "manager" and "agent" are not used in this document because, in the RFC3411 architecture, all SNMP entities have the capability of acting as manager, agent, or both depending on the SNMP application types supported in the implementation. Where distinction is necessary, the application names of command generator, command responder, notification originator, notification receiver, and proxy forwarder are used. See "SNMP Applications" (RFC3411) for further information.

Throughout this document, the terms "client" and "server" are used to refer to the two ends of the TLS transport connection. The client actively opens the TLS connection, and the server passively listens for the incoming TLS connection. An SNMP entity MAY act as a TLS client or server or both, depending on the SNMP applications supported.

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

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", NOT RECOMMENDED, "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119].

2. Changes from RFC 6353

This document updates [RFC6353]. The changes from [RFC6353] are defined in the following clauses.

2.1. TLSTM Fingerprint

[RFC6353] defines a fingerprint algorithm that references the one-octet TLS 1.2 hash algorithm identifier. TLS 1.3 replaced the one-octet hash algorithm identifier with a two-octet TLS 1.3 cipher suite identifier. The TLS community does not plan to ever add additional values to the TLS 1.2 hash algorithm registry because some might incorrectly infer that using a new hash algorithm with TLS 1.2 would overcome the limitations of TLS 1.2. However, there is still a need within TLSTM to support new values as they are developed.

This document updates the definition of SnmpTLSFingerprint to clarify that the one-octet identifier in the fingerprint algorithm uses the IANA SNMP-TLSTM HashAlgorithm Registry; this registry is consistent with the IANA TLS HashAlgorithm Registry for its initial values but can be extended as needed to support new hashing algorithms without implying that the new values can be used by TLS version 1.2. This change allows the reuse of the existing fingerprint TEXTUAL-CONVENTION and minimizes the impact to [RFC6353]. The initial values for the SNMP-TLSTM HashAlgorithm Registry are defined below:

Table 1: Table 1: SNMP-TLSTM Hash Algorithms
Value Description Recommended Reference
0 none N [RFC5246]
1 md5 N [RFC5246]
2 sha1 N [RFC5246]
3 sha224 Y [RFC5246]
4 sha256 Y [RFC5246]
5 sha384 Y [RFC5246]
6 sha512 Y [RFC5246]
7 reserved [RFC8447]
8 intrinsic N [RFC8422]
9-223 none N [RFC8447]
224-255 none N [RFC5246]

Values zero through 2 MUST NOT be used by implementations of this document but are listed for historical consistency.

2.2. Security Level

The RFC3411 architecture recognizes three levels of security:

  • without authentication and without privacy (noAuthNoPriv)
  • with authentication but without privacy (authNoPriv)
  • with authentication and with privacy (authPriv)

With (D)TLS 1.3, authentication and privacy are always provided. Hence, all exchanges conforming to the rules of this document will include authentication and privacy, regardless of the security level requested.

2.3. TLS Version

[RFC6353] stated that TLSTM clients and servers MUST NOT request, offer, or use SSL 2.0. [RFC8996] prohibits the use of (D)TLS versions prior to version 1.2. TLSTMv1.3 MUST only be used with (D)TLS version 1.2 and later.

3. Additional Rules for TLS 1.3

This document specifies additional rules and clarifications for the use of TLS 1.3. These rules may additionally apply to future versions of TLS.

3.1. Zero Round Trip Time Resumption (0-RTT)

TLS 1.3 implementations for SNMP MUST NOT enable the 0-RTT mode of session resumption (either sending or accepting) and MUST NOT automatically resend 0-RTT data if it is rejected by the server. The reason 0-RTT is disallowed is that there are no "safe" messages that if replayed will be guaranteed to cause no harm at a server side: all incoming notification or command responses are meant to be acted upon only once. See Security considerations section for further details.

TLS TM clients and servers MUST NOT request, offer or use the 0-RTT mode of TLS 1.3. [RFC8446] removed the renegotiation supported in TLS 1.2 [RFC5246]; for session resumption, it introduced a zero-RTT (0-RTT) mode, saving a round-trip at connection setup at the cost of increased risk of replay attacks (it is possible for servers to guard against this attack by keeping track of all the messages received). [RFC8446] requires a profile be written for any application that wants to use 0-RTT, specifying which messages are "safe to use" on this mode. The reason 0-RTT is disallowed here is that there are no "safe" SNMP messages that if replayed will be sure to cause no harm at a server side: all incoming notification or command responses have consequences and are to be acted upon only once.

Renegotiation of sessions is not supported as it is not supported by TLS 1.3.

3.2. TLS ciphersuites, extensions and protocol invariants

[RFC8446] section 9 requires that, in the absence of application profiles, certain cipher suites, TLS extensions, and TLS protocol invariants are mandatory to implement. This document does not specify an application profile, hence all of the compliance requirements in [RFC8446] apply.

4. MIB Module Definition 

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

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

snmpTlstmMIB MODULE-IDENTITY
    LAST-UPDATED "202203050000Z"

    ORGANIZATION "OPSA Working Group"
    CONTACT-INFO "WG-EMail:   opsawg@ietf.org
               Mailing list subscription info:
               https://www.ietf.org/mailman/listinfo/opsawg

               Kenneth Vaughn
               Trevilon LLC
               6606 FM 1488 RD, STE 503
               Magnolia, TX 77354
               United States
               Phone: +1 571 331 5670
               Email: kvaughn@trevilon.com"
    DESCRIPTION  "
        The TLS Transport Model MIB

        Copyright (c) 2010-2022 IETF Trust and the persons identified
        as authors of the code.  All rights reserved.

        Redistribution and use in source and binary forms, with or
        without modification, is permitted pursuant to, and subject
        to the license terms contained in, the Revised BSD License
        set forth in Section 4.c of the IETF Trust's Legal Provisions
        Relating to IETF Documents
        (http://trustee.ietf.org/license-info)."

        REVISION    "202203050000Z"
        DESCRIPTION "This version of this MIB module is part of
                    RFC XXXX; see the RFC itself for full legal
                    notices.  This version:
                    1. Updates the definition of SnmpTLSFingerprint
                       to clarify the registry used for the one-octet
                       hash algorithm identifier.
                    2. Capitalizes key words in conformance with
                       BCP 14
                    3. Replaces 'may not' with 'MUST NOT' to clarify
                       intent in several locations."

       REVISION     "201107190000Z"
       DESCRIPTION  "This version of this MIB module is part of
                     RFC 6353; see the RFC itself for full legal
                     notices.  The only change was to introduce
                     new wording to reflect require changes for
                     IDNA addresses in the SnmpTLSAddress TC."

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

-- ************************************************
-- subtrees of the SNMP-TLS-TM-MIB
-- ************************************************

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

-- ************************************************
-- snmpTlstmObjects - Objects
-- ************************************************

snmpTLSTCPDomain OBJECT-IDENTITY
    STATUS      current
    DESCRIPTION
        "The SNMP over TLS via TCP transport domain.  The
        corresponding transport address is of type SnmpTLSAddress.

        The securityName prefix to be associated with the
        snmpTLSTCPDomain is 'tls'.  This prefix MAY be used by
        security models or other components to identify which secure
        transport infrastructure authenticated a securityName."
    REFERENCE
      "RFC 2579: Textual Conventions for SMIv2"
    ::= { snmpDomains 8 }

snmpDTLSUDPDomain OBJECT-IDENTITY
    STATUS      current
    DESCRIPTION
        "The SNMP over DTLS via UDP transport domain.  The
        corresponding transport address is of type SnmpTLSAddress.

        The securityName prefix to be associated with the
        snmpDTLSUDPDomain is 'dtls'.  This prefix MAY be used by
        security models or other components to identify which secure
        transport infrastructure authenticated a securityName."
    REFERENCE
      "RFC 2579: Textual Conventions for SMIv2"
    ::= { snmpDomains 9 }

SnmpTLSAddress ::= TEXTUAL-CONVENTION
    DISPLAY-HINT "1a"
    STATUS       current
    DESCRIPTION
        "Represents an IPv4 address, an IPv6 address, or a
         US-ASCII-encoded hostname and port number.

        An IPv4 address MUST be in dotted decimal format followed by a
        colon ':' (US-ASCII character 0x3A) and a decimal port number
        in US-ASCII.

        An IPv6 address MUST be a colon-separated format (as described
        in RFC 5952), surrounded by square brackets ('[', US-ASCII
        character 0x5B, and ']', US-ASCII character 0x5D), followed by
        a colon ':' (US-ASCII character 0x3A) and a decimal port number
        in US-ASCII.

        A hostname is always in US-ASCII (as per RFC 1123);
        internationalized hostnames are encoded as A-labels as specified
        in  RFC 5890.  The hostname is followed by a
        colon ':' (US-ASCII character 0x3A) and a decimal port number
        in US-ASCII.  The name SHOULD be fully qualified whenever
        possible.

        Values of this textual convention MUST NOT be directly usable
        as transport-layer addressing information, and may require
        run-time resolution.  As such, applications that write them
        MUST be prepared for handling errors if such values are not
        supported, or cannot be resolved (if resolution occurs at the
        time of the management operation).

        The DESCRIPTION clause of TransportAddress objects that may
        have SnmpTLSAddress values MUST fully describe how (and
        when) such names are to be resolved to IP addresses and vice
        versa.

        This textual convention SHOULD NOT be used directly in object
        definitions since it restricts addresses to a specific
        format.  However, if it is used, it MAY be used either on its
        own or in conjunction with TransportAddressType or
        TransportDomain as a pair.

        When this textual convention is used as a syntax of an index
        object, there may be issues with the limit of 128
        sub-identifiers specified in SMIv2 (STD 58).  It is RECOMMENDED
        that all MIB documents using this textual convention make
        explicit any limitations on index component lengths that
        management software MUST observe.  This MAY be done either by

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

SnmpTLSFingerprint ::= TEXTUAL-CONVENTION
    DISPLAY-HINT "1x:1x"
    STATUS       current
    DESCRIPTION
       "A fingerprint value that can be used to uniquely reference
       other data of potentially arbitrary length.

       An SnmpTLSFingerprint value is composed of a 1-octet hashing
       algorithm identifier followed by the fingerprint value.  The
       octet value encoded is based on the IANA TLS HashAlgorithm
       Registry (RFC 5246), However, this registry is only applicable
       to (D)TLS protocol versions prior to 1.3, which are now
       designated as obsolete and are not expected to ever support
       additional values. To allow the fingerprint algorithm to support
       additional hashing algorithms that might be used by later
       versions of (D)TLS, the octet value encoded is taken from IANA
       SNMP-TLSTM HashAlgorithm Registry, The initial values within
       this registry are identical to the values in the TLS
       HashAlgorithm registry but can be extended to support new
       hashing algorithms as needed.

       This TEXTUAL-CONVENTION allows for a zero-length (blank)
       SnmpTLSFingerprint value for use in tables where the
       fingerprint value MAY be optional.  MIB definitions or
       implementations MAY refuse to accept a zero-length value as
       appropriate."
       REFERENCE "https://www.iana.org/assignments/smi-numbers/smi-numbers.xhtml"
    SYNTAX OCTET STRING (SIZE (0..255))

-- Identities for use in the snmpTlstmCertToTSNTable

snmpTlstmCertToTSNMIdentities OBJECT IDENTIFIER
    ::= { snmpTlstmIdentities 1 }

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

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

snmpTlstmCertSANRFC822Name OBJECT-IDENTITY
    STATUS        current
    DESCRIPTION  "Maps a subjectAltName's rfc822Name to a
                  tmSecurityName.  The local part of the rfc822Name is
                  passed unaltered but the host-part of the name MUST
                  be passed in lowercase.  This mapping results in a
                  1:1 correspondence between equivalent subjectAltName
                  rfc822Name values and tmSecurityName values except
                  that the host-part of the name MUST be passed in
                  lowercase.

                  Example rfc822Name Field:  FooBar@Example.COM
                  is mapped to tmSecurityName: FooBar@example.com."
    ::= { snmpTlstmCertToTSNMIdentities 2 }

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

snmpTlstmCertSANIpAddress OBJECT-IDENTITY
    STATUS        current
    DESCRIPTION  "Maps a subjectAltName's iPAddress to a
                  tmSecurityName by transforming the binary encoded
                  address as follows:

                  1) for IPv4, the value is converted into a
                     decimal-dotted quad address (e.g., '192.0.2.1').

                  2) for IPv6 addresses, the value is converted into a
                     32-character all lowercase hexadecimal string
                     without any colon separators.

                  This mapping results in a 1:1 correspondence between
                  subjectAltName iPAddress values and the
                  tmSecurityName values.

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

snmpTlstmCertSANAny OBJECT-IDENTITY
    STATUS        current
    DESCRIPTION  "Maps any of the following fields using the
                  corresponding mapping algorithms:

                  |------------+----------------------------|
                  | Type       | Algorithm                  |
                  |------------+----------------------------|
                  | rfc822Name | snmpTlstmCertSANRFC822Name |
                  | dNSName    | snmpTlstmCertSANDNSName    |
                  | iPAddress  | snmpTlstmCertSANIpAddress  |
                  |------------+----------------------------|

                  The first matching subjectAltName value found in the
                  certificate of the above types MUST be used when
                  deriving the tmSecurityName.  The mapping algorithm
                  specified in the 'Algorithm' column MUST be used to
                  derive the tmSecurityName.

                  This mapping results in a 1:1 correspondence between
                  subjectAltName values and tmSecurityName values.  The
                  three sub-mapping algorithms produced by this
                  combined algorithm cannot produce conflicting
                  results between themselves."
    ::= { snmpTlstmCertToTSNMIdentities 5 }

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

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

-- The snmpTlstmSession Group

snmpTlstmSession           OBJECT IDENTIFIER ::= { snmpTlstmObjects 1 }

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

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

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

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

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

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

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

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

snmpTlstmSessionInvalidServerCertificates OBJECT-TYPE
    SYNTAX       Counter32
    MAX-ACCESS   read-only
    STATUS       current
    DESCRIPTION
        "The number of times an outgoing session was not established
         on a (D)TLS client because the server certificate presented
         by an SNMP over (D)TLS server could not be validated even if
         the fingerprint or expected validation path was known.  That
         is, a cryptographic validation error occurred during
         certificate validation processing.

        Reasons for invalidation include, but are not
        limited to, cryptographic validation failures."
    ::= { snmpTlstmSession 9 }

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

-- Configuration Objects

snmpTlstmConfig             OBJECT IDENTIFIER ::= { snmpTlstmObjects 2 }

-- Certificate mapping

snmpTlstmCertificateMapping OBJECT IDENTIFIER ::= { snmpTlstmConfig 1 }

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

snmpTlstmCertToTSNTableLastChanged OBJECT-TYPE
    SYNTAX      TimeStamp
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
        "The value of sysUpTime.0 when the snmpTlstmCertToTSNTable was
        last modified through any means, or 0 if it has not been
        modified since the command responder was started."
    ::= { snmpTlstmCertificateMapping 2 }

snmpTlstmCertToTSNTable OBJECT-TYPE
    SYNTAX      SEQUENCE OF SnmpTlstmCertToTSNEntry
    MAX-ACCESS  not-accessible
    STATUS      current
    DESCRIPTION
        "This table is used by a (D)TLS server to map the (D)TLS
        client's presented X.509 certificate to a tmSecurityName.

        On an incoming (D)TLS/SNMP connection, the client's presented
        certificate MUST either be validated based on an established
        trust anchor, or it MUST directly match a fingerprint in this
        table.  This table does not provide any mechanisms for
        configuring the trust anchors; the transfer of any needed
        trusted certificates for path validation is expected to occur
        through an out-of-band transfer.

        Once the certificate has been found acceptable (either by path
        validation or directly matching a fingerprint in this table),
        this table is consulted to determine the appropriate
        tmSecurityName to identify with the remote connection.  This
        is done by considering each active row from this table in
        prioritized order according to its snmpTlstmCertToTSNID value.
        Each row's snmpTlstmCertToTSNFingerprint value determines
        whether the row is a match for the incoming connection:

            1) If the row's snmpTlstmCertToTSNFingerprint value
               identifies the presented certificate, then consider the
               row as a successful match.

            2) If the row's snmpTlstmCertToTSNFingerprint value
               identifies a locally held copy of a trusted CA
               certificate and that CA certificate was used to
               validate the path to the presented certificate, then
               consider the row as a successful match.

        Once a matching row has been found, the
        snmpTlstmCertToTSNMapType value can be used to determine how
        the tmSecurityName to associate with the session should be
        determined.  See the snmpTlstmCertToTSNMapType column's
        DESCRIPTION for details on determining the tmSecurityName
        value.  If it is impossible to determine a tmSecurityName from
        the row's data combined with the data presented in the

        certificate, then additional rows MUST be searched looking for
        another potential match.  If a resulting tmSecurityName mapped
        from a given row is not compatible with the needed
        requirements of a tmSecurityName (e.g., VACM imposes a
        32-octet-maximum length and the certificate derived
        securityName could be longer), then it MUST be considered an
        invalid match and additional rows MUST be searched looking for
        another potential match.

        If no matching and valid row can be found, the connection MUST
        be closed and SNMP messages MUST NOT be accepted over it.

        Missing values of snmpTlstmCertToTSNID are acceptable and
        implementations SHOULD continue to the next highest numbered
        row.  It is RECOMMENDED that administrators skip index values
        to leave room for the insertion of future rows (for example,
        use values of 10 and 20 when creating initial rows).

        Users are encouraged to make use of certificates with
        subjectAltName fields that can be used as tmSecurityNames so
        that a single root CA certificate can allow all child
        certificate's subjectAltName to map directly to a
        tmSecurityName via a 1:1 transformation.  However, this table
        is flexible to allow for situations where existing deployed
        certificate infrastructures do not provide adequate
        subjectAltName values for use as tmSecurityNames.
        Certificates MAY also be mapped to tmSecurityNames using the
        CommonName portion of the Subject field.  However, the usage
        of the CommonName field is deprecated and thus this usage is
        NOT RECOMMENDED.  Direct mapping from each individual
        certificate fingerprint to a tmSecurityName is also possible
        but requires one entry in the table per tmSecurityName and
        requires more management operations to completely configure a
        device."
    ::= { snmpTlstmCertificateMapping 3 }

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

SnmpTlstmCertToTSNEntry ::= SEQUENCE {
    snmpTlstmCertToTSNID           Unsigned32,
    snmpTlstmCertToTSNFingerprint  SnmpTLSFingerprint,
    snmpTlstmCertToTSNMapType      AutonomousType,
    snmpTlstmCertToTSNData         OCTET STRING,
    snmpTlstmCertToTSNStorageType  StorageType,
    snmpTlstmCertToTSNRowStatus    RowStatus
}

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

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

snmpTlstmCertToTSNMapType OBJECT-TYPE
    SYNTAX      AutonomousType
    MAX-ACCESS  read-create
    STATUS      current
    DESCRIPTION
        "Specifies the mapping type for deriving a tmSecurityName from
        a certificate.  Details for mapping of a particular type SHALL
        be specified in the DESCRIPTION clause of the OBJECT-IDENTITY
        that describes the mapping.  If a mapping succeeds it will
        return a tmSecurityName for use by the TLSTM model and
        processing stops.

        If the resulting mapped value is not compatible with the
        needed requirements of a tmSecurityName (e.g., VACM imposes a
        32-octet-maximum length and the certificate derived
        securityName could be longer), then future rows MUST be
        searched for additional snmpTlstmCertToTSNFingerprint matches
        to look for a mapping that succeeds.

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

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

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

snmpTlstmCertToTSNRowStatus OBJECT-TYPE
    SYNTAX      RowStatus
    MAX-ACCESS  read-create
    STATUS      current
    DESCRIPTION
        "The status of this conceptual row.  This object MAY be used
        to create or remove rows from this table.

        To create a row in this table, an administrator MUST set this
        object to either createAndGo(4) or createAndWait(5).

        Until instances of all corresponding columns are appropriately
        configured, the value of the corresponding instance of the
        snmpTlstmParamsRowStatus column is notReady(3).

        In particular, a newly created row cannot be made active until
        the corresponding snmpTlstmCertToTSNFingerprint,
        snmpTlstmCertToTSNMapType, and snmpTlstmCertToTSNData columns
        have been set.

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

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

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

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

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

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

SnmpTlstmParamsEntry ::= SEQUENCE {
    snmpTlstmParamsClientFingerprint SnmpTLSFingerprint,
    snmpTlstmParamsStorageType       StorageType,
    snmpTlstmParamsRowStatus         RowStatus
}

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

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

snmpTlstmParamsRowStatus OBJECT-TYPE
    SYNTAX      RowStatus
    MAX-ACCESS  read-create
    STATUS      current
    DESCRIPTION
        "The status of this conceptual row.  This object MAY be used
        to create or remove rows from this table.

        To create a row in this table, an administrator MUST set this
        object to either createAndGo(4) or createAndWait(5).

        Until instances of all corresponding columns are appropriately
        configured, the value of the corresponding instance of the
        snmpTlstmParamsRowStatus column is notReady(3).

        In particular, a newly created row cannot be made active until
        the corresponding snmpTlstmParamsClientFingerprint column has
        been set.

        The snmpTlstmParamsClientFingerprint object MUST NOT be modified
        while the value of this object is active(1).

        An attempt to set these objects while the value of
        snmpTlstmParamsRowStatus is active(1) will result in
        an inconsistentValue error."
    ::= { snmpTlstmParamsEntry 3 }

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

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

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

        snmpTargetAddrTable so that the client can verify that the
        correct server has been reached.  This verification can use
        either a certificate fingerprint, or an identity
        authenticated via certification path validation.

        If there is an active row in this table corresponding to the
        entry in the SNMP-TARGET-MIB that was used to establish the
        connection, and the row's snmpTlstmAddrServerFingerprint
        column has non-empty value, then the server's presented
        certificate is compared with the
        snmpTlstmAddrServerFingerprint value (and the
        snmpTlstmAddrServerIdentity column is ignored).  If the
        fingerprint matches, the verification has succeeded.  If the
        fingerprint does not match, then the connection MUST be
        closed.

        If the server's presented certificate has passed
        certification path validation [RFC5280] to a configured
        trust anchor, and an active row exists with a zero-length
        snmpTlstmAddrServerFingerprint value, then the
        snmpTlstmAddrServerIdentity column contains the expected
        host name.  This expected host name is then compared against
        the server's certificate as follows:

          - Implementations MUST support matching the expected host
          name against a dNSName in the subjectAltName extension
          field and MAY support checking the name against the
          CommonName portion of the subject distinguished name.

          - The '*' (ASCII 0x2a) wildcard character is allowed in the
          dNSName of the subjectAltName extension (and in common
          name, if used to store the host name), but only as the
          left-most (least significant) DNS label in that value.
          This wildcard matches any left-most DNS label in the
          server name.  That is, the subject *.example.com matches
          the server names a.example.com and b.example.com, but does
          not match example.com or a.b.example.com.  Implementations
          MUST support wildcards in certificates as specified above,
          but MAY provide a configuration option to disable them.

          - 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."
    ::= { snmpTlstmCertificateMapping 9 }

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

SnmpTlstmAddrEntry ::= SEQUENCE {
    snmpTlstmAddrServerFingerprint    SnmpTLSFingerprint,
    snmpTlstmAddrServerIdentity       SnmpAdminString,
    snmpTlstmAddrStorageType          StorageType,
    snmpTlstmAddrRowStatus            RowStatus
}

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

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

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

snmpTlstmAddrRowStatus OBJECT-TYPE
    SYNTAX      RowStatus
    MAX-ACCESS  read-create
    STATUS      current
    DESCRIPTION
        "The status of this conceptual row.  This object may be used
        to create or remove rows from this table.

        To create a row in this table, an administrator MUST set this
        object to either createAndGo(4) or createAndWait(5).

        Until instances of all corresponding columns are
        appropriately configured, the value of the
        corresponding instance of the snmpTlstmAddrRowStatus
        column is notReady(3).

        In particular, a newly created row cannot be made active until
        the corresponding snmpTlstmAddrServerFingerprint column has been
        set.

        Rows MUST NOT be active if the snmpTlstmAddrServerFingerprint
        column is blank and the snmpTlstmAddrServerIdentity is set to
        '*' since this would insecurely accept any presented
        certificate.

        The snmpTlstmAddrServerFingerprint object MUST NOT be modified
        while the value of this object is active(1).

        An attempt to set these objects while the value of
        snmpTlstmAddrRowStatus is active(1) will result in
        an inconsistentValue error."
    ::= { snmpTlstmAddrEntry 4 }

-- ************************************************
--  snmpTlstmNotifications - Notifications Information
-- ************************************************

snmpTlstmServerCertificateUnknown NOTIFICATION-TYPE
    OBJECTS { snmpTlstmSessionUnknownServerCertificate }
    STATUS  current
    DESCRIPTION
        "Notification that the server certificate presented by an SNMP
         over (D)TLS server was invalid because no configured
         fingerprint or CA was acceptable to validate it.  This may be
         because there was no entry in the snmpTlstmAddrTable or
         because no path could be found to known Certification
         Authority.

         To avoid notification loops, this notification MUST NOT be
         sent to servers that themselves have triggered the
         notification."
    ::= { snmpTlstmNotifications 1 }

snmpTlstmServerInvalidCertificate NOTIFICATION-TYPE
    OBJECTS { snmpTlstmAddrServerFingerprint,
              snmpTlstmSessionInvalidServerCertificates}
    STATUS  current
    DESCRIPTION
        "Notification that the server certificate presented by an SNMP
         over (D)TLS server could not be validated even if the
         fingerprint or expected validation path was known.  That is, a
         cryptographic validation error occurred during certificate
         validation processing.

         To avoid notification loops, this notification MUST NOT be
         sent to servers that themselves have triggered the
         notification."
    ::= { snmpTlstmNotifications 2 }

-- ************************************************
-- snmpTlstmCompliances - Conformance Information
-- ************************************************

snmpTlstmCompliances OBJECT IDENTIFIER ::= { snmpTlstmConformance 1 }

snmpTlstmGroups OBJECT IDENTIFIER ::= { snmpTlstmConformance 2 }

-- ************************************************
-- Compliance statements
-- ************************************************

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

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

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

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

snmpTlstmNotificationGroup NOTIFICATION-GROUP
    NOTIFICATIONS {
        snmpTlstmServerCertificateUnknown,
        snmpTlstmServerInvalidCertificate
    }
    STATUS current
    DESCRIPTION
        "Notifications"
    ::= { snmpTlstmGroups 4 }

END

5. Security Considerations

This document updates a transport model that permits SNMP to utilize (D)TLS security services. The security threats and how the TLS transport model mitigates these threats are covered throughout this document and in [RFC6353]. Security considerations for TLS are described in Section 10 and Appendix E of TLS 1.3 [RFC8446].

SNMP versions prior to SNMPv3 did not include adequate security. Even if the network itself is secure (for example, by using IPsec), even then, there is no control as to who on the secure network is allowed to access and GET/SET (read/change/create/delete) the objects in this MIB module.

It is RECOMMENDED that only SNMPv3 messages using the Transport Security Model (TSM) or another secure-transport aware security model be sent over the TLSTM transport.

6. IANA Considerations

IANA is asked to create a new registry called the SNMP-TLSTM HashAlgorithm Registry in the Structure of Management Information (SMI) Numbers (MIB Module Registrations) Group and to update the proposed URL reference in the above MIB ( listed as "https://www.iana.org/assignments/smi-numbers/smi-numbers.xhtml" under SnmpTLSFingerprint), if needed, to accurately reflect its location.

The registry should have the following fields: value, description, recommended, and reference. The range of values is zero to 255, with initial assignments shown in Section 2.1. The "recommended" column indicates "Y" for hashing algorithms that are deemed to be acceptable for current use and "N" for hashing algorithms that reflect historical meanings that are not recommended (e.g., because they do not provide sufficient security for modern systems).

The policy for updates is Expert Review. The expert should consult the Security Area, e.g. via the mailing list of the TLS WG (the initial values of this registry are taken from an existing TLS Registry so the TLS WG would seem the best fit for this).

In addition, a new entry MUST be added to the SNMP-TLSTM HashAlgorithm Registry every time a new hash algorithm is approved for any version of TLS or DTLS. A separate entry MUST NOT be created when an existing hash algorithm is used as a part of a new (D)TLS cipher suite.

While future additions to the IANA TLS HashAlgorithm Registry are not expected, any future addition to the IANA TLS HashAlgorithm Registry MUST be consistent with the values assigned in the IANA SNMP-TLSTM HashAlgorithm Registry.

7. Acknowledgements

This document is based on [RFC6353]. This document was reviewed by the following people who helped provide useful comments: Michaela Vanderveen, Joe Clarke, Jurgen Schonwalder, and Tom Petch

8. References

8.1. Normative References

[RFC2119]
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <https://www.rfc-editor.org/info/rfc2119>.
[RFC5280]
Cooper, D., Santesson, S., Farrell, S., Boeyen, S., Housley, R., and W. Polk, "Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, , <https://www.rfc-editor.org/info/rfc5280>.
[RFC6353]
Hardaker, W., "Transport Layer Security (TLS) Transport Model for the Simple Network Management Protocol (SNMP)", STD 78, RFC 6353, DOI 10.17487/RFC6353, , <https://www.rfc-editor.org/info/rfc6353>.
[RFC8446]
Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, , <https://www.rfc-editor.org/info/rfc8446>.
[RFC8996]
Moriarty, K. and S. Farrell, "Deprecating TLS 1.0 and TLS 1.1", BCP 195, RFC 8996, DOI 10.17487/RFC8996, , <https://www.rfc-editor.org/info/rfc8996>.
[RFC9147]
Rescorla, E., Tschofenig, H., and N. Modadugu, "The Datagram Transport Layer Security (DTLS) Protocol Version 1.3", RFC 9147, DOI 10.17487/RFC9147, , <https://www.rfc-editor.org/info/rfc9147>.
[STD62]
Harrington, D., Presuhn, R., and B. Wijnen, "An Architecture for Describing Simple Network Management Protocol (SNMP) Management Frameworks", STD 62, RFC 3411, .
Case, J., Harrington, D., Presuhn, R., and B. Wijnen, "Message Processing and Dispatching for the Simple Network Management Protocol (SNMP)", STD 62, RFC 3412, .
Levi, D., Meyer, P., and B. Stewart, "Simple Network Management Protocol (SNMP) Applications", STD 62, RFC 3413, .
Blumenthal, U. and B. Wijnen, "User-based Security Model (USM) for version 3 of the Simple Network Management Protocol (SNMPv3)", STD 62, RFC 3414, .
Wijnen, B., Presuhn, R., and K. McCloghrie, "View-based Access Control Model (VACM) for the Simple Network Management Protocol (SNMP)", STD 62, RFC 3415, .
Presuhn, R., Ed., "Version 2 of the Protocol Operations for the Simple Network Management Protocol (SNMP)", STD 62, RFC 3416, .
Presuhn, R., Ed., "Transport Mappings for the Simple Network Management Protocol (SNMP)", STD 62, RFC 3417, .
Presuhn, R., Ed., "Management Information Base (MIB) for the Simple Network Management Protocol (SNMP)", STD 62, RFC 3418, .

8.2. Informative References

[RFC5246]
Dierks, T. and E. Rescorla, "The Transport Layer Security (TLS) Protocol Version 1.2", RFC 5246, DOI 10.17487/RFC5246, , <https://www.rfc-editor.org/info/rfc5246>.
[STD58]
McCloghrie, K., Ed., Perkins, D., Ed., and J. Schoenwaelder, Ed., "Structure of Management Information Version 2 (SMIv2)", STD 58, RFC 2578, .
McCloghrie, K., Ed., Perkins, D., Ed., and J. Schoenwaelder, Ed., "Textual Conventions for SMIv2", STD 58, RFC 2579, .
McCloghrie, K., Ed., Perkins, D., Ed., and J. Schoenwaelder, Ed., "Conformance Statements for SMIv2", STD 58, RFC 2580, .

Author's Address

Kenneth Vaughn (editor)
Trevilon LLC
6606 FM 1488 RD
Suite 148-503
Magnolia, TX 77354
United States of America
Phone: +1 571 331 5670