NETCONF Working Group K. Watsen Internet-Draft Watsen Networks Intended status: Standards Track 12 December 2022 Expires: 15 June 2023 RESTCONF Client and Server Models draft-ietf-netconf-restconf-client-server-28 Abstract This document defines two YANG modules, one module to configure a RESTCONF client and the other module to configure a RESTCONF server. Both modules support the TLS transport protocol with both standard RESTCONF and RESTCONF Call Home connections. Editorial Note (To be removed by RFC Editor) This draft contains 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 (note: not all may be present): * AAAA --> the assigned RFC value for draft-ietf-netconf-crypto- types * BBBB --> the assigned RFC value for draft-ietf-netconf-trust- anchors * CCCC --> the assigned RFC value for draft-ietf-netconf-keystore * DDDD --> the assigned RFC value for draft-ietf-netconf-tcp-client- server * EEEE --> the assigned RFC value for draft-ietf-netconf-ssh-client- server * FFFF --> the assigned RFC value for draft-ietf-netconf-tls-client- server * GGGG --> the assigned RFC value for draft-ietf-netconf-http- client-server Watsen Expires 15 June 2023 [Page 1] Internet-Draft RESTCONF Client and Server Models December 2022 * HHHH --> the assigned RFC value for draft-ietf-netconf-netconf- client-server * IIII --> the assigned RFC value for this draft Artwork in this document contains placeholder values for the date of publication of this draft. Please apply the following replacement: * 2022-12-12 --> the publication date of this draft The "Relation to other RFCs" section Section 1.1 contains the text "one or more YANG modules" and, later, "modules". This text is sourced from a file in a context where it is unknown how many modules a draft defines. The text is not wrong as is, but it may be improved by stating more directly how many modules are defined. The "Relation to other RFCs" section Section 1.1 contains a self- reference to this draft, along with a corresponding Informative Reference in the Appendix. The following Appendix section is to be removed prior to publication: * Appendix A. Change Log 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 15 June 2023. Copyright Notice Copyright (c) 2022 IETF Trust and the persons identified as the document authors. All rights reserved. Watsen Expires 15 June 2023 [Page 2] Internet-Draft RESTCONF Client and Server Models December 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 . . . . . . . . . . . . . . . . . . . . . . . . 4 1.1. Relation to other RFCs . . . . . . . . . . . . . . . . . 4 1.2. Specification Language . . . . . . . . . . . . . . . . . 6 1.3. Adherence to the NMDA . . . . . . . . . . . . . . . . . . 6 1.4. Conventions . . . . . . . . . . . . . . . . . . . . . . . 6 2. The "ietf-restconf-client" Module . . . . . . . . . . . . . . 6 2.1. Data Model Overview . . . . . . . . . . . . . . . . . . . 6 2.2. Example Usage . . . . . . . . . . . . . . . . . . . . . . 11 2.3. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 15 3. The "ietf-restconf-server" Module . . . . . . . . . . . . . . 26 3.1. Data Model Overview . . . . . . . . . . . . . . . . . . . 26 3.2. Example Usage . . . . . . . . . . . . . . . . . . . . . . 31 3.3. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 35 4. Security Considerations . . . . . . . . . . . . . . . . . . . 47 4.1. The "ietf-restconf-client" YANG Module . . . . . . . . . 48 4.2. The "ietf-restconf-server" YANG Module . . . . . . . . . 48 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 49 5.1. The "IETF XML" Registry . . . . . . . . . . . . . . . . . 49 5.2. The "YANG Module Names" Registry . . . . . . . . . . . . 49 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 49 6.1. Normative References . . . . . . . . . . . . . . . . . . 49 6.2. Informative References . . . . . . . . . . . . . . . . . 51 Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 52 A.1. 00 to 01 . . . . . . . . . . . . . . . . . . . . . . . . 52 A.2. 01 to 02 . . . . . . . . . . . . . . . . . . . . . . . . 52 A.3. 02 to 03 . . . . . . . . . . . . . . . . . . . . . . . . 52 A.4. 03 to 04 . . . . . . . . . . . . . . . . . . . . . . . . 53 A.5. 04 to 05 . . . . . . . . . . . . . . . . . . . . . . . . 53 A.6. 05 to 06 . . . . . . . . . . . . . . . . . . . . . . . . 53 A.7. 06 to 07 . . . . . . . . . . . . . . . . . . . . . . . . 53 A.8. 07 to 08 . . . . . . . . . . . . . . . . . . . . . . . . 54 A.9. 08 to 09 . . . . . . . . . . . . . . . . . . . . . . . . 54 A.10. 09 to 10 . . . . . . . . . . . . . . . . . . . . . . . . 54 A.11. 10 to 11 . . . . . . . . . . . . . . . . . . . . . . . . 54 A.12. 11 to 12 . . . . . . . . . . . . . . . . . . . . . . . . 54 A.13. 12 to 13 . . . . . . . . . . . . . . . . . . . . . . . . 55 A.14. 13 to 14 . . . . . . . . . . . . . . . . . . . . . . . . 55 Watsen Expires 15 June 2023 [Page 3] Internet-Draft RESTCONF Client and Server Models December 2022 A.15. 14 to 15 . . . . . . . . . . . . . . . . . . . . . . . . 55 A.16. 15 to 16 . . . . . . . . . . . . . . . . . . . . . . . . 56 A.17. 16 to 17 . . . . . . . . . . . . . . . . . . . . . . . . 56 A.18. 17 to 18 . . . . . . . . . . . . . . . . . . . . . . . . 56 A.19. 18 to 19 . . . . . . . . . . . . . . . . . . . . . . . . 56 A.20. 19 to 20 . . . . . . . . . . . . . . . . . . . . . . . . 56 A.21. 20 to 21 . . . . . . . . . . . . . . . . . . . . . . . . 56 A.22. 21 to 22 . . . . . . . . . . . . . . . . . . . . . . . . 57 A.23. 22 to 23 . . . . . . . . . . . . . . . . . . . . . . . . 57 A.24. 23 to 24 . . . . . . . . . . . . . . . . . . . . . . . . 57 A.25. 24 to 25 . . . . . . . . . . . . . . . . . . . . . . . . 57 A.26. 25 to 26 . . . . . . . . . . . . . . . . . . . . . . . . 57 A.27. 26 to 27 . . . . . . . . . . . . . . . . . . . . . . . . 57 A.28. 27 to 28 . . . . . . . . . . . . . . . . . . . . . . . . 57 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 58 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 58 1. Introduction This document defines two YANG [RFC7950] modules, one module to configure a RESTCONF client and the other module to configure a RESTCONF server [RFC8040]. Both modules support the TLS [RFC8446] transport protocol with both standard RESTCONF and RESTCONF Call Home connections [RFC8071]. 1.1. Relation to other RFCs This document presents one or more YANG modules [RFC7950] that are part of a collection of RFCs that work together to, ultimately, enable the configuration of both the clients and servers of both the NETCONF [RFC6241] and RESTCONF [RFC8040] protocols. The normative dependency relationship between the various RFCs in this collection is presented in the below diagram. The labels in the diagram represent the primary purpose provided by each RFC. Hyperlinks to each RFC are provided below the diagram. Watsen Expires 15 June 2023 [Page 4] Internet-Draft RESTCONF Client and Server Models December 2022 crypto-types ^ ^ / \ / \ truststore keystore ^ ^ ^ ^ | +---------+ | | | | | | | +------------+ | tcp-client-server | / | | ^ ^ ssh-client-server | | | | ^ tls-client-server | | | ^ ^ http-client-server | | | | | ^ | | | +-----+ +---------+ | | | | | | | | +-----------|--------|--------------+ | | | | | | | | +-----------+ | | | | | | | | | | | | | | | | | netconf-client-server restconf-client-server +======================+===========================================+ |Label in Diagram | Originating RFC | +======================+===========================================+ |crypto-types | [I-D.ietf-netconf-crypto-types] | +----------------------+-------------------------------------------+ |truststore | [I-D.ietf-netconf-trust-anchors] | +----------------------+-------------------------------------------+ |keystore | [I-D.ietf-netconf-keystore] | +----------------------+-------------------------------------------+ |tcp-client-server | [I-D.ietf-netconf-tcp-client-server] | +----------------------+-------------------------------------------+ |ssh-client-server | [I-D.ietf-netconf-ssh-client-server] | +----------------------+-------------------------------------------+ |tls-client-server | [I-D.ietf-netconf-tls-client-server] | +----------------------+-------------------------------------------+ |http-client-server | [I-D.ietf-netconf-http-client-server] | +----------------------+-------------------------------------------+ |netconf-client-server | [I-D.ietf-netconf-netconf-client-server] | +----------------------+-------------------------------------------+ |restconf-client-server| [I-D.ietf-netconf-restconf-client-server] | +----------------------+-------------------------------------------+ Table 1: Label to RFC Mapping Watsen Expires 15 June 2023 [Page 5] Internet-Draft RESTCONF Client and Server Models December 2022 1.2. Specification 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. 1.3. Adherence to the NMDA This document is compliant with the Network Management Datastore Architecture (NMDA) [RFC8342]. For instance, as described in [I-D.ietf-netconf-trust-anchors] and [I-D.ietf-netconf-keystore], trust anchors and keys installed during manufacturing are expected to appear in . 1.4. Conventions Various examples used in this document use a placeholder value for binary data that has been base64 encoded (e.g., "BASE64VALUE="). This placeholder value is used as real base64 encoded structures are often many lines long and hence distracting to the example being presented. 2. The "ietf-restconf-client" Module The RESTCONF client model presented in this section supports both clients initiating connections to servers, as well as clients listening for connections from servers calling home. YANG feature statements are used to enable implementations to advertise which potentially uncommon parts of the model the RESTCONF client supports. 2.1. Data Model Overview This section provides an overview of the "ietf-restconf-client" module in terms of its features and groupings. 2.1.1. Features The following diagram lists all the "feature" statements defined in the "ietf-restconf-client" module: Watsen Expires 15 June 2023 [Page 6] Internet-Draft RESTCONF Client and Server Models December 2022 Features: +-- https-initiate +-- http-listen +-- https-listen +-- central-restconf-client-supported The diagram above uses syntax that is similar to but not defined in [RFC8340]. 2.1.2. Groupings The "ietf-restconf-client" module defines the following "grouping" statements: * restconf-client-grouping * restconf-client-initiate-stack-grouping * restconf-client-listen-stack-grouping * restconf-client-app-grouping Each of these groupings are presented in the following subsections. 2.1.2.1. The "restconf-client-grouping" Grouping The following tree diagram [RFC8340] illustrates the "restconf- client-grouping" grouping: grouping restconf-client-grouping ---> : Comments: * This grouping does not define any nodes, but is maintained so that downstream modules can augment nodes into it if needed. * The "restconf-client-grouping" defines, if it can be called that, the configuration for just "RESTCONF" part of a protocol stack. It does not, for instance, define any configuration for the "TCP", "TLS", or "HTTP" protocol layers (for that, see Section 2.1.2.2 and Section 2.1.2.3). 2.1.2.2. The "restconf-client-initiate-stack-grouping" Grouping The following tree diagram [RFC8340] illustrates the "restconf- client-initiate-stack-grouping" grouping: Watsen Expires 15 June 2023 [Page 7] Internet-Draft RESTCONF Client and Server Models December 2022 grouping restconf-client-initiate-stack-grouping: +-- (transport) +--:(https) {https-initiate}? +-- https +-- tcp-client-parameters | +---u tcpc:tcp-client-grouping +-- tls-client-parameters | +---u tlsc:tls-client-grouping +-- http-client-parameters | +---u httpc:http-client-grouping +-- restconf-client-parameters +---u rcc:restconf-client-grouping Comments: * The "restconf-client-initiate-stack-grouping" defines the configuration for a full RESTCONF protocol stack, for RESTCONF clients that initiate connections to RESTCONF servers, as opposed to receiving call-home [RFC8071] connections. * The "transport" choice node enables transport options to be configured. This document only defines an "https" option, but other options MAY be augmented in. * For the referenced grouping statement(s): - The "tcp-client-grouping" grouping is discussed in Section 3.1.2.1 of [I-D.ietf-netconf-tcp-client-server]. - The "tls-client-grouping" grouping is discussed in Section 3.1.2.1 of [I-D.ietf-netconf-tls-client-server]. - The "http-client-grouping" grouping is discussed in Section 2.1.2.2 of [I-D.ietf-netconf-http-client-server]. - The "restconf-client-grouping" grouping is discussed in Section 2.1.2.1 in this document. 2.1.2.3. The "restconf-client-listen-stack-grouping" Grouping The following tree diagram [RFC8340] illustrates the "restconf- client-listen-stack-grouping" grouping: Watsen Expires 15 June 2023 [Page 8] Internet-Draft RESTCONF Client and Server Models December 2022 grouping restconf-client-listen-stack-grouping: +-- (transport) +--:(http) {http-listen}? | +-- http | +-- tcp-server-parameters | | +---u tcps:tcp-server-grouping | +-- http-client-parameters | | +---u httpc:http-client-grouping | +-- restconf-client-parameters | +---u rcc:restconf-client-grouping +--:(https) {https-listen}? +-- https +-- tcp-server-parameters | +---u tcps:tcp-server-grouping +-- tls-client-parameters | +---u tlsc:tls-client-grouping +-- http-client-parameters | +---u httpc:http-client-grouping +-- restconf-client-parameters +---u rcc:restconf-client-grouping Comments: * The "restconf-client-listen-stack-grouping" defines the configuration for a full RESTCONF protocol stack, for RESTCONF clients that receive call-home [RFC8071] connections from RESTCONF servers. * The "transport" choice node enables both the HTTP and HTTPS transports to be configured, with each option enabled by a "feature" statement. Note that RESTCONF requires HTTPS, the HTTP option is provided to support cases where a TLS-terminator is deployed in front of the RESTCONF-client. * For the referenced grouping statement(s): - The "tcp-server-grouping" grouping is discussed in Section 4.1.2.1 of [I-D.ietf-netconf-tcp-client-server]. - The "tls-client-grouping" grouping is discussed in Section 3.1.2.1 of [I-D.ietf-netconf-tls-client-server]. - The "http-client-grouping" grouping is discussed in Section 2.1.2.2 of [I-D.ietf-netconf-http-client-server]. - The "restconf-client-grouping" grouping is discussed in Section 2.1.2.1 in this document. Watsen Expires 15 June 2023 [Page 9] Internet-Draft RESTCONF Client and Server Models December 2022 2.1.2.4. The "restconf-client-app-grouping" Grouping The following tree diagram [RFC8340] illustrates the "restconf- client-app-grouping" grouping: grouping restconf-client-app-grouping: +-- initiate! {https-initiate}? | +-- restconf-server* [name] | +-- name? string | +-- endpoints | | +-- endpoint* [name] | | +-- name? string | | +---u restconf-client-initiate-stack-grouping | +-- connection-type | | +-- (connection-type) | | +--:(persistent-connection) | | | +-- persistent! | | +--:(periodic-connection) | | +-- periodic! | | +-- period? uint16 | | +-- anchor-time? yang:date-and-time | | +-- idle-timeout? uint16 | +-- reconnect-strategy | +-- start-with? enumeration | +-- max-wait? uint16 | +-- max-attempts? uint8 +-- listen! {http-listen or https-listen}? +-- idle-timeout? uint16 +-- endpoint* [name] +-- name? string +---u restconf-client-listen-stack-grouping Comments: * The "restconf-client-app-grouping" defines the configuration for a RESTCONF client that supports both initiating connections to RESTCONF servers as well as receiving call-home connections from RESTCONF servers. * Both the "initiate" and "listen" subtrees must be enabled by "feature" statements. * For the referenced grouping statement(s): - The "restconf-client-initiate-stack-grouping" grouping is discussed in Section 2.1.2.2 in this document. - The "restconf-client-listen-stack-grouping" grouping is discussed in Section 2.1.2.3 in this document. Watsen Expires 15 June 2023 [Page 10] Internet-Draft RESTCONF Client and Server Models December 2022 2.1.3. Protocol-accessible Nodes The following tree diagram [RFC8340] lists all the protocol- accessible nodes defined in the "ietf-restconf-client" module: module: ietf-restconf-client +--rw restconf-client {central-restconf-client-supported}? +---u restconf-client-app-grouping Comments: * Protocol-accessible nodes are those nodes that are accessible when the module is "implemented", as described in Section 5.6.5 of [RFC7950]. * The top-level node "restconf-client" is additionally constrained by the feature "central-restconf-client-supported". * The "restconf-client-app-grouping" grouping is discussed in Section 2.1.2.4 in this document. * The reason for why "restconf-client-app-grouping" exists separate from the protocol-accessible nodes definition is so as to enable instances of restconf-client-app-grouping to be instantiated in other locations, as may be needed or desired by some modules. 2.2. Example Usage The following example illustrates configuring a RESTCONF client to initiate connections, as well as to listen for call-home connections. This example is consistent with the examples presented in Section 2.2 of [I-D.ietf-netconf-trust-anchors] and Section 2.2 of [I-D.ietf-netconf-keystore]. =============== NOTE: '\' line wrapping per RFC 8792 ================ corp-fw1 corp-fw1.example.com Watsen Expires 15 June 2023 [Page 11] Internet-Draft RESTCONF Client and Server Models December 2022 corp-fw1.example.com 15 3 30 rsa-asymmetric-key ex-rsa-cert trusted-server-ca-certs trusted-server-ee-certs 30 3 bob secret corp-fw2.example.com Watsen Expires 15 June 2023 [Page 12] Internet-Draft RESTCONF Client and Server Models December 2022 corp-fw2.example.com 15 3 30 rsa-asymmetric-key ex-rsa-cert trusted-server-ca-certs trusted-server-ee-certs 30 3 bob secret Watsen Expires 15 June 2023 [Page 13] Internet-Draft RESTCONF Client and Server Models December 2022 Intranet-facing listener 11.22.33.44 rsa-asymmetric-key ex-rsa-cert trusted-server-ca-certs trusted-server-ee-certs bob secret Watsen Expires 15 June 2023 [Page 14] Internet-Draft RESTCONF Client and Server Models December 2022 2.3. YANG Module This YANG module has normative references to [RFC6991], [RFC8040], and [RFC8071], [I-D.ietf-netconf-tcp-client-server], [I-D.ietf-netconf-tls-client-server], and [I-D.ietf-netconf-http-client-server]. file "ietf-restconf-client@2022-12-12.yang" module ietf-restconf-client { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-restconf-client"; prefix rcc; import ietf-yang-types { prefix yang; reference "RFC 6991: Common YANG Data Types"; } import ietf-tcp-client { prefix tcpc; reference "RFC DDDD: YANG Groupings for TCP Clients and TCP Servers"; } import ietf-tcp-server { prefix tcps; reference "RFC DDDD: YANG Groupings for TCP Clients and TCP Servers"; } import ietf-tls-client { prefix tlsc; reference "RFC FFFF: YANG Groupings for TLS Clients and TLS Servers"; } import ietf-http-client { prefix httpc; reference "RFC GGGG: YANG Groupings for HTTP Clients and HTTP Servers"; } organization "IETF NETCONF (Network Configuration) Working Group"; contact Watsen Expires 15 June 2023 [Page 15] Internet-Draft RESTCONF Client and Server Models December 2022 "WG Web: https://datatracker.ietf.org/wg/netconf WG List: NETCONF WG list Author: Kent Watsen "; description "This module contains a collection of YANG definitions for configuring RESTCONF clients. 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 IIII (https://www.rfc-editor.org/info/rfcIIII); see the RFC itself for full legal notices. The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'NOT RECOMMENDED', 'MAY', and 'OPTIONAL' in this document are to be interpreted as described in BCP 14 (RFC 2119) (RFC 8174) when, and only when, they appear in all capitals, as shown here."; revision 2022-12-12 { description "Initial version"; reference "RFC IIII: RESTCONF Client and Server Models"; } // Features feature https-initiate { description "The 'https-initiate' feature indicates that the RESTCONF client supports initiating HTTPS connections to RESTCONF servers. This feature exists as HTTPS might not be a mandatory to implement transport in the future."; reference "RFC 8040: RESTCONF Protocol"; } Watsen Expires 15 June 2023 [Page 16] Internet-Draft RESTCONF Client and Server Models December 2022 feature http-listen { description "The 'http-listen' feature indicates that the RESTCONF client supports opening a port to listen for incoming RESTCONF server call-home connections. This feature exists as not all RESTCONF clients may support RESTCONF call home."; reference "RFC 8071: NETCONF Call Home and RESTCONF Call Home"; } feature https-listen { description "The 'https-listen' feature indicates that the RESTCONF client supports opening a port to listen for incoming RESTCONF server call-home connections. This feature exists as not all RESTCONF clients may support RESTCONF call home."; reference "RFC 8071: NETCONF Call Home and RESTCONF Call Home"; } feature central-restconf-client-supported { description "The 'central-restconf-client-supported' feature indicates that the server that implements this module supports the top-level 'restconf-client' node. This feature is needed as some servers may want to use features defined in this module, which requires this module to be implemented, without having to support the top-level 'restconf-client' node."; } // Groupings grouping restconf-client-grouping { description "A reusable grouping for configuring a RESTCONF client without any consideration for how underlying transport sessions are established. This grouping currently does not define any nodes. It exists only so the model can be consistent with other 'client-server' models."; } grouping restconf-client-initiate-stack-grouping { description "A reusable grouping for configuring a RESTCONF client Watsen Expires 15 June 2023 [Page 17] Internet-Draft RESTCONF Client and Server Models December 2022 'initiate' protocol stack for a single connection."; choice transport { mandatory true; description "Selects between available transports. This is a 'choice' statement so as to support additional transport options to be augmented in."; case https { if-feature "https-initiate"; container https { must 'tls-client-parameters/client-identity or http-client-parameters/client-identity'; description "Specifies HTTPS-specific transport configuration."; container tcp-client-parameters { description "A wrapper around the TCP client parameters to avoid name collisions."; uses tcpc:tcp-client-grouping { refine "remote-port" { default "443"; description "The RESTCONF client will attempt to connect to the IANA-assigned well-known port value for 'https' (443) if no value is specified."; } } } container tls-client-parameters { description "A wrapper around the TLS client parameters to avoid name collisions."; uses tlsc:tls-client-grouping; } container http-client-parameters { description "A wrapper around the HTTP client parameters to avoid name collisions."; uses httpc:http-client-grouping; } container restconf-client-parameters { description "A wrapper around the RESTCONF client parameters to avoid name collisions. Watsen Expires 15 June 2023 [Page 18] Internet-Draft RESTCONF Client and Server Models December 2022 This container does not define any nodes. It exists as a potential augmentation target by other modules."; uses rcc:restconf-client-grouping; } } } } } // restconf-client-initiate-stack-grouping grouping restconf-client-listen-stack-grouping { description "A reusable grouping for configuring a RESTCONF client 'listen' protocol stack for a single connection. The 'listen' stack supports call home connections, as described in RFC 8071"; reference "RFC 8071: NETCONF Call Home and RESTCONF Call Home"; choice transport { mandatory true; description "Selects between available transports. This is a 'choice' statement so as to support additional transport options to be augmented in."; case http { if-feature "http-listen"; container http { description "HTTP-specific listening configuration for inbound connections. This transport option is made available to support deployments where the TLS connections are terminated by another system (e.g., a load balancer) fronting the client."; container tcp-server-parameters { description "A wrapper around the TCP client parameters to avoid name collisions."; uses tcps:tcp-server-grouping { refine "local-port" { default "4336"; description "The RESTCONF client will listen on the IANA- assigned well-known port for 'restconf-ch-tls' (4336) if no value is specified."; } } Watsen Expires 15 June 2023 [Page 19] Internet-Draft RESTCONF Client and Server Models December 2022 } container http-client-parameters { description "A wrapper around the HTTP client parameters to avoid name collisions."; uses httpc:http-client-grouping; } container restconf-client-parameters { description "A wrapper around the RESTCONF client parameters to avoid name collisions. This container does not define any nodes. It exists as a potential augmentation target by other modules."; uses rcc:restconf-client-grouping; } } } case https { if-feature "https-listen"; container https { must 'tls-client-parameters/client-identity or http-client-parameters/client-identity'; description "HTTPS-specific listening configuration for inbound connections."; container tcp-server-parameters { description "A wrapper around the TCP client parameters to avoid name collisions."; uses tcps:tcp-server-grouping { refine "local-port" { default "4336"; description "The RESTCONF client will listen on the IANA- assigned well-known port for 'restconf-ch-tls' (4336) if no value is specified."; } } } container tls-client-parameters { description "A wrapper around the TLS client parameters to avoid name collisions."; uses tlsc:tls-client-grouping; } container http-client-parameters { Watsen Expires 15 June 2023 [Page 20] Internet-Draft RESTCONF Client and Server Models December 2022 description "A wrapper around the HTTP client parameters to avoid name collisions."; uses httpc:http-client-grouping; } container restconf-client-parameters { description "A wrapper around the RESTCONF client parameters to avoid name collisions. This container does not define any nodes. It exists as a potential augmentation target by other modules."; uses rcc:restconf-client-grouping; } } } } } // restconf-client-listen-stack-grouping grouping restconf-client-app-grouping { description "A reusable grouping for configuring a RESTCONF client application that supports both 'initiate' and 'listen' protocol stacks for a multiplicity of connections."; container initiate { if-feature "https-initiate"; presence "Indicates that client-initiated connections have been configured. This statement is present so the mandatory descendant nodes do not imply that this node must be configured."; description "Configures client initiating underlying TCP connections."; list restconf-server { key "name"; min-elements 1; description "List of RESTCONF servers the RESTCONF client is to maintain simultaneous connections with."; leaf name { type string; description "An arbitrary name for the RESTCONF server."; } container endpoints { description "Container for the list of endpoints."; Watsen Expires 15 June 2023 [Page 21] Internet-Draft RESTCONF Client and Server Models December 2022 list endpoint { key "name"; min-elements 1; ordered-by user; description "A non-empty user-ordered list of endpoints for this RESTCONF client to try to connect to in sequence. Defining more than one enables high-availability."; leaf name { type string; description "An arbitrary name for this endpoint."; } uses restconf-client-initiate-stack-grouping; } } container connection-type { description "Indicates the RESTCONF client's preference for how the RESTCONF connection is maintained."; choice connection-type { mandatory true; description "Selects between available connection types."; case persistent-connection { container persistent { presence "Indicates that a persistent connection is to be maintained."; description "Maintain a persistent connection to the RESTCONF server. If the connection goes down, immediately start trying to reconnect to the RESTCONF server, using the reconnection strategy. This connection type minimizes any RESTCONF server to RESTCONF client data-transfer delay, albeit at the expense of holding resources longer."; } } case periodic-connection { container periodic { presence "Indicates that a periodic connection is to be maintained."; description "Periodically connect to the RESTCONF server. Watsen Expires 15 June 2023 [Page 22] Internet-Draft RESTCONF Client and Server Models December 2022 This connection type decreases resource utilization, albeit with increased delay in RESTCONF server to RESTCONF client interactions. The RESTCONF client SHOULD gracefully close the underlying TLS connection upon completing planned activities. In the case that the previous connection is still active, establishing a new connection is NOT RECOMMENDED."; leaf period { type uint16; units "minutes"; default "60"; description "Duration of time between periodic connections."; } leaf anchor-time { type yang:date-and-time { // constrained to minute-level granularity pattern '\d{4}-\d{2}-\d{2}T\d{2}:\d{2}' + '(Z|[\+\-]\d{2}:\d{2})'; } description "Designates a timestamp before or after which a series of periodic connections are determined. The periodic connections occur at a whole multiple interval from the anchor time. For example, for an anchor time is 15 minutes past midnight and a period interval of 24 hours, then a periodic connection will occur 15 minutes past midnight everyday."; } leaf idle-timeout { type uint16; units "seconds"; default "120"; // two minutes description "Specifies the maximum number of seconds that the underlying TCP session may remain idle. A TCP session will be dropped if it is idle for an interval longer than this number of seconds If set to zero, then the RESTCONF client will never drop a session because it is idle."; Watsen Expires 15 June 2023 [Page 23] Internet-Draft RESTCONF Client and Server Models December 2022 } } } // periodic-connection } // connection-type } // connection-type container reconnect-strategy { description "The reconnection strategy directs how a RESTCONF client reconnects to a RESTCONF server, after discovering its connection to the server has dropped, even if due to a reboot. The RESTCONF client starts with the specified endpoint and tries to connect to it max-attempts times before trying the next endpoint in the list (round robin)."; leaf start-with { type enumeration { enum first-listed { description "Indicates that reconnections should start with the first endpoint listed."; } enum last-connected { description "Indicates that reconnections should start with the endpoint last connected to. If no previous connection has ever been established, then the first endpoint configured is used. RESTCONF clients SHOULD be able to remember the last endpoint connected to across reboots."; } enum random-selection { description "Indicates that reconnections should start with a random endpoint."; } } default "first-listed"; description "Specifies which of the RESTCONF server's endpoints the RESTCONF client should start with when trying to connect to the RESTCONF server."; } leaf max-wait { type uint16 { range "1..max"; Watsen Expires 15 June 2023 [Page 24] Internet-Draft RESTCONF Client and Server Models December 2022 } units "seconds"; default "5"; description "Specifies the amount of time in seconds after which, if the connection is not established, an endpoint connection attempt is considered unsuccessful."; } leaf max-attempts { type uint8 { range "1..max"; } default "3"; description "Specifies the number times the RESTCONF client tries to connect to a specific endpoint before moving on to the next endpoint in the list (round robin)."; } } } } // initiate container listen { if-feature "http-listen or https-listen"; presence "Indicates that client-listening ports have been configured. This statement is present so the mandatory descendant nodes do not imply that this node must be configured."; description "Configures the client to accept call-home TCP connections."; leaf idle-timeout { type uint16; units "seconds"; default "3600"; // one hour description "Specifies the maximum number of seconds that an underlying TCP session may remain idle. A TCP session will be dropped if it is idle for an interval longer then this number of seconds. If set to zero, then the server will never drop a session because it is idle. Sessions that have a notification subscription active are never dropped."; } list endpoint { key "name"; min-elements 1; description "List of endpoints to listen for RESTCONF connections."; Watsen Expires 15 June 2023 [Page 25] Internet-Draft RESTCONF Client and Server Models December 2022 leaf name { type string; description "An arbitrary name for the RESTCONF listen endpoint."; } uses restconf-client-listen-stack-grouping; } } } // restconf-client-app-grouping // Protocol accessible node for servers that implement this module. container restconf-client { if-feature central-restconf-client-supported; uses restconf-client-app-grouping; description "Top-level container for RESTCONF client configuration."; } } 3. The "ietf-restconf-server" Module The RESTCONF server model presented in this section supports both listening for connections as well as initiating call-home connections. YANG feature statements are used to enable implementations to advertise which potentially uncommon parts of the model the RESTCONF server supports. 3.1. Data Model Overview This section provides an overview of the "ietf-restconf-server" module in terms of its features and groupings. 3.1.1. Features The following diagram lists all the "feature" statements defined in the "ietf-restconf-server" module: Features: +-- http-listen +-- https-listen +-- https-call-home +-- central-restconf-server-supported Watsen Expires 15 June 2023 [Page 26] Internet-Draft RESTCONF Client and Server Models December 2022 The diagram above uses syntax that is similar to but not defined in [RFC8340]. 3.1.2. Groupings The "ietf-restconf-server" module defines the following "grouping" statements: * restconf-server-grouping * restconf-server-listen-stack-grouping * restconf-server-callhome-stack-grouping * restconf-server-app-grouping Each of these groupings are presented in the following subsections. 3.1.2.1. The "restconf-server-grouping" Grouping The following tree diagram [RFC8340] illustrates the "restconf- server-grouping" grouping: grouping restconf-server-grouping: +-- client-identity-mappings +---u x509c2n:cert-to-name Comments: * The "restconf-server-grouping" defines the configuration for just "RESTCONF" part of a protocol stack. It does not, for instance, define any configuration for the "TCP", "TLS", or "HTTP" protocol layers (for that, see Section 3.1.2.2 and Section 3.1.2.3). * The "client-identity-mappings" node, which must be enabled by "feature" statements, defines a mapping from certificate fields to RESTCONF user names. * For the referenced grouping statement(s): - The "cert-to-name" grouping is discussed in Section 4.1 of [RFC7407]. 3.1.2.2. The "restconf-server-listen-stack-grouping" Grouping The following tree diagram [RFC8340] illustrates the "restconf- server-listen-stack-grouping" grouping: Watsen Expires 15 June 2023 [Page 27] Internet-Draft RESTCONF Client and Server Models December 2022 grouping restconf-server-listen-stack-grouping: +-- (transport) +--:(http) {http-listen}? | +-- http | +-- external-endpoint! | | +-- address inet:ip-address | | +-- port? inet:port-number | +-- tcp-server-parameters | | +---u tcps:tcp-server-grouping | +-- http-server-parameters | | +---u https:http-server-grouping | +-- restconf-server-parameters | +---u rcs:restconf-server-grouping +--:(https) {https-listen}? +-- https +-- tcp-server-parameters | +---u tcps:tcp-server-grouping +-- tls-server-parameters | +---u tlss:tls-server-grouping +-- http-server-parameters | +---u https:http-server-grouping +-- restconf-server-parameters +---u rcs:restconf-server-grouping Comments: * The "restconf-server-listen-stack-grouping" defines the configuration for a full RESTCONF protocol stack for RESTCONF servers that listen for standard connections from RESTCONF clients, as opposed to initiating call-home [RFC8071] connections. * The "transport" choice node enables both the HTTP and HTTPS transports to be configured, with each option enabled by a "feature" statement. The HTTP option is provided to support cases where a TLS-terminator is deployed in front of the RESTCONF- server. * For the referenced grouping statement(s): - The "tcp-server-grouping" grouping is discussed in Section 4.1.2.1 of [I-D.ietf-netconf-tcp-client-server]. - The "tls-server-grouping" grouping is discussed in Section 4.1.2.1 of [I-D.ietf-netconf-tls-client-server]. - The "http-server-grouping" grouping is discussed in Section 3.1.2.1 of [I-D.ietf-netconf-http-client-server]. - The "restconf-server-grouping" is discussed in Section 3.1.2.1 of this document. Watsen Expires 15 June 2023 [Page 28] Internet-Draft RESTCONF Client and Server Models December 2022 3.1.2.3. The "restconf-server-callhome-stack-grouping" Grouping The following tree diagram [RFC8340] illustrates the "restconf- server-callhome-stack-grouping" grouping: grouping restconf-server-callhome-stack-grouping: +-- (transport) +--:(https) {https-listen}? +-- https +-- tcp-client-parameters | +---u tcpc:tcp-client-grouping +-- tls-server-parameters | +---u tlss:tls-server-grouping +-- http-server-parameters | +---u https:http-server-grouping +-- restconf-server-parameters +---u rcs:restconf-server-grouping Comments: * The "restconf-server-callhome-stack-grouping" defines the configuration for a full RESTCONF protocol stack, for RESTCONF servers that initiate call-home [RFC8071] connections to RESTCONF clients. * The "transport" choice node enables transport options to be configured. This document only defines an "https" option, but other options MAY be augmented in. * For the referenced grouping statement(s): - The "tcp-client-grouping" grouping is discussed in Section 3.1.2.1 of [I-D.ietf-netconf-tcp-client-server]. - The "tls-server-grouping" grouping is discussed in Section 4.1.2.1 of [I-D.ietf-netconf-tls-client-server]. - The "http-server-grouping" grouping is discussed in Section 3.1.2.1 of [I-D.ietf-netconf-http-client-server]. - The "restconf-server-grouping" is discussed in Section 3.1.2.1 of this document. 3.1.2.4. The "restconf-server-app-grouping" Grouping The following tree diagram [RFC8340] illustrates the "restconf- server-app-grouping" grouping: Watsen Expires 15 June 2023 [Page 29] Internet-Draft RESTCONF Client and Server Models December 2022 grouping restconf-server-app-grouping: +-- listen! {http-listen or https-listen}? | +-- endpoint* [name] | +-- name? string | +---u restconf-server-listen-stack-grouping +-- call-home! {https-call-home}? +-- restconf-client* [name] +-- name? string +-- endpoints | +-- endpoint* [name] | +-- name? string | +---u restconf-server-callhome-stack-grouping +-- connection-type | +-- (connection-type) | +--:(persistent-connection) | | +-- persistent! | +--:(periodic-connection) | +-- periodic! | +-- period? uint16 | +-- anchor-time? yang:date-and-time | +-- idle-timeout? uint16 +-- reconnect-strategy +-- start-with? enumeration +-- max-wait? uint16 +-- max-attempts? uint8 Comments: * The "restconf-server-app-grouping" defines the configuration for a RESTCONF server that supports both listening for connections from RESTCONF clients as well as initiating call-home connections to RESTCONF clients. * Both the "listen" and "call-home" subtrees must be enabled by "feature" statements. * For the referenced grouping statement(s): - The "restconf-server-listen-stack-grouping" grouping is discussed in Section 3.1.2.2 in this document. - The "restconf-server-callhome-stack-grouping" grouping is discussed in Section 3.1.2.3 in this document. 3.1.3. Protocol-accessible Nodes The following tree diagram [RFC8340] lists all the protocol- accessible nodes defined in the "ietf-restconf-server" module: Watsen Expires 15 June 2023 [Page 30] Internet-Draft RESTCONF Client and Server Models December 2022 module: ietf-restconf-server +--rw restconf-server {central-restconf-server-supported}? +---u restconf-server-app-grouping Comments: * Protocol-accessible nodes are those nodes that are accessible when the module is "implemented", as described in Section 5.6.5 of [RFC7950]. * The top-level node "restconf-server" is additionally constrained by the feature "central-restconf-server-supported". * The "restconf-server-app-grouping" grouping is discussed in Section 3.1.2.4 in this document. * The reason for why "restconf-server-app-grouping" exists separate from the protocol-accessible nodes definition is so as to enable instances of restconf-server-app-grouping to be instantiated in other locations, as may be needed or desired by some modules. 3.2. Example Usage The following example illustrates configuring a RESTCONF server to listen for RESTCONF client connections, as well as configuring call- home to one RESTCONF client. This example is consistent with the examples presented in Section 2.2 of [I-D.ietf-netconf-trust-anchors] and Section 2.2 of [I-D.ietf-netconf-keystore]. =============== NOTE: '\' line wrapping per RFC 8792 ================ restconf/https 11.22.33.44 Watsen Expires 15 June 2023 [Page 31] Internet-Draft RESTCONF Client and Server Models December 2022 rsa-asymmetric-key ex-rsa-cert trusted-client-ca-certs trusted-client-ee-certs foo.example.com 1 11:0A:05:11:00 x509c2n:specified scooby-doo 2 x509c2n:san-any config-manager east-data-center Watsen Expires 15 June 2023 [Page 32] Internet-Draft RESTCONF Client and Server Models December 2022 east.example.com 15 3 30 rsa-asymmetric-key ex-rsa-cert trusted-client-ca-certs trusted-client-ee-certs 30 3 foo.example.com 1 11:0A:05:11:00 x509c2n:specified scooby-doo Watsen Expires 15 June 2023 [Page 33] Internet-Draft RESTCONF Client and Server Models December 2022 2 x509c2n:san-any west-data-center west.example.com 15 3 30 rsa-asymmetric-key ex-rsa-cert trusted-client-ca-certs trusted-client-ee-certs 30 3 foo.example.com Watsen Expires 15 June 2023 [Page 34] Internet-Draft RESTCONF Client and Server Models December 2022 1 11:0A:05:11:00 x509c2n:specified scooby-doo 2 x509c2n:san-any 300 60 last-connected 3 3 3.3. YANG Module This YANG module has normative references to [RFC6991], [RFC7407], [RFC8040], [RFC8071], [I-D.ietf-netconf-tcp-client-server], [I-D.ietf-netconf-tls-client-server], and [I-D.ietf-netconf-http-client-server]. file "ietf-restconf-server@2022-12-12.yang" module ietf-restconf-server { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-restconf-server"; prefix rcs; import ietf-yang-types { prefix yang; Watsen Expires 15 June 2023 [Page 35] Internet-Draft RESTCONF Client and Server Models December 2022 reference "RFC 6991: Common YANG Data Types"; } import ietf-inet-types { prefix inet; reference "RFC 6991: Common YANG Data Types"; } import ietf-x509-cert-to-name { prefix x509c2n; reference "RFC 7407: A YANG Data Model for SNMP Configuration"; } import ietf-tcp-client { prefix tcpc; reference "RFC DDDD: YANG Groupings for TCP Clients and TCP Servers"; } import ietf-tcp-server { prefix tcps; reference "RFC DDDD: YANG Groupings for TCP Clients and TCP Servers"; } import ietf-tls-server { prefix tlss; reference "RFC FFFF: YANG Groupings for TLS Clients and TLS Servers"; } import ietf-http-server { prefix https; reference "RFC GGGG: YANG Groupings for HTTP Clients and HTTP Servers"; } organization "IETF NETCONF (Network Configuration) Working Group"; contact "WG Web: https://datatracker.ietf.org/wg/netconf WG List: NETCONF WG list Author: Kent Watsen "; Watsen Expires 15 June 2023 [Page 36] Internet-Draft RESTCONF Client and Server Models December 2022 description "This module contains a collection of YANG definitions for configuring RESTCONF servers. 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 IIII (https://www.rfc-editor.org/info/rfcIIII); see the RFC itself for full legal notices. The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'NOT RECOMMENDED', 'MAY', and 'OPTIONAL' in this document are to be interpreted as described in BCP 14 (RFC 2119) (RFC 8174) when, and only when, they appear in all capitals, as shown here."; revision 2022-12-12 { description "Initial version"; reference "RFC IIII: RESTCONF Client and Server Models"; } // Features feature http-listen { description "The 'http-listen' feature indicates that the RESTCONF server supports opening a port to listen for incoming RESTCONF over TPC client connections, whereby the TLS connections are terminated by an external system."; reference "RFC 8040: RESTCONF Protocol"; } feature https-listen { description "The 'https-listen' feature indicates that the RESTCONF server supports opening a port to listen for incoming RESTCONF over Watsen Expires 15 June 2023 [Page 37] Internet-Draft RESTCONF Client and Server Models December 2022 TLS client connections, whereby the TLS connections are terminated by the server itself."; reference "RFC 8040: RESTCONF Protocol"; } feature https-call-home { description "The 'https-call-home' feature indicates that the RESTCONF server supports initiating connections to RESTCONF clients."; reference "RFC 8071: NETCONF Call Home and RESTCONF Call Home"; } feature central-restconf-server-supported { description "The 'central-restconf-server-supported' feature indicates that the server supports the top-level 'restconf-server' node. This feature is needed as some servers may want to use features defined in this module, which requires this module to be implemented, without having to support the top-level 'restconf-server' node."; } // Groupings grouping restconf-server-grouping { description "A reusable grouping for configuring a RESTCONF server without any consideration for how underlying transport sessions are established. Note that this grouping uses a fairly typical descendant node name such that a stack of 'uses' statements will have name conflicts. It is intended that the consuming data model will resolve the issue by wrapping the 'uses' statement in a container called, e.g., 'restconf-server-parameters'. This model purposely does not do this itself so as to provide maximum flexibility to consuming models."; container client-identity-mappings { description "Specifies mappings through which RESTCONF client X.509 certificates are used to determine a RESTCONF username. If no matching and valid cert-to-name list entry can be Watsen Expires 15 June 2023 [Page 38] Internet-Draft RESTCONF Client and Server Models December 2022 found, then the RESTCONF server MUST close the connection, and MUST NOT accept RESTCONF messages over it."; reference "RFC 7407: A YANG Data Model for SNMP Configuration."; uses x509c2n:cert-to-name { refine "cert-to-name/fingerprint" { mandatory false; description "A 'fingerprint' value does not need to be specified when the 'cert-to-name' mapping is independent of fingerprint matching. A 'cert-to-name' having no fingerprint value will match any client certificate and therefore should only be present at the end of the user-ordered 'cert-to-name' list."; } } } } grouping restconf-server-listen-stack-grouping { description "A reusable grouping for configuring a RESTCONF server 'listen' protocol stack for a single connection."; choice transport { mandatory true; description "Selects between available transports. This is a 'choice' statement so as to support additional transport options to be augmented in."; case http { if-feature "http-listen"; container http { description "Configures RESTCONF server stack assuming that TLS-termination is handled externally."; container external-endpoint { presence "Identifies that an external endpoint has been configured. This statement is present so the mandatory descendant nodes do not imply that this node must be configured."; description "Identifies contact information for the external system that terminates connections before passing them thru to this server (e.g., a network address translator or a load balancer). These values have no effect on the local operation of this server, but may be used by the application when needing to Watsen Expires 15 June 2023 [Page 39] Internet-Draft RESTCONF Client and Server Models December 2022 inform other systems how to contact this server."; leaf address { type inet:ip-address; mandatory true; description "The IP address or hostname of the external system that terminates incoming RESTCONF client connections before forwarding them to this server."; } leaf port { type inet:port-number; default "443"; description "The port number that the external system listens on for incoming RESTCONF client connections that are forwarded to this server. The default HTTPS port (443) is used, as expected for a RESTCONF connection."; } } container tcp-server-parameters { description "A wrapper around the TCP server parameters to avoid name collisions."; uses tcps:tcp-server-grouping { refine "local-port" { default "80"; description "The RESTCONF server will listen on the IANA- assigned well-known port value for 'http' (80) if no value is specified."; } } } container http-server-parameters { description "A wrapper around the HTTP server parameters to avoid name collisions."; uses https:http-server-grouping; } container restconf-server-parameters { description "A wrapper around the RESTCONF server parameters to avoid name collisions."; uses rcs:restconf-server-grouping; } } Watsen Expires 15 June 2023 [Page 40] Internet-Draft RESTCONF Client and Server Models December 2022 } case https { if-feature "https-listen"; container https { description "Configures RESTCONF server stack assuming that TLS-termination is handled internally."; container tcp-server-parameters { description "A wrapper around the TCP server parameters to avoid name collisions."; uses tcps:tcp-server-grouping { refine "local-port" { default "443"; description "The RESTCONF server will listen on the IANA- assigned well-known port value for 'https' (443) if no value is specified."; } } } container tls-server-parameters { description "A wrapper around the TLS server parameters to avoid name collisions."; uses tlss:tls-server-grouping; } container http-server-parameters { description "A wrapper around the HTTP server parameters to avoid name collisions."; uses https:http-server-grouping; } container restconf-server-parameters { description "A wrapper around the RESTCONF server parameters to avoid name collisions."; uses rcs:restconf-server-grouping; } } } } } grouping restconf-server-callhome-stack-grouping { description "A reusable grouping for configuring a RESTCONF server 'call-home' protocol stack, for a single connection."; Watsen Expires 15 June 2023 [Page 41] Internet-Draft RESTCONF Client and Server Models December 2022 choice transport { mandatory true; description "Selects between available transports. This is a 'choice' statement so as to support additional transport options to be augmented in."; case https { if-feature "https-listen"; container https { description "Configures RESTCONF server stack assuming that TLS-termination is handled internally."; container tcp-client-parameters { description "A wrapper around the TCP client parameters to avoid name collisions."; uses tcpc:tcp-client-grouping { refine "remote-port" { default "4336"; description "The RESTCONF server will attempt to connect to the IANA-assigned well-known port for 'restconf-ch-tls' (4336) if no value is specified."; } } } container tls-server-parameters { description "A wrapper around the TLS server parameters to avoid name collisions."; uses tlss:tls-server-grouping; } container http-server-parameters { description "A wrapper around the HTTP server parameters to avoid name collisions."; uses https:http-server-grouping; } container restconf-server-parameters { description "A wrapper around the RESTCONF server parameters to avoid name collisions."; uses rcs:restconf-server-grouping; } } } } Watsen Expires 15 June 2023 [Page 42] Internet-Draft RESTCONF Client and Server Models December 2022 } grouping restconf-server-app-grouping { description "A reusable grouping for configuring a RESTCONF server application that supports both 'listen' and 'call-home' protocol stacks for a multiplicity of connections."; container listen { if-feature "http-listen or https-listen"; presence "Identifies that the server has been configured to listen for incoming client connections. This statement is present so the mandatory descendant nodes do not imply that this node must be configured."; description "Configures the RESTCONF server to listen for RESTCONF client connections."; list endpoint { key "name"; min-elements 1; description "List of endpoints to listen for RESTCONF connections."; leaf name { type string; description "An arbitrary name for the RESTCONF listen endpoint."; } uses restconf-server-listen-stack-grouping; } } container call-home { if-feature "https-call-home"; presence "Identifies that the server has been configured to initiate call home connections. This statement is present so the mandatory descendant nodes do not imply that this node must be configured."; description "Configures the RESTCONF server to initiate the underlying transport connection to RESTCONF clients."; list restconf-client { key "name"; min-elements 1; description "List of RESTCONF clients the RESTCONF server is to maintain simultaneous call-home connections with."; leaf name { type string; Watsen Expires 15 June 2023 [Page 43] Internet-Draft RESTCONF Client and Server Models December 2022 description "An arbitrary name for the remote RESTCONF client."; } container endpoints { description "Container for the list of endpoints."; list endpoint { key "name"; min-elements 1; ordered-by user; description "User-ordered list of endpoints for this RESTCONF client. Defining more than one enables high- availability."; leaf name { type string; description "An arbitrary name for this endpoint."; } uses restconf-server-callhome-stack-grouping; } } container connection-type { description "Indicates the RESTCONF server's preference for how the RESTCONF connection is maintained."; choice connection-type { mandatory true; description "Selects between available connection types."; case persistent-connection { container persistent { presence "Indicates that a persistent connection is to be maintained."; description "Maintain a persistent connection to the RESTCONF client. If the connection goes down, immediately start trying to reconnect to the RESTCONF client, using the reconnection strategy. This connection type minimizes any RESTCONF client to RESTCONF server data-transfer delay, albeit at the expense of holding resources longer."; } } case periodic-connection { Watsen Expires 15 June 2023 [Page 44] Internet-Draft RESTCONF Client and Server Models December 2022 container periodic { presence "Indicates that a periodic connection is to be maintained."; description "Periodically connect to the RESTCONF client. This connection type decreases resource utilization, albeit with increased delay in RESTCONF client to RESTCONF client interactions. The RESTCONF client SHOULD gracefully close the underlying TLS connection upon completing planned activities. If the underlying TLS connection is not closed gracefully, the RESTCONF server MUST immediately attempt to reestablish the connection. In the case that the previous connection is still active (i.e., the RESTCONF client has not closed it yet), establishing a new connection is NOT RECOMMENDED."; leaf period { type uint16; units "minutes"; default "60"; description "Duration of time between periodic connections."; } leaf anchor-time { type yang:date-and-time { // constrained to minute-level granularity pattern '\d{4}-\d{2}-\d{2}T\d{2}:\d{2}' + '(Z|[\+\-]\d{2}:\d{2})'; } description "Designates a timestamp before or after which a series of periodic connections are determined. The periodic connections occur at a whole multiple interval from the anchor time. For example, for an anchor time is 15 minutes past midnight and a period interval of 24 hours, then a periodic connection will occur 15 minutes past midnight everyday."; } leaf idle-timeout { type uint16; Watsen Expires 15 June 2023 [Page 45] Internet-Draft RESTCONF Client and Server Models December 2022 units "seconds"; default "120"; // two minutes description "Specifies the maximum number of seconds that the underlying TCP session may remain idle. A TCP session will be dropped if it is idle for an interval longer than this number of seconds. If set to zero, then the server will never drop a session because it is idle."; } } } } } container reconnect-strategy { description "The reconnection strategy directs how a RESTCONF server reconnects to a RESTCONF client after discovering its connection to the client has dropped, even if due to a reboot. The RESTCONF server starts with the specified endpoint and tries to connect to it max-attempts times before trying the next endpoint in the list (round robin)."; leaf start-with { type enumeration { enum first-listed { description "Indicates that reconnections should start with the first endpoint listed."; } enum last-connected { description "Indicates that reconnections should start with the endpoint last connected to. If no previous connection has ever been established, then the first endpoint configured is used. RESTCONF servers SHOULD be able to remember the last endpoint connected to across reboots."; } enum random-selection { description "Indicates that reconnections should start with a random endpoint."; } } default "first-listed"; description "Specifies which of the RESTCONF client's endpoints Watsen Expires 15 June 2023 [Page 46] Internet-Draft RESTCONF Client and Server Models December 2022 the RESTCONF server should start with when trying to connect to the RESTCONF client."; } leaf max-wait { type uint16 { range "1..max"; } units "seconds"; default "5"; description "Specifies the amount of time in seconds after which, if the connection is not established, an endpoint connection attempt is considered unsuccessful."; } leaf max-attempts { type uint8 { range "1..max"; } default "3"; description "Specifies the number times the RESTCONF server tries to connect to a specific endpoint before moving on to the next endpoint in the list (round robin)."; } } } // restconf-client } // call-home } // restconf-server-app-grouping // Protocol accessible node for servers that implement this module. container restconf-server { if-feature central-restconf-server-supported; uses restconf-server-app-grouping; description "Top-level container for RESTCONF server configuration."; } } 4. Security Considerations Watsen Expires 15 June 2023 [Page 47] Internet-Draft RESTCONF Client and Server Models December 2022 4.1. The "ietf-restconf-client" YANG Module The "ietf-restconf-client" YANG module defines data nodes that are 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 Network 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. None of the readable data nodes in this YANG module are considered sensitive or vulnerable in network environments. The NACM "default- deny-all" extension has not been set for any data nodes defined in this module. None of the writable data nodes in this YANG module are considered sensitive or vulnerable in network environments. The NACM "default- deny-write" extension has not been set for any data nodes defined in this module. This module does not define any RPCs, actions, or notifications, and thus the security consideration for such is not provided here. Please be aware that this module uses groupings defined in other RFCs that define data nodes that do set the NACM "default-deny-all" and "default-deny-write" extensions. 4.2. The "ietf-restconf-server" YANG Module The "ietf-restconf-server" YANG module defines data nodes that are 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 Network 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. None of the readable data nodes in this YANG module are considered sensitive or vulnerable in network environments. The NACM "default- deny-all" extension has not been set for any data nodes defined in this module. Watsen Expires 15 June 2023 [Page 48] Internet-Draft RESTCONF Client and Server Models December 2022 None of the writable data nodes in this YANG module are considered sensitive or vulnerable in network environments. The NACM "default- deny-write" extension has not been set for any data nodes defined in this module. This module does not define any RPCs, actions, or notifications, and thus the security consideration for such is not provided here. Please be aware that this module uses groupings defined in other RFCs that define data nodes that do set the NACM "default-deny-all" and "default-deny-write" extensions. 5. IANA Considerations 5.1. The "IETF XML" Registry This document registers two URIs in the "ns" subregistry of the IETF XML Registry [RFC3688]. Following the format in [RFC3688], the following registrations are requested: URI: urn:ietf:params:xml:ns:yang:ietf-restconf-client Registrant Contact: The IESG XML: N/A, the requested URI is an XML namespace. URI: urn:ietf:params:xml:ns:yang:ietf-restconf-server Registrant Contact: The IESG XML: N/A, the requested URI is an XML namespace. 5.2. The "YANG Module Names" Registry This document registers two YANG modules in the YANG Module Names registry [RFC6020]. Following the format in [RFC6020], the following registrations are requested: name: ietf-restconf-client namespace: urn:ietf:params:xml:ns:yang:ietf-restconf-client prefix: rcc reference: RFC IIII name: ietf-restconf-server namespace: urn:ietf:params:xml:ns:yang:ietf-restconf-server prefix: rcs reference: RFC IIII 6. References 6.1. Normative References Watsen Expires 15 June 2023 [Page 49] Internet-Draft RESTCONF Client and Server Models December 2022 [I-D.ietf-netconf-http-client-server] Watsen, K., "YANG Groupings for HTTP Clients and HTTP Servers", Work in Progress, Internet-Draft, draft-ietf- netconf-http-client-server-11, 19 October 2022, . [I-D.ietf-netconf-keystore] Watsen, K., "A YANG Data Model for a Keystore", Work in Progress, Internet-Draft, draft-ietf-netconf-keystore-26, 19 October 2022, . [I-D.ietf-netconf-tcp-client-server] Watsen, K. and M. Scharf, "YANG Groupings for TCP Clients and TCP Servers", Work in Progress, Internet-Draft, draft- ietf-netconf-tcp-client-server-14, 19 October 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-31, 19 October 2022, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, October 2010, . [RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types", RFC 6991, DOI 10.17487/RFC6991, July 2013, . [RFC7407] Bjorklund, M. and J. Schoenwaelder, "A YANG Data Model for SNMP Configuration", RFC 7407, DOI 10.17487/RFC7407, December 2014, . [RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, August 2016, . Watsen Expires 15 June 2023 [Page 50] Internet-Draft RESTCONF Client and Server Models December 2022 [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017, . [RFC8071] Watsen, K., "NETCONF Call Home and RESTCONF Call Home", RFC 8071, DOI 10.17487/RFC8071, 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, . 6.2. Informative 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-25, 19 October 2022, . [I-D.ietf-netconf-netconf-client-server] Watsen, K., "NETCONF Client and Server Models", Work in Progress, Internet-Draft, draft-ietf-netconf-netconf- client-server-27, 19 October 2022, . [I-D.ietf-netconf-restconf-client-server] Watsen, K., "RESTCONF Client and Server Models", Work in Progress, Internet-Draft, draft-ietf-netconf-restconf- client-server-27, 19 October 2022, . [I-D.ietf-netconf-ssh-client-server] Watsen, K., "YANG Groupings for SSH Clients and SSH Servers", Work in Progress, Internet-Draft, draft-ietf- netconf-ssh-client-server-31, 19 October 2022, . [I-D.ietf-netconf-trust-anchors] Watsen, K., "A YANG Data Model for a Truststore", Work in Progress, Internet-Draft, draft-ietf-netconf-trust- anchors-19, 19 October 2022, . Watsen Expires 15 June 2023 [Page 51] Internet-Draft RESTCONF Client and Server Models December 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, . [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, . [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, . Appendix A. Change Log This section is to be removed before publishing as an RFC. A.1. 00 to 01 * Renamed "keychain" to "keystore". A.2. 01 to 02 * Filled in previously missing 'ietf-restconf-client' module. * Updated the ietf-restconf-server module to accommodate new grouping 'ietf-tls-server-grouping'. A.3. 02 to 03 * Refined use of tls-client-grouping to add a must statement indicating that the TLS client must specify a client-certificate. * Changed restconf-client??? to be a grouping (not a container). Watsen Expires 15 June 2023 [Page 52] Internet-Draft RESTCONF Client and Server Models December 2022 A.4. 03 to 04 * Added RFC 8174 to Requirements Language Section. * Replaced refine statement in ietf-restconf-client to add a mandatory true. * Added refine statement in ietf-restconf-server to add a must statement. * Now there are containers and groupings, for both the client and server models. * Now tree diagrams reference ietf-netmod-yang-tree-diagrams * Updated examples to inline key and certificates (no longer a leafref to keystore) A.5. 04 to 05 * Now tree diagrams reference ietf-netmod-yang-tree-diagrams * Updated examples to inline key and certificates (no longer a leafref to keystore) A.6. 05 to 06 * Fixed change log missing section issue. * Updated examples to match latest updates to the crypto-types, trust-anchors, and keystore drafts. * Reduced line length of the YANG modules to fit within 69 columns. A.7. 06 to 07 * removed "idle-timeout" from "persistent" connection config. * Added "random-selection" for reconnection-strategy's "starts-with" enum. * Replaced "connection-type" choice default (persistent) with "mandatory true". * Reduced the periodic-connection's "idle-timeout" from 5 to 2 minutes. * Replaced reconnect-timeout with period/anchor-time combo. Watsen Expires 15 June 2023 [Page 53] Internet-Draft RESTCONF Client and Server Models December 2022 A.8. 07 to 08 * Modified examples to be compatible with new crypto-types algs A.9. 08 to 09 * Corrected use of "mandatory true" for "address" leafs. * Updated examples to reflect update to groupings defined in the keystore draft. * Updated to use groupings defined in new TCP and HTTP drafts. * Updated copyright date, boilerplate template, affiliation, and folding algorithm. A.10. 09 to 10 * Reformatted YANG modules. A.11. 10 to 11 * Adjusted for the top-level "demux container" added to groupings imported from other modules. * Added "must" expressions to ensure that keepalives are not configured for "periodic" connections. * Updated the boilerplate text in module-level "description" statement to match copyeditor convention. * Moved "expanded" tree diagrams to the Appendix. A.12. 11 to 12 * Removed the 'must' statement limiting keepalives in periodic connections. * Updated models and examples to reflect removal of the "demux" containers in the imported models. * Updated the "periodic-connnection" description statements to better describe behavior when connections are not closed gracefully. * Updated text to better reference where certain examples come from (e.g., which Section in which draft). Watsen Expires 15 June 2023 [Page 54] Internet-Draft RESTCONF Client and Server Models December 2022 * In the server model, commented out the "must 'pinned-ca-certs or pinned-client-certs'" statement to reflect change made in the TLS draft whereby the trust anchors MAY be defined externally. * Replaced the 'listen', 'initiate', and 'call-home' features with boolean expressions. A.13. 12 to 13 * Updated to reflect changes in trust-anchors drafts (e.g., s/trust- anchors/truststore/g + s/pinned.//) * In ietf-restconf-server, Added 'http-listen' (not https-listen) choice, to support case when server is behind a TLS-terminator. * Refactored server module to be more like other 'server' models. If folks like it, will also apply to the client model, as well as to both the netconf client/server models. Now the 'restconf- server-grouping' is just the RC-specific bits (i.e., the "demux" container minus the container), 'restconf-server- [listen|callhome]-stack-grouping' is the protocol stack for a single connection, and 'restconf-server-app-grouping' is effectively what was before (both listen+callhome for many inbound/outbound endpoints). A.14. 13 to 14 * Updated examples to reflect ietf-crypto-types change (e.g., identities --> enumerations) * Adjusting from change in TLS client model (removing the top-level 'certificate' container). * Added "external-endpoint" to the "http-listen" choice in ietf- restconf-server. A.15. 14 to 15 * Added missing "or https-listen" clause in a "must" expression. * Refactored the client module similar to how the server module was refactored in -13. Now the 'restconf-client-grouping' is just the RC-specific bits, the 'restconf-client-[initiate|listen]-stack- grouping' is the protocol stack for a single connection, and 'restconf-client-app-grouping' is effectively what was before (both listen+callhome for many inbound/outbound endpoints). Watsen Expires 15 June 2023 [Page 55] Internet-Draft RESTCONF Client and Server Models December 2022 A.16. 15 to 16 * Added refinement to make "cert-to-name/fingerprint" be mandatory false. * Commented out refinement to "tls-server-grouping/client- authentication" until a better "must" expression is defined. * Updated restconf-client example to reflect that http-client- grouping no longer has a "protocol-version" leaf. A.17. 16 to 17 * Updated examples to include the "*-key-format" nodes. * Updated examples to remove the "required" nodes. A.18. 17 to 18 * Updated examples to reflect new "bag" addition to truststore. A.19. 18 to 19 * Updated examples to remove the 'algorithm' nodes. * Updated examples to reflect the new TLS keepalives structure. * Removed the 'protocol-versions' node from the restconf-server examples. * Added a "Note to Reviewers" note to first page. A.20. 19 to 20 * Moved and changed "must" statement so that either TLS *or* HTTP auth must be configured. * Expanded "Data Model Overview section(s) [remove "wall" of tree diagrams]. * Updated the Security Considerations section. A.21. 20 to 21 * Cleaned up titles in the IANA Consideratons section * Fixed issues found by the SecDir review of the "keystore" draft. Watsen Expires 15 June 2023 [Page 56] Internet-Draft RESTCONF Client and Server Models December 2022 A.22. 21 to 22 * Addressed comments raised by YANG Doctor in the ct/ts/ks drafts. A.23. 22 to 23 * Further clarified why some 'presence' statements are present. * Addressed nits found in YANG Doctor reviews. * Aligned modules with `pyang -f` formatting. A.24. 23 to 24 * Removed Appendix A with fully-expanded tree diagrams. * Replaced "base64encodedvalue==" with "BASE64VALUE=" in examples. * Minor editorial nits A.25. 24 to 25 * Fixed up the 'WG Web' and 'WG List' lines in YANG module(s) * Fixed up copyright (i.e., s/Simplified/Revised/) in YANG module(s) A.26. 25 to 26 * Added feature "central-restconf-client-supported" to top-level node "restconf-client". * Added feature "central-restconf-server-supported" to top-level node "restconf-server". A.27. 26 to 27 * Updated per Shepherd reviews impacting the suite of drafts. * Added "max-wait" leaf to the "reconnect-strategy" nodes. A.28. 27 to 28 * Updated per Shepherd reviews impacting the suite of drafts. Watsen Expires 15 June 2023 [Page 57] Internet-Draft RESTCONF Client and Server Models December 2022 Acknowledgements The authors would like to thank for following for lively discussions on list and in the halls (ordered by first name): Alan Luchuk, Andy Bierman, Balazs Kovacs, Benoit Claise, Bert Wijnen David Lamparter, Juergen Schoenwaelder, Ladislav Lhotka, Martin Bjoerklund, Mehmet Ersue, Michal Vasko, Phil Shafer, Qiufang Ma, Radek Krejci, Ramkumar Dhanapal, Sean Turner, and Tom Petch. Author's Address Kent Watsen Watsen Networks Email: kent+ietf@watsen.net Watsen Expires 15 June 2023 [Page 58]