RFC 9456
Updates to the TLS Transport Model for SNMP
RFC 9456: Updates to the TLS Transport Model for SNMP 🎀
Part 1 of 7 💖
Okay bestie, this is RFC 9456, titled Updates to the TLS Transport Model for SNMP. It was written by K. Vaughn, Ed. from Trevilon LLC, it's a Standards Track document, and it's dated November 2023 🦋. It updates RFC 6353, and its header has no Obsoletes line. The ISSN is 2070-1721 ✨.
Abstract ✨
So this doc is a glow-up for RFC 6353 ("Transport Layer Security (TLS) Transport Model for the Simple Network Management Protocol (SNMP)"). It makes that spec work with Transport Layer Security version 1.3 (TLS 1.3) and Datagram Transport Layer Security version 1.3 (DTLS 1.3), which together get called "(D)TLS 1.3" 💅. It stays compatible with (D)TLS 1.2 and is meant to play nicely with future versions of SNMP and (D)TLS 🌈.
It also updates the SNMP-TLS-TM-MIB that RFC 6353 defines 🎀.
Status of This Memo 👑
This is an Internet Standards Track document, so it's the real deal. It's a product of the Internet Engineering Task Force (IETF), and it represents the consensus of the IETF community. It got public review and was approved for publication by the Internet Engineering Steering Group (IESG). If you want more on Internet Standards, check out Section 2 of RFC 7841 📚.
For info on the current status of this document, any errata, and how to send feedback, head to https://www.rfc-editor.org/info/rfc9456 💌.
Copyright Notice 🔒
Copyright (c) 2023 IETF Trust and the persons identified as the document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) as they're in effect on the date this document is published. Please read these carefully, because they spell out your rights and restrictions for this document. Code Components pulled out of this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions, and they come without warranty as described in the Revised BSD License 🫶.
Table of Contents 🧚
1. Introduction
1.1. The Internet-Standard Management Framework
1.2. Conventions
2. Changes from RFC 6353
2.1. TLSTM Fingerprint
2.2. Security Level
2.3. (D)TLS Version
3. Additional Rules for TLS 1.3
4. MIB Module Definitions
5. Security Considerations
6. IANA Considerations
7. References
7.1. Normative References
7.2. Informative References
Acknowledgements
Author's Address1. Introduction 🌸
This doc updates and clarifies how the rules of [RFC6353] apply when you're using Transport Layer Security (TLS) or Datagram Transport Layer Security (DTLS) versions later than 1.2. Together, these two protocols are called "(D)TLS" 💜. The update also puts emphasis on the requirement in [RFC8996] that prohibits using TLS versions prior to TLS 1.2 [RFC5246] when you're using SNMP. The text specifically talks about SNMPv3 and (D)TLS 1.3, but this document may be applicable to future versions of these protocols, and it's backwards compatible with (D)TLS 1.2 🦋.
1.1. The Internet-Standard Management Framework 🗂️
For a detailed overview of the documents that describe the current Internet-Standard Management Framework, check out Section 7 of [RFC3410].
Managed objects are accessed through a virtual information store called the Management Information Base, or MIB. MIB objects are generally accessed through the Simple Network Management Protocol (SNMP). Objects in the MIB are defined using the mechanisms in the Structure of Management Information (SMI). This memo specifies a MIB module that is compliant to the SMIv2, which is described in RFCs 2578, 2579, and 2580 [STD58] ✨.
1.2. Conventions 🎀
Within this document, the terms "TLS", "DTLS", and "(D)TLS" apply to all versions of the indicated protocols. The term "SNMP" means "SNMPv3" unless a specific version number is indicated. Specific version numbers only show up when the text needs to really stress a version number 💅.
For consistency with SNMP-related specifications, this document goes with terminology defined in [STD62], rather than terminology that matches non-SNMP specifications. This is consistent with the IESG decision not to require that SNMP terminology be changed to match the usage in other non-SNMP specifications when SNMP was advanced to an Internet Standard. "Authentication" in this document typically means 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" aren't used here, because in the architecture defined in RFC 3411 [STD62], all SNMP entities can act as a manager, an agent, or both, depending on the SNMP application types supported in the implementation. Where a distinction is needed, the application names are command generator, command responder, notification originator, notification receiver, and proxy forwarder. See "An Architecture for Describing Simple Network Management Protocol (SNMP) Management Frameworks" (RFC 3411 [STD62]) for more info 🧠.
Throughout this document, "client" and "server" 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, a TLS server, or both, depending on the SNMP applications it supports 🦄.
Throughout this document, "session" refers to a secure association between two instances of the TLS Transport Model (TLSTM) 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. These two concepts are related, but when this document says "session," it means the TLSTM's specific session, not the TLS protocol's session directly 🌈.
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 BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here 🔥.
2. Changes from RFC 6353 🔄
This document updates [RFC6353]. The changes from [RFC6353] are defined in the subsections below 🍓.
2.1. TLSTM Fingerprint 🔐
[RFC6353] defines the SnmpTLSFingerprint textual convention to include the one-octet TLS 1.2 hash algorithm identifier. This one-octet algorithm identifier only applies to (D)TLS protocol versions prior to 1.3. The TLS community doesn't plan to ever add more values to the "TLS HashAlgorithm" registry [RFC5246], because some people might wrongly infer that using a new hash algorithm with TLS 1.2 would fix the limitations of TLS 1.2 😭. Still, TLSTM does need to support new values as they're developed.
This document updates the definition of SnmpTLSFingerprint to clarify that the one-octet algorithm identifier uses the values in the IANA "SNMP-TLSTM HashAlgorithms" registry. This registry matches the IANA "TLS HashAlgorithm" registry for its initial values, but it 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 lets the existing fingerprint textual convention be reused and keeps the impact on [RFC6353] minimal 💖.
A "Y" in the "Recommended" column (Table 1) means the registered value has been recommended through a formal Standards Action [RFC8126]. Not every parameter defined in Standards Track documents is marked as "Recommended" ✨.
An "N" in the "Recommended" column doesn't necessarily mean the value is flawed. It just means the item either hasn't been through the IETF consensus process, has limited applicability, or is only meant for specific use cases 🙈.
The initial values for the "SNMP-TLSTM HashAlgorithms" registry are below 👇:
+=========+==========================+=============+============+
| Value | Description | Recommended | References |
+=========+==========================+=============+============+
| 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 | Unassigned | | |
+---------+--------------------------+-------------+------------+
| 224-255 | Reserved for Private Use | | [RFC5246] |
+---------+--------------------------+-------------+------------+
Table 1: SNMP-TLSTM Hash Algorithms🚨 Values 0 through 2 are a no-go: implementations of this document are not allowed to use them (they're just listed for historical consistency). The text reads "MUST NOT be used," so no exceptions, bestie 😭.
2.2. Security Level 🛡️
The architecture defined in RFC 3411 [STD62] recognizes three levels of security:
- without authentication and without privacy (
noAuthNoPriv) - with authentication but without privacy (
authNoPriv) - with authentication and with privacy (
authPriv)
Cipher suites for (D)TLS 1.3 defined in [RFC8446] provide both authentication and privacy 🔏. Cipher suites defined in [RFC9150] for (D)TLS 1.3 provide only authentication, with no privacy protection at all 👀. Implementations MAY choose to force (D)TLS 1.3 to only allow cipher suites that provide both authentication and privacy 💅.
2.3. (D)TLS Version 📜
[RFC6353] states 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. TLSTM MUST only be used with (D)TLS versions 1.2 and later 🙅♀️.
3. Additional Rules for TLS 1.3 🌟
This document specifies additional rules and clarifications for using TLS 1.3. These rules may additionally apply to future versions of TLS 🦋.
3.1. Zero Round-Trip Time Resumption (0-RTT) 💖
Okay bestie, this one is serious 😭 TLS 1.3 implementations for SNMP MUST NOT turn on the 0-RTT mode of session resumption, whether that means sending or accepting. They also MUST NOT automatically resend 0-RTT data if the server rejects it. Why? There are no "safe" SNMP messages that you could replay and be guaranteed no harm on the server side. Every incoming notification or command response is meant to be acted on exactly once 🙈 See Section 5 ("Security Considerations") for the full tea.
So here's the deal: TLSTM clients and servers MUST NOT request, offer, or use the 0-RTT mode of TLS 1.3 🚫 [RFC8446] got rid of the renegotiation that TLS 1.2 [RFC5246] supported. For session resumption, it added 0-RTT, which saves a round trip at connection setup. The catch is a higher risk of replay attacks. Servers can guard against that by keeping track of every message they've received, but it's still extra work and extra risk. [RFC8446] also says that any application that wants 0-RTT needs a profile spelling out which messages are "safe to use" with it. In SNMP, there are no messages that qualify, so 0-RTT is a hard no ✨
Renegotiation isn't supported either, since TLS 1.3 doesn't support it. If a future version of TLS brings renegotiation back, this RFC should be updated to say whether there are extra requirements for using it. We'll cross that bridge later 🌸
3.2. TLS Cipher Suites, Extensions, and Protocol Invariants 🎀
Here's the vibe check: [RFC8446] in Section 9 says that, when there's no application profile, certain cipher suites, TLS extensions, and TLS protocol invariants have to be mandatory to implement. This document doesn't define an application profile, so all the compliance requirements in [RFC8446] apply to you. No shortcuts, babe 💅
4. MIB Module Definitions ✨
Time for the MIB module 🧚 This SNMP-TLS-TM-MIB module imports items from RFCs 2578, 2579, and 2580 [STD58], plus RFCs 3411 and 3413 [STD62]. It also references [RFC1123], [RFC5246], [RFC5280], [RFC5591], [RFC5890], [RFC5952], [RFC5953], [RFC6353], and RFC 2579 [STD58]. Here's the full code, copied exactly 🫶
<CODE BEGINS> file "SNMP-TLS-TM-MIB"
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 "202311080000Z"
ORGANIZATION "Operations and Management Area Working Group
<mailto:opsawg@ietf.org>"
CONTACT-INFO
"Author: Kenneth Vaughn
<mailto:kvaughn@trevilon.com>"
DESCRIPTION
"This is the MIB module for the TLS Transport Model
(TLSTM).
Copyright (c) 2023 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 (https://trustee.ietf.org/license-info).
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 BCP 14 (RFC 2119)
(RFC 8174) when, and only when, they appear in all
capitals, as shown here."
REVISION "202311080000Z"
DESCRIPTION
"This version of this MIB module is part of
RFC 9456; see the RFC itself for full legal
notices. This version does the following:
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.
4) Replaces 'may not' with a clarification within
the definition of SnmpTLSAddress.
5) Applies cosmetic grammar improvements and
reformatting causing whitespace changes."
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 required changes for
Internationalized Domain Names for Applications
(IDNA) addresses in the SnmpTLSAddress textual
convention (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 }
snmpTlstmHashAlgorithms OBJECT-IDENTITY
STATUS current
DESCRIPTION
"A node used to register hashing algorithm identifiers
recorded in the IANA 'SNMP-TLSTM HashAlgorithms' registry."
::= { snmpTlstmMIB 4 }
-- ************************************************
-- snmpTlstmObjects - Objects
-- ************************************************
snmpTLSTCPDomain OBJECT-IDENTITY
STATUS current
DESCRIPTION
"The OBJECT IDENTIFIER representing the TDomain for 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
"TDomain, as defined in RFC 2579: Textual Conventions
for SMIv2"
::= { snmpDomains 8 }
snmpDTLSUDPDomain OBJECT-IDENTITY
STATUS current
DESCRIPTION
"The OBJECT IDENTIFIER representing the TDomain for 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
"TDomain, as defined in 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 an
ASCII-encoded host name and port number.
An IPv4 address MUST be in dotted decimal format followed
by a colon ':' (ASCII character 0x3A) and a decimal
port number in ASCII.
An IPv6 address MUST be a colon-separated format (as
described in RFC 5952), surrounded by square brackets
('[', ASCII character 0x5B, and ']', ASCII character
0x5D), followed by a colon ':' (ASCII character 0x3A)
and a decimal port number in ASCII.
A host name MUST be in ASCII (as per RFC 1123);
internationalized host names MUST be encoded as A-labels as
specified in RFC 5890. The host name is followed by a
colon ':' (ASCII character 0x3A) and a decimal port
number in ASCII. The name SHOULD be fully qualified
whenever possible.
Values of this textual convention are not guaranteed to be
directly usable as transport-layer addressing information,
potentially requiring additional processing, such as
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 by either 1) including SIZE constraints
on the index components or 2) specifying applicable
constraints in the conceptual row's 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 one-octet
hashing algorithm identifier followed by the fingerprint
value. The one-octet identifier value encoded is taken
from the IANA 'SNMP-TLSTM HashAlgorithms' registry. The
remaining octets of the SnmpTLSFingerprint value are
filled using the results of the hashing algorithm.Okay so picking up right where the fingerprint description leaves off 💖
Historically, the one-octet hashing algorithm identifier
was based on the IANA 'TLS HashAlgorithm' registry
(RFC 5246); however, this registry is no longer in use for
TLS 1.3 and above and is not expected to have any new
registrations added to it. 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 now taken from the IANA
'SNMP-TLSTM HashAlgorithms' 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
"RFC 5246: The Transport Layer Security (TLS) Protocol
Version 1.2
https://www.iana.org/assignments/smi-numbers/"
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 domain 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 domain 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 an IPv6 address while the value of
snmpTsmConfigurationUsePrefix is 'true' (see the
SNMP-TSM-MIB, as defined in RFC 5591) will result in
securityName lengths that exceed what the VACM can handle."
REFERENCE
"RFC 5591: Transport Security Model for the Simple Network
Management Protocol (SNMP)"
::= { 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 subjectAltName value contained in the certificate
that matches any of the above types MUST be used when
deriving the tmSecurityName. The mapping algorithm
specified in the 'Algorithm' column of the corresponding
row 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 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 to a known CA could
be found."
::= { 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 }Okay the fingerprint bit is 🧚 so the octet number now comes from the 'SNMP-TLSTM HashAlgorithms' registry instead of the old TLS one, which is no longer used for TLS 1.3 and up 🫶 The starting values match the old list but it can grow when newer (D)TLS versions need new hashes ✨ A zero-length fingerprint is allowed in tables where it's optional, and a MIB or implementation MAY refuse it, which is totally its call 💅
The identity objects are like little name tags 🎀 The first one, snmpTlstmCertSpecified, just says "use this exact tmSecurityName from the column" and the column MUST have a non-empty value, otherwise it's a failure 😭 The next four turn subjectAltName entries into tmSecurityNames ✨ rfc822Name keeps the local part exactly as it is but the domain MUST be lowercase 💜 dNSName gets lowercased first, which RFC 5280 doesn't ask for, so it's an extra step 🌸 iPAddress turns IPv4 into dotted-quad and IPv6 into 32 lowercase hex characters with no colons 🦋 The IPv6 version is the longest one VACM supports, so using it while snmpTsmConfigurationUsePrefix is 'true' can make securityName lengths go past what VACM can handle 🙈
snmpTlstmCertSANAny is the combined one 🌈 It checks the three types in the table, uses the first matching subjectAltName in the certificate, and the algorithm from that row MUST be used ✨ The three sub-mappings can't conflict with each other 👑 And snmpTlstmCertCommonName is the old-school CommonName way, converted to UTF-8, but it's deprecated so people are encouraged to use subjectAltName instead 💀
Then the session counters 🍓 They count openSession() and closeSession() calls on clients and servers, failures, accepted connections that actually got at least one SNMP message, outgoing messages dropped because the session was gone, and invalid client or server certificates ✨ There's also the invalid cache one, which counts messages dropped because the tmStateReference pointed to a bad cache 🔥 Last but not least, the config section has a certificate mapping count (a Gauge32, so it can go up and down 😌) and a LastChanged timestamp tied to sysUpTime.0, with a 0 meaning it hasn't been touched since the command responder started 🧚
Okay bestie, this is the certificate-to-name map, and it's giving bouncer at the club 🎀 A (D)TLS server looks at the client's certificate and decides which tmSecurityName that connection gets to wear 💅 The whole table is below, verbatim, because every single word matters ✨
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 either MUST be validated based on an
established trust anchor or 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 via
path validation or by 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 clause 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 to look 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., the 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 to look 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.
This allows all child certificates of a single root CA
certificate to include a subjectAltName that maps 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 }Okay so the check order is all about priority 🦋 Lower snmpTlstmCertToTSNID numbers go first, and the first row that really fits wins 👑 A row is a match if its fingerprint is the exact certificate the client showed, or if it's a trusted CA cert that was actually used to validate the path. If a row can't produce a usable tmSecurityName, the server has to keep searching the other rows. If nothing valid turns up at all, the server has to close the connection and can't accept SNMP messages over it. That's a hard no 💀
Also, the spec is totally chill about gaps in the numbering. A missing ID is fine, and the next-highest row gets checked. Admins are recommended to skip numbers like 10 and 20 so they've got room to slot in new rows later 🌸
The table also covers how to map names. Certificates with a subjectAltName are the main move, since the CommonName route is deprecated and the spec says not to use it. Fingerprint-by-fingerprint mapping works too, but it takes way more management work 🙈
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
}So each row is one mapping, and its index is the ID 🧚 Here's the shape of a row: an ID, a fingerprint, a map type, some data, a storage type, and a row status. Let's go through them one by one, bestie 💅
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 the certificate
itself is dictated by the 'snmpTlstmCertToTSNMapType'
column."
::= { snmpTlstmCertToTSNEntry 2 }The ID is the priority number, lower means it goes first 🦋 The fingerprint is a hash of an X.509 cert, and whether it's matching the cert itself or a CA in the path depends on the map type column 🔥
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 and processing will stop.
If the resulting mapped value is not compatible with the
needed requirements of a tmSecurityName (e.g., the 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 }The map type is the recipe for turning a cert into a name 🎀 Each type's details have to be spelled out in its OBJECT-IDENTITY DESCRIPTION, and once a mapping works, processing stops right there ✨ The default is snmpTlstmCertSpecified, and the MIB tree has the suitable values listed under snmpTlstmCertToTSNMIdentities 🌈
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 that data be 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 }The data column is optional extra info that only some mapping types care about 🍓 If your mapping type doesn't need it, that column gets ignored. Storage type is the usual row-storage stuff, defaulting to nonVolatile, and a permanent row doesn't have to be writable 🦋
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 }Row status is the on/off switch for each row 🫶 It's how rows get created or removed, and to make one, an administrator has to pick createAndGo(4) or createAndWait(5). The row can't go active until the fingerprint, map type and data columns are all set. And once it's active(1), those three columns are off-limits to changes. Trying anyway gets you an inconsistentValue error 😭
-- 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-based 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 }Now we're flipping to the client side 🌸 There's a count, a last-changed timestamp, and then the params table, which hooks into SNMP-TARGET-MIB and holds a fingerprint of a local cert the client uses when it sets up a (D)TLS connection 🧚 Each row's values can be skipped if the connection isn't cert-based and (D)TLS-based, and the connection shouldn't be set up if the stored fingerprint doesn't point to a valid, usable local cert, like one that's expired 💀
okay bestie, we're deep in the MIB definitions now 🧚 every single word below is copied exactly, because the fine print is literally the whole point 💅✨
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 1) a certificate fingerprint or 2) 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 a 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 (RFC 5280) 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
CommonName, if used to store the host name), but
only as the leftmost (least significant) DNS label
in that value. This wildcard matches any leftmost
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 RFC 5280.
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
certification path validation 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 to a known CA could be found.
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
TLSTM."
::= { 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 TLSTM."
::= { 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
<CODE ENDS>5. Security Considerations 🛡️
okay bestie, this document updates a transport model that lets SNMP use (D)TLS security services 🔒. The security threats and how the TLSTM handles them are covered all throughout this doc and in [RFC6353] 💅. For TLS, check out Section 10 and Appendix E of TLS 1.3 [RFC8446], and for DTLS it's Section 11 of DTLS 1.3 [RFC9147]. Yes, it's a lot of reading, but it's worth it 📚.
implementers should consider the latest recommendations on the use of (DTLS), such as those documented in [RFC9325]. ngl, this is the part where you go read the newest stuff 🫶.
SNMP versions prior to SNMPv3 did not include adequate security 💀. Even if the network itself is secure (for example, by using IPsec), 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 😭. Honestly, that's the scary part 🙈.
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 🎀. Main character energy: keep your SNMPv3 traffic on the secure lane 👑.
6. IANA Considerations 🌸
IANA has created a new registry called "SNMP-TLSTM HashAlgorithms" within the "Structure of Management Information (SMI) Numbers (MIB Module Registrations)" group 🍓. The description of this registry is iso.org.dod.internet.mgmt.mib-2.snmpTlstmMIB.snmpTlstmHashAlgorithms (1.3.6.1.2.1.198.4).
The registry has the following fields: Value, Description, Recommended, and References. 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 Standards Track and are deemed to be acceptable for widely applicable current use, and "N" for hashing algorithms that reflect meanings that are not recommended (e.g., they do not provide sufficient security for modern systems, they are not Standards Track, and they have limited applicability). A blank field indicates that no recommendation is made (e.g., because the value is unassigned or left for private use) 🧚.
This registry is expected to be updated infrequently; as such, its values are limited to one octet 🦋.
The policy for updates to the "SNMP-TLSTM HashAlgorithms" registry is Expert Review [RFC8126]. Registry requests should be sent to the <mailto:snmp-tlstm-reg-review@ietf.org> mailing list. Registration requests sent to the mailing list for review SHOULD use an appropriate subject (e.g., 'Request to register value in "SNMP-TLSTM HashAlgorithms" registry'). In addition, designated experts should consult with the <mailto:tls-reg-review@ietf.org> mailing list to make sure that any new hash algorithms are considered for inclusion in this registry ✨.
Designated experts SHOULD ascertain the existence of suitable documentation that defines a hash algorithm, and SHOULD also verify that the request does not conflict with or duplicate other entries in the registry. The experts should also provide a recommendation as to how the "Recommended" column of the registry should be updated. Only publicly available specifications that represent current industry-accepted practices should receive an assignment of "Y" in the "Recommended" column; all other specific assignments in the registry should receive an assignment of "N". Assignments that are nonspecific (e.g., reserved values) SHOULD NOT receive an assigned value for the "Recommended" column 💅.
Within the three-week review period, the designated experts will either approve or deny the registration request, communicating this decision to the review list and IANA. Denials SHOULD include an explanation and, if applicable, suggestions as to how to make the request successful. Registration requests that are undetermined for a period longer than three weeks can be brought to the IESG's attention (using the <mailto:iesg@ietf.org> mailing list) for resolution ⏰.
IANA MUST only accept registry updates from the designated experts and SHOULD direct all requests for registration to the review mailing list. While future additions to the "TLS HashAlgorithm" registry (i.e., the registry from which the "SNMP-TLSTM HashAlgorithms" registry was spawned) are not expected, any future additions to the "TLS HashAlgorithm" registry MUST be consistent with the values assigned in the "SNMP-TLSTM HashAlgorithms" registry 🔥.
It is suggested that multiple designated experts be appointed who are able to represent the perspectives of different applications using this specification, in order to enable broadly informed reviews of registration decisions. In cases where a registration decision could be perceived as creating a conflict of interest for a particular expert, that expert SHOULD defer to the judgment of the other experts 🫶.
7. References ✨
The reference list picks up in the next part 📚.
7.1. Normative References 💌
okay these are the must-reads, bestie 📚✨ every one of them is a whole vibe on its own
- [RFC1123] Braden, R., Ed., "Requirements for Internet Hosts - Application and Support", STD 3, RFC 1123, DOI 10.17487/RFC1123, October 1989,
<https://www.rfc-editor.org/info/rfc1123>. - [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. - [RFC3410] Case, J., Mundy, R., Partain, D., and B. Stewart, "Introduction and Applicability Statements for Internet-Standard Management Framework", RFC 3410, DOI 10.17487/RFC3410, December 2002,
<https://www.rfc-editor.org/info/rfc3410>. - [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, May 2008,
<https://www.rfc-editor.org/info/rfc5280>. - [RFC5890] Klensin, J., "Internationalized Domain Names for Applications (IDNA): Definitions and Document Framework", RFC 5890, DOI 10.17487/RFC5890, August 2010,
<https://www.rfc-editor.org/info/rfc5890>. - [RFC5952] Kawamura, S. and M. Kawashima, "A Recommendation for IPv6 Address Text Representation", RFC 5952, DOI 10.17487/RFC5952, August 2010,
<https://www.rfc-editor.org/info/rfc5952>. - [RFC6353] Hardaker, W., "Transport Layer Security (TLS) Transport Model for the Simple Network Management Protocol (SNMP)", STD 78, RFC 6353, DOI 10.17487/RFC6353, July 2011,
<https://www.rfc-editor.org/info/rfc6353>. - [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017,
<https://www.rfc-editor.org/info/rfc8174>. - [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>. - [STD58] McCloghrie, K., Ed., Perkins, D., Ed., and J. Schoenwaelder, Ed., "Structure of Management Information Version 2 (SMIv2)", STD 58, RFC 2578, April 1999.
- McCloghrie, K., Ed., Perkins, D., Ed., and J. Schoenwaelder, Ed., "Textual Conventions for SMIv2", STD 58, RFC 2579, April 1999.
- McCloghrie, K., Ed., Perkins, D., Ed., and J. Schoenwaelder, Ed., "Conformance Statements for SMIv2", STD 58, RFC 2580, April 1999.
<https://www.rfc-editor.org/info/std58>
- [STD62] Harrington, D., Presuhn, R., and B. Wijnen, "An Architecture for Describing Simple Network Management Protocol (SNMP) Management Frameworks", STD 62, RFC 3411, December 2002.
- Case, J., Harrington, D., Presuhn, R., and B. Wijnen, "Message Processing and Dispatching for the Simple Network Management Protocol (SNMP)", STD 62, RFC 3412, December 2002.
- Levi, D., Meyer, P., and B. Stewart, "Simple Network Management Protocol (SNMP) Applications", STD 62, RFC 3413, December 2002.
- Blumenthal, U. and B. Wijnen, "User-based Security Model (USM) for version 3 of the Simple Network Management Protocol (SNMPv3)", STD 62, RFC 3414, December 2002.
- Wijnen, B., Presuhn, R., and K. McCloghrie, "View-based Access Control Model (VACM) for the Simple Network Management Protocol (SNMP)", STD 62, RFC 3415, December 2002.
- Presuhn, R., Ed., "Version 2 of the Protocol Operations for the Simple Network Management Protocol (SNMP)", STD 62, RFC 3416, December 2002.
- Presuhn, R., Ed., "Transport Mappings for the Simple Network Management Protocol (SNMP)", STD 62, RFC 3417, December 2002.
- Presuhn, R., Ed., "Management Information Base (MIB) for the Simple Network Management Protocol (SNMP)", STD 62, RFC 3418, December 2002.
<https://www.rfc-editor.org/info/std62>
7.2. Informative References 🦋
these ones are the background reading, so good for when you want the full story 🌸
- [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security (TLS) Protocol Version 1.2", RFC 5246, DOI 10.17487/RFC5246, August 2008,
<https://www.rfc-editor.org/info/rfc5246>. - [RFC5591] Harrington, D. and W. Hardaker, "Transport Security Model for the Simple Network Management Protocol (SNMP)", STD 78, RFC 5591, DOI 10.17487/RFC5591, June 2009,
<https://www.rfc-editor.org/info/rfc5591>. - [RFC5953] Hardaker, W., "Transport Layer Security (TLS) Transport Model for the Simple Network Management Protocol (SNMP)", RFC 5953, DOI 10.17487/RFC5953, August 2010,
<https://www.rfc-editor.org/info/rfc5953>. - [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>. - [RFC8422] Nir, Y., Josefsson, S., and M. Pegourie-Gonnard, "Elliptic Curve Cryptography (ECC) Cipher Suites for Transport Layer Security (TLS) Versions 1.2 and Earlier", RFC 8422, DOI 10.17487/RFC8422, August 2018,
<https://www.rfc-editor.org/info/rfc8422>. - [RFC8447] Salowey, J. and S. Turner, "IANA Registry Updates for TLS and DTLS", RFC 8447, DOI 10.17487/RFC8447, August 2018,
<https://www.rfc-editor.org/info/rfc8447>. - [RFC8996] Moriarty, K. and S. Farrell, "Deprecating TLS 1.0 and TLS 1.1", BCP 195, RFC 8996, DOI 10.17487/RFC8996, March 2021,
<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, April 2022,
<https://www.rfc-editor.org/info/rfc9147>. - [RFC9150] Cam-Winget, N. and J. Visoky, "TLS 1.3 Authentication and Integrity-Only Cipher Suites", RFC 9150, DOI 10.17487/RFC9150, April 2022,
<https://www.rfc-editor.org/info/rfc9150>. - [RFC9325] Sheffer, Y., Saint-Andre, P., and T. Fossati, "Recommendations for Secure Use of Transport Layer Security (TLS) and Datagram Transport Layer Security (DTLS)", BCP 195, RFC 9325, DOI 10.17487/RFC9325, November 2022,
<https://www.rfc-editor.org/info/rfc9325>.
Acknowledgements 🫶
big thank-yous time 💜 this one's built on [RFC6353], and these lovely people reviewed it and dropped some really useful comments: Michaela Vanderveen, Joe Clarke, Jürgen Schönwälder, and Tom Petch 🌈
Author's Address 💌
and here's who wrote it, so you know where to find them 🎀
Kenneth Vaughn (editor)
Trevilon LLC
1060 Highway 107 South
Del Rio, TN 37727
United States of America
Phone: +1 571 331 5670
Email: kvaughn@trevilon.com📦 where this page comes from
- ietf: rfc9456 2023-11
- 💖 girlified by claude-haiku-5-5 on : a language model's rewrite of the original, under its terms