NETCONF Working Group K. Watsen Internet-Draft Watsen Networks Intended status: Standards Track 8 July 2020 Expires: 9 January 2021 NETCONF Client and Server Models draft-ietf-netconf-netconf-client-server-20 Abstract This document defines two YANG modules, one module to configure a NETCONF client and the other module to configure a NETCONF server. Both modules support both the SSH and TLS transport protocols, and support both standard NETCONF and NETCONF 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 * "HHHH" --> the assigned RFC value for this draft Watsen Expires 9 January 2021 [Page 1] Internet-Draft NETCONF Client and Server Models July 2020 Artwork in this document contains placeholder values for the date of publication of this draft. Please apply the following replacement: * "2020-07-08" --> the publication date of this draft 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 9 January 2021. Copyright Notice Copyright (c) 2020 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/ license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Relation to other RFCs . . . . . . . . . . . . . . . . . 4 1.2. Specification Language . . . . . . . . . . . . . . . . . 5 1.3. Adherence to the NMDA . . . . . . . . . . . . . . . . . . 5 2. The "ietf-netconf-client" Module . . . . . . . . . . . . . . 5 2.1. Data Model Overview . . . . . . . . . . . . . . . . . . . 6 Watsen Expires 9 January 2021 [Page 2] Internet-Draft NETCONF Client and Server Models July 2020 2.2. Example Usage . . . . . . . . . . . . . . . . . . . . . . 10 2.3. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 14 3. The "ietf-netconf-server" Module . . . . . . . . . . . . . . 25 3.1. Data Model Overview . . . . . . . . . . . . . . . . . . . 25 3.2. Example Usage . . . . . . . . . . . . . . . . . . . . . . 30 3.3. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 36 4. Security Considerations . . . . . . . . . . . . . . . . . . . 49 4.1. The "ietf-netconf-client" YANG Module . . . . . . . . . . 49 4.2. The "ietf-netconf-server" YANG Module . . . . . . . . . . 49 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 50 5.1. The IETF XML Registry . . . . . . . . . . . . . . . . . . 50 5.2. The YANG Module Names Registry . . . . . . . . . . . . . 50 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 50 6.1. Normative References . . . . . . . . . . . . . . . . . . 50 6.2. Informative References . . . . . . . . . . . . . . . . . 52 Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 53 A.1. 00 to 01 . . . . . . . . . . . . . . . . . . . . . . . . 53 A.2. 01 to 02 . . . . . . . . . . . . . . . . . . . . . . . . 53 A.3. 02 to 03 . . . . . . . . . . . . . . . . . . . . . . . . 54 A.4. 03 to 04 . . . . . . . . . . . . . . . . . . . . . . . . 54 A.5. 04 to 05 . . . . . . . . . . . . . . . . . . . . . . . . 54 A.6. 05 to 06 . . . . . . . . . . . . . . . . . . . . . . . . 54 A.7. 06 to 07 . . . . . . . . . . . . . . . . . . . . . . . . 54 A.8. 07 to 08 . . . . . . . . . . . . . . . . . . . . . . . . 55 A.9. 08 to 09 . . . . . . . . . . . . . . . . . . . . . . . . 55 A.10. 09 to 10 . . . . . . . . . . . . . . . . . . . . . . . . 55 A.11. 10 to 11 . . . . . . . . . . . . . . . . . . . . . . . . 55 A.12. 11 to 12 . . . . . . . . . . . . . . . . . . . . . . . . 55 A.13. 12 to 13 . . . . . . . . . . . . . . . . . . . . . . . . 56 A.14. 13 to 14 . . . . . . . . . . . . . . . . . . . . . . . . 56 A.15. 14 to 15 . . . . . . . . . . . . . . . . . . . . . . . . 56 A.16. 15 to 16 . . . . . . . . . . . . . . . . . . . . . . . . 56 A.17. 16 to 17 . . . . . . . . . . . . . . . . . . . . . . . . 56 A.18. 17 to 18 . . . . . . . . . . . . . . . . . . . . . . . . 57 A.19. 18 to 19 . . . . . . . . . . . . . . . . . . . . . . . . 57 A.20. 19 to 20 . . . . . . . . . . . . . . . . . . . . . . . . 57 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 57 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 57 1. Introduction This document defines two YANG [RFC7950] modules, one module to configure a NETCONF [RFC6241] client and the other module to configure a NETCONF server. Both modules support both NETCONF over SSH [RFC6242] and NETCONF over TLS [RFC7589] and NETCONF Call Home connections [RFC8071]. Watsen Expires 9 January 2021 [Page 3] Internet-Draft NETCONF Client and Server Models July 2020 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 define configuration modules for clients and servers of both the NETCONF [RFC6241] and RESTCONF [RFC8040] protocols. The modules have been defined in a modular fashion to enable their use by other efforts, some of which are known to be in progress at the time of this writing, with many more expected to be defined in time. The relationship between the various RFCs in the collection is presented in the below diagram. The labels in the diagram represent the primary purpose provided by each RFC. Links the each RFC are provided below the diagram. crypto-types ^ ^ / \ / \ truststore keystore ^ ^ ^ ^ | +---------+ | | | | | | | +------------+ | tcp-client-server | / | | ^ ^ ssh-client-server | | | | ^ tls-client-server | | | ^ ^ http-client-server | | | | | ^ | | | +-----+ +---------+ | | | | | | | | +-----------|--------|--------------+ | | | | | | | | +-----------+ | | | | | | | | | | | | | | | | | netconf-client-server restconf-client-server Watsen Expires 9 January 2021 [Page 4] Internet-Draft NETCONF Client and Server Models July 2020 +=======================+===========================================+ | 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 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 in 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 . 2. The "ietf-netconf-client" Module The NETCONF client model presented in this section supports both clients initiating connections to servers, as well as clients listening for connections from servers calling home, using either the SSH and TLS transport protocols. Watsen Expires 9 January 2021 [Page 5] Internet-Draft NETCONF Client and Server Models July 2020 YANG feature statements are used to enable implementations to advertise which potentially uncommon parts of the model the NETCONF client supports. 2.1. Data Model Overview 2.1.1. Features The following diagram lists all the "feature" statements defined in the "ietf-netconf-client" module: Features: +-- ssh-initiate +-- tls-initiate +-- ssh-listen +-- tls-listen 2.1.2. Groupings The following diagram lists all the "grouping" statements defined in the "ietf-netconf-client" module: Groupings: +-- netconf-client-grouping +-- netconf-client-initiate-stack-grouping +-- netconf-client-listen-stack-grouping +-- netconf-client-app-grouping Each of these groupings are presented in the following subsections. 2.1.2.1. The "netconf-client-grouping" Grouping The following tree diagram [RFC8340] illustrates the "netconf-client- grouping" grouping: grouping netconf-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 "netconf-client-grouping" defines, if it can be called that, the configuration for just "NETCONF" part of a protocol stack. It does not, for instance, define any configuration for the "TCP", "SSH" or "TLS" protocol layers (for that, see Section 2.1.2.2 and Section 2.1.2.3). Watsen Expires 9 January 2021 [Page 6] Internet-Draft NETCONF Client and Server Models July 2020 2.1.2.2. The "netconf-client-initiate-stack-grouping" Grouping The following tree diagram [RFC8340] illustrates the "netconf-client- initiate-stack-grouping" grouping: grouping netconf-client-initiate-stack-grouping +-- (transport) +--:(ssh) {ssh-initiate}? | +-- ssh | +-- tcp-client-parameters | | +---u tcpc:tcp-client-grouping | +-- ssh-client-parameters | | +---u sshc:ssh-client-grouping | +-- netconf-client-parameters | +--u ncc:netconf-client-grouping +--:(tls) {tls-initiate}? +-- tls +-- tcp-client-parameters | +---u tcpc:tcp-client-grouping +-- tls-client-parameters | +---u tlsc:tls-client-grouping +-- netconf-client-parameters +---u ncc:netconf-client-grouping Comments: * The "netconf-client-initiate-stack-grouping" defines the configuration for a full NETCONF protocol stack, for NETCONF clients that initiate connections to NETCONF servers, as opposed to receiving call-home [RFC8071] connections. * The "transport" choice node enables both the SSH and TLS transports to be configured, with each option enabled by a "feature" statement. * 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 "ssh-client-grouping" grouping is discussed in Section 3.1.2.1 of [I-D.ietf-netconf-ssh-client-server]. - The "tls-client-grouping" grouping is discussed in Section 3.1.2.1 of [I-D.ietf-netconf-tls-client-server]. - The "netconf-client-grouping" grouping is discussed in Section 2.1.2.1 in this document. Watsen Expires 9 January 2021 [Page 7] Internet-Draft NETCONF Client and Server Models July 2020 2.1.2.3. The "netconf-client-listen-stack-grouping" Grouping The following tree diagram [RFC8340] illustrates the "netconf-client- listen-stack-grouping" grouping: grouping netconf-client-listen-stack-grouping +-- (transport) +--:(ssh) {ssh-listen}? | +-- ssh | +-- tcp-server-parameters | | +---u tcps:tcp-server-grouping | +-- ssh-client-parameters | | +---u sshc:ssh-client-grouping | +-- netconf-client-parameters | +--u ncc:netconf-client-grouping +--:(tls) {tls-listen}? +-- tls +-- tcp-server-parameters | +---u tcps:tcp-server-grouping +-- tls-client-parameters | +---u tlsc:tls-client-grouping +-- netconf-client-parameters +---u ncc:netconf-client-grouping Comments: * The "netconf-client-listen-stack-grouping" defines the configuration for a full NETCONF protocol stack, for NETCONF clients that receive call-home [RFC8071] connections from NETCONF servers. * The "transport" choice node enables both the SSH and TLS transports to be configured, with each option enabled by a "feature" statement. * 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 "ssh-client-grouping" grouping is discussed in Section 3.1.2.1 of [I-D.ietf-netconf-ssh-client-server]. - The "tls-client-grouping" grouping is discussed in Section 3.1.2.1 of [I-D.ietf-netconf-tls-client-server]. - The "netconf-client-grouping" grouping is discussed in Section 2.1.2.1 in this document. Watsen Expires 9 January 2021 [Page 8] Internet-Draft NETCONF Client and Server Models July 2020 2.1.2.4. The "netconf-client-app-grouping" Grouping The following tree diagram [RFC8340] illustrates the "netconf-client- app-grouping" grouping: grouping netconf-client-app-grouping +-- initiate! {ssh-initiate or tls-initiate}? | +-- netconf-server* [name] | +-- name? string | +-- endpoints | | +-- endpoint* [name] | | +-- name? string | | +---u netconf-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-attempts? uint8 +-- listen! {ssh-listen or tls-listen}? +-- idle-timeout? uint16 +-- endpoint* [name] +-- name? string +---u netconf-client-listen-stack-grouping Comments: * The "netconf-client-app-grouping" defines the configuration for a NETCONF client that supports both initiating connections to NETCONF servers as well as receiving call-home connections from NETCONF servers. * Both the "initiate" and "listen" subtrees must be enabled by "feature" statements. * For the referenced grouping statement(s): - The "netconf-client-initiate-stack-grouping" grouping is discussed in Section 2.1.2.2 in this document. - The "netconf-client-listen-stack-grouping" grouping is discussed in Section 2.1.2.3 in this document. Watsen Expires 9 January 2021 [Page 9] Internet-Draft NETCONF Client and Server Models July 2020 2.1.3. Protocol-accessible Nodes The following diagram lists all the protocol-accessible nodes defined in the "ietf-netconf-client" module: module: ietf-netconf-client +--rw netconf-client +---u netconf-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]. * For the "ietf-netconf-client" module, the protocol-accessible nodes are an instance of the "netconf-client-app-grouping" discussed in Section 2.1.2.4 grouping. * The reason for why "netconf-client-app-grouping" exists separate from the protocol-accessible nodes definition is so as to enable instances of netconf-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 NETCONF client to initiate connections, using both the SSH and TLS transport protocols, as well as to listen for call-home connections, again using both the SSH and TLS transport protocols. 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 9 January 2021 [Page 10] Internet-Draft NETCONF Client and Server Models July 2020 corp-fw1.example.com 15 3 30 foobar ssh-rsa-key trusted-server-ca-certs trusted-server-ee-certs 30 3 corp-fw2.example.com corp-fw2.example.com 15 3 30 Watsen Expires 9 January 2021 [Page 11] Internet-Draft NETCONF Client and Server Models July 2020 rsa-asymmetric-key ex-rsa-cert trusted-server-ca-certs trusted-server-ee-certs 30 3 last-connected Intranet-facing SSH listener Watsen Expires 9 January 2021 [Page 12] Internet-Draft NETCONF Client and Server Models July 2020 192.0.2.7 foobar ssh-rsa-key trusted-server-ca-certs trusted-server-ee-certs trusted-ssh-public-keys Intranet-facing TLS listener 192.0.2.7 rsa-asymmetric-key ex-rsa-cert trusted-server-ca-certs Watsen Expires 9 January 2021 [Page 13] Internet-Draft NETCONF Client and Server Models July 2020 trusted-server-ee-certs 2.3. YANG Module This YANG module has normative references to [RFC6242], [RFC6991], [RFC7589], [RFC8071], [I-D.ietf-netconf-tcp-client-server], [I-D.ietf-netconf-ssh-client-server], and [I-D.ietf-netconf-tls-client-server]. file "ietf-netconf-client@2020-07-08.yang" module ietf-netconf-client { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-netconf-client"; prefix ncc; 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"; Watsen Expires 9 January 2021 [Page 14] Internet-Draft NETCONF Client and Server Models July 2020 } import ietf-ssh-client { prefix sshc; revision-date 2020-07-08; // stable grouping definitions reference "RFC EEEE: YANG Groupings for SSH Clients and SSH Servers"; } import ietf-tls-client { prefix tlsc; revision-date 2020-07-08; // stable grouping definitions reference "RFC FFFF: YANG Groupings for TLS Clients and TLS Servers"; } organization "IETF NETCONF (Network Configuration) Working Group"; contact "WG Web: WG List: Author: Kent Watsen Author: Gary Wu "; description "This module contains a collection of YANG definitions for configuring NETCONF clients. Copyright (c) 2020 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 Simplified 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 HHHH (https://www.rfc-editor.org/info/rfcHHHH); 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 Watsen Expires 9 January 2021 [Page 15] Internet-Draft NETCONF Client and Server Models July 2020 capitals, as shown here."; revision 2020-07-08 { description "Initial version"; reference "RFC HHHH: NETCONF Client and Server Models"; } // Features feature ssh-initiate { description "The 'ssh-initiate' feature indicates that the NETCONF client supports initiating SSH connections to NETCONF servers."; reference "RFC 6242: Using the NETCONF Protocol over Secure Shell (SSH)"; } feature tls-initiate { description "The 'tls-initiate' feature indicates that the NETCONF client supports initiating TLS connections to NETCONF servers."; reference "RFC 7589: Using the NETCONF Protocol over Transport Layer Security (TLS) with Mutual X.509 Authentication"; } feature ssh-listen { description "The 'ssh-listen' feature indicates that the NETCONF client supports opening a port to listen for incoming NETCONF server call-home SSH connections."; reference "RFC 8071: NETCONF Call Home and RESTCONF Call Home"; } feature tls-listen { description "The 'tls-listen' feature indicates that the NETCONF client supports opening a port to listen for incoming NETCONF server call-home TLS connections."; reference "RFC 8071: NETCONF Call Home and RESTCONF Call Home"; } // Groupings Watsen Expires 9 January 2021 [Page 16] Internet-Draft NETCONF Client and Server Models July 2020 grouping netconf-client-grouping { description "A reusable grouping for configuring a NETCONF client without any consideration for how underlying transport sessions are established. This grouping currently doesn't define any nodes."; } grouping netconf-client-initiate-stack-grouping { description "A reusable grouping for configuring a NETCONF client 'initiate' protocol stack for a single connection."; choice transport { mandatory true; description "Selects between available transports."; case ssh { if-feature "ssh-initiate"; container ssh { description "Specifies IP and SSH specific configuration for the connection."; 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 "830"; description "The NETCONF client will attempt to connect to the IANA-assigned well-known port value for 'netconf-ssh' (830) if no value is specified."; } } } container ssh-client-parameters { description "A wrapper around the SSH client parameters to avoid name collisions."; uses sshc:ssh-client-grouping; } container netconf-client-parameters { description "A wrapper around the NETCONF client parameters to avoid name collisions."; Watsen Expires 9 January 2021 [Page 17] Internet-Draft NETCONF Client and Server Models July 2020 uses ncc:netconf-client-grouping; } } } case tls { if-feature "tls-initiate"; container tls { description "Specifies IP and TLS specific configuration for the connection."; 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 "6513"; description "The NETCONF client will attempt to connect to the IANA-assigned well-known port value for 'netconf-tls' (6513) if no value is specified."; } } } container tls-client-parameters { must "client-identity" { description "NETCONF/TLS clients MUST pass some authentication credentials."; } description "A wrapper around the TLS client parameters to avoid name collisions."; uses tlsc:tls-client-grouping; } container netconf-client-parameters { description "A wrapper around the NETCONF client parameters to avoid name collisions."; uses ncc:netconf-client-grouping; } } } } } // netconf-client-initiate-stack-grouping grouping netconf-client-listen-stack-grouping { Watsen Expires 9 January 2021 [Page 18] Internet-Draft NETCONF Client and Server Models July 2020 description "A reusable grouping for configuring a NETCONF 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."; case ssh { if-feature "ssh-listen"; container ssh { description "SSH-specific listening configuration for inbound connections."; 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 "4334"; description "The NETCONF client will listen on the IANA- assigned well-known port for 'netconf-ch-ssh' (4334) if no value is specified."; } } } container ssh-client-parameters { description "A wrapper around the SSH client parameters to avoid name collisions."; uses sshc:ssh-client-grouping; } container netconf-client-parameters { description "A wrapper around the NETCONF client parameters to avoid name collisions."; uses ncc:netconf-client-grouping; } } } case tls { if-feature "tls-listen"; container tls { Watsen Expires 9 January 2021 [Page 19] Internet-Draft NETCONF Client and Server Models July 2020 description "TLS-specific listening configuration for inbound connections."; 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 "4334"; description "The NETCONF client will listen on the IANA- assigned well-known port for 'netconf-ch-ssh' (4334) if no value is specified."; } } } container tls-client-parameters { must "client-identity" { description "NETCONF/TLS clients MUST pass some authentication credentials."; } description "A wrapper around the TLS client parameters to avoid name collisions."; uses tlsc:tls-client-grouping; } container netconf-client-parameters { description "A wrapper around the NETCONF client parameters to avoid name collisions."; uses ncc:netconf-client-grouping; } } } } } // netconf-client-listen-stack-grouping grouping netconf-client-app-grouping { description "A reusable grouping for configuring a NETCONF client application that supports both 'initiate' and 'listen' protocol stacks for a multiplicity of connections."; container initiate { if-feature "ssh-initiate or tls-initiate"; presence "Enables client to initiate TCP connections"; description Watsen Expires 9 January 2021 [Page 20] Internet-Draft NETCONF Client and Server Models July 2020 "Configures client initiating underlying TCP connections."; list netconf-server { key "name"; min-elements 1; description "List of NETCONF servers the NETCONF client is to maintain simultaneous connections with."; leaf name { type string; description "An arbitrary name for the NETCONF server."; } container endpoints { description "Container for the list of endpoints."; list endpoint { key "name"; min-elements 1; ordered-by user; description "A user-ordered list of endpoints that the NETCONF client will attempt to connect to in the specified sequence. Defining more than one enables high-availability."; leaf name { type string; description "An arbitrary name for the endpoint."; } uses netconf-client-initiate-stack-grouping; } // list endpoint } // container endpoints container connection-type { description "Indicates the NETCONF client's preference for how the NETCONF 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 NETCONF server. If the connection goes down, immediately Watsen Expires 9 January 2021 [Page 21] Internet-Draft NETCONF Client and Server Models July 2020 start trying to reconnect to the NETCONF server, using the reconnection strategy. This connection type minimizes any NETCONF server to NETCONF 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 NETCONF server. This connection type increases resource utilization, albeit with increased delay in NETCONF server to NETCONF client interactions. The NETCONF client should close the underlying TCP 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."; } Watsen Expires 9 January 2021 [Page 22] Internet-Draft NETCONF Client and Server Models July 2020 leaf idle-timeout { type uint16; units "seconds"; default 120; // two minutes description "Specifies the maximum number of seconds that a NETCONF session may remain idle. A NETCONF session will be dropped if it is idle for an interval longer then this number of seconds. If set to zero, then the NETCONF client will never drop a session because it is idle."; } } } } } container reconnect-strategy { description "The reconnection strategy directs how a NETCONF client reconnects to a NETCONF server, after discovering its connection to the server has dropped, even if due to a reboot. The NETCONF 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. NETCONF 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"; Watsen Expires 9 January 2021 [Page 23] Internet-Draft NETCONF Client and Server Models July 2020 description "Specifies which of the NETCONF server's endpoints the NETCONF client should start with when trying to connect to the NETCONF server."; } leaf max-attempts { type uint8 { range "1..max"; } default "3"; description "Specifies the number times the NETCONF client tries to connect to a specific endpoint before moving on to the next endpoint in the list (round robin)."; } } } // netconf-server } // initiate container listen { if-feature "ssh-listen or tls-listen"; presence "Enables client to accept call-home connections"; 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 a NETCONF session may remain idle. A NETCONF 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. Sessions that have a notification subscription active are never dropped."; } list endpoint { key "name"; min-elements 1; description "List of endpoints to listen for NETCONF connections."; leaf name { type string; description "An arbitrary name for the NETCONF listen endpoint."; } uses netconf-client-listen-stack-grouping; Watsen Expires 9 January 2021 [Page 24] Internet-Draft NETCONF Client and Server Models July 2020 } // endpoint } // listen } // netconf-client-app-grouping // Protocol accessible node, for servers that implement // this module. container netconf-client { uses netconf-client-app-grouping; description "Top-level container for NETCONF client configuration."; } } 3. The "ietf-netconf-server" Module The NETCONF server model presented in this section supports both listening for connections as well as initiating call-home connections, using either the SSH and TLS transport protocols. YANG feature statements are used to enable implementations to advertise which potentially uncommon parts of the model the NETCONF server supports. 3.1. Data Model Overview 3.1.1. Features The following diagram lists all the "feature" statements defined in the "ietf-netconf-server" module: Features: +-- ssh-listen +-- tls-listen +-- ssh-call-home +-- tls-call-home 3.1.2. Groupings The following diagram lists all the "grouping" statements defined in the "ietf-netconf-server" module: Groupings: +-- netconf-server-grouping +-- netconf-server-listen-stack-grouping +-- netconf-server-callhome-stack-grouping +-- netconf-server-app-grouping Watsen Expires 9 January 2021 [Page 25] Internet-Draft NETCONF Client and Server Models July 2020 Each of these groupings are presented in the following subsections. 3.1.2.1. The "netconf-server-grouping" Grouping The following tree diagram [RFC8340] illustrates the "netconf-server- grouping" grouping: =============== NOTE: '\' line wrapping per RFC 8792 ================ grouping netconf-server-grouping +-- client-identity-mappings {(tls-listen or tls-call-home) and (sshcmn:ssh-x509-cert\ s)}? +---u x509c2n:cert-to-name Comments: * The "netconf-server-grouping" defines the configuration for just "NETCONF" part of a protocol stack. It does not, for instance, define any configuration for the "TCP", "SSH" or "TLS" 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 NETCONF 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 "netconf-server-listen-stack-grouping" Grouping The following tree diagram [RFC8340] illustrates the "netconf-server- listen-stack-grouping" grouping: Watsen Expires 9 January 2021 [Page 26] Internet-Draft NETCONF Client and Server Models July 2020 grouping netconf-server-listen-stack-grouping +-- (transport) +--:(ssh) {ssh-listen}? | +-- ssh | +-- tcp-server-parameters | | +---u tcps:tcp-server-grouping | +-- ssh-server-parameters | | +---u sshs:ssh-server-grouping | +-- netconf-server-parameters | +---u ncs:netconf-server-grouping +--:(tls) {tls-listen}? +-- tls +-- tcp-server-parameters | +---u tcps:tcp-server-grouping +-- tls-server-parameters | +---u tlss:tls-server-grouping +-- netconf-server-parameters +---u ncs:netconf-server-grouping Comments: * The "netconf-server-listen-stack-grouping" defines the configuration for a full NETCONF protocol stack for NETCONF servers that listen for standard connections from NETCONF clients, as opposed to initiating call-home [RFC8071] connections. * The "transport" choice node enables both the SSH and TLS transports to be configured, with each option enabled by a "feature" statement. * 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 "ssh-server-grouping" grouping is discussed in Section 4.1.2.1 of [I-D.ietf-netconf-ssh-client-server]. - The "tls-server-grouping" grouping is discussed in Section 4.1.2.1 of [I-D.ietf-netconf-tls-client-server]. - The "netconf-server-grouping" is discussed in Section 3.1.2.1 of this document. 3.1.2.3. The "netconf-server-callhome-stack-grouping" Grouping The following tree diagram [RFC8340] illustrates the "netconf-server- callhome-stack-grouping" grouping: Watsen Expires 9 January 2021 [Page 27] Internet-Draft NETCONF Client and Server Models July 2020 grouping netconf-server-callhome-stack-grouping +-- (transport) +--:(ssh) {ssh-call-home}? | +-- ssh | +-- tcp-client-parameters | | +---u tcpc:tcp-client-grouping | +-- ssh-server-parameters | | +---u sshs:ssh-server-grouping | +-- netconf-server-parameters | +---u ncs:netconf-server-grouping +--:(tls) {tls-call-home}? +-- tls +-- tcp-client-parameters | +---u tcpc:tcp-client-grouping +-- tls-server-parameters | +---u tlss:tls-server-grouping +-- netconf-server-parameters +---u ncs:netconf-server-grouping Comments: * The "netconf-server-callhome-stack-grouping" defines the configuration for a full NETCONF protocol stack, for NETCONF servers that initiate call-home [RFC8071] connections to NETCONF clients. * The "transport" choice node enables both the SSH and TLS transports to be configured, with each option enabled by a "feature" statement. * 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 "ssh-server-grouping" grouping is discussed in Section 4.1.2.1 of [I-D.ietf-netconf-ssh-client-server]. - The "tls-server-grouping" grouping is discussed in Section 4.1.2.1 of [I-D.ietf-netconf-tls-client-server]. - The "netconf-server-grouping" is discussed in Section 3.1.2.1 of this document. 3.1.2.4. The "netconf-server-app-grouping" Grouping The following tree diagram [RFC8340] illustrates the "netconf-server- app-grouping" grouping: Watsen Expires 9 January 2021 [Page 28] Internet-Draft NETCONF Client and Server Models July 2020 grouping netconf-server-app-grouping +-- listen! {ssh-listen or tls-listen}? | +-- idle-timeout? uint16 | +-- endpoint* [name] | +-- name? string | +---u netconf-server-listen-stack-grouping +-- call-home! {ssh-call-home or tls-call-home}? +-- netconf-client* [name] +-- name? string +-- endpoints | +-- endpoint* [name] | +-- name? string | +---u netconf-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-attempts? uint8 Comments: * The "netconf-server-app-grouping" defines the configuration for a NETCONF server that supports both listening for connections from NETCONF clients as well as initiatiating call-home connections to NETCONF clients. * Both the "listen" and "call-home" subtrees must be enabled by "feature" statements. * For the referenced grouping statement(s): - The "netconf-server-listen-stack-grouping" grouping is discussed in Section 3.1.2.2 in this document. - The "netconf-server-callhome-stack-grouping" grouping is discussed in Section 3.1.2.3 in this document. 3.1.3. Protocol-accessible Nodes The following diagram lists all the protocol-accessible nodes defined in the "ietf-netconf-server" module: Watsen Expires 9 January 2021 [Page 29] Internet-Draft NETCONF Client and Server Models July 2020 module: ietf-netconf-server +--rw netconf-server +---u netconf-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]. * For the "ietf-netconf-server" module, the protocol-accessible nodes are an instance of the "netconf-server-app-grouping" discussed in Section 3.1.2.4 grouping. * The reason for why "netconf-server-app-grouping" exists separate from the protocol-accessible nodes definition is so as to enable instances of netconf-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 NETCONF server to listen for NETCONF client connections using both the SSH and TLS transport protocols, as well as configuring call-home to two NETCONF clients, one using SSH and the other using TLS. 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 ================ netconf/ssh 192.0.2.7 Watsen Expires 9 January 2021 [Page 30] Internet-Draft NETCONF Client and Server Models July 2020 deployment-specific-certificate ssh-rsa-key netconf/tls 192.0.2.7 rsa-asymmetric-key ex-rsa-cert trusted-client-ca-certs trusted-client-ee-certs Watsen Expires 9 January 2021 [Page 31] Internet-Draft NETCONF Client and Server Models July 2020 1 11:0A:05:11:00 x509c2n:specified scooby-doo 2 x509c2n:san-any config-mgr east-data-center east.config-mgr.example.com 15 3 30 deployment-specific-certificate ssh-rsa-key Watsen Expires 9 January 2021 [Page 32] Internet-Draft NETCONF Client and Server Models July 2020 west-data-center west.config-mgr.example.com deployment-specific-certificate ssh-rsa-key 300 60 last-connected 3 data-collector Watsen Expires 9 January 2021 [Page 33] Internet-Draft NETCONF Client and Server Models July 2020 east-data-center east.analytics.example.com 15 3 30 rsa-asymmetric-key ex-rsa-cert trusted-client-ca-certs trusted-client-ee-certs 30 3 1 11:0A:05:11:00 x509c2n:specified scooby-doo Watsen Expires 9 January 2021 [Page 34] Internet-Draft NETCONF Client and Server Models July 2020 2 x509c2n:san-any west-data-center west.analytics.example.com 15 3 30 rsa-asymmetric-key ex-rsa-cert trusted-client-ca-certs trusted-client-ee-certs 30 3 Watsen Expires 9 January 2021 [Page 35] Internet-Draft NETCONF Client and Server Models July 2020 1 11:0A:05:11:00 x509c2n:specified scooby-doo 2 x509c2n:san-any first-listed 3 3.3. YANG Module This YANG module has normative references to [RFC6242], [RFC6991], [RFC7407], [RFC7589], [RFC8071], [I-D.ietf-netconf-tcp-client-server], [I-D.ietf-netconf-ssh-client-server], and [I-D.ietf-netconf-tls-client-server]. file "ietf-netconf-server@2020-07-08.yang" module ietf-netconf-server { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-netconf-server"; prefix ncs; import ietf-yang-types { prefix yang; reference "RFC 6991: Common YANG Data Types"; } Watsen Expires 9 January 2021 [Page 36] Internet-Draft NETCONF Client and Server Models July 2020 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-ssh-common { prefix sshcmn; revision-date 2020-07-08; // stable grouping definitions reference "RFC EEEE: YANG Groupings for SSH Clients and SSH Servers"; } import ietf-ssh-server { prefix sshs; revision-date 2020-07-08; // stable grouping definitions reference "RFC EEEE: YANG Groupings for SSH Clients and SSH Servers"; } import ietf-tls-server { prefix tlss; revision-date 2020-07-08; // stable grouping definitions reference "RFC FFFF: YANG Groupings for TLS Clients and TLS Servers"; } organization "IETF NETCONF (Network Configuration) Working Group"; contact "WG Web: WG List: Author: Kent Watsen Author: Gary Wu Author: Juergen Schoenwaelder Watsen Expires 9 January 2021 [Page 37] Internet-Draft NETCONF Client and Server Models July 2020 "; description "This module contains a collection of YANG definitions for configuring NETCONF servers. Copyright (c) 2020 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 Simplified 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 HHHH (https://www.rfc-editor.org/info/rfcHHHH); 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 2020-07-08 { description "Initial version"; reference "RFC HHHH: NETCONF Client and Server Models"; } // Features feature ssh-listen { description "The 'ssh-listen' feature indicates that the NETCONF server supports opening a port to accept NETCONF over SSH client connections."; reference "RFC 6242: Using the NETCONF Protocol over Secure Shell (SSH)"; } feature tls-listen { description Watsen Expires 9 January 2021 [Page 38] Internet-Draft NETCONF Client and Server Models July 2020 "The 'tls-listen' feature indicates that the NETCONF server supports opening a port to accept NETCONF over TLS client connections."; reference "RFC 7589: Using the NETCONF Protocol over Transport Layer Security (TLS) with Mutual X.509 Authentication"; } feature ssh-call-home { description "The 'ssh-call-home' feature indicates that the NETCONF server supports initiating a NETCONF over SSH call home connection to NETCONF clients."; reference "RFC 8071: NETCONF Call Home and RESTCONF Call Home"; } feature tls-call-home { description "The 'tls-call-home' feature indicates that the NETCONF server supports initiating a NETCONF over TLS call home connection to NETCONF clients."; reference "RFC 8071: NETCONF Call Home and RESTCONF Call Home"; } // Groupings grouping netconf-server-grouping { description "A reusable grouping for configuring a NETCONF server without any consideration for how underlying transport sessions are established. Note that this grouping uses a fairly typical descendent 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., 'netconf-server-parameters'. This model purposely does not do this itself so as to provide maximum flexibility to consuming models."; container client-identity-mappings { if-feature "(tls-listen or tls-call-home) and (sshcmn:ssh-x509-certs)"; description Watsen Expires 9 January 2021 [Page 39] Internet-Draft NETCONF Client and Server Models July 2020 "Specifies mappings through which NETCONF client X.509 certificates are used to determine a NETCONF username. If no matching and valid cert-to-name list entry can be found, then the NETCONF server MUST close the connection, and MUST NOT accept NETCONF 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 netconf-server-listen-stack-grouping { description "A reusable grouping for configuring a NETCONF server 'listen' protocol stack for a single connection."; choice transport { mandatory true; description "Selects between available transports."; case ssh { if-feature "ssh-listen"; container ssh { description "SSH-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 "830"; description "The NETCONF server will listen on the IANA-assigned well-known port value for 'netconf-ssh' (830) if no value is specified."; Watsen Expires 9 January 2021 [Page 40] Internet-Draft NETCONF Client and Server Models July 2020 } } } container ssh-server-parameters { description "A wrapper around the SSH server parameters to avoid name collisions."; uses sshs:ssh-server-grouping; } container netconf-server-parameters { description "A wrapper around the NETCONF server parameters to avoid name collisions."; uses ncs:netconf-server-grouping; } } } case tls { if-feature "tls-listen"; container tls { description "TLS-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 "6513"; description "The NETCONF server will listen on the IANA-assigned well-known port value for 'netconf-tls' (6513) 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 { refine "client-authentication" { must 'ca-certs or ee-certs'; description "NETCONF/TLS servers MUST validate client certificates. This configures certificates Watsen Expires 9 January 2021 [Page 41] Internet-Draft NETCONF Client and Server Models July 2020 at the socket-level (i.e. bags), more discriminating client-certificate checks SHOULD be implemented by the application."; reference "RFC 7589: Using the NETCONF Protocol over Transport Layer Security (TLS) with Mutual X.509 Authentication"; } } } container netconf-server-parameters { description "A wrapper around the NETCONF server parameters to avoid name collisions."; uses ncs:netconf-server-grouping; } } } } } grouping netconf-server-callhome-stack-grouping { description "A reusable grouping for configuring a NETCONF server 'call-home' protocol stack, for a single connection."; choice transport { mandatory true; description "Selects between available transports."; case ssh { if-feature "ssh-call-home"; container ssh { description "Specifies SSH-specific call-home 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 "4334"; description "The NETCONF server will attempt to connect to the IANA-assigned well-known port for 'netconf-ch-tls' (4334) if no value is specified."; } Watsen Expires 9 January 2021 [Page 42] Internet-Draft NETCONF Client and Server Models July 2020 } } container ssh-server-parameters { description "A wrapper around the SSH server parameters to avoid name collisions."; uses sshs:ssh-server-grouping; } container netconf-server-parameters { description "A wrapper around the NETCONF server parameters to avoid name collisions."; uses ncs:netconf-server-grouping; } } } case tls { if-feature "tls-call-home"; container tls { description "Specifies TLS-specific call-home 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 "4335"; description "The NETCONF server will attempt to connect to the IANA-assigned well-known port for 'netconf-ch-tls' (4335) 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 { refine "client-authentication" { must 'ca-certs or ee-certs'; description "NETCONF/TLS servers MUST validate client certificates. This configures certificates at the socket-level (i.e. bags), more Watsen Expires 9 January 2021 [Page 43] Internet-Draft NETCONF Client and Server Models July 2020 discriminating client-certificate checks SHOULD be implemented by the application."; reference "RFC 7589: Using the NETCONF Protocol over Transport Layer Security (TLS) with Mutual X.509 Authentication"; } } } container netconf-server-parameters { description "A wrapper around the NETCONF server parameters to avoid name collisions."; uses ncs:netconf-server-grouping; } } } } } grouping netconf-server-app-grouping { description "A reusable grouping for configuring a NETCONF server application that supports both 'listen' and 'call-home' protocol stacks for a multiplicity of connections."; container listen { if-feature "ssh-listen or tls-listen"; presence "Enables server to listen for NETCONF client connections."; description "Configures listen behavior"; leaf idle-timeout { type uint16; units "seconds"; default 3600; // one hour description "Specifies the maximum number of seconds that a NETCONF session may remain idle. A NETCONF 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. Sessions that have a notification subscription active are never dropped."; } list endpoint { key "name"; min-elements 1; description Watsen Expires 9 January 2021 [Page 44] Internet-Draft NETCONF Client and Server Models July 2020 "List of endpoints to listen for NETCONF connections."; leaf name { type string; description "An arbitrary name for the NETCONF listen endpoint."; } uses netconf-server-listen-stack-grouping; } } container call-home { if-feature "ssh-call-home or tls-call-home"; presence "Enables the NETCONF server to initiate the underlying transport connection to NETCONF clients."; description "Configures call home behavior."; list netconf-client { key "name"; min-elements 1; description "List of NETCONF clients the NETCONF server is to maintain simultaneous call-home connections with."; leaf name { type string; description "An arbitrary name for the remote NETCONF client."; } container endpoints { description "Container for the list of endpoints."; list endpoint { key "name"; min-elements 1; ordered-by user; description "A non-empty user-ordered list of endpoints for this NETCONF server 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 netconf-server-callhome-stack-grouping; } } container connection-type { description "Indicates the NETCONF server's preference for how the Watsen Expires 9 January 2021 [Page 45] Internet-Draft NETCONF Client and Server Models July 2020 NETCONF 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 NETCONF client. If the connection goes down, immediately start trying to reconnect to the NETCONF client, using the reconnection strategy. This connection type minimizes any NETCONF client to NETCONF server 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 NETCONF client. This connection type increases resource utilization, albeit with increased delay in NETCONF client to NETCONF client interactions. The NETCONF client SHOULD gracefully close the connection using upon completing planned activities. If the NETCONF session is not closed gracefully, the NETCONF server MUST immediately attempt to reestablish the connection. In the case that the previous connection is still active (i.e., the NETCONF 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."; } Watsen Expires 9 January 2021 [Page 46] Internet-Draft NETCONF Client and Server Models July 2020 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 a NETCONF session may remain idle. A NETCONF 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."; } } } // case periodic-connection } // choice connection-type } // container connection-type container reconnect-strategy { description "The reconnection strategy directs how a NETCONF server reconnects to a NETCONF client, after discovering its connection to the client has dropped, even if due to a reboot. The NETCONF 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."; } Watsen Expires 9 January 2021 [Page 47] Internet-Draft NETCONF Client and Server Models July 2020 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. NETCONF 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 NETCONF client's endpoints the NETCONF server should start with when trying to connect to the NETCONF client."; } leaf max-attempts { type uint8 { range "1..max"; } default "3"; description "Specifies the number times the NETCONF server tries to connect to a specific endpoint before moving on to the next endpoint in the list (round robin)."; } } // container reconnect-strategy } // list netconf-client } // container call-home } // grouping netconf-server-app-grouping // Protocol accessible node, for servers that implement // this module. container netconf-server { uses netconf-server-app-grouping; description "Top-level container for NETCONF server configuration."; } } Watsen Expires 9 January 2021 [Page 48] Internet-Draft NETCONF Client and Server Models July 2020 4. Security Considerations 4.1. The "ietf-netconf-client" YANG Module The "ietf-netconf-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 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. None of the readable data nodes defined 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 defined 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-netconf-server" YANG Module The "ietf-netconf-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 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. None of the readable data nodes defined 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 9 January 2021 [Page 49] Internet-Draft NETCONF Client and Server Models July 2020 None of the writable data nodes defined 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-netconf-client Registrant Contact: The NETCONF WG of the IETF. XML: N/A, the requested URI is an XML namespace. URI: urn:ietf:params:xml:ns:yang:ietf-netconf-server Registrant Contact: The NETCONF WG of the IETF. 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 the following registrations are requested: name: ietf-netconf-client namespace: urn:ietf:params:xml:ns:yang:ietf-netconf-client prefix: ncc reference: RFC HHHH name: ietf-netconf-server namespace: urn:ietf:params:xml:ns:yang:ietf-netconf-server prefix: ncs reference: RFC HHHH 6. References 6.1. Normative References Watsen Expires 9 January 2021 [Page 50] Internet-Draft NETCONF Client and Server Models July 2020 [I-D.ietf-netconf-keystore] Watsen, K., "A YANG Data Model for a Keystore", Work in Progress, Internet-Draft, draft-ietf-netconf-keystore-17, 20 May 2020, . [I-D.ietf-netconf-ssh-client-server] Watsen, K. and G. Wu, "YANG Groupings for SSH Clients and SSH Servers", Work in Progress, Internet-Draft, draft- ietf-netconf-ssh-client-server-19, 20 May 2020, . [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-06, 16 June 2020, . [I-D.ietf-netconf-tls-client-server] Watsen, K. and G. Wu, "YANG Groupings for TLS Clients and TLS Servers", Work in Progress, Internet-Draft, draft- ietf-netconf-tls-client-server-19, 20 May 2020, . [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, . [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, . [RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011, . Watsen Expires 9 January 2021 [Page 51] Internet-Draft NETCONF Client and Server Models July 2020 [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, . [RFC7589] Badra, M., Luchuk, A., and J. Schoenwaelder, "Using the NETCONF Protocol over Transport Layer Security (TLS) with Mutual X.509 Authentication", RFC 7589, DOI 10.17487/RFC7589, June 2015, . [RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, August 2016, . [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., "Common YANG Data Types for Cryptography", Work in Progress, Internet-Draft, draft-ietf-netconf- crypto-types-15, 20 May 2020, . [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-03, 20 May 2020, . [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-19, 20 May 2020, . [I-D.ietf-netconf-restconf-client-server] Watsen, K., "RESTCONF Client and Server Models", Work in Progress, Internet-Draft, draft-ietf-netconf-restconf- Watsen Expires 9 January 2021 [Page 52] Internet-Draft NETCONF Client and Server Models July 2020 client-server-19, 20 May 2020, . [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-10, 20 May 2020, . [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, January 2004, . [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, . [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. 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 * Added to ietf-netconf-client ability to connected to a cluster of endpoints, including a reconnection-strategy. Watsen Expires 9 January 2021 [Page 53] Internet-Draft NETCONF Client and Server Models July 2020 * Added to ietf-netconf-client the ability to configure connection- type and also keep-alive strategy. * Updated both modules to accommodate new groupings in the ssh/tls drafts. 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 'netconf-client' to be a grouping (not a container). A.4. 03 to 04 * Added RFC 8174 to Requirements Language Section. * Replaced refine statement in ietf-netconf-client to add a mandatory true. * Added refine statement in ietf-netconf-server to add a must statement. * Now there are containers and groupings, for both the client and server models. 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. Watsen Expires 9 January 2021 [Page 54] Internet-Draft NETCONF Client and Server Models July 2020 * 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. 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 "Design Considerations" section. * Removed the 'must' statement limiting keepalives in periodic connections. Watsen Expires 9 January 2021 [Page 55] Internet-Draft NETCONF Client and Server Models July 2020 * Updated models and examples to reflect removal of the "demux" containers in the imported models. * Updated the "periodic-connnection" description statements to be more like the RESTCONF draft, especially where it described dropping the underlying TCP connection. * Updated text to better reference where certain examples come from (e.g., which Section in which draft). * 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.//) A.14. 13 to 14 * Adjusting from change in TLS client model (removing the top-level 'certificate' container), by swapping refining-in a 'mandatory true' statement with a 'must' statement outside the 'uses' statement. * Updated examples to reflect ietf-crypto-types change (e.g., identities --> enumerations) A.15. 14 to 15 * Refactored both the client and server modules similar to how the ietf-restconf-server module was refactored in -13 of that draft, and the ietf-restconf-client grouping. 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. A.17. 16 to 17 Watsen Expires 9 January 2021 [Page 56] Internet-Draft NETCONF Client and Server Models July 2020 * Updated examples to include the "*-key-format" nodes. * Updated examples to remove the "required" nodes. * Updated examples to remove the "client-auth-defined-elsewhere" 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. * Added keepalives to the tcp-client-parameters section in the netconf-server SSH-based call-home example. * Added a TLS-based call-home example to the netconf-client example. * Added a "Note to Reviewers" note to first page. A.20. 19 to 20 * Expanded "Data Model Overview section(s) [remove "wall" of tree diagrams]. * Removed expanded tree diagrams that were listed in the Appendix. * Updated the Security Considerations section. Acknowledgements The authors would like to thank for following for lively discussions on list and in the halls (ordered by last name): Andy Bierman, Martin Bjorklund, Benoit Claise, Ramkumar Dhanapal, Mehmet Ersue, Balazs Kovacs, David Lamparter, Ladislav Lhotka, Alan Luchuk, Radek Krejci, Tom Petch, Juergen Schoenwaelder, Phil Shafer, Sean Turner, and Bert Wijnen. Author's Address Kent Watsen Watsen Networks Email: kent+ietf@watsen.net Watsen Expires 9 January 2021 [Page 57]