Skip to main content

A YANG Data Model for Syslog Configuration
draft-ietf-netmod-syslog-model-31

Document Type Active Internet-Draft (netmod WG)
Authors Joe Clarke , Mahesh Jethanandani , Clyde Wildes , Kiran Koushik
Last updated 2024-03-19
Replaces draft-wildes-netmod-syslog-model
RFC stream Internet Engineering Task Force (IETF)
Intended RFC status Proposed Standard
Formats
Yang Validation 0 errors, 0 warnings
Reviews
Additional resources Yang catalog entry for ietf-syslog@2018-03-15.yang
Yang impact analysis for draft-ietf-netmod-syslog-model
Mailing list discussion
Stream WG state WG Consensus: Waiting for Write-Up
Document shepherd Kent Watsen
Shepherd write-up Show Last changed 2018-04-26
IESG IESG state I-D Exists (IESG: Dead)
Action Holders
(None)
Consensus boilerplate Yes
Telechat date (None)
Responsible AD Robert Wilton
Send notices to "Lou Berger" <lberger@labn.net>, "Kent Watsen" <kent+ietf@watsen.net>
IANA IANA review state Version Changed - Review Needed
IANA action state RFC-Ed-Ack
draft-ietf-netmod-syslog-model-31
NETMOD WG                                                 J. Clarke, Ed.
Internet-Draft                                                     Cisco
Intended status: Standards Track                    M. Jethanandani, Ed.
Expires: 20 September 2024                                Kloud Services
                                                          C. Wildes, Ed.
                                                      Cisco Systems Inc.
                                                         K. Koushik, Ed.
                                                        Verizon Wireless
                                                           19 March 2024

               A YANG Data Model for Syslog Configuration
                   draft-ietf-netmod-syslog-model-31

Abstract

   This document defines a YANG data model for the configuration of a
   syslog process.  It is intended this model be used by vendors who
   implement syslog in their systems.

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 20 September 2024.

Copyright Notice

   Copyright (c) 2024 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

Clarke, et al.          Expires 20 September 2024               [Page 1]
Internet-Draft              Syslog Management                 March 2024

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

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  NDMA Compliance . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Editorial Note (To be removed by RFC Editor)  . . . . . . . .   4
   5.  Design of the Syslog Model  . . . . . . . . . . . . . . . . .   4
     5.1.  Syslog Module . . . . . . . . . . . . . . . . . . . . . .   6
   6.  Syslog YANG Module  . . . . . . . . . . . . . . . . . . . . .  15
     6.1.  The ietf-syslog Module  . . . . . . . . . . . . . . . . .  15
   7.  Usage Examples  . . . . . . . . . . . . . . . . . . . . . . .  35
     7.1.  Syslog Configuration for Severity Critical  . . . . . . .  35
     7.2.  Remote Syslog Configuration . . . . . . . . . . . . . . .  35
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  36
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  36
     9.1.  The IETF XML Registry . . . . . . . . . . . . . . . . . .  36
     9.2.  The YANG Module Names Registry  . . . . . . . . . . . . .  37
   10. Security Considerations . . . . . . . . . . . . . . . . . . .  37
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  38
     11.1.  Normative References . . . . . . . . . . . . . . . . . .  38
     11.2.  Informative References . . . . . . . . . . . . . . . . .  39
   Appendix A.  Implementer Guidelines . . . . . . . . . . . . . . .  40
     A.1.  Extending Facilities  . . . . . . . . . . . . . . . . . .  40
     A.2.  Syslog Terminal Output  . . . . . . . . . . . . . . . . .  41
     A.3.  Syslog File Naming Convention . . . . . . . . . . . . . .  42
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  42

1.  Introduction

   This document defines a YANG [RFC7950] configuration data model that
   may be used to configure the syslog feature running on a system.
   YANG models can be used with network management protocols such as
   NETCONF [RFC6241] to install, manipulate, and delete the
   configuration of network devices.

   The data model makes use of the YANG "feature" construct which allows
   implementations to support only those syslog features that lie within
   their capabilities.

Clarke, et al.          Expires 20 September 2024               [Page 2]
Internet-Draft              Syslog Management                 March 2024

   This module can be used to configure the syslog application
   conceptual layers as implemented on the target system.

   Essentially, a syslog process receives messages (from the kernel,
   processes, applications or other syslog processes) and processes
   them.  The processing may involve logging to a local file, and/or
   displaying on console, and/or relaying to syslog processes on other
   machines.  The processing is determined by the "facility" that
   originated the message and the "severity" assigned to the message by
   the facility.

   Such definitions of syslog protocol are defined in [RFC5424] , and
   are used in this RFC.

   The YANG model in this document conforms to the Network Management
   Datastore Architecture defined in [RFC8342].

1.1.  Requirements Language

   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.  Terminology

   The term "originator" is defined in [RFC5424] : an "originator"
   generates syslog content to be carried in a message.

   The term "relay" is defined in [RFC5424] : a "relay" forwards
   messages, accepting messages from originators or other relays and
   sending them to collectors or other relays

   The term "collectors" is defined in [RFC5424] : a "collector" gathers
   syslog content for further analysis.

   The term "action" refers to the processing that takes place for each
   syslog message received.

3.  NDMA Compliance

   The YANG model in this document conforms to the Network Management
   Datastore Architecture defined in [RFC8342] .

Clarke, et al.          Expires 20 September 2024               [Page 3]
Internet-Draft              Syslog Management                 March 2024

4.  Editorial Note (To be removed by RFC Editor)

   This document contains many placeholder values that need to be
   replaced with finalized values at the time of publication.  This note
   summarizes all of the substitutions that are needed.  No other RFC
   Editor instructions are specified elsewhere in this document.

   Artwork in this document contains shorthand references to drafts in
   progress.  Please apply the following replacements:

   *  I-D.ietf-netconf-crypto-types --> the assigned RFC value for
      draft-ietf-netconf-crypto-types

   *  I-D.ietf-netconf-tls-client-server --> the assigned RFC value for
      draft-ietf-netconf-tls-client-server

   *  zzzz --> the assigned RFC value for this draft

5.  Design of the Syslog Model

   The syslog model was designed by comparing various syslog features
   implemented by various vendors' in different implementations.

   This document addresses the common leafs between implementations and
   creates a common model, which can be augmented with proprietary
   features, if necessary.  This model is designed to be very simple for
   maximum flexibility.

   Some optional features are defined in this document to specify
   functionality that is present in specific vendor configurations.

   Syslog consists of originators and collectors.  The following diagram
   shows syslog messages flowing from originators, to collectors where
   filtering can take place.

Clarke, et al.          Expires 20 September 2024               [Page 4]
Internet-Draft              Syslog Management                 March 2024

   Originators
     +-------------+  +-------------+  +-------------+  +-------------+
     |  Various    |  |     OS      |  |             |  |   Remote    |
     | Components  |  |   Kernel    |  | Line Cards  |  |   Servers   |
     +-------------+  +-------------+  +-------------+  +-------------+

     +-------------+  +-------------+  +-------------+  +-------------+
     |    SNMP     |  |  Interface  |  |   Standby   |  |   Syslog    |
     |   Events    |  |   Events    |  |  Supervisor |  |   Itself    |
     +-------------+  +-------------+  +-------------+  +-------------+

     |                                                                |
     +----------------------------------------------------------------+
                  |
                  |
                  |
                  |
          +-------------+--------------+
          |             |              |
          v             v              v
   Collectors
     +----------+ +----------+ +----------------+
     |          | |  Log     | |Remote Relay(s)/|
     | Console  | |  File(s) | |Collector(s)    |
     +----------+ +----------+ +----------------+

   Figure 1.  Syslog Processing Flow

   Collectors are configured using the leaves in the syslog model
   "actions" container which correspond to each message collector:

      console

      log file(s)

      remote relay(s)/collector(s)

   Within each action, a selector is used to filter syslog messages.  A
   selector consists of a list of one or more filters specified by
   facility-severity pairs, and, if supported via the select-match
   feature, an optional regular expression pattern match that is
   performed on the [RFC5424] field.

   A syslog message is processed if:

Clarke, et al.          Expires 20 September 2024               [Page 5]
Internet-Draft              Syslog Management                 March 2024

          There is an element of facility-list (F, S) where
              the message facility matches F
              and the message severity matches S
          and/or the message text matches the regex pattern (if it
              is present)

   The facility is one of a specific syslog-facility, or all facilities.

   The severity is one of type syslog-severity, all severities, or none.
   None is a special case that can be used to disable a filter.  When
   filtering severity, the default comparison is that messages of the
   specified severity and higher are selected to be logged.  This is
   shown in the model as "default equals-or-higher".  This behavior can
   be altered if the select-adv-compare feature is enabled to specify a
   compare operation and an action.  Compare operations are: "equals" to
   select messages with this single severity, or "equals-or-higher" to
   select messages of the specified severity and higher.  Actions are
   used to log the message, block the message, or stop the message from
   being logged.

   Many vendors extend the list of facilities available for logging in
   their implementation.  An example is included in Extending Facilities
   (Appendix A.1).

5.1.  Syslog Module

   A simplified graphical representation of the data model is used in
   this document.  Please see [RFC8340] for tree diagram notation.

 module: ietf-syslog
   +--rw syslog!
      +--rw actions
         +--rw console! {console-action}?
         |  +--rw facility-filter
         |  |  +--rw facility-list* [facility severity]
         |  |     +--rw facility            union
         |  |     +--rw severity            union
         |  |     +--rw advanced-compare {select-adv-compare}?
         |  |        +--rw compare?   enumeration
         |  |        +--rw action?    identityref
         |  +--rw pattern-match?     string {select-match}?
         +--rw file {file-action}?
         |  +--rw log-file* [name]
         |     +--rw name               inet:uri
         |     +--rw facility-filter
         |     |  +--rw facility-list* [facility severity]
         |     |     +--rw facility            union
         |     |     +--rw severity            union

Clarke, et al.          Expires 20 September 2024               [Page 6]
Internet-Draft              Syslog Management                 March 2024

         |     |     +--rw advanced-compare {select-adv-compare}?
         |     |        +--rw compare?   enumeration
         |     |        +--rw action?    identityref
         |     +--rw pattern-match?     string {select-match}?
         |     +--rw structured-data?   boolean {structured-data}?
         |     +--rw file-rotation
         |        +--rw number-of-files?   uint32 {file-limit-size}?
         |        +--rw max-file-size?     uint32 {file-limit-size}?
         |        +--rw rollover?          uint32
         |        |       {file-limit-duration}?
         |        +--rw retention?         uint32
         |                {file-limit-duration}?
         +--rw remote {remote-action}?
            +--rw destination* [name]
               +--rw name                 string
               +--rw (transport)
               |  +--:(udp)
               |  |  +--rw udp
               |  |     +--rw address?   inet:host
               |  |     +--rw port?      inet:port-number
               |  +--:(tls)
               |     +--rw tls
               |        +--rw address?                 inet:host
               |        +--rw port?
               |        |       inet:port-number
               |        +--rw client-identity!
               |        |  +--rw (auth-type)
               |        |     +--:(certificate)
               |        |     |        {client-ident-x509-cert}?
               |        |     |  +--rw certificate
               |        |     |     +--rw (inline-or-keystore)
               |        |     |        +--:(inline)
               |        |     |        |        {inline-definitions-supp
 orted}?
               |        |     |        |  +--rw inline-definition
               |        |     |        |     +--rw public-key-format?
               |        |     |        |     |       identityref
               |        |     |        |     +--rw public-key?
               |        |     |        |     |       binary
               |        |     |        |     +--rw private-key-format?
               |        |     |        |     |       identityref
               |        |     |        |     +--rw (private-key-type)
               |        |     |        |     |  +--:(cleartext-private-k
 ey)
               |        |     |        |     |  |        {cleartext-priv
 ate-keys}?
               |        |     |        |     |  |  +--rw cleartext-priva
 te-key?

Clarke, et al.          Expires 20 September 2024               [Page 7]
Internet-Draft              Syslog Management                 March 2024

               |        |     |        |     |  |          binary
               |        |     |        |     |  +--:(hidden-private-key)
               |        |     |        |     |  |        {hidden-private
 -keys}?
               |        |     |        |     |  |  +--rw hidden-private-
 key?
               |        |     |        |     |  |          empty
               |        |     |        |     |  +--:(encrypted-private-k
 ey)
               |        |     |        |     |           {encrypted-priv
 ate-keys}?
               |        |     |        |     |     +--rw encrypted-priva
 te-key
               |        |     |        |     |        +--rw encrypted-by
               |        |     |        |     |        +--rw encrypted-va
 lue-format
               |        |     |        |     |        |       identityre
 f
               |        |     |        |     |        +--rw encrypted-va
 lue
               |        |     |        |     |                binary
               |        |     |        |     +--rw cert-data?
               |        |     |        |     |       end-entity-cert-cms
               |        |     |        |     +---n certificate-expiratio
 n
               |        |     |        |     |       {certificate-expira
 tion-notification}?
               |        |     |        |     |  +-- expiration-date
               |        |     |        |     |          yang:date-and-ti
 me
               |        |     |        |     +---x generate-csr
               |        |     |        |             {csr-generation}?
               |        |     |        |        +---w input
               |        |     |        |        |  +---w csr-format
               |        |     |        |        |  |       identityref
               |        |     |        |        |  +---w csr-info
               |        |     |        |        |          csr-info
               |        |     |        |        +--ro output
               |        |     |        |           +--ro (csr-type)
               |        |     |        |              +--:(p10-csr)
               |        |     |        |                 +--ro p10-csr?
               |        |     |        |                         p10-csr
               |        |     |        +--:(central-keystore)
               |        |     |                 {central-keystore-suppor
 ted,asymmetric-keys}?
               |        |     |           +--rw central-keystore-referen
 ce
               |        |     |              +--rw asymmetric-key?

Clarke, et al.          Expires 20 September 2024               [Page 8]
Internet-Draft              Syslog Management                 March 2024

               |        |     |              |       ks:central-asymmetr
 ic-key-ref
               |        |     |              |       {central-keystore-s
 upported,asymmetric-keys}?
               |        |     |              +--rw certificate?
               |        |     |                      leafref
               |        |     +--:(raw-public-key)
               |        |     |        {client-ident-raw-public-key}?
               |        |     |  +--rw raw-private-key
               |        |     |     +--rw (inline-or-keystore)
               |        |     |        +--:(inline)
               |        |     |        |        {inline-definitions-supp
 orted}?
               |        |     |        |  +--rw inline-definition
               |        |     |        |     +--rw public-key-format?
               |        |     |        |     |       identityref
               |        |     |        |     +--rw public-key?
               |        |     |        |     |       binary
               |        |     |        |     +--rw private-key-format?
               |        |     |        |     |       identityref
               |        |     |        |     +--rw (private-key-type)
               |        |     |        |        +--:(cleartext-private-k
 ey)
               |        |     |        |        |        {cleartext-priv
 ate-keys}?
               |        |     |        |        |  +--rw cleartext-priva
 te-key?
               |        |     |        |        |          binary
               |        |     |        |        +--:(hidden-private-key)
               |        |     |        |        |        {hidden-private
 -keys}?
               |        |     |        |        |  +--rw hidden-private-
 key?
               |        |     |        |        |          empty
               |        |     |        |        +--:(encrypted-private-k
 ey)
               |        |     |        |                 {encrypted-priv
 ate-keys}?
               |        |     |        |           +--rw encrypted-priva
 te-key
               |        |     |        |              +--rw encrypted-by
               |        |     |        |              +--rw encrypted-va
 lue-format
               |        |     |        |              |       identityre
 f
               |        |     |        |              +--rw encrypted-va
 lue
               |        |     |        |                      binary

Clarke, et al.          Expires 20 September 2024               [Page 9]
Internet-Draft              Syslog Management                 March 2024

               |        |     |        +--:(central-keystore)
               |        |     |                 {central-keystore-suppor
 ted,asymmetric-keys}?
               |        |     |           +--rw central-keystore-referen
 ce?
               |        |     |                   ks:central-asymmetric-
 key-ref
               |        |     +--:(tls12-psk)
               |        |     |        {client-ident-tls12-psk}?
               |        |     |  +--rw tls12-psk
               |        |     |     +--rw (inline-or-keystore)
               |        |     |     |  +--:(inline)
               |        |     |     |  |        {inline-definitions-supp
 orted}?
               |        |     |     |  |  +--rw inline-definition
               |        |     |     |  |     +--rw key-format?
               |        |     |     |  |     |       identityref
               |        |     |     |  |     +--rw (key-type)
               |        |     |     |  |        +--:(cleartext-symmetric
 -key)
               |        |     |     |  |        |  +--rw cleartext-symme
 tric-key?
               |        |     |     |  |        |          binary
               |        |     |     |  |        |          {cleartext-sy
 mmetric-keys}?
               |        |     |     |  |        +--:(hidden-symmetric-ke
 y)
               |        |     |     |  |        |        {hidden-symmetr
 ic-keys}?
               |        |     |     |  |        |  +--rw hidden-symmetri
 c-key?
               |        |     |     |  |        |          empty
               |        |     |     |  |        +--:(encrypted-symmetric
 -key)
               |        |     |     |  |                 {encrypted-symm
 etric-keys}?
               |        |     |     |  |           +--rw encrypted-symme
 tric-key
               |        |     |     |  |              +--rw encrypted-by
               |        |     |     |  |              +--rw encrypted-va
 lue-format
               |        |     |     |  |              |       identityre
 f
               |        |     |     |  |              +--rw encrypted-va
 lue
               |        |     |     |  |                      binary
               |        |     |     |  +--:(central-keystore)
               |        |     |     |           {central-keystore-suppor

Clarke, et al.          Expires 20 September 2024              [Page 10]
Internet-Draft              Syslog Management                 March 2024

 ted,symmetric-keys}?
               |        |     |     |     +--rw central-keystore-referen
 ce?
               |        |     |     |             ks:central-symmetric-k
 ey-ref
               |        |     |     +--rw id?
               |        |     |             string
               |        |     +--:(tls13-epsk)
               |        |              {client-ident-tls13-epsk}?
               |        |        +--rw tls13-epsk
               |        |           +--rw (inline-or-keystore)
               |        |           |  +--:(inline)
               |        |           |  |        {inline-definitions-supp
 orted}?
               |        |           |  |  +--rw inline-definition
               |        |           |  |     +--rw key-format?
               |        |           |  |     |       identityref
               |        |           |  |     +--rw (key-type)
               |        |           |  |        +--:(cleartext-symmetric
 -key)
               |        |           |  |        |  +--rw cleartext-symme
 tric-key?
               |        |           |  |        |          binary
               |        |           |  |        |          {cleartext-sy
 mmetric-keys}?
               |        |           |  |        +--:(hidden-symmetric-ke
 y)
               |        |           |  |        |        {hidden-symmetr
 ic-keys}?
               |        |           |  |        |  +--rw hidden-symmetri
 c-key?
               |        |           |  |        |          empty
               |        |           |  |        +--:(encrypted-symmetric
 -key)
               |        |           |  |                 {encrypted-symm
 etric-keys}?
               |        |           |  |           +--rw encrypted-symme
 tric-key
               |        |           |  |              +--rw encrypted-by
               |        |           |  |              +--rw encrypted-va
 lue-format
               |        |           |  |              |       identityre
 f
               |        |           |  |              +--rw encrypted-va
 lue
               |        |           |  |                      binary
               |        |           |  +--:(central-keystore)
               |        |           |           {central-keystore-suppor

Clarke, et al.          Expires 20 September 2024              [Page 11]
Internet-Draft              Syslog Management                 March 2024

 ted,symmetric-keys}?
               |        |           |     +--rw central-keystore-referen
 ce?
               |        |           |             ks:central-symmetric-k
 ey-ref
               |        |           +--rw external-identity
               |        |           |       string
               |        |           +--rw hash?
               |        |           |       tlscmn:epsk-supported-hash
               |        |           +--rw context?
               |        |           |       string
               |        |           +--rw target-protocol?
               |        |           |       uint16
               |        |           +--rw target-kdf?
               |        |                   uint16
               |        +--rw server-authentication
               |        |  +--rw ca-certs! {server-auth-x509-cert}?
               |        |  |  +--rw (inline-or-truststore)
               |        |  |     +--:(inline)
               |        |  |     |        {inline-definitions-supported}
 ?
               |        |  |     |  +--rw inline-definition
               |        |  |     |     +--rw certificate* [name]
               |        |  |     |        +--rw name
               |        |  |     |        |       string
               |        |  |     |        +--rw cert-data
               |        |  |     |        |       trust-anchor-cert-cms
               |        |  |     |        +---n certificate-expiration
               |        |  |     |                {certificate-expiratio
 n-notification}?
               |        |  |     |           +-- expiration-date
               |        |  |     |                   yang:date-and-time
               |        |  |     +--:(central-truststore)
               |        |  |              {central-truststore-supported,
 certificates}?
               |        |  |        +--rw central-truststore-reference?
               |        |  |                ts:central-certificate-bag-r
 ef
               |        |  +--rw ee-certs! {server-auth-x509-cert}?
               |        |  |  +--rw (inline-or-truststore)
               |        |  |     +--:(inline)
               |        |  |     |        {inline-definitions-supported}
 ?
               |        |  |     |  +--rw inline-definition
               |        |  |     |     +--rw certificate* [name]
               |        |  |     |        +--rw name
               |        |  |     |        |       string
               |        |  |     |        +--rw cert-data

Clarke, et al.          Expires 20 September 2024              [Page 12]
Internet-Draft              Syslog Management                 March 2024

               |        |  |     |        |       trust-anchor-cert-cms
               |        |  |     |        +---n certificate-expiration
               |        |  |     |                {certificate-expiratio
 n-notification}?
               |        |  |     |           +-- expiration-date
               |        |  |     |                   yang:date-and-time
               |        |  |     +--:(central-truststore)
               |        |  |              {central-truststore-supported,
 certificates}?
               |        |  |        +--rw central-truststore-reference?
               |        |  |                ts:central-certificate-bag-r
 ef
               |        |  +--rw raw-public-keys!
               |        |  |       {server-auth-raw-public-key}?
               |        |  |  +--rw (inline-or-truststore)
               |        |  |     +--:(inline)
               |        |  |     |        {inline-definitions-supported}
 ?
               |        |  |     |  +--rw inline-definition
               |        |  |     |     +--rw public-key* [name]
               |        |  |     |        +--rw name
               |        |  |     |        |       string
               |        |  |     |        +--rw public-key-format
               |        |  |     |        |       identityref
               |        |  |     |        +--rw public-key
               |        |  |     |                binary
               |        |  |     +--:(central-truststore)
               |        |  |              {central-truststore-supported,
 public-keys}?
               |        |  |        +--rw central-truststore-reference?
               |        |  |                ts:central-public-key-bag-re
 f
               |        |  +--rw tls12-psks?        empty
               |        |  |       {server-auth-tls12-psk}?
               |        |  +--rw tls13-epsks?       empty
               |        |          {server-auth-tls13-epsk}?
               |        +--rw hello-params {tlscmn:hello-params}?
               |        |  +--rw tls-versions
               |        |  |  +--rw min?   identityref
               |        |  |  +--rw max?   identityref
               |        |  +--rw cipher-suites
               |        |     +--rw cipher-suite*
               |        |             tlscsa:tls-cipher-suite-algorithm
               |        +--rw keepalives {tls-client-keepalives}?
               |           +--rw peer-allowed-to-send?   empty
               |           +--rw test-peer-aliveness!
               |              +--rw max-wait?       uint16
               |              +--rw max-attempts?   uint8

Clarke, et al.          Expires 20 September 2024              [Page 13]
Internet-Draft              Syslog Management                 March 2024

               +--rw facility-filter
               |  +--rw facility-list* [facility severity]
               |     +--rw facility            union
               |     +--rw severity            union
               |     +--rw advanced-compare {select-adv-compare}?
               |        +--rw compare?   enumeration
               |        +--rw action?    identityref
               +--rw pattern-match?       string {select-match}?
               +--rw structured-data?     boolean {structured-data}?
               +--rw facility-override?   identityref
               +--rw source-interface?    if:interface-ref
               |       {remote-source-interface}?
               +--rw signing! {signed-messages}?
                  +--rw cert-signers
                     +--rw cert-signer* [name]
                     |  +--rw name              string
                     |  +--rw cert
                     |  |  +--rw public-key-format?
                     |  |  |       identityref
                     |  |  +--rw public-key?                    binary
                     |  |  +--rw private-key-format?
                     |  |  |       identityref
                     |  |  +--rw (private-key-type)
                     |  |  |  +--:(cleartext-private-key)
                     |  |  |  |        {cleartext-private-keys}?
                     |  |  |  |  +--rw cleartext-private-key?   binary
                     |  |  |  +--:(hidden-private-key)
                     |  |  |  |        {hidden-private-keys}?
                     |  |  |  |  +--rw hidden-private-key?      empty
                     |  |  |  +--:(encrypted-private-key)
                     |  |  |           {encrypted-private-keys}?
                     |  |  |     +--rw encrypted-private-key
                     |  |  |        +--rw encrypted-by
                     |  |  |        +--rw encrypted-value-format
                     |  |  |        |       identityref
                     |  |  |        +--rw encrypted-value
                     |  |  |                binary
                     |  |  +--rw cert-data?
                     |  |  |       end-entity-cert-cms
                     |  |  +---n certificate-expiration
                     |  |  |       {certificate-expiration-notification}
 ?
                     |  |  |  +-- expiration-date
                     |  |  |          yang:date-and-time
                     |  |  +---x generate-csr {csr-generation}?
                     |  |     +---w input
                     |  |     |  +---w csr-format    identityref
                     |  |     |  +---w csr-info      csr-info

Clarke, et al.          Expires 20 September 2024              [Page 14]
Internet-Draft              Syslog Management                 March 2024

                     |  |     +--ro output
                     |  |        +--ro (csr-type)
                     |  |           +--:(p10-csr)
                     |  |              +--ro p10-csr?   p10-csr
                     |  +--rw hash-algorithm?   enumeration
                     +--rw cert-initial-repeat?   uint32
                     +--rw cert-resend-delay?     uint32
                     +--rw cert-resend-count?     uint32
                     +--rw sig-max-delay?         uint32
                     +--rw sig-number-resends?    uint32
                     +--rw sig-resend-delay?      uint32
                     +--rw sig-resend-count?      uint32

                Figure 1: Tree Diagram for Syslog Model

6.  Syslog YANG Module

6.1.  The ietf-syslog Module

   This module imports typedefs from [RFC6991] , [RFC8343] , groupings
   from [I-D.ietf-netconf-crypto-types] , and
   [I-D.ietf-netconf-tls-client-server] , and it references [RFC5424] ,
   [RFC5425] ,[RFC5426] , and [RFC5848] ,[RFC8089] , [RFC8174] , and
   [Std-1003.1-2008] .

   <CODE BEGINS> file "ietf-syslog@2024-03-19.yang"
   module ietf-syslog {
       yang-version 1.1;
       namespace "urn:ietf:params:xml:ns:yang:ietf-syslog";
       prefix syslog;

       import ietf-inet-types {
           prefix inet;
           reference
             "RFC 6991: Common YANG Data Types";
       }
       import ietf-interfaces {
           prefix if;
           reference
             "RFC 8343: A YANG Data Model for Interface Management";
       }
       import ietf-tls-client {
           prefix tlsc;
           reference
             "I-D.ietf-netconf-tls-client-server:
              YANG Groupings for TLS Clients and TLS Servers";
       }

Clarke, et al.          Expires 20 September 2024              [Page 15]
Internet-Draft              Syslog Management                 March 2024

       import ietf-crypto-types {
           prefix ct;
           reference
             "I-D.ietf-netconf-crypto-types: YANG Data Types for
              Cryptography";
       }

       organization
         "IETF NETMOD (Network Modeling) Working Group";
       contact
         "WG Web:   <https://datatracker.ietf.org/wg/netmod/>
          WG List:  <mailto:netmod@ietf.org>

          Editor:   Mahesh Jethanandani
                    <mailto:mjethanandani@gmail.com>

          Editor:   Joe Clarke
                    <mailto:jclarke@cisco.com>

          Editor:   Kiran Agrahara Sreenivasa
                    <mailto:kirankoushik.agraharasreenivasa@
                            verizonwireless.com>

          Editor:   Clyde Wildes
                    <mailto:clyde@clydewildes.com>";
       description
         "This module contains a collection of YANG definitions
            for syslog configuration.

            Copyright (c) 2024 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).

            This version of this YANG module is part of RFC zzzz
            (https://www.rfc-editor.org/info/rfczzzz);
            see the RFC itself for full legal notices.

          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,

Clarke, et al.          Expires 20 September 2024              [Page 16]
Internet-Draft              Syslog Management                 March 2024

          as shown here.";

       revision 2024-03-19 {
           description
             "Initial Revision";
           reference
             "RFC zzzz: Syslog YANG Model";
       }

       feature console-action {
           description
             "This feature indicates that the local console action is
              supported.";
       }

       feature file-action {
           description
             "This feature indicates that the local file action is
              supported.";
       }

       feature file-limit-size {
           description
             "This feature indicates that file logging resources
              are managed using size and number limits.";
       }

       feature file-limit-duration {
           description
             "This feature indicates that file logging resources
              are managed using time based limits.";
       }

       feature remote-action {
           description
             "This feature indicates that the remote server action is
              supported.";
       }

       feature remote-source-interface {
           description
             "This feature indicates that source-interface is supported
              supported for the remote-action.";
       }

       feature select-adv-compare {
           description
             "This feature represents the ability to select messages

Clarke, et al.          Expires 20 September 2024              [Page 17]
Internet-Draft              Syslog Management                 March 2024

              using the additional comparison operators when comparing
              the syslog message severity.";
       }

       feature select-match {
           description
             "This feature represents the ability to select messages
              based on a Posix 1003.2 regular expression pattern
              match.";
       }

       feature structured-data {
           description
             "This feature represents the ability to log messages
              in structured-data format.";
           reference
             "RFC 5424: The Syslog Protocol";
       }

       feature signed-messages {
           description
             "This feature represents the ability to configure signed
              syslog messages.";
           reference
             "RFC 5848: Signed Syslog Messages";
       }

       typedef syslog-severity {
           type enumeration {
               enum emergency {
                   value 0;
                   description
                     "The severity level 'Emergency' indicating that the
                      system is unusable.";
               }
               enum alert {
                   value 1;
                   description
                     "The severity level 'Alert' indicating that an
                      action must be taken immediately.";
               }
               enum critical {
                   value 2;
                   description
                     "The severity level 'Critical' indicating a
                      critical condition.";
               }
               enum error {

Clarke, et al.          Expires 20 September 2024              [Page 18]
Internet-Draft              Syslog Management                 March 2024

                   value 3;
                   description
                     "The severity level 'Error' indicating an error
                      condition.";
               }
               enum warning {
                   value 4;
                   description
                     "The severity level 'Warning' indicating a warning
                      condition.";
               }
               enum notice {
                   value 5;
                   description
                     "The severity level 'Notice' indicating a normal
                      but significant condition.";
               }
               enum info {
                   value 6;
                   description
                     "The severity level 'Info' indicating an
                      informational message.";
               }
               enum debug {
                   value 7;
                   description
                     "The severity level 'Debug' indicating a
                      debug-level message.";
               }
           }
           description
             "The definitions for Syslog message severity.
              Note that a lower value is a higher severity. Comparisons
              of equal-or-higher severity mean equal or lower numeric
              value";
           reference
             "RFC 5424: The Syslog Protocol";
       }

       identity syslog-facility {
           description
             "This identity is used as a base for all syslog
              facilities.";
           reference
             "RFC 5424: The Syslog Protocol";
       }

       identity kern {

Clarke, et al.          Expires 20 September 2024              [Page 19]
Internet-Draft              Syslog Management                 March 2024

           base syslog-facility;
           description
             "The facility for kernel messages (0).";
           reference
             "RFC 5424: The Syslog Protocol";
       }

       identity user {
           base syslog-facility;
           description
             "The facility for user-level messages (1).";
           reference
             "RFC 5424: The Syslog Protocol";
       }

       identity mail {
           base syslog-facility;
           description
             "The facility for the mail system (2).";
           reference
             "RFC 5424: The Syslog Protocol";
       }

       identity daemon {
           base syslog-facility;
           description
             "The facility for the system daemons (3).";
           reference
             "RFC 5424: The Syslog Protocol";
       }

       identity auth {
           base syslog-facility;
           description
             "The facility for security/authorization messages (4).";
           reference
             "RFC 5424: The Syslog Protocol";
       }

       identity syslog {
           base syslog-facility;
           description
             "The facility for messages generated internally by syslogd
              facility (5).";
           reference
             "RFC 5424: The Syslog Protocol";
       }

Clarke, et al.          Expires 20 September 2024              [Page 20]
Internet-Draft              Syslog Management                 March 2024

       identity lpr {
           base syslog-facility;
           description
             "The facility for the line printer subsystem (6).";
           reference
             "RFC 5424: The Syslog Protocol";
       }

       identity news {
           base syslog-facility;
           description
             "The facility for the network news subsystem (7).";
           reference
             "RFC 5424: The Syslog Protocol";
       }

       identity uucp {
           base syslog-facility;
           description
             "The facility for the UUCP subsystem (8).";
           reference
             "RFC 5424: The Syslog Protocol";
       }

       identity cron {
           base syslog-facility;
           description
             "The facility for the clock daemon (9).";
           reference
             "RFC 5424: The Syslog Protocol";
       }

       identity authpriv {
           base syslog-facility;
           description
             "The facility for privileged security/authorization
              messages (10).";
           reference
             "RFC 5424: The Syslog Protocol";
       }

       identity ftp {
           base syslog-facility;
           description
             "The facility for the FTP daemon (11).";
           reference
             "RFC 5424: The Syslog Protocol";
       }

Clarke, et al.          Expires 20 September 2024              [Page 21]
Internet-Draft              Syslog Management                 March 2024

       identity ntp {
           base syslog-facility;
           description
             "The facility for the NTP subsystem (12).";
           reference
             "RFC 5424: The Syslog Protocol";
       }

       identity audit {
           base syslog-facility;
           description
             "The facility for log audit messages (13).";
           reference
             "RFC 5424: The Syslog Protocol";
       }

       identity console {
           base syslog-facility;
           description
             "The facility for log alert messages (14).";
           reference
             "RFC 5424: The Syslog Protocol";
       }

       identity cron2 {
           base syslog-facility;
           description
             "The facility for the second clock daemon (15).";
           reference
             "RFC 5424: The Syslog Protocol";
       }

       identity local0 {
           base syslog-facility;
           description
             "The facility for local use 0 messages (16).";
           reference
             "RFC 5424: The Syslog Protocol";
       }

       identity local1 {
           base syslog-facility;
           description
             "The facility for local use 1 messages (17).";
           reference
             "RFC 5424: The Syslog Protocol";
       }

Clarke, et al.          Expires 20 September 2024              [Page 22]
Internet-Draft              Syslog Management                 March 2024

       identity local2 {
           base syslog-facility;
           description
             "The facility for local use 2 messages (18).";
           reference
             "RFC 5424: The Syslog Protocol";
       }

       identity local3 {
           base syslog-facility;
           description
             "The facility for local use 3 messages (19).";
           reference
             "RFC 5424: The Syslog Protocol";
       }

       identity local4 {
           base syslog-facility;
           description
             "The facility for local use 4 messages (20).";
           reference
             "RFC 5424: The Syslog Protocol";
       }

       identity local5 {
           base syslog-facility;
           description
             "The facility for local use 5 messages (21).";
           reference
             "RFC 5424: The Syslog Protocol";
       }

       identity local6 {
           base syslog-facility;
           description
             "The facility for local use 6 messages (22).";
           reference
             "RFC 5424: The Syslog Protocol";
       }

       identity local7 {
           base syslog-facility;
           description
             "The facility for local use 7 messages (23).";
           reference
             "RFC 5424: The Syslog Protocol";
       }

Clarke, et al.          Expires 20 September 2024              [Page 23]
Internet-Draft              Syslog Management                 March 2024

       identity action {
           description
             "Base identity for action for how a message will be
              handled.";
       }

       identity log {
           base action;
           description
             "This identity specifies that if the compare operation is
              true the message will be logged.";
       }

       identity block {
           base action;
           description
             "This identity specifies that if the compare operation is
              true the message will not be logged.";
       }

       identity stop {
           base action;
           description
             "This identity specifies that if the compare operation is
              true the message will not be logged and no further
              processing will occur for it.";
       }

       grouping severity-filter {
           description
             "This grouping defines the processing used to select
              log messages by comparing syslog message severity using
              the following processing rules:
               - if 'none', do not match.
               - if 'all', match.
               - else compare message severity with the specified
                 severity according to the default compare rule (all
                 messages of the specified severity and greater match)
                 or if the select-adv-compare feature is present, use
                 the advance-compare rule.";
           leaf severity {
               type union {
                   type syslog-severity;
                   type enumeration {
                       enum none {
                           value 2147483647;
                           description
                             "This enum describes the case where no

Clarke, et al.          Expires 20 September 2024              [Page 24]
Internet-Draft              Syslog Management                 March 2024

                              severities are selected.";
                       }
                       enum all {
                           value -2147483648;
                           description
                             "This enum describes the case where all
                              severities are selected.";
                       }
                   }
               }
               mandatory true;
               description
                 "This leaf specifies the syslog message severity.";
           }
           container advanced-compare {
               when "../severity != \"all\" and
               ../severity != \"none\"" {
                   description
                     "The advanced compare container is not applicable
                      for severity 'all' or severity 'none'";
               }
               if-feature "select-adv-compare";
               leaf compare {
                   type enumeration {
                       enum equals {
                           description
                             "This enum specifies that the severity
                              comparison operation will be equals.";
                       }
                       enum equals-or-higher {
                           description
                             "This enum specifies that the severity
                              comparison operation will be equals or
                              higher.";
                       }
                   }
                   default "equals-or-higher";
                   description
                     "The compare can be used to specify the comparison
                      operator that should be used to compare the syslog
                      message severity with the specified severity.";
               }
               leaf action {
                   type identityref {
                       base "action";
                   }
                   default "log";
                   description

Clarke, et al.          Expires 20 September 2024              [Page 25]
Internet-Draft              Syslog Management                 March 2024

                     "The action can be used to specify how the message
                      should be handled. This may include logging the
                      message, not logging the message (i.e., blocking
                      it), or stopping further processing.";
               }
               description
                 "This container describes additional severity compare
                  operations that can be used in place of the default
                  severity comparison. The compare leaf specifies the
                  type of the compare that is done and the action leaf
                  specifies the intended result.
                  Example: compare->equals and action->block means
                  messages that have a severity that are equal to the
                  specified severity will not be logged.";
           }
       }

       grouping selector {
           description
             "This grouping defines a syslog selector which is used to
              select log messages for the log-actions (console, file,
              remote, etc.). Choose one or both of the following:
                facility [<facility> <severity>...]
                pattern-match regular-expression-match-string
              If both facility and pattern-match are specified, both
              must match in order for a log message to be selected.";
           container facility-filter {
               description
                 "This container describes the syslog filter
                  parameters.";
               list facility-list {
                   key "facility severity";
                   ordered-by user;
                   description
                     "This list describes a collection of syslog
                      facilities and severities.";
                   leaf facility {
                       type union {
                           type identityref {
                               base syslog-facility;
                           }
                           type enumeration {
                               enum all {
                                   description
                                     "This enum describes the case where
                                      all facilities are requested.";
                               }
                           }

Clarke, et al.          Expires 20 September 2024              [Page 26]
Internet-Draft              Syslog Management                 March 2024

                       }
                       description
                         "The leaf uniquely identifies a syslog
                          facility.";
                   }
                   uses severity-filter;
               }
           }
           leaf pattern-match {
               if-feature "select-match";
               type string;
               description
                 "This leaf describes a Posix 1003.2 regular expression
                  string that can be used to select a syslog message for
                  logging. The match is performed on the SYSLOG-MSG
                  field.";
               reference
                 "RFC 5424: The Syslog Protocol
                  Std-1003.1-2008 Regular Expressions";
           }
       }

       grouping structured-data {
           description
             "This grouping defines the syslog structured data option
              which is used to select the format used to write log
              messages.";
           leaf structured-data {
               if-feature "structured-data";
               type boolean;
               default "false";
               description
                 "This leaf describes how log messages are written.
                  If true, messages will be written with one or more
                  STRUCTURED-DATA elements; if false, messages will be
                  written with STRUCTURED-DATA = NILVALUE.";
               reference
                 "RFC 5424: The Syslog Protocol";
           }
       }

       container syslog {
           presence
             "Enables logging.";
           description
             "This container describes the configuration parameters for
              syslog.";
           container actions {

Clarke, et al.          Expires 20 September 2024              [Page 27]
Internet-Draft              Syslog Management                 March 2024

               description
                 "This container describes the log-action parameters
                  for syslog.";
               container console {
                   if-feature "console-action";
                   presence
                     "Enables logging to the console";
                   description
                     "This container describes the configuration
                      parameters for console logging.";
                   uses selector;
               }
               container file {
                   if-feature "file-action";
                   description
                     "This container describes the configuration
                      parameters for file logging. If file-archive
                      limits are not supplied, it is assumed that
                      the local implementation defined limits will
                      be used.";
                   list log-file {
                       key "name";
                       description
                         "This list describes a collection of local
                          logging files.";
                       leaf name {
                           type inet:uri {
                               pattern
                                 'file:.*';
                           }
                           description
                             "This leaf specifies the name of the log
                              file which MUST use the uri scheme
                              file:.";
                           reference
                             "RFC 8089: The file URI Scheme";
                       }
                       uses selector;
                       uses structured-data;
                       container file-rotation {
                           description
                             "This container describes the configuration
                              parameters for log file rotation.";
                           leaf number-of-files {
                               if-feature "file-limit-size";
                               type uint32;
                               default "1";
                               description

Clarke, et al.          Expires 20 September 2024              [Page 28]
Internet-Draft              Syslog Management                 March 2024

                                 "This leaf specifies the maximum number
                                  of log files retained. Specify 1 for
                                  implementations that only support one
                                  log file.";
                           }
                           leaf max-file-size {
                               if-feature "file-limit-size";
                               type uint32;
                               units "megabytes";
                               description
                                 "This leaf specifies the maximum log
                                  file size.";
                           }
                           leaf rollover {
                               if-feature "file-limit-duration";
                               type uint32;
                               units "minutes";
                               description
                                 "This leaf specifies the length of time
                                  that log events should be written to a
                                  specific log file. Log events that
                                  arrive after the rollover period cause
                                  the current log file to be closed and
                                  a new log file to be opened.";
                           }
                           leaf retention {
                               if-feature "file-limit-duration";
                               type uint32;
                               units "minutes";
                               description
                                 "This leaf specifies the length of time
                                  that completed/closed log event files
                                  should be stored in the file system
                                  before they are removed.";
                           }
                       }
                   }
               }
               container remote {
                   if-feature "remote-action";
                   description
                     "This container describes the configuration
                      parameters for forwarding syslog messages
                      to remote relays or collectors.";
                   list destination {
                       key "name";
                       description
                         "This list describes a collection of remote

Clarke, et al.          Expires 20 September 2024              [Page 29]
Internet-Draft              Syslog Management                 March 2024

                          logging destinations.";
                       leaf name {
                           type string;
                           description
                             "An arbitrary name for the endpoint to
                              connect to.";
                       }
                       choice transport {
                           mandatory true;
                           description
                             "This choice describes the transport
                              option.";
                           case udp {
                               container udp {
                                   description
                                     "This container describes the UDP
                                      transport options.";
                                   reference
                                     "RFC 5426: Transmission of Syslog
                                      Messages over UDP";
                                   leaf address {
                                       type inet:host;
                                       description
                                         "The leaf uniquely specifies
                                          the address of the remote
                                          host. One of the following
                                          must be specified: an ipv4
                                          address, an ipv6 address, or a
                                          host name.";
                                   }
                                   leaf port {
                                       type inet:port-number;
                                       default "514";
                                       description
                                         "This leaf specifies the port
                                          number used to deliver
                                          messages to the remote
                                          server.";
                                   }
                               }
                           }
                           case tls {
                               container tls {
                                   description
                                     "This container describes the TLS
                                      transport options.";
                                   reference
                                     "RFC 5425: Transport Layer Security

Clarke, et al.          Expires 20 September 2024              [Page 30]
Internet-Draft              Syslog Management                 March 2024

                                      (TLS) Transport Mapping for
                                      Syslog ";
                                   leaf address {
                                       type inet:host;
                                       description
                                         "The leaf uniquely specifies
                                          the address of the remote
                                          host. One of the following
                                          must be specified: an ipv4
                                          address, an ipv6 address, or
                                          a host name.";
                                   }
                                   leaf port {
                                       type inet:port-number;
                                       default "6514";
                                       description
                                         "TCP port 6514 has been
                                          allocated as the default port
                                          for syslog over TLS.";
                                   }
                                   uses tlsc:tls-client-grouping;
                               }
                           }
                       }
                       uses selector;
                       uses structured-data;
                       leaf facility-override {
                           type identityref {
                               base syslog-facility;
                           }
                           description
                             "If specified, this leaf specifies the
                              facility used to override the facility
                              in messages delivered to the remote
                              server.";
                       }
                       leaf source-interface {
                           if-feature "remote-source-interface";
                           type if:interface-ref;
                           description
                             "This leaf sets the source interface to be
                              used to send messages to the remote syslog
                              server. If not set, messages can be sent
                              on any interface.";
                       }
                       container signing {
                           if-feature "signed-messages";
                           presence

Clarke, et al.          Expires 20 September 2024              [Page 31]
Internet-Draft              Syslog Management                 March 2024

                             "If present, syslog-signing options is
                              activated.";
                           description
                             "This container describes the configuration
                              parameters for signed syslog messages.";
                           reference
                             "RFC 5848: Signed Syslog Messages";
                           container cert-signers {
                               description
                                 "This container describes the signing
                                  certificate configuration for
                                  Signature Group 0 which covers the
                                  case for administrators who want all
                                  Signature Blocks to be sent to a
                                  single destination.";
                               list cert-signer {
                                   key "name";
                                   description
                                     "This list describes a collection
                                      of syslog message signers.";
                                   leaf name {
                                       type string;
                                       description
                                         "This leaf specifies the name
                                          of the syslog message
                                          signer.";
                                   }
                                   container cert {
                                       uses ct:asymmetric-key-pair-with-cert-grouping;
                                       description
                                         "This is the certificate that
                                          is periodically sent to the
                                          remote receiver. The
                                          certificate is inherently
                                          associated with its private
                                          and public keys.";
                                   }
                                   leaf hash-algorithm {
                                       type enumeration {
                                           enum SHA1 {
                                               value 1;
                                               description
                                                 "This enum describes
                                                  the SHA1 algorithm.";
                                           }
                                           enum SHA256 {
                                               value 2;
                                               description

Clarke, et al.          Expires 20 September 2024              [Page 32]
Internet-Draft              Syslog Management                 March 2024

                                                 "This enum describes
                                                  the SHA256
                                                  algorithm.";
                                           }
                                       }
                                       description
                                         "This leaf describes the syslog
                                          signer hash algorithm used.";
                                   }
                               }
                               leaf cert-initial-repeat {
                                   type uint32;
                                   default "3";
                                   description
                                     "This leaf specifies the number of
                                      times each Certificate Block
                                      should be sent before the first
                                      message is sent.";
                               }
                               leaf cert-resend-delay {
                                   type uint32;
                                   units "seconds";
                                   default "3600";
                                   description
                                     "This leaf specifies the maximum
                                      time delay in seconds until
                                      resending the Certificate Block.";
                               }
                               leaf cert-resend-count {
                                   type uint32;
                                   default "0";
                                   description
                                     "This leaf specifies the maximum
                                      number of other syslog messages to
                                      send until resending the
                                      Certificate Block.";
                               }
                               leaf sig-max-delay {
                                   type uint32;
                                   units "seconds";
                                   default "60";
                                   description
                                     "This leaf specifies when to
                                      generate a new Signature Block. If
                                      this many seconds have elapsed
                                      since the message with the first
                                      message number of the Signature
                                      Block was sent, a new Signature

Clarke, et al.          Expires 20 September 2024              [Page 33]
Internet-Draft              Syslog Management                 March 2024

                                      Block should be generated.";
                               }
                               leaf sig-number-resends {
                                   type uint32;
                                   default "0";
                                   description
                                     "This leaf specifies the number of
                                      times a Signature Block is resent.
                                      (It is recommended to select a
                                      value of greater than 0 in
                                      particular when the UDP transport
                                      RFC 5426 is used.).";
                               }
                               leaf sig-resend-delay {
                                   type uint32;
                                   units "seconds";
                                   default "5";
                                   description
                                     "This leaf specifies when to send
                                      the next Signature Block
                                      transmission based on time. If
                                      this many seconds have elapsed
                                      since the previous sending of this
                                      Signature Block, resend it.";
                               }
                               leaf sig-resend-count {
                                   type uint32;
                                   default "0";
                                   description
                                     "This leaf specifies when to send
                                      the next Signature Block
                                      transmission based on a count. If
                                      this many other syslog messages
                                      have been sent since the previous
                                      sending of this Signature Block,
                                      resend it. A value of 0 means that
                                      you don't resend based on the
                                      number of messages.";
                               }
                           }
                       }
                   }
               }
           }
       }
   }
   <CODE ENDS>

Clarke, et al.          Expires 20 September 2024              [Page 34]
Internet-Draft              Syslog Management                 March 2024

                         Figure 2: Sylog YANG Model

7.  Usage Examples

7.1.  Syslog Configuration for Severity Critical

   [note: '\' line wrapping for formatting only]

   <!--
        Enable console logging of syslogs of severity critical
   -->

   <?xml version="1.0" encoding="UTF-8"?>
   <syslog xmlns="urn:ietf:params:xml:ns:yang:ietf-syslog">
     <actions>
       <console>
         <facility-filter>
           <facility-list>
             <facility>all</facility>
             <severity>critical</severity>
           </facility-list>
         </facility-filter>
       </console>
     </actions>
   </syslog>

            Figure 3: Syslog Configuration for Severity Critical

7.2.  Remote Syslog Configuration

Clarke, et al.          Expires 20 September 2024              [Page 35]
Internet-Draft              Syslog Management                 March 2024

   [note: '\' line wrapping for formatting only]

   <!--
         Enable remote logging of syslogs to udp destination
         foo.example.com for facility auth, severity error
   -->
   <?xml version="1.0" encoding="UTF-8"?>
   <syslog xmlns="urn:ietf:params:xml:ns:yang:ietf-syslog">
     <actions>
       <remote>
         <destination>
           <name>remote1</name>
           <udp>
             <address>foo.example.com</address>
           </udp>
           <facility-filter>
             <facility-list>
               <facility>auth</facility>
               <severity>error</severity>
             </facility-list>
           </facility-filter>
         </destination>
       </remote>
     </actions>
   </syslog>

                   Figure 4: Remote Syslog Configuration

8.  Acknowledgements

   The authors wish to thank the following who commented on this
   proposal:

   Andy Bierman, Martin Bjorklund, Alex Campbell, Alex Clemm, Francis
   Dupont, Jim Gibson, Jeffrey Haas, Bob Harold, John Heasley, Giles
   Heron, Lisa Huang, Mahesh Jethanandani, Warren Kumari, Jeffrey K
   Lange, Jan Lindblad, Chris Lonvick, Alexey Melnikov, Kathleen
   Moriarty, Tom Petch, Adam Roach, Juergen Schoenwaelder, Phil Shafer,
   Yaron Sheffer, Jason Sterne, Peter Van Horne, Kent Watsen, Bert
   Wijnen, Dale R Worley, and Aleksandr Zhdankin.

9.  IANA Considerations

9.1.  The IETF XML Registry

   This document registers one URI in the IETF XML registry [RFC3688] .
   Following the format in [RFC3688] , the following registration is
   requested:

Clarke, et al.          Expires 20 September 2024              [Page 36]
Internet-Draft              Syslog Management                 March 2024

      URI: urn:ietf:params:xml:ns:yang:ietf-syslog
      Registrant Contact: The IESG.
      XML: N/A, the requested URI is an XML namespace.

9.2.  The YANG Module Names Registry

   This document registers one YANG module in the YANG Module Names
   registry [RFC8525] . Following the format in [RFC7950] , the
   following registration is requested:

      name:         ietf-syslog
      namespace:    urn:ietf:params:xml:ns:yang:ietf-syslog
      prefix:       ietf-syslog
      reference:    RFC zzzz

10.  Security Considerations

   The YANG module defined in this document is designed to be accessed
   via YANG based management protocols, such as NETCONF [RFC6241] and
   RESTCONF [RFC8040] . Both of these protocols have mandatory-to-
   implement secure transport layers (e.g., SSH, TLS) with mutual
   authentication.

   The NETCONF access control model (NACM) [RFC8341] provides the means
   to restrict access for particular users to a pre-configured subset of
   all available protocol operations and content.

   There are a number of data nodes defined in this YANG module that are
   writable/creatable/deletable (i.e., config true, which is the
   default).  These data nodes should be considered sensitive or
   vulnerable in all network environments.  Logging in particular is
   used to assess the state of systems and can be used to indicate a
   network compromise.  If logging were to be disabled through malicious
   means, attacks may not be readily detectable.  Therefore write
   operations (e.g., edit-config) to these data nodes without proper
   protection can have a negative effect on network operations and on
   network security.

   In addition there are data nodes that require careful analysis and
   review.  These are the subtrees and data nodes and their sensitivity/
   vulnerability:

   facility-filter/pattern-match:  When writing this node,
         implementations MUST ensure that the regular expression pattern
         match is not constructed to cause a regular expression denial
         of service attack due to a pattern that causes the regular
         expression implementation to work very slowly (exponentially
         related to input size).

Clarke, et al.          Expires 20 September 2024              [Page 37]
Internet-Draft              Syslog Management                 March 2024

   remote/destination/signing/cert-signer:  When writing this subtree,
         implementations MUST NOT specify a private key that is used for
         any other purpose.

   Some of the readable data nodes in this YANG module may be considered
   sensitive or vulnerable in some network environments.  It is thus
   important to control read access (e.g., via get, get-config, or
   notification) to these data nodes.  These are the subtrees and data
   nodes and their sensitivity/vulnerability:

   remote/destination/transport:  This subtree contains information
         about other hosts in the network, and the TLS transport
         certificate properties if TLS is selected as the transport
         protocol.

   remote/destination/signing:  This subtree contains information about
         the syslog message signing properties including signing
         certificate information.

   There are no RPC operations defined in this YANG module.

11.  References

11.1.  Normative References

   [I-D.ietf-netconf-crypto-types]
              Watsen, K., "YANG Data Types and Groupings for
              Cryptography", Work in Progress, Internet-Draft, draft-
              ietf-netconf-crypto-types-33, 1 March 2024,
              <https://datatracker.ietf.org/doc/html/draft-ietf-netconf-
              crypto-types-33>.

   [I-D.ietf-netconf-tls-client-server]
              Watsen, K., "YANG Groupings for TLS Clients and TLS
              Servers", Work in Progress, Internet-Draft, draft-ietf-
              netconf-tls-client-server-40, 1 March 2024,
              <https://datatracker.ietf.org/doc/html/draft-ietf-netconf-
              tls-client-server-40>.

   [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>.

   [RFC5424]  Gerhards, R., "The Syslog Protocol", RFC 5424,
              DOI 10.17487/RFC5424, March 2009,
              <https://www.rfc-editor.org/info/rfc5424>.

Clarke, et al.          Expires 20 September 2024              [Page 38]
Internet-Draft              Syslog Management                 March 2024

   [RFC5425]  Miao, F., Ed., Ma, Y., Ed., and J. Salowey, Ed.,
              "Transport Layer Security (TLS) Transport Mapping for
              Syslog", RFC 5425, DOI 10.17487/RFC5425, March 2009,
              <https://www.rfc-editor.org/info/rfc5425>.

   [RFC5426]  Okmianski, A., "Transmission of Syslog Messages over UDP",
              RFC 5426, DOI 10.17487/RFC5426, March 2009,
              <https://www.rfc-editor.org/info/rfc5426>.

   [RFC5848]  Kelsey, J., Callas, J., and A. Clemm, "Signed Syslog
              Messages", RFC 5848, DOI 10.17487/RFC5848, May 2010,
              <https://www.rfc-editor.org/info/rfc5848>.

   [RFC6991]  Schoenwaelder, J., Ed., "Common YANG Data Types",
              RFC 6991, DOI 10.17487/RFC6991, July 2013,
              <https://www.rfc-editor.org/info/rfc6991>.

   [RFC7950]  Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
              RFC 7950, DOI 10.17487/RFC7950, August 2016,
              <https://www.rfc-editor.org/info/rfc7950>.

   [RFC8089]  Kerwin, M., "The "file" URI Scheme", RFC 8089,
              DOI 10.17487/RFC8089, February 2017,
              <https://www.rfc-editor.org/info/rfc8089>.

   [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>.

   [RFC8343]  Bjorklund, M., "A YANG Data Model for Interface
              Management", RFC 8343, DOI 10.17487/RFC8343, March 2018,
              <https://www.rfc-editor.org/info/rfc8343>.

   [RFC8525]  Bierman, A., Bjorklund, M., Schoenwaelder, J., Watsen, K.,
              and R. Wilton, "YANG Library", RFC 8525,
              DOI 10.17487/RFC8525, March 2019,
              <https://www.rfc-editor.org/info/rfc8525>.

   [Std-1003.1-2008]
              Group, I. A. T. O., ""Chapter 9: Regular Expressions". The
              Open Group Base Specifications Issue 6, IEEE Std
              1003.1-2008, 2016 Edition.", September 2016,
              <http://pubs.opengroup.org/onlinepubs/9699919799/>.

11.2.  Informative References

Clarke, et al.          Expires 20 September 2024              [Page 39]
Internet-Draft              Syslog Management                 March 2024

   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              DOI 10.17487/RFC3688, January 2004,
              <https://www.rfc-editor.org/info/rfc3688>.

   [RFC6241]  Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
              and A. Bierman, Ed., "Network Configuration Protocol
              (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
              <https://www.rfc-editor.org/info/rfc6241>.

   [RFC8040]  Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
              Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
              <https://www.rfc-editor.org/info/rfc8040>.

   [RFC8340]  Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
              BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
              <https://www.rfc-editor.org/info/rfc8340>.

   [RFC8341]  Bierman, A. and M. Bjorklund, "Network Configuration
              Access Control Model", STD 91, RFC 8341,
              DOI 10.17487/RFC8341, March 2018,
              <https://www.rfc-editor.org/info/rfc8341>.

   [RFC8342]  Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K.,
              and R. Wilton, "Network Management Datastore Architecture
              (NMDA)", RFC 8342, DOI 10.17487/RFC8342, March 2018,
              <https://www.rfc-editor.org/info/rfc8342>.

Appendix A.  Implementer Guidelines

A.1.  Extending Facilities

   Many vendors extend the list of facilities available for logging in
   their implementation.  Additional facilities may not work with the
   syslog protocol as defined in [RFC5424] and hence such facilities
   apply for local syslog-like logging functionality.

   The following is an example that shows how additional facilities
   could be added to the list of available facilities (in this example
   two facilities are added):

Clarke, et al.          Expires 20 September 2024              [Page 40]
Internet-Draft              Syslog Management                 March 2024

   module example-vendor-syslog-types {
     namespace "http://example.com/ns/vendor-syslog-types";
     prefix vendor-syslogtypes;

     import ietf-syslog {
       prefix syslogtypes;
     }

     organization "Example, Inc.";
     contact
       "Example, Inc.
        Customer Service

        E-mail: syslog-yang@example.com";

     description
       "This module contains a collection of vendor-specific YANG type
        definitions for SYSLOG.";

     revision 2017-08-11 {
       description
         "Version 1.0";
       reference
         "Vendor SYSLOG Types: SYSLOG YANG Model";
     }

     identity vendor_specific_type_1 {
       base syslogtypes:syslog-facility;
       description
         "Adding vendor specific type 1 to syslog-facility";
     }

     identity vendor_specific_type_2 {
       base syslogtypes:syslog-facility;
       description
         "Adding vendor specific type 2 to syslog-facility";
     }
   }

A.2.  Syslog Terminal Output

   Terminal output with requirements more complex than the console
   subtree currently provides, are expected to be supported via vendor
   extensions rather than handled via the file subtree.

Clarke, et al.          Expires 20 September 2024              [Page 41]
Internet-Draft              Syslog Management                 March 2024

A.3.  Syslog File Naming Convention

   The syslog/file/log-file/file-rotation container contains
   configuration parameters for syslog file rotation.  This section
   describes how these fields might be used by an implementer to name
   syslog files in a rotation process.  This information is offered as
   an informative guide only.

   When an active syslog file with a name specified by log-file/name,
   reaches log-file/max-file-size and/or syslog events arrive after the
   period specified by log-file/rollover, the logging system can close
   the file, can compress it, and can name the archive file <log-file/
   name>.0.gz.  The logging system can then open a new active syslog
   file <log-file/name>.

   When the new syslog file reaches either of the size limits referenced
   above, <log-file/name>.0.gz can be renamed <log-file/name>.1.gz and
   the new syslog file can be closed, compressed and renamed <log-file/
   name>.0.gz.  Each time that a new syslog file is closed, each of the
   prior syslog archive files named <log-file/name>.<n>.gz can be
   renamed to <log-file/name>.<n + 1>.gz.

   Removal of archive log files could occur when either or both:

   - log-file/number-of-files specified - the logging system can create
   up to log-file/number-of-files syslog archive files after which, the
   contents of the oldest archived file could be overwritten.

   - log-file/retention specified - the logging system can remove those
   syslog archive files whose file expiration time (file creation time
   plus the specified log-file/retention time) is prior to the current
   time.

Authors' Addresses

   Joe Clarke (editor)
   Cisco
   United States of America
   Email: jclarke@cisco.com

   Mahesh Jethanandani (editor)
   Kloud Services
   United States of America
   Email: mjethanandani@gmail.com

Clarke, et al.          Expires 20 September 2024              [Page 42]
Internet-Draft              Syslog Management                 March 2024

   Clyde Wildes (editor)
   Cisco Systems Inc.
   170 West Tasman Drive
   San Jose, CA 95134
   United States of America
   Phone: +1 415 819-6111
   Email: clyde@clydewildes.com

   Kiran Koushik (editor)
   Verizon Wireless
   500 W Dove Rd.
   Southlake, TX 76092
   United States of America
   Phone: +1 512 650-0210
   Email: kirankoushik.agraharasreenivasa@verizonwireless.com

Clarke, et al.          Expires 20 September 2024              [Page 43]