NETMOD WG J. Clarke, Ed. Internet-Draft Cisco Intended status: Standards Track M. Jethanandani, Ed. Expires: 14 April 2023 Kloud Services C. Wildes, Ed. Cisco Systems Inc. K. Koushik, Ed. Verizon Wireless 11 October 2022 A YANG Data Model for Syslog Configuration draft-ietf-netmod-syslog-model-28 Abstract This document defines a YANG data model for the configuration of a syslog process. It is intended this model be used by vendors who implement syslog in their systems. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on 14 April 2023. Copyright Notice Copyright (c) 2022 IETF Trust and the persons identified as the document authors. All rights reserved. Clarke, et al. Expires 14 April 2023 [Page 1] Internet-Draft Syslog Management October 2022 This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/ license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. NDMA Compliance . . . . . . . . . . . . . . . . . . . . . . . 3 4. Editorial Note (To be removed by RFC Editor) . . . . . . . . 4 5. Design of the Syslog Model . . . . . . . . . . . . . . . . . 4 5.1. Syslog Module . . . . . . . . . . . . . . . . . . . . . . 6 6. Syslog YANG Module . . . . . . . . . . . . . . . . . . . . . 14 6.1. The ietf-syslog Module . . . . . . . . . . . . . . . . . 14 7. Usage Examples . . . . . . . . . . . . . . . . . . . . . . . 32 7.1. Syslog Configuration for Severity Critical . . . . . . . 32 7.2. Remote Syslog Configuration . . . . . . . . . . . . . . . 33 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 34 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 34 9.1. The IETF XML Registry . . . . . . . . . . . . . . . . . . 34 9.2. The YANG Module Names Registry . . . . . . . . . . . . . 35 10. Security Considerations . . . . . . . . . . . . . . . . . . . 35 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 36 11.1. Normative References . . . . . . . . . . . . . . . . . . 36 11.2. Informative References . . . . . . . . . . . . . . . . . 37 Appendix A. Implementer Guidelines . . . . . . . . . . . . . . . 38 A.1. Extending Facilities . . . . . . . . . . . . . . . . . . 38 A.2. Syslog Terminal Output . . . . . . . . . . . . . . . . . 39 A.3. Syslog File Naming Convention . . . . . . . . . . . . . . 40 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 40 1. Introduction This document defines a YANG [RFC7950] configuration data model that may be used to configure the syslog feature running on a system. YANG models can be used with network management protocols such as NETCONF [RFC6241] to install, manipulate, and delete the configuration of network devices. The data model makes use of the YANG "feature" construct which allows implementations to support only those syslog features that lie within their capabilities. Clarke, et al. Expires 14 April 2023 [Page 2] Internet-Draft Syslog Management October 2022 This module can be used to configure the syslog application conceptual layers as implemented on the target system. Essentially, a syslog process receives messages (from the kernel, processes, applications or other syslog processes) and processes them. The processing may involve logging to a local file, and/or displaying on console, and/or relaying to syslog processes on other machines. The processing is determined by the "facility" that originated the message and the "severity" assigned to the message by the facility. Such definitions of syslog protocol are defined in [RFC5424], and are used in this RFC. The YANG model in this document conforms to the Network Management Datastore Architecture defined in [RFC8342]. 1.1. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. 2. Terminology The term "originator" is defined in [RFC5424]: an "originator" generates syslog content to be carried in a message. The term "relay" is defined in [RFC5424]: a "relay" forwards messages, accepting messages from originators or other relays and sending them to collectors or other relays The term "collectors" is defined in [RFC5424]: a "collector" gathers syslog content for further analysis. The term "action" refers to the processing that takes place for each syslog message received. 3. NDMA Compliance The YANG model in this document conforms to the Network Management Datastore Architecture defined in [RFC8342]. Clarke, et al. Expires 14 April 2023 [Page 3] Internet-Draft Syslog Management October 2022 4. Editorial Note (To be removed by RFC Editor) This document contains many placeholder values that need to be replaced with finalized values at the time of publication. This note summarizes all of the substitutions that are needed. No other RFC Editor instructions are specified elsewhere in this document. Artwork in this document contains shorthand references to drafts in progress. Please apply the following replacements: * I-D.ietf-netconf-crypto-types --> the assigned RFC value for draft-ietf-netconf-crypto-types * I-D.ietf-netconf-tls-client-server --> the assigned RFC value for draft-ietf-netconf-tls-client-server * zzzz --> the assigned RFC value for this draft 5. Design of the Syslog Model The syslog model was designed by comparing various syslog features implemented by various vendors' in different implementations. This document addresses the common leafs between implementations and creates a common model, which can be augmented with proprietary features, if necessary. This model is designed to be very simple for maximum flexibility. Some optional features are defined in this document to specify functionality that is present in specific vendor configurations. Syslog consists of originators and collectors. The following diagram shows syslog messages flowing from originators, to collectors where filtering can take place. Clarke, et al. Expires 14 April 2023 [Page 4] Internet-Draft Syslog Management October 2022 Originators +-------------+ +-------------+ +-------------+ +-------------+ | Various | | OS | | | | Remote | | Components | | Kernel | | Line Cards | | Servers | +-------------+ +-------------+ +-------------+ +-------------+ +-------------+ +-------------+ +-------------+ +-------------+ | SNMP | | Interface | | Standby | | Syslog | | Events | | Events | | Supervisor | | Itself | +-------------+ +-------------+ +-------------+ +-------------+ | | +----------------------------------------------------------------+ | | | | +-------------+--------------+ | | | v v v Collectors +----------+ +----------+ +----------------+ | | | Log | |Remote Relay(s)/| | Console | | File(s) | |Collector(s) | +----------+ +----------+ +----------------+ Figure 1. Syslog Processing Flow Collectors are configured using the leaves in the syslog model "actions" container which correspond to each message collector: console log file(s) remote relay(s)/collector(s) Within each action, a selector is used to filter syslog messages. A selector consists of a list of one or more filters specified by facility-severity pairs, and, if supported via the select-match feature, an optional regular expression pattern match that is performed on the [RFC5424] field. A syslog message is processed if: Clarke, et al. Expires 14 April 2023 [Page 5] Internet-Draft Syslog Management October 2022 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). 5.1. Syslog Module A simplified graphical representation of the data model is used in this document. Please see [RFC8340] for tree diagram notation. module: ietf-syslog +--rw syslog! +--rw actions +--rw console! {console-action}? | +--rw facility-filter | | +--rw facility-list* [facility severity] | | +--rw facility union | | +--rw severity union | | +--rw advanced-compare {select-adv-compare}? | | +--rw compare? enumeration | | +--rw action? 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}? Clarke, et al. Expires 14 April 2023 [Page 6] Internet-Draft Syslog Management October 2022 | | +--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-identity! | | +--rw (auth-type) | | +--:(certificate) | | | {client-ident-x509-cert}? | | | +--rw certificate | | | +--rw (local-or-keystore) | | | +--:(local) | | | | {local-definitions-suppo rted,asymmetric-keys}? | | | | +--rw local-definition | | | | +--rw public-key-format | | | | | identityref | | | | +--rw public-key | | | | | binary | | | | +--rw private-key-format? | | | | | identityref | | | | +--rw (private-key-type) | | | | | +--:(cleartext-private-k ey) | | | | | | +--rw cleartext-priva te-key? | | | | | | binary | | | | | +--:(hidden-private-key) | | | | | | {hidden-keys}? Clarke, et al. Expires 14 April 2023 [Page 7] Internet-Draft Syslog Management October 2022 | | | | | | +--rw hidden-private- key? | | | | | | empty | | | | | +--:(encrypted-private-k ey) | | | | | {private-key-en cryption}? | | | | | +--rw encrypted-priva te-key | | | | | +--rw encrypted-by | | | | | +--rw encrypted-va lue-format | | | | | | identityre f | | | | | +--rw encrypted-va lue | | | | | binary | | | | +--rw cert-data? | | | | | end-entity-cert-cms | | | | +---n certificate-expiratio n | | | | | {certificate-expira tion-notification}? | | | | | +-- expiration-date | | | | | yang:date-and-ti me | | | | +---x generate-certificate- signing-request | | | | {certificate-signin g-request-generation}? | | | | +---w input | | | | | +---w csr-info | | | | | ct:csr-info | | | | +--ro output | | | | +--ro certificate-sig ning-request | | | | ct:csr | | | +--:(keystore) | | | {central-keystore-suppor ted,asymmetric-keys}? | | | +--rw keystore-reference | | | +--rw asymmetric-key? | | | | ks:asymmetric-key-r ef | | | | {central-keystore-s upported,asymmetric-keys}? | | | +--rw certificate? lea fref Clarke, et al. Expires 14 April 2023 [Page 8] Internet-Draft Syslog Management October 2022 | | +--:(raw-public-key) | | | {client-ident-raw-public-key}? | | | +--rw raw-private-key | | | +--rw (local-or-keystore) | | | +--:(local) | | | | {local-definitions-suppo rted,asymmetric-keys}? | | | | +--rw local-definition | | | | +--rw public-key-format | | | | | identityref | | | | +--rw public-key | | | | | binary | | | | +--rw private-key-format? | | | | | identityref | | | | +--rw (private-key-type) | | | | +--:(cleartext-private-k ey) | | | | | +--rw cleartext-priva te-key? | | | | | binary | | | | +--:(hidden-private-key) | | | | | {hidden-keys}? | | | | | +--rw hidden-private- key? | | | | | empty | | | | +--:(encrypted-private-k ey) | | | | {private-key-en cryption}? | | | | +--rw encrypted-priva te-key | | | | +--rw encrypted-by | | | | +--rw encrypted-va lue-format | | | | | identityre f | | | | +--rw encrypted-va lue | | | | binary | | | +--:(keystore) | | | {central-keystore-suppor ted,asymmetric-keys}? | | | +--rw keystore-reference? | | | ks:asymmetric-key-ref | | +--:(tls12-psk) | | | {client-ident-tls12-psk}? | | | +--rw tls12-psk | | | +--rw (local-or-keystore) Clarke, et al. Expires 14 April 2023 [Page 9] Internet-Draft Syslog Management October 2022 | | | | +--:(local) | | | | | {local-definitions-suppo rted,symmetric-keys}? | | | | | +--rw local-definition | | | | | +--rw key-format? | | | | | | identityref | | | | | +--rw (key-type) | | | | | +--:(cleartext-key) | | | | | | +--rw cleartext-key? | | | | | | binary | | | | | +--:(hidden-key) | | | | | | {hidden-keys}? | | | | | | +--rw hidden-key? | | | | | | empty | | | | | +--:(encrypted-key) | | | | | {symmetric-key- encryption}? | | | | | +--rw encrypted-key | | | | | +--rw encrypted-by | | | | | +--rw encrypted-va lue-format | | | | | | identityre f | | | | | +--rw encrypted-va lue | | | | | binary | | | | +--:(keystore) | | | | {central-keystore-suppor ted,symmetric-keys}? | | | | +--rw keystore-reference? | | | | ks:symmetric-key-ref | | | +--rw id? | | | string | | +--:(tls13-epsk) | | {client-ident-tls13-epsk}? | | +--rw tls13-epsk | | +--rw (local-or-keystore) | | | +--:(local) | | | | {local-definitions-suppo rted,symmetric-keys}? | | | | +--rw local-definition | | | | +--rw key-format? | | | | | identityref | | | | +--rw (key-type) | | | | +--:(cleartext-key) | | | | | +--rw cleartext-key? | | | | | binary | | | | +--:(hidden-key) Clarke, et al. Expires 14 April 2023 [Page 10] Internet-Draft Syslog Management October 2022 | | | | | {hidden-keys}? | | | | | +--rw hidden-key? | | | | | empty | | | | +--:(encrypted-key) | | | | {symmetric-key- encryption}? | | | | +--rw encrypted-key | | | | +--rw encrypted-by | | | | +--rw encrypted-va lue-format | | | | | identityre f | | | | +--rw encrypted-va lue | | | | binary | | | +--:(keystore) | | | {central-keystore-suppor ted,symmetric-keys}? | | | +--rw keystore-reference? | | | ks:symmetric-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 (local-or-truststore) | | | +--:(local) | | | | {local-definitions-supported}? | | | | +--rw local-definition | | | | +--rw certificate* [name] | | | | +--rw name | | | | | string | | | | +--rw cert-data | | | | | trust-anchor-cert-cms | | | | +---n certificate-expiration | | | | {certificate-expiratio n-notification}? | | | | +-- expiration-date | | | | yang:date-and-time | | | +--:(truststore) | | | {central-truststore-supported, Clarke, et al. Expires 14 April 2023 [Page 11] Internet-Draft Syslog Management October 2022 certificates}? | | | +--rw truststore-reference? | | | ts:certificate-bag-ref | | +--rw ee-certs! {server-auth-x509-cert}? | | | +--rw (local-or-truststore) | | | +--:(local) | | | | {local-definitions-supported}? | | | | +--rw local-definition | | | | +--rw certificate* [name] | | | | +--rw name | | | | | string | | | | +--rw cert-data | | | | | trust-anchor-cert-cms | | | | +---n certificate-expiration | | | | {certificate-expiratio n-notification}? | | | | +-- expiration-date | | | | yang:date-and-time | | | +--:(truststore) | | | {central-truststore-supported, certificates}? | | | +--rw truststore-reference? | | | ts:certificate-bag-ref | | +--rw raw-public-keys! | | | {server-auth-raw-public-key}? | | | +--rw (local-or-truststore) | | | +--:(local) | | | | {local-definitions-supported}? | | | | +--rw local-definition | | | | +--rw public-key* [name] | | | | +--rw name | | | | | string | | | | +--rw public-key-format | | | | | identityref | | | | +--rw public-key | | | | binary | | | +--:(truststore) | | | {central-truststore-supported, public-keys}? | | | +--rw truststore-reference? | | | ts: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 tls-version* identityref Clarke, et al. Expires 14 April 2023 [Page 12] Internet-Draft Syslog Management October 2022 | | +--rw cipher-suites | | +--rw cipher-suite* identityref | +--rw keepalives {tls-client-keepalives}? | +--rw peer-allowed-to-send? empty | +--rw test-peer-aliveness! | +--rw max-wait? uint16 | +--rw max-attempts? uint8 +--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 public-key-format | | | identityref | | +--rw public-key | | | binary | | +--rw private-key-format? | | | identityref | | +--rw (private-key-type) | | | +--:(cleartext-private-key) | | | | +--rw cleartext-private-key? | | | | binary | | | +--:(hidden-private-key) {hidden-keys}? | | | | +--rw hidden-private-key? | | | | empty | | | +--:(encrypted-private-key) | | | {private-key-encryption}? | | | +--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 Clarke, et al. Expires 14 April 2023 [Page 13] Internet-Draft Syslog Management October 2022 | | | {certificate-expiration-notification} ? | | | +-- expiration-date | | | yang:date-and-time | | +---x generate-certificate-signing-request | | {certificate-signing-request-generati on}? | | +---w input | | | +---w csr-info ct:csr-info | | +--ro output | | +--ro certificate-signing-request | | ct:csr | +--rw hash-algorithm? enumeration +--rw cert-initial-repeat? uint32 +--rw cert-resend-delay? uint32 +--rw cert-resend-count? uint32 +--rw sig-max-delay? uint32 +--rw sig-number-resends? uint32 +--rw sig-resend-delay? uint32 +--rw sig-resend-count? uint32 Figure 1: Tree Diagram for Syslog Model 6. Syslog YANG Module 6.1. The ietf-syslog Module This module imports typedefs from [RFC6991], [RFC8343], groupings from [I-D.ietf-netconf-crypto-types], and [I-D.ietf-netconf-tls-client-server], and it references [RFC5424], [RFC5425], [RFC5426], and [RFC5848], [RFC8089], [RFC8174], and [Std-1003.1-2008]. file "ietf-syslog@2022-10-11.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"; Clarke, et al. Expires 14 April 2023 [Page 14] Internet-Draft Syslog Management October 2022 } import ietf-tls-client { prefix tlsc; reference "I-D.ietf-netconf-tls-client-server: YANG Groupings for TLS Clients and TLS Servers"; } import ietf-crypto-types { prefix ct; reference "I-D.ietf-netconf-crypto-types: YANG Data Types for Cryptography"; } organization "IETF NETMOD (Network Modeling) Working Group"; contact "WG Web: WG List: Editor: Mahesh Jethanandani Editor: Joe Clarke Editor: Kiran Agrahara Sreenivasa Editor: Clyde Wildes "; description "This module contains a collection of YANG definitions for syslog configuration. Copyright (c) 2022 IETF Trust and the persons identified as authors of the code. All rights reserved. Redistribution and use in source and binary forms, with or without modification, is permitted pursuant to, and subject to the license terms contained in, the Revised BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info). This version of this YANG module is part of RFC zzzz (https://www.rfc-editor.org/info/rfczzzz); see the RFC itself Clarke, et al. Expires 14 April 2023 [Page 15] Internet-Draft Syslog Management October 2022 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 2022-10-11 { description "Initial Revision"; reference "RFC zzzz: Syslog YANG Model"; } feature console-action { description "This feature indicates that the local console action is supported."; } feature file-action { description "This feature indicates that the local file action is supported."; } feature file-limit-size { description "This feature indicates that file logging resources are managed using size and number limits."; } feature file-limit-duration { description "This feature indicates that file logging resources are managed using time based limits."; } feature remote-action { description "This feature indicates that the remote server action is supported."; } feature remote-source-interface { description "This feature indicates that source-interface is supported Clarke, et al. Expires 14 April 2023 [Page 16] Internet-Draft Syslog Management October 2022 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; Clarke, et al. Expires 14 April 2023 [Page 17] Internet-Draft Syslog Management October 2022 description "The severity level 'Critical' indicating a critical condition."; } 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"; Clarke, et al. Expires 14 April 2023 [Page 18] Internet-Draft Syslog Management October 2022 } identity kern { base syslog-facility; description "The facility for kernel messages (0)."; reference "RFC 5424: The Syslog Protocol"; } identity user { base syslog-facility; description "The facility for user-level messages (1)."; reference "RFC 5424: The Syslog Protocol"; } identity mail { base syslog-facility; description "The facility for the mail system (2)."; reference "RFC 5424: The Syslog Protocol"; } identity daemon { base syslog-facility; description "The facility for the system daemons (3)."; reference "RFC 5424: The Syslog Protocol"; } identity auth { base syslog-facility; description "The facility for security/authorization messages (4)."; reference "RFC 5424: The Syslog Protocol"; } identity syslog { base syslog-facility; description "The facility for messages generated internally by syslogd facility (5)."; reference Clarke, et al. Expires 14 April 2023 [Page 19] Internet-Draft Syslog Management October 2022 "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)."; 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)."; Clarke, et al. Expires 14 April 2023 [Page 20] Internet-Draft Syslog Management October 2022 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 { 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)."; Clarke, et al. Expires 14 April 2023 [Page 21] Internet-Draft Syslog Management October 2022 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"; } 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)."; Clarke, et al. Expires 14 April 2023 [Page 22] Internet-Draft Syslog Management October 2022 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."; } } } 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 { Clarke, et al. Expires 14 April 2023 [Page 23] Internet-Draft Syslog Management October 2022 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 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."; } } Clarke, et al. Expires 14 April 2023 [Page 24] Internet-Draft Syslog Management October 2022 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 [ ...] 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 "RFC 5424: The Syslog Protocol Std-1003.1-2008 Regular Expressions"; } Clarke, et al. Expires 14 April 2023 [Page 25] Internet-Draft Syslog Management October 2022 } 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 Clarke, et al. Expires 14 April 2023 [Page 26] Internet-Draft Syslog Management October 2022 "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; Clarke, et al. Expires 14 April 2023 [Page 27] Internet-Draft Syslog Management October 2022 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"; 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"; Clarke, et al. Expires 14 April 2023 [Page 28] Internet-Draft Syslog Management October 2022 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 { 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 Clarke, et al. Expires 14 April 2023 [Page 29] Internet-Draft Syslog Management October 2022 "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 inherintly associated with its private and public keys."; } leaf hash-algorithm { type enumeration { enum SHA1 { value 1; description "This enum describes the SHA1 algorithm."; } enum SHA256 { value 2; description Clarke, et al. Expires 14 April 2023 [Page 30] Internet-Draft Syslog Management October 2022 "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 Clarke, et al. Expires 14 April 2023 [Page 31] Internet-Draft Syslog Management October 2022 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."; } } } } } } } } Figure 2: Sylog YANG Model 7. Usage Examples 7.1. Syslog Configuration for Severity Critical Clarke, et al. Expires 14 April 2023 [Page 32] Internet-Draft Syslog Management October 2022 [note: '\' line wrapping for formatting only] all critical Figure 3: Syslog Configuration for Severity Critical 7.2. Remote Syslog Configuration Clarke, et al. Expires 14 April 2023 [Page 33] Internet-Draft Syslog Management October 2022 [note: '\' line wrapping for formatting only] remote1
foo.example.com
 auth error Figure 4: Remote Syslog Configuration 8. Acknowledgements The authors wish to thank the following who commented on this proposal: Andy Bierman, Martin Bjorklund, Alex Campbell, Alex Clemm, Francis Dupont, Jim Gibson, Jeffrey Haas, Bob Harold, John Heasley, Giles Heron, Lisa Huang, Mahesh Jethanandani, Warren Kumari, Jeffrey K Lange, Jan Lindblad, Chris Lonvick, Alexey Melnikov, Kathleen Moriarty, Tom Petch, Adam Roach, Juergen Schoenwaelder, Phil Shafer, Yaron Sheffer, Jason Sterne, Peter Van Horne, Kent Watsen, Bert Wijnen, Dale R Worley, and Aleksandr Zhdankin. 9. IANA Considerations 9.1. The IETF XML Registry This document registers one URI in the IETF XML registry [RFC3688] . Following the format in [RFC3688], the following registration is requested: Clarke, et al. Expires 14 April 2023 [Page 34] Internet-Draft Syslog Management October 2022 URI: urn:ietf:params:xml:ns:yang:ietf-syslog Registrant Contact: The IESG. XML: N/A, the requested URI is an XML namespace. 9.2. The YANG Module Names Registry This document registers one YANG module in the YANG Module Names registry [RFC8525]. Following the format in [RFC7950], the following registration is requested: name: ietf-syslog namespace: urn:ietf:params:xml:ns:yang:ietf-syslog prefix: ietf-syslog reference: RFC zzzz 10. Security Considerations The YANG module defined in this document is designed to be accessed via YANG based management protocols, such as NETCONF [RFC6241] and RESTCONF [RFC8040]. Both of these protocols have mandatory-to- implement secure transport layers (e.g., SSH, TLS) with mutual authentication. The NETCONF access control model (NACM) [RFC8341] provides the means to restrict access for particular users to a pre-configured subset of all available protocol operations and content. There are a number of data nodes defined in this YANG module that are writable/creatable/deletable (i.e., config true, which is the default). These data nodes should be considered sensitive or vulnerable in all network environments. Logging in particular is used to assess the state of systems and can be used to indicate a network compromise. If logging were to be disabled through malicious means, attacks may not be readily detectable. Therefore write operations (e.g., edit-config) to these data nodes without proper protection can have a negative effect on network operations and on network security. In addition there are data nodes that require careful analysis and review. These are the subtrees and data nodes and their sensitivity/ vulnerability: facility-filter/pattern-match: When writing this node, implementations MUST ensure that the regular expression pattern match is not constructed to cause a regular expression denial of service attack due to a pattern that causes the regular expression implementation to work very slowly (exponentially related to input size). Clarke, et al. Expires 14 April 2023 [Page 35] Internet-Draft Syslog Management October 2022 remote/destination/signing/cert-signer: When writing this subtree, implementations MUST NOT specify a private key that is used for any other purpose. Some of the readable data nodes in this YANG module may be considered sensitive or vulnerable in some network environments. It is thus important to control read access (e.g., via get, get-config, or notification) to these data nodes. These are the subtrees and data nodes and their sensitivity/vulnerability: remote/destination/transport: This subtree contains information about other hosts in the network, and the TLS transport certificate properties if TLS is selected as the transport protocol. remote/destination/signing: This subtree contains information about the syslog message signing properties including signing certificate information. There are no RPC operations defined in this YANG module. 11. References 11.1. Normative References [I-D.ietf-netconf-crypto-types] Watsen, K., "YANG Data Types and Groupings for Cryptography", Work in Progress, Internet-Draft, draft- ietf-netconf-crypto-types-24, 7 July 2022, . [I-D.ietf-netconf-tls-client-server] Watsen, K., "YANG Groupings for TLS Clients and TLS Servers", Work in Progress, Internet-Draft, draft-ietf- netconf-tls-client-server-30, 30 August 2022, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC5424] Gerhards, R., "The Syslog Protocol", RFC 5424, DOI 10.17487/RFC5424, March 2009, . Clarke, et al. Expires 14 April 2023 [Page 36] Internet-Draft Syslog Management October 2022 [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, . [RFC5426] Okmianski, A., "Transmission of Syslog Messages over UDP", RFC 5426, DOI 10.17487/RFC5426, March 2009, . [RFC5848] Kelsey, J., Callas, J., and A. Clemm, "Signed Syslog Messages", RFC 5848, DOI 10.17487/RFC5848, May 2010, . [RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types", RFC 6991, DOI 10.17487/RFC6991, July 2013, . [RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, August 2016, . [RFC8089] Kerwin, M., "The "file" URI Scheme", RFC 8089, DOI 10.17487/RFC8089, February 2017, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC8343] Bjorklund, M., "A YANG Data Model for Interface Management", RFC 8343, DOI 10.17487/RFC8343, March 2018, . [RFC8525] Bierman, A., Bjorklund, M., Schoenwaelder, J., Watsen, K., and R. Wilton, "YANG Library", RFC 8525, DOI 10.17487/RFC8525, March 2019, . [Std-1003.1-2008] Group, I. A. T. O., ""Chapter 9: Regular Expressions". The Open Group Base Specifications Issue 6, IEEE Std 1003.1-2008, 2016 Edition.", September 2016, . 11.2. Informative References Clarke, et al. Expires 14 April 2023 [Page 37] Internet-Draft Syslog Management October 2022 [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, January 2004, . [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, . [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017, . [RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams", BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018, . [RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration Access Control Model", STD 91, RFC 8341, DOI 10.17487/RFC8341, March 2018, . [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, . Appendix A. Implementer Guidelines A.1. Extending Facilities Many vendors extend the list of facilities available for logging in their implementation. Additional facilities may not work with the syslog protocol as defined in [RFC5424] and hence such facilities apply for local syslog-like logging functionality. The following is an example that shows how additional facilities could be added to the list of available facilities (in this example two facilities are added): Clarke, et al. Expires 14 April 2023 [Page 38] Internet-Draft Syslog Management October 2022 module example-vendor-syslog-types { namespace "http://example.com/ns/vendor-syslog-types"; prefix vendor-syslogtypes; import ietf-syslog { prefix syslogtypes; } organization "Example, Inc."; contact "Example, Inc. Customer Service E-mail: syslog-yang@example.com"; description "This module contains a collection of vendor-specific YANG type definitions for SYSLOG."; revision 2017-08-11 { description "Version 1.0"; reference "Vendor SYSLOG Types: SYSLOG YANG Model"; } identity vendor_specific_type_1 { base syslogtypes:syslog-facility; description "Adding vendor specific type 1 to syslog-facility"; } identity vendor_specific_type_2 { base syslogtypes:syslog-facility; description "Adding vendor specific type 2 to syslog-facility"; } } A.2. Syslog Terminal Output Terminal output with requirements more complex than the console subtree currently provides, are expected to be supported via vendor extensions rather than handled via the file subtree. Clarke, et al. Expires 14 April 2023 [Page 39] Internet-Draft Syslog Management October 2022 A.3. Syslog File Naming Convention The syslog/file/log-file/file-rotation container contains configuration parameters for syslog file rotation. This section describes how these fields might be used by an implementer to name syslog files in a rotation process. This information is offered as an informative guide only. When an active syslog file with a name specified by log-file/name, reaches log-file/max-file-size and/or syslog events arrive after the period specified by log-file/rollover, the logging system can close the file, can compress it, and can name the archive file .0.gz. The logging system can then open a new active syslog file . When the new syslog file reaches either of the size limits referenced above, .0.gz can be renamed .1.gz and the new syslog file can be closed, compressed and renamed .0.gz. Each time that a new syslog file is closed, each of the prior syslog archive files named ..gz can be renamed to ..gz. Removal of archive log files could occur when either or both: - log-file/number-of-files specified - the logging system can create up to log-file/number-of-files syslog archive files after which, the contents of the oldest archived file could be overwritten. - log-file/retention specified - the logging system can remove those syslog archive files whose file expiration time (file creation time plus the specified log-file/retention time) is prior to the current time. Authors' Addresses Joe Clarke (editor) Cisco United States of America Email: jclarke@cisco.com Mahesh Jethanandani (editor) Kloud Services United States of America Email: mjethanandani@gmail.com Clarke, et al. Expires 14 April 2023 [Page 40] Internet-Draft Syslog Management October 2022 Clyde Wildes (editor) Cisco Systems Inc. 170 West Tasman Drive San Jose, CA 95134 United States of America Phone: +1 408 527-2672 Email: cwildes@cisco.com Kiran Koushik (editor) Verizon Wireless 500 W Dove Rd. Southlake, TX 76092 United States of America Phone: +1 512 650-0210 Email: kirankoushik.agraharasreenivasa@verizonwireless.com Clarke, et al. Expires 14 April 2023 [Page 41]