NETMOD WG C. Wildes, Ed.
Internet-Draft Cisco Systems Inc.
Intended status: Standards Track K. Koushik, Ed.
Expires: September 14, 2018 Verizon Wireless
March 15, 2018
A YANG Data Model for Syslog Configuration
draft-ietf-netmod-syslog-model-26
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 http://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 September 14, 2018.
Copyright Notice
Copyright (c) 2018 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 (http://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 Simplified BSD License text
as described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 2
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
1.3. NDMA Compliance . . . . . . . . . . . . . . . . . . . . . 3
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1.4. Editorial Note (To be removed by RFC Editor) . . . . . . . 3
2. Design of the Syslog Model . . . . . . . . . . . . . . . . . . 3
2.1. Syslog Module . . . . . . . . . . . . . . . . . . . . . . 5
3. Syslog YANG Module . . . . . . . . . . . . . . . . . . . . . . 7
3.1. The ietf-syslog Module . . . . . . . . . . . . . . . . . . 8
4. Usage Examples . . . . . . . . . . . . . . . . . . . . . . . . 25
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 25
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 26
6.1. The IETF XML Registry . . . . . . . . . . . . . . . . . . 26
6.2. The YANG Module Names Registry . . . . . . . . . . . . . . 26
7. Security Considerations . . . . . . . . . . . . . . . . . . . 26
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 27
8.1. Normative References . . . . . . . . . . . . . . . . . . . 27
8.2. Informative References . . . . . . . . . . . . . . . . . . 29
Appendix A. Implementer Guidelines . . . . . . . . . . . . . . . . 29
Appendix A.1. Extending Facilities . . . . . . . . . . . . . . 29
Appendix A.2. Syslog Terminal Output . . . . . . . . . . . . . 30
Appendix A.3. Syslog File Naming Convention . . . . . . . . . . 30
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 31
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.
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 [draft-ietf-netmod-revised-
datastores].
1.1. Requirements Language
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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.
1.2. 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.
1.3. NDMA Compliance
The YANG model in this document conforms to the Network Management
Datastore Architecture defined in I-D.ietf-netmod-revised-datastores
[I-D.ietf-netmod-revised-datastores].
1.4. 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:
o "I-D.ietf-netconf-keystore" --> the assigned RFC value for draft-
ietf-netconf-keystore
o "I-D.ietf-netconf-tls-client-server" --> the assigned RFC value
for draft-ietf-netconf-tls-client-server
o "zzzz" --> the assigned RFC value for this draft
o I-D.ietf-netmod-revised-datastores --> the assigned RFC value for
draft-ietf-netmod-revised-datastores
2. Design of the Syslog Model
The syslog model was designed by comparing various syslog features
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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.
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)
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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:
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 or block 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).
2.1. Syslog Module
A simplified graphical representation of the data model is used in
this document. Please see [I-D.ietf-netmod-yang-tree-diagrams] for
tree diagram notation.
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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? enumeration
| +--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
| | +--rw advanced-compare {select-adv-compare}?
| | +--rw compare? enumeration
| | +--rw action? enumeration
| +--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-auth
| | +--rw (auth-type)?
| | +--:(certificate)
| | +--rw certificate? leafref
| +--rw server-auth
| | +--rw pinned-ca-certs? leafref
| | +--rw pinned-server-certs? leafref
| +--rw hello-params
| {tls-client-hello-params-config}?
| +--rw tls-versions
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| | +--rw tls-version* identityref
| +--rw cipher-suites
| +--rw cipher-suite* identityref
+--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? enumeration
+--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 algorithm?
| | | identityref
| | +--rw private-key?
| | | union
| | +--rw public-key?
| | | binary
| | +---x generate-private-key
| | | +---w input
| | | +---w algorithm?
| | | identityref
| | +--rw certificates
| | | +--rw certificate* [name]
| | | +--rw name string
| | | +--rw value? binary
| | +---x generate-certificate-signing-request
| | +---w input
| | | +---w subject binary
| | | +---w attributes? binary
| | +--ro output
| | +--ro certificate-signing-request
| | binary
| +--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 2. ietf-syslog Module Tree
3. Syslog YANG Module
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3.1. The ietf-syslog Module
This module imports typedefs from [RFC6991],
[I-D.ietf-netmod-rfc7223bis], groupings from
[I-D.ietf-netconf-keystore], and
[I-D.ietf-netconf-tls-client-server], and it references [RFC5424],
[RFC5425], [RFC5426], [RFC5848], [RFC8089], [RFC8174], and
[Std-1003.1-2008].
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<CODE BEGINS> file "ietf-syslog@2018-03-15.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
"I-D.ietf-netmod-rfc7223bis: 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";
}
import ietf-keystore {
prefix ks;
reference
"I-D.ietf-netconf-keystore: YANG Data Model for a
Keystore Mechanism";
}
organization
"IETF NETMOD (Network Modeling) Working Group";
contact
"WG Web: <http://tools.ietf.org/wg/netmod/>
WG List: <mailto:netmod@ietf.org>
Editor: Kiran Agrahara Sreenivasa
<mailto:kirankoushik.agraharasreenivasa@
verizonwireless.com>
Editor: Clyde Wildes
<mailto:cwildes@cisco.com>";
description
"This module contains a collection of YANG definitions
for syslog configuration.
Copyright (c) 2018 IETF Trust and the persons identified as
authors of the code. All rights reserved.
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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 Simplified BSD License set
forth in Section 4.c of the IETF Trust's Legal Provisions
Relating to IETF Documents
(http://trustee.ietf.org/license-info).
The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL
NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'MAY', and
'OPTIONAL' in the module text are to be interpreted as
described in RFC 2119 (http://tools.ietf.org/html/rfc2119).
This version of this YANG module is part of RFC zzzz
(http://tools.ietf.org/html/rfczzzz); see the RFC itself for
full legal notices.";
revision 2018-03-15 {
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.";
}
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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
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.";
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}
enum "error" {
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 {
base syslog-facility;
description
"The facility for kernel messages (0).";
reference
"RFC 5424: The Syslog Protocol";
}
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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";
}
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).";
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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";
}
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 {
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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";
}
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";
}
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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";
}
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.";
}
}
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}
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 enumeration {
enum log {
description
"This enum specifies that if the compare operation is
true the message will be logged.";
}
enum block {
description
"This enum specifies that if the compare operation is
true the message will not be logged.";
}
}
default log;
description
"The action can be used to specify if the message should
be logged or blocked based on the outcome of the compare
operation.";
}
description
"This container describes additional severity compare
operations that can be used in place of the default
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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.";
}
}
}
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
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"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 {
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 {
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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.";
}
}
}
}
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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";
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 ";
leaf address {
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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";
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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 ks:private-key-grouping;
uses ks:certificate-grouping;
description
"This is the certificate that is periodically
sent to the remote receiver. Selection of the
certificate also implicitly selects the private
key used to sign the syslog messages.";
}
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;
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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 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.";
}
}
}
}
}
}
}
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}
<CODE ENDS>
Figure 3. ietf-syslog Module
4. Usage Examples
Requirement:
Enable console logging of syslogs of severity critical
<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>
Enable remote logging of syslogs to udp destination
foo.example.com for facility auth, severity error
<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. ietf-syslog Examples
5. Acknowledgements
The authors wish to thank the following who commented on this
proposal:
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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.
6. IANA Considerations
6.1. 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:
URI: urn:ietf:params:xml:ns:yang:ietf-syslog
Registrant Contact: The IESG.
XML: N/A, the requested URI is an XML namespace.
6.2. The YANG Module Names Registry
This document registers one YANG module in the YANG Module Names
registry [RFC7895]. 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
7. 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) [RFC6536] provides the means
to restrict access for particular users to a pre-configured subset of
all available protocol operations and content.
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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).
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.
8. References
8.1. Normative References
[I-D.ietf-netconf-keystore]
Watsen, K., "YANG Data Model for a "Keystore" Mechanism",
Internet-Draft draft-ietf-netconf-keystore-04, October
2017.
[I-D.ietf-netconf-tls-client-server]
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Watsen, K. and G. Wu, "YANG Groupings for TLS Clients and
TLS Servers", Internet-Draft draft-ietf-netconf-tls-
client-server-05, October 2017.
[I-D.ietf-netmod-rfc7223bis]
Bjorklund, M., "A YANG Data Model for Interface
Management", Internet-Draft draft-ietf-netmod-
rfc7223bis-03, January 2018.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/
RFC2119, March 1997, <http://www.rfc-editor.org/info/
rfc2119>.
[RFC5424] Gerhards, R., "The Syslog Protocol", RFC 5424, DOI
10.17487/RFC5424, March 2009, <http://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, <http://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,
<http://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>.
[RFC7895] Bierman, A., Bjorklund, M. and K. Watsen, "YANG Module
Library", RFC 7895, DOI 10.17487/RFC7895, June 2016,
<http://www.rfc-editor.org/info/rfc7895>.
[RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
RFC 7950, DOI 10.17487/RFC7950, August 2016, <http://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, <http://www.rfc-editor.org/info/rfc8174>.
[Std-1003.1-2008]
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The Open Group, ""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/>.
8.2. Informative References
[I-D.ietf-netmod-revised-datastores]
Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K.
and R. Wilton, "Network Management Datastore
Architecture", Internet-Draft draft-ietf-netmod-revised-
datastores-10, January 2018.
[I-D.ietf-netmod-yang-tree-diagrams]
Bjorklund, M. and L. Berger, "YANG Tree Diagrams",
Internet-Draft draft-ietf-netmod-yang-tree-diagrams-06,
February 2018.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004, <http://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,
<http://www.rfc-editor.org/info/rfc6241>.
[RFC6536] Bierman, A. and M. Bjorklund, "Network Configuration
Protocol (NETCONF) Access Control Model", RFC 6536, DOI
10.17487/RFC6536, March 2012, <https://www.rfc-editor.org/
info/rfc6536>.
[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>.
Appendix A. Implementer Guidelines
Appendix 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):
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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";
}
}
Appendix 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.
Appendix 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.
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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
Clyde Wildes, editor
Cisco Systems Inc.
170 West Tasman Drive
San Jose, CA 95134
US
Phone: +1 408 527-2672
Email: cwildes@cisco.com
Kiran Koushik, editor
Verizon Wireless
500 W Dove Rd.
Southlake, TX 76092
US
Phone: +1 512 650-0210
Email: kirankoushik.agraharasreenivasa@verizonwireless.com
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