RFC 9742
A YANG Data Model for Syslog Management
RFC 9742: A YANG Data Model for Syslog Management 🎀
Part 1 of 9 💖
Who wrote it: J. Clarke (Cisco), M. Jethanandani (Kloud Services), C. Wildes (Cisco Systems Inc.), and K. Koushik (Verizon Wireless). Clarke, Jethanandani, Wildes, and Koushik are all listed as Ed. (editors) ✍️
What kind of doc it is: Standards Track, which means it's an official Internet standard 👑
When: April 2025 📅
ISSN: 2070-1721
Obsoletes / Updates: This title block doesn't list any documents that it obsoletes or updates 🙈
Abstract ✨
Okay bestie, so this doc defines a YANG data model for managing a syslog process 💅. It's meant to be used by vendors who implement syslog collectors in their systems 🫶.
Status of This Memo 📜
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 7841.
Info about the current status of this document, any errata, and how to give feedback on it can be found at https://www.rfc-editor.org/info/rfc9742 🦋.
Copyright Notice ©️
Copyright (c) 2025 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) 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
1.1. Requirements Language
2. Terminology
3. NMDA Compliance
4. Design of the Syslog Model
4.1. Syslog Module
5. Syslog YANG Module
5.1. The ietf-syslog Module
6. Usage Examples
6.1. Syslog Configuration for Severity Critical
6.2. Remote Syslog Configuration
7. IANA Considerations
7.1. The IETF XML Registry
7.2. The YANG Module Names Registry
8. Security Considerations
9. References
9.1. Normative References
9.2. Informative References
Appendix A. Tree Diagrams
A.1. Complete Tree Diagram
Appendix B. Implementer Guidelines
B.1. Extending Facilities
B.2. Syslog Terminal Output
B.3. Syslog File Naming Convention
Acknowledgements
Authors' Addresses1. Introduction 💫
This doc defines a YANG [RFC7950] data model that can be used to configure the syslog feature running on a system. YANG data models can be used with network management protocols, like NETCONF [RFC6241], to install, manipulate, and delete the configuration of network devices 🍓.
The data model uses the YANG feature construct, which lets implementations support only the syslog features that fit within their capabilities 🌸.
This module can be used to configure the syslog application conceptual layers as implemented on the syslog collector 🧚.
Essentially, a syslog process receives messages (from the kernel, processes, applications, or other syslog processes) and processes them 💅. Processing may involve logging to a local file, displaying on the console, and/or relaying to syslog processes on other machines. How it's processed depends on the "facility" that originated the message and the "severity" the facility assigned to it 🔥.
Syslog protocol definitions like these are defined in [RFC5424], and they're used in this RFC ✨.
The YANG data 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 following terms are used throughout this document 💖:
- Originator: An "originator" is an entity that generates syslog content to be carried in a message. The term is defined in [RFC5424].
- Relay: A "relay" is an entity that forwards syslog messages. It accepts messages from originators or other relays and sends them to collectors or other relays. The term is defined in [RFC5424].
- Collector: A "collector" gathers syslog content for further analysis. The term is defined in [RFC5424].
- Action: The term "action" refers to the process that takes place for each syslog message received 🦋.
3. NMDA Compliance 💜
The YANG data model in this document conforms to the Network Management Datastore Architecture (NMDA) defined in [RFC8342] ✅.
4. Design of the Syslog Model 🌈
The syslog model was designed by comparing various syslog features implemented by different vendors in their various implementations 👀.
The module defines leafs that are common across implementations. Its simple design is meant to offer maximum flexibility 🫶. However, not all optional features defined in this document are present in all vendor implementations, so vendors need to use the feature statements to specify the optional features they support. At the same time, vendors can augment the model to add proprietary features. "Extending Facilities" (Appendix B.1) shows an example of how that can be done ✨.
Syslog consists of originators and collectors. The diagram below shows the syslog processing flow from originators to collectors, where filtering can take place 🦋.
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 FlowCollectors are configured using the leafs in the syslog model's actions container that 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 is made up of a list of one or more filters, specified by facility-severity pairs. If the select-match feature is supported, it can also include an optional regular expression pattern match that runs on the MSG field described in Section 6.4 of [RFC5424] 💅.
A syslog message is processed if there is an element
of facility-list (F, S) where
the message facility matches F,
the message severity matches S,
and/or the message text matches the regex pattern (if it
is present)The facility is either one specific syslog-facility or all facilities 🌟.
The model lets you pick the transport that a user might want for a remote relay or collector 🚀. You can choose between UDP or TLS-based sessions. You can configure multiple relays or collectors, but they have to use the same transport 🙈.
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 on severity, the default comparison is that messages of the specified severity and higher are selected to be logged. The model shows this as "default equals-or-higher" 💀. This behavior can be changed if the select-adv-compare feature is enabled, so you can specify a compare operation and an action 👑. The compare operations are: "equals", which selects messages with this single severity, and "equals-or-higher", which selects 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 B.1) 🎀.
4.1. Syslog Module ✨
okay so bestie, here's the tree view of the whole data model 🌳💖 It's a simplified picture, and if you want to know what all the little symbols mean, check out [RFC8340] for the tree diagram notation 🤓
module: ietf-syslog
+--rw syslog!
+--rw actions
+--rw console! {console-action}?
| +--rw 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 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 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 udp* [address]
| | +--rw address inet:host
| | +--rw port? inet:port-number
| +--:(tls)
| +--rw tls
| +--rw tls* [address]
| +--rw address inet:host
| +--rw port?
| | inet:port-number
| +--rw client-identity!
| | +--rw (auth-type)
| | ...
| +--rw server-authentication
| | +--rw ca-certs! {server-auth-x509-cert}?
| | | ...
| | +--rw ee-certs! {server-auth-x509-cert}?
| | | ...
| | +--rw raw-public-keys!
| | | {server-auth-raw-public-key}?
| | | ...
| | +--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 cipher-suites
| | ...
| +--rw keepalives {tls-client-keepalives}?
| +--rw peer-allowed-to-send? empty
| +--rw test-peer-aliveness!
| ...
+--rw 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}?
| | | | ...
| | | +--:(hidden-private-key)
| | | | {hidden-private-keys}?
| | | | ...
| | | +--:(encrypted-private-key)
| | | {encrypted-private-keys}?
| | | ...
| | +--rw cert-data?
| | | end-entity-cert-cms
| | +---n certificate-expiration
| | | {certificate-expiration-notificati\
on}?
| | | +-- expiration-date
| | | yang:date-and-time
| | +---x generate-csr {csr-generation}?
| | +---w input
| | | ...
| | +--ro output
| | ...
| +--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? uint32Figure 2: Tree Diagram for Syslog Model 🎀
5. Syslog YANG Module 🦋
5.1. The ietf-syslog Module 💅
this module pulls in typedefs from [RFC6991], [RFC8343], and groupings from [RFC9640] and [RFC9645] 🧚 it also references [RFC5424], [RFC5425], [RFC5426], [RFC5848], [RFC8089], [RFC8174], and [Std-1003.1-2024]. the full YANG module is below, and yes it's long, but every line is part of the spec 😭🫶
<CODE BEGINS> file "ietf-syslog@2025-04-30.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
"RFC 9645: YANG Groupings for TLS Clients and TLS Servers";
}
import ietf-crypto-types {
prefix ct;
reference
"RFC 9640: YANG Data Types and Groupings 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 management.
Copyright (c) 2025 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 9742
(https://www.rfc-editor.org/info/rfc9742);
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,
as shown here.";
revision 2025-04-30 {
description
"Initial Revision";
reference
"RFC 9742: Syslog YANG Module";
}
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
for the remote-action.";
}
feature select-adv-compare {
description
"This feature represents the ability to select messages
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";
}okay bestie, we're still in the YANG module 🎀 this part is all about severity levels (lower number = more serious 🚨), facilities (the sources of messages 🧚), and the filters that decide what gets logged 💅
typedef syslog-severity {
type enumeration {
enum emergency {
value 0;
description
"The severity level 'Emergency' indicates that the
system is unusable.";
}
enum alert {
value 1;
description
"The severity level 'Alert' indicates that an
action must be taken immediately.";
}
enum critical {
value 2;
description
"The severity level 'Critical' indicates a
critical condition.";
}
enum error {
value 3;
description
"The severity level 'Error' indicates an error
condition.";
}
enum warning {
value 4;
description
"The severity level 'Warning' indicates a warning
condition.";
}
enum notice {
value 5;
description
"The severity level 'Notice' indicates a normal
but significant condition.";
}
enum info {
value 6;
description
"The severity level 'Info' indicates an
informational message.";
}
enum debug {
value 7;
description
"The severity level 'Debug' indicates 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 {
base syslog-facility;
description
"The facility for kernel messages (numerical code 0).";
reference
"RFC 5424: The Syslog Protocol, Section 6.2.1.";
}
identity user {
base syslog-facility;
description
"The facility for user-level messages (numerical code 1).";
reference
"RFC 5424: The Syslog Protocol, Section 6.2.1.";
}
identity mail {
base syslog-facility;
description
"The facility for the mail system (numerical code 2).";
reference
"RFC 5424: The Syslog Protocol, Section 6.2.1.";
}
identity daemon {
base syslog-facility;
description
"The facility for the system daemons (numerical code 3).";
reference
"RFC 5424: The Syslog Protocol, Section 6.2.1.";
}
identity auth {
base syslog-facility;
description
"The facility for security/authorization messages (numerical
code 4).";
reference
"RFC 5424: The Syslog Protocol, Section 6.2.1.";
}
identity syslog {
base syslog-facility;
description
"The facility for messages generated internally by a syslog
daemon facility (numerical code 5).";
reference
"RFC 5424: The Syslog Protocol, Section 6.2.1.";
}
identity lpr {
base syslog-facility;
description
"The facility for the line printer subsystem (numerical code
6).";
reference
"RFC 5424: The Syslog Protocol, Section 6.2.1.";
}
identity news {
base syslog-facility;
description
"The facility for the network news subsystem (numerical code
7).";
reference
"RFC 5424: The Syslog Protocol, Section 6.2.1.";
}
identity uucp {
base syslog-facility;
description
"The facility for the Unix-to-Unix Copy (UUCP) subsystem
(numerical code 8).";
reference
"RFC 5424: The Syslog Protocol, Section 6.2.1.";
}
identity cron {
base syslog-facility;
description
"The facility for the clock daemon (numerical code 9).";
reference
"RFC 5424: The Syslog Protocol, Section 6.2.1.";
}
identity authpriv {
base syslog-facility;
description
"The facility for privileged security/authorization messages
(numerical code 10).";
reference
"RFC 5424: The Syslog Protocol, Section 6.2.1.";
}
identity ftp {
base syslog-facility;
description
"The facility for the FTP daemon (numerical code 11).";
reference
"RFC 5424: The Syslog Protocol, Section 6.2.1.";
}
identity ntp {
base syslog-facility;
description
"The facility for the NTP subsystem (numerical code 12).";
reference
"RFC 5424: The Syslog Protocol, Section 6.2.1.";
}
identity audit {
base syslog-facility;
description
"The facility for log audit messages (numerical code 13).";
reference
"RFC 5424: The Syslog Protocol, Section 6.2.1.";
}
identity console {
base syslog-facility;
description
"The facility for log alert messages (numerical code 14).";
reference
"RFC 5424: The Syslog Protocol, Section 6.2.1.";
}
identity cron2 {
base syslog-facility;
description
"The facility for the second clock daemon (numerical code
15).";
reference
"RFC 5424: The Syslog Protocol, Section 6.2.1.";
}
identity local0 {
base syslog-facility;
description
"The facility for local use 0 messages (numerical code 16).";
reference
"RFC 5424: The Syslog Protocol, Section 6.2.1.";
}
identity local1 {
base syslog-facility;
description
"The facility for local use 1 messages (numerical code 17).";
reference
"RFC 5424: The Syslog Protocol, Section 6.2.1.";
}
identity local2 {
base syslog-facility;
description
"The facility for local use 2 messages (numerical code 18).";
reference
"RFC 5424: The Syslog Protocol, Section 6.2.1.";
}
identity local3 {
base syslog-facility;
description
"The facility for local use 3 messages (numerical code 19).";
reference
"RFC 5424: The Syslog Protocol";
}
identity local4 {
base syslog-facility;
description
"The facility for local use 4 messages (numerical code 20).";
reference
"RFC 5424: The Syslog Protocol, Section 6.2.1.";
}
identity local5 {
base syslog-facility;
description
"The facility for local use 5 messages (numerical code 21).";
reference
"RFC 5424: The Syslog Protocol, Section 6.2.1.";
}
identity local6 {
base syslog-facility;
description
"The facility for local use 6 messages (numerical code 22).";
reference
"RFC 5424: The Syslog Protocol, Section 6.2.1.";
}
identity local7 {
base syslog-facility;
description
"The facility for local use 7 messages (numerical code 23).";
reference
"RFC 5424: The Syslog Protocol, Section 6.2.1.";
}
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
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 operation 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
"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 compare operation 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.";
}
}Okay bestie, this part is where the syslog selectors and the structured-data switch live, and they're so satisfying 💅✨
Here's the selector grouping, verbatim, because the YANG is the spec and we do not touch it 🫶
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 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.";
}
}
}
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-1003.1-2024 Regular Expressions";
}
}So the vibe here: a selector is how a log-action (console, file, remote, etc.) decides which messages it gets 🎀 You pick a facility list, a pattern-match, or both 👑 If you use both, a message only gets through when it passes both checks. That's giving strict bouncer energy 💀
The filter container holds the facility-list, which is keyed on facility plus severity and is ordered-by user 🌸 The facility can be any syslog-facility identity, or the special all enum if you want everything 🌈 Then uses severity-filter brings in the severity part. The pattern-match leaf is a Posix 1003.2 regular expression matched against the SYSLOG-MSG field, and it only exists when the select-match feature is turned on 🧚 It points back to RFC 5424 and Std-1003.1-2024 for the regex stuff 🦋
Now the second grouping, which is giving main character energy 👑
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";
}
}This is the structured-data switch 💖 It's a boolean that's false by default, and it's only there when the structured-data feature is enabled. Set it to true and messages get written with one or more STRUCTURED-DATA elements. Leave it false and messages get STRUCTURED-DATA = NILVALUE instead 🙈 The whole thing is defined by RFC 5424, so that's where you go for the deep dive 🫶
Okay, the YANG module is where things get spicy 🌶️ Let's keep going with the signing settings and the resend knobs 💅
container syslog {
presence "Enables logging.";
description
"This container describes the configuration parameters for
syslog.";
container actions {
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
"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 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";
list udp {
key "address";
description
"List of all UDP sessions.";
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 (TLS) Transport
Mapping for Syslog ";
list tls {
key "address";
description
"List of all TLS-based sessions.";
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 "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
"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
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 as in 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>Figure 3: Syslog YANG Module
6. Usage Examples ✨
okay so the examples in this section are all in XML 💅 [W3C.REC-xml-20081126] 🎀
6.1. Syslog Configuration for Severity Critical
bestie, this one shows how to switch on console logging for syslog messages of severity critical 🖥️✨
<?xml version="1.0" encoding="UTF-8"?>
<syslog xmlns="urn:ietf:params:xml:ns:yang:ietf-syslog">
<actions>
<console>
<filter>
<facility-list>
<facility>all</facility>
<severity>critical</severity>
</facility-list>
</filter>
</console>
</actions>
</syslog>Figure 4: Syslog Configuration for Severity Critical
6.2. Remote Syslog Configuration
this example is giving remote logging 📡 it sends syslogs to the UDP destination foo.example.com for facility auth and severity error, and it's honestly so clean 🦋
<?xml version="1.0" encoding="UTF-8"?>
<syslog xmlns="urn:ietf:params:xml:ns:yang:ietf-syslog">
<actions>
<remote>
<destination>
<name>remote1</name>
<udp>
<udp>
<address>foo.example.com</address>
</udp>
</udp>
<filter>
<facility-list>
<facility>auth</facility>
<severity>error</severity>
</facility-list>
</filter>
</destination>
</remote>
</actions>
</syslog>Figure 5: Remote Syslog Configuration
7. IANA Considerations 🌸
7.1. The IETF XML Registry
this document registers one URI in the "IETF XML Registry", following the format defined in [RFC3688] 🧚
URI: urn:ietf:params:xml:ns:yang:ietf-syslog
Registrant Contact: The IESG.
XML: N/A; the requested URI is an XML namespace.7.2. The YANG Module Names Registry
this document also registers one YANG module in the "YANG Module Names" registry [RFC8525], following the format in [RFC7950] 💜
Name: ietf-syslog
Namespace: urn:ietf:params:xml:ns:yang:ietf-syslog
Prefix: syslog
Reference: RFC 97428. Security Considerations 🔐💀
okay, this part is serious bestie, so read it closely 🫶
This section is modeled after the template defined in [YANG-GUIDELINES].
The "ietf-syslog" YANG module defines a data model that is designed to be accessed via YANG-based management protocols, such as NETCONF [RFC6241] and RESTCONF [RFC8040]. These protocols have to use a secure transport layer (e.g., SSH [RFC4252], TLS [RFC8446], and QUIC [RFC9000]) and have to use mutual authentication.
The Network Configuration Access Control Model (NACM) [RFC8341] provides the means to restrict access for particular NETCONF or RESTCONF users to a preconfigured subset of all available NETCONF or RESTCONF protocol operations and content.
This module imports groupings from the ietf-crypto-types YANG module defined in YANG Groupings for Crypto Types [RFC9640]. Security considerations described in that document apply to this module also. 🔑
There are a number of data nodes defined in this YANG module that are writable, creatable, and deletable (i.e., "config true", which is the default). All writable data nodes are likely to be reasonably sensitive or vulnerable in some network environments. Write operations (e.g., edit-config) and delete operations to these data nodes without proper protection or authentication can have a negative effect on network operations. The following subtrees and data nodes have particular sensitivities and vulnerabilities:
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). 🚨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. Specifically, the following subtrees and data nodes have particular sensitivities and vulnerabilities:
remote/destination/transport:This subtree contains information about other hosts in the network, the services available on those hosts, and the TLS transport certificate properties if TLS is selected as the transport protocol. Knowing that a service like syslog (udp/514) is enabled on the host will allow a malicious user to spam the host on that port. 👀remote/destination/signing:This subtree contains information about the syslog message signing properties, including signing certificate information.
There are no particularly sensitive RPC or action operations. ✨
9. References 📚
9.1. Normative References
these are the must-read refs, no skipping 💅
[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>.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004,
<https://www.rfc-editor.org/info/rfc3688>.
[RFC5424] Gerhards, R., "The Syslog Protocol", RFC 5424,
DOI 10.17487/RFC5424, March 2009,
<https://www.rfc-editor.org/info/rfc5424>.
[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>.
[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>.
[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>.
[RFC9640] Watsen, K., "YANG Data Types and Groupings for
Cryptography", RFC 9640, DOI 10.17487/RFC9640, October
2024, <https://www.rfc-editor.org/info/rfc9640>.
[RFC9645] Watsen, K., "YANG Groupings for TLS Clients and TLS
Servers", RFC 9645, DOI 10.17487/RFC9645, October 2024,
<https://www.rfc-editor.org/info/rfc9645>.
[Std-1003.1-2024]
The Open Group, ""Chapter 9: Regular Expressions" The Open
Group Base Specifications Issue 8, IEEE Std 1003.1-2024",
2024, <https://pubs.opengroup.org/onlinepubs/9799919799>.
[W3C.REC-xml-20081126]
Bray, T., Paoli, J., Sperberg-McQueen, C.M., Maler, E.,
and F. Yergeau, "Extensible Markup Language (XML) 1.0
(Fifth Edition)", World Wide Web Consortium
Recommendation REC-xml-20081126, November 2008,
<https://www.w3.org/TR/2008/REC-xml-20081126/>.9.2. Informative References
these ones are good background reading, bestie 🌈
[RFC4252] Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH)
Authentication Protocol", RFC 4252, DOI 10.17487/RFC4252,
January 2006, <https://www.rfc-editor.org/info/rfc4252>.
[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>.
[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>.
[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>.
[RFC9000] Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based
Multiplexed and Secure Transport", RFC 9000,
DOI 10.17487/RFC9000, May 2021,
<https://www.rfc-editor.org/info/rfc9000>.
[YANG-GUIDELINES]
Bierman, A., Boucadair, M., and Q. Wu, "Guidelines for
Authors and Reviewers of Documents Containing YANG Data
Models", Work in Progress, Internet-Draft, draft-ietf-
netmod-rfc8407bis-24, 18 April 2025,
<https://datatracker.ietf.org/doc/html/draft-ietf-netmod-
rfc8407bis-24>.Appendix A. Tree Diagrams 🌳
A.1. Complete Tree Diagram
[note: '\' line wrapping for formatting only]
Okay bestie, this part is the tree diagram, and it's giving a lot 🌳💖 Here's the rest of it, exactly as the spec has it:
| | | | identityref
| | | +--rw public-key?Wait, that's not right, let me paste the full stretch from where the earlier parts left off:
| | | | | identityref
| | | | +--rw public-key?
| | | | | binary
| | | | +--rw private-key-for\
mat?
| | | | | identityref
| | | | +--rw (private-key-ty\
pe)
| | | | | +--:(cleartext-pri\
vate-key)
| | | | | | {cleartex\
t-private-keys}?
| | | | | | +--rw cleartext\
-private-key?
| | | | | | binary
| | | | | +--:(hidden-privat\
e-key)
| | | | | | {hidden-p\
rivate-keys}?
| | | | | | +--rw hidden-pr\
ivate-key?
| | | | | | empty
| | | | | +--:(encrypted-pri\
vate-key)
| | | | | {encrypte\
d-private-keys}?
| | | | | +--rw encrypted\
-private-key
| | | | | +--rw encryp\
ted-by
| | | | | +--rw encryp\
ted-value-format
| | | | | | iden\
tityref
| | | | | +--rw encryp\
ted-value
| | | | | bina\
ry
| | | | +--rw cert-data?
| | | | | end-entity-ce\
rt-cms
| | | | +---n certificate-exp\
iration
| | | | | {certificate-\
expiration-notification}?
| | | | | +-- expiration-dat\
e
| | | | | yang:date-\
and-time
| | | | +---x generate-csr
| | | | {csr-generati\
on}?
| | | | +---w input
| | | | | +---w csr-forma\
t
| | | | | | identit\
yref
| | | | | +---w csr-info
| | | | | csr-inf\
o
| | | | +--ro output
| | | | +--ro (csr-type\
)
| | | | +--:(p10-csr\
)
| | | | +--ro p10\
-csr?
| | | | p\
10-csr
| | | +--:(central-keystore)
| | | {central-keystore-\
supported,asymmetric-keys}?
| | | +--rw central-keystore-r\
eference
| | | +--rw asymmetric-key?\okay bestie, this tree is giving spaghetti 🍝 but every branch is doing something important, so let's keep it all exactly as it is 🌸
| | | | ks:central-as\
ymmetric-key-ref
| | | | {central-keys\
tore-supported,asymmetric-keys}?
| | | +--rw certificate?
| | | leafref
| | +--:(raw-public-key)
| | | {client-ident-raw-public-ke\
y}?
| | | +--rw raw-private-key
| | | +--rw (inline-or-keystore)
| | | +--:(inline)
| | | | {inline-definition\
s-supported}?
| | | | +--rw inline-definition
| | | | +--rw public-key-form\
at?
| | | | | identityref
| | | | +--rw public-key?
| | | | | binary
| | | | +--rw private-key-for\
mat?
| | | | | identityref
| | | | +--rw (private-key-ty\
pe)
| | | | +--:(cleartext-pri\
vate-key)
| | | | | {cleartex\
t-private-keys}?
| | | | | +--rw cleartext\
-private-key?
| | | | | binary
| | | | +--:(hidden-privat\
e-key)
| | | | | {hidden-p\
rivate-keys}?
| | | | | +--rw hidden-pr\
ivate-key?
| | | | | empty
| | | | +--:(encrypted-pri\
vate-key)
| | | | {encrypte\
d-private-keys}?
| | | | +--rw encrypted\
-private-key
| | | | +--rw encryp\
ted-by
| | | | +--rw encryp\
ted-value-format
| | | | | iden\
tityref
| | | | +--rw encryp\
ted-value
| | | | bina\
ry
| | | +--:(central-keystore)
| | | {central-keystore-\
supported,asymmetric-keys}?
| | | +--rw central-keystore-r\
eference?
| | | ks:central-asymm\
etric-key-ref
| | +--:(tls12-psk)
| | | {client-ident-tls12-psk}?
| | | +--rw tls12-psk
| | | +--rw (inline-or-keystore)
| | | | +--:(inline)
| | | | | {inline-definition\
s-supported}?
| | | | | +--rw inline-definition
| | | | | +--rw key-format?
| | | | | | identityref
| | | | | +--rw (key-type)
| | | | | +--:(cleartext-sym\
metric-key)
| | | | | | +--rw cleartext\
-symmetric-key?
| | | | | | binary
| | | | | | {cleart\
ext-symmetric-keys}?
| | | | | +--:(hidden-symmet\
ric-key)
| | | | | | {hidden-s\
ymmetric-keys}?
| | | | | | +--rw hidden-sy\
mmetric-key?
| | | | | | empty
| | | | | +--:(encrypted-sym\
metric-key)
| | | | | {encrypte\
d-symmetric-keys}?
| | | | | +--rw encrypted\
-symmetric-key
| | | | | +--rw encryp\
ted-by
| | | | | +--rw encryp\
ted-value-format
| | | | | | iden\
tityref
| | | | | +--rw encryp\
ted-value
| | | | | bina\
ry
| | | | +--:(central-keystore)
| | | | {central-keystore-\
supported,symmetric-keys}?
| | | | +--rw central-keystore-r\
eference?
| | | | ks:central-symme\
tric-key-ref
| | | +--rw id?
| | | string
| | +--:(tls13-epsk)
| | {client-ident-tls13-epsk}?
| | +--rw tls13-epsk
| | +--rw (inline-or-keystore)
| | | +--:(inline)
| | | | {inline-definition\
s-supported}?
| | | | +--rw inline-definition
| | | | +--rw key-format?
| | | | | identityref
| | | | +--rw (key-type)
| | | | +--:(cleartext-sym\
metric-key)
| | | | | +--rw cleartext\
-symmetric-key?
| | | | | binary
| | | | | {cleart\
ext-symmetric-keys}?
| | | | +--:(hidden-symmet\
ric-key)
| | | | | {hidden-s\
ymmetric-keys}?
| | | | | +--rw hidden-sy\
mmetric-key?
| | | | | empty
| | | | +--:(encrypted-sym\
metric-key)
| | | | {encrypte\
d-symmetric-keys}?
| | | | +--rw encrypted\
-symmetric-key
| | | | +--rw encryp\
ted-by
| | | | +--rw encryp\
ted-value-format
| | | | | iden\
tityref
| | | | +--rw encryp\
ted-value
| | | | bina\
ry
| | | +--:(central-keystore)
| | | {central-keystore-\
supported,symmetric-keys}?
| | | +--rw central-keystore-r\
eference?
| | | ks:central-symme\
tric-key-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-supp\
orted}?
| | | | +--rw inline-definition
| | | | +--rw certificate* [name]
| | | | +--rw name
| | | | | string
| | | | +--rw cert-data
| | | | | trust-anchor-cer\
t-cms
| | | | +---n certificate-expira\
tion
| | | | {certificate-exp\
iration-notification}?
| | | | +-- expiration-date
| | | | yang:date-and\
-time
| | | +--:(central-truststore)
| | | {central-truststore-supp\
orted,certificates}?
| | | +--rw central-truststore-refer\
ence?
| | | ts:central-certificate\
-bag-ref
| | +--rw ee-certs! {server-auth-x509-cert}\
?
| | | +--rw (inline-or-truststore)
| | | +--:(inline)
| | | | {inline-definitions-supp\
orted}?
| | | | +--rw inline-definition
| | | | +--rw certificate* [name]
| | | | +--rw name
| | | | | string
| | | | +--rw cert-data
| | | | | trust-anchor-cer\
t-cms
| | | | +---n certificate-expira\
tion
| | | | {certificate-exp\
iration-notification}?
| | | | +-- expiration-date
| | | | yang:date-and\
-time
| | | +--:(central-truststore)
| | | {central-truststore-supp\
orted,certificates}?
| | | +--rw central-truststore-refer\
ence?
| | | ts:central-certificate\
-bag-ref
| | +--rw raw-public-keys!
| | | {server-auth-raw-public-key}?
| | | +--rw (inline-or-truststore)
| | | +--:(inline)
| | | | {inline-definitions-supp\
orted}?
| | | | +--rw inline-definition
| | | | +--rw public-key* [name]
| | | | +--rw name
| | | | | string
| | | | +--rw public-key-format
| | | | | identityref | | | | +--rw public-key
| | | | binary
| | | +--:(central-truststore)
| | | {central-truststore-supp\
orted,public-keys}?
| | | +--rw central-truststore-refer\
ence?
| | | ts:central-public-key-\
bag-ref
| | +--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-algo\
rithm
| +--rw keepalives {tls-client-keepalives}?
| +--rw peer-allowed-to-send? empty
| +--rw test-peer-aliveness!
| +--rw max-wait? uint16
| +--rw max-attempts? uint8
+--rw 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? binar\
y
| | +--rw private-key-format?
| | | identityref
| | +--rw (private-key-type)
| | | +--:(cleartext-private-key)
| | | | {cleartext-private-keys}?
| | | | +--rw cleartext-private-key? binar\
y
| | | +--:(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-notificati\
on}?
| | | +-- expiration-date
| | | yang:date-and-time
| | +---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
| +--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? uint32Appendix B. Implementer Guidelines ✨
B.1. Extending Facilities 🧚
Okay so a bunch of vendors add their own extra facilities to the list of stuff you can log under 💅. The catch is that these extras might not play nicely with the syslog protocol defined in [RFC5424] 🙈. So they're really meant for local syslog-like logging, lowkey.
Here's an example showing how you could add extra facilities to the list. This one adds two 🦋:
module example-vendor-syslog-types {
namespace "http://example.com/ns/vendor-syslog-types";
prefix vendor-syslogtypes;
import ietf-syslog {
prefix syslog;
}
organization
"Example, Inc.";
contact
"Example, Inc.
Customer Service
Email: syslog-yang@example.com";
description
"This module contains a collection of vendor-specific YANG type
definitions for Syslog.";
revision 2025-04-30 {
description
"Version 1.0";
reference
"Vendor Syslog Types: Syslog YANG Module";
}
identity vendor_specific_type_1 {
base syslog:syslog-facility;
description
"Adding vendor-specific type 1 to syslog-facility";
}
identity vendor_specific_type_2 {
base syslog:syslog-facility;
description
"Adding vendor-specific type 2 to syslog-facility";
}
}B.2. Syslog Terminal Output 🖥️
Terminal output that needs fancier requirements than the console subtree currently gives you is expected to be supported through vendor extensions, not handled through the file subtree. That's a main character move 👑.
B.3. Syslog File Naming Convention 🗂️
The syslog/file/log-file/file-rotation container holds the config params for syslog file rotation 🌸. This section walks through how an implementer might use those fields to name syslog files during a rotation. Just so you know, it's an informative guide only 🫶.
When an active syslog file with a name set by log-file/name hits log-file/max-file-size and/or syslog events show up after the period set by log-file/rollover, the logging system can close the file, compress it, and name the archive <log-file/name>.0.gz. The logging system can then open a new active syslog file called <log-file/name>.
When the new syslog file hits either of the size limits mentioned above, <log-file/name>.0.gz can be renamed to <log-file/name>.1.gz, and the new syslog file can be closed, compressed, and renamed <log-file/name>.0.gz. Every time a new syslog file gets closed, each of the older archive files named <log-file/name>.<n>.gz can be renamed to <log-file/name>.<n + 1>.gz.
Removing archive log files could happen when either or both of these are set:
log-file/number-of-filesis specified. The logging system can create up tolog-file/number-of-filessyslog archive files, and after that the contents of the oldest archived file could be overwritten.log-file/retentionis specified. The logging system can remove those syslog archive files whose file expiration time (file creation time plus the specifiedlog-file/retentiontime) is earlier than the current time.
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 🌈.
Authors' Addresses 💌
Joe Clarke (editor)
Cisco
United States of America
Email: jclarke@cisco.comMahesh Jethanandani (editor)
Kloud Services
United States of America
Email: mjethanandani@gmail.comClyde 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.comKiran 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📦 where this page comes from
- ietf: rfc9742 2025-04
- 💖 girlified by claude-haiku-5-5 on : a language model's rewrite of the original, under its terms