NETCONF Working Group K. Watsen Internet-Draft Juniper Networks Intended status: Standards Track G. Wu Expires: December 6, 2018 Cisco Networks June 4, 2018 NETCONF Client and Server Models draft-ietf-netconf-netconf-client-server-06 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 many placeholder values that need to be replaced with finalized values at the time of publication. This note summarizes all of the substitutions that are needed. No other RFC Editor instructions are specified elsewhere in this document. This document contains references to other drafts in progress, both in the Normative References section, as well as in body text throughout. Please update the following references to reflect their final RFC assignments: o I-D.ietf-netconf-keystore o I-D.ietf-netconf-ssh-client-server o I-D.ietf-netconf-tls-client-server Artwork in this document contains shorthand references to drafts in progress. Please apply the following replacements: o "XXXX" --> the assigned RFC value for this draft o "YYYY" --> the assigned RFC value for I-D.ietf-netconf-ssh-client- server o "ZZZZ" --> the assigned RFC value for I-D.ietf-netconf-tls-client- server Artwork in this document contains placeholder values for the date of publication of this draft. Please apply the following replacement: Watsen & Wu Expires December 6, 2018 [Page 1] Internet-Draft NETCONF Client and Server Models June 2018 o "2018-06-04" --> the publication date of this draft The following Appendix section is to be removed prior to publication: o 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 December 6, 2018. Copyright Notice Copyright (c) 2018 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (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 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. The NETCONF Client Model . . . . . . . . . . . . . . . . . . 4 3.1. Tree Diagram . . . . . . . . . . . . . . . . . . . . . . 4 3.2. Example Usage . . . . . . . . . . . . . . . . . . . . . . 9 3.3. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 11 4. The NETCONF Server Model . . . . . . . . . . . . . . . . . . 22 4.1. Tree Diagram . . . . . . . . . . . . . . . . . . . . . . 22 Watsen & Wu Expires December 6, 2018 [Page 2] Internet-Draft NETCONF Client and Server Models June 2018 4.2. Example Usage . . . . . . . . . . . . . . . . . . . . . . 28 4.3. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 33 5. Design Considerations . . . . . . . . . . . . . . . . . . . . 44 5.1. Support all NETCONF transports . . . . . . . . . . . . . 45 5.2. Enable each transport to select which keys to use . . . . 45 5.3. Support authenticating NETCONF clients certificates . . . 45 5.4. Support mapping authenticated NETCONF client certificates to usernames . . . . . . . . . . . . . . . . . . . . . . 45 5.5. Support both listening for connections and call home . . 45 5.6. For Call Home connections . . . . . . . . . . . . . . . . 46 5.6.1. Support more than one NETCONF client . . . . . . . . 46 5.6.2. Support NETCONF clients having more than one endpoint 46 5.6.3. Support a reconnection strategy . . . . . . . . . . . 46 5.6.4. Support both persistent and periodic connections . . 46 5.6.5. Reconnection strategy for periodic connections . . . 46 5.6.6. Keep-alives for persistent connections . . . . . . . 47 5.6.7. Customizations for periodic connections . . . . . . . 47 6. Security Considerations . . . . . . . . . . . . . . . . . . . 47 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 48 7.1. The IETF XML Registry . . . . . . . . . . . . . . . . . . 48 7.2. The YANG Module Names Registry . . . . . . . . . . . . . 48 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 49 8.1. Normative References . . . . . . . . . . . . . . . . . . 49 8.2. Informative References . . . . . . . . . . . . . . . . . 50 Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 51 A.1. 00 to 01 . . . . . . . . . . . . . . . . . . . . . . . . 51 A.2. 01 to 02 . . . . . . . . . . . . . . . . . . . . . . . . 51 A.3. 02 to 03 . . . . . . . . . . . . . . . . . . . . . . . . 51 A.4. 03 to 04 . . . . . . . . . . . . . . . . . . . . . . . . 51 A.5. 04 to 05 . . . . . . . . . . . . . . . . . . . . . . . . 51 A.6. 05 to 06 . . . . . . . . . . . . . . . . . . . . . . . . 52 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 52 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 52 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]. 2. Terminology 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 Watsen & Wu Expires December 6, 2018 [Page 3] Internet-Draft NETCONF Client and Server Models June 2018 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. 3. The NETCONF Client Model 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. This model supports both the SSH and TLS transport protocols, using the SSH client and TLS client groupings defined in [I-D.ietf-netconf-ssh-client-server] and [I-D.ietf-netconf-tls-client-server] respectively. All private keys and trusted certificates are held in the keystore model defined in [I-D.ietf-netconf-keystore]. YANG feature statements are used to enable implementations to advertise which parts of the model the NETCONF client supports. 3.1. Tree Diagram The following tree diagram [RFC8340] provides an overview of the data model for the "ietf-netconf-client" module. Just the container is displayed below, but there is also a reuable grouping by the same name that the container is using. [Note: '\' line wrapping for formatting only] module: ietf-netconf-client +--rw netconf-client +--rw initiate! {initiate}? | +--rw netconf-server* [name] | +--rw name string | +--rw endpoints | | +--rw endpoint* [name] | | +--rw name string | | +--rw (transport) | | +--:(ssh) {ssh-initiate}? | | | +--rw ssh | | | +--rw address? inet:host | | | +--rw port? inet:port-number\ | | | +--rw client-identity | | | | +--rw username? string | | | | +--rw (auth-type) | | | | +--:(password) Watsen & Wu Expires December 6, 2018 [Page 4] Internet-Draft NETCONF Client and Server Models June 2018 | | | | | +--rw password? string | | | | +--:(public-key) | | | | | +--rw public-key | | | | | +--rw (local-or-keystore) | | | | | +--:(local) | | | | | | +--rw algorithm | | | | | | | ct:key-algorithm\ -ref | | | | | | +--rw public-key bin\ ary | | | | | | +--rw private-key uni\ on | | | | | +--:(keystore) | | | | | {keystore-implemen\ ted}? | | | | | +--rw reference | | | | | ks:asymmetric-ke\ y-ref | | | | +--:(certificate) | | | | +--rw certificate | | | | {sshcmn:ssh-x509-certs}? | | | | +--rw (local-or-keystore) | | | | +--:(local) | | | | | +--rw algorithm | | | | | | ct:key-algorithm\ -ref | | | | | +--rw public-key | | | | | | binary | | | | | +--rw private-key | | | | | | union | | | | | +--rw cert | | | | | | ct:end-entity-ce\ rt-cms | | | | | +---n certificate-expira\ tion | | | | | +-- expiration-date? | | | | | yang:date-and\ -time | | | | +--:(keystore) | | | | {keystore-implemen\ ted}? | | | | +--rw reference | | | | ks:asymmetric-ke\ y-certificate-ref | | | +--rw server-auth | | | | +--rw pinned-ssh-host-keys? | | | | | ta:pinned-host-keys-ref | | | | +--rw pinned-ca-certs? Watsen & Wu Expires December 6, 2018 [Page 5] Internet-Draft NETCONF Client and Server Models June 2018 | | | | | ta:pinned-certificates-ref | | | | | {sshcmn:ssh-x509-certs}? | | | | +--rw pinned-server-certs? | | | | ta:pinned-certificates-ref | | | | {sshcmn:ssh-x509-certs}? | | | +--rw transport-params | | | {ssh-client-transport-params-confi\ g}? | | | +--rw host-key | | | | +--rw host-key-alg* identityref | | | +--rw key-exchange | | | | +--rw key-exchange-alg* identityre\ f | | | +--rw encryption | | | | +--rw encryption-alg* identityref | | | +--rw mac | | | +--rw mac-alg* identityref | | +--:(tls) {tls-initiate}? | | +--rw tls | | +--rw address? inet:host | | +--rw port? inet:port-number | | +--rw client-identity | | | +--rw (auth-type) | | | +--:(certificate) | | | +--rw certificate | | | +--rw (local-or-keystore) | | | +--:(local) | | | | +--rw algorithm | | | | | ct:key-algorithm\ -ref | | | | +--rw public-key | | | | | binary | | | | +--rw private-key | | | | | union | | | | +--rw cert | | | | | ct:end-entity-ce\ rt-cms | | | | +---n certificate-expira\ tion | | | | +-- expiration-date? | | | | yang:date-and\ -time | | | +--:(keystore) | | | {keystore-implemen\ ted}? | | | +--rw reference | | | ks:asymmetric-ke\ y-certificate-ref Watsen & Wu Expires December 6, 2018 [Page 6] Internet-Draft NETCONF Client and Server Models June 2018 | | +--rw server-auth | | | +--rw pinned-ca-certs? | | | | ta:pinned-certificates-ref | | | +--rw pinned-server-certs? | | | ta:pinned-certificates-ref | | +--rw hello-params | | {tls-client-hello-params-config}? | | +--rw tls-versions | | | +--rw tls-version* identityref | | +--rw cipher-suites | | +--rw cipher-suite* identityref | +--rw connection-type | | +--rw (connection-type)? | | +--:(persistent-connection) | | | +--rw persistent! | | | +--rw idle-timeout? uint32 | | | +--rw keep-alives | | | +--rw max-wait? uint16 | | | +--rw max-attempts? uint8 | | +--:(periodic-connection) | | +--rw periodic! | | +--rw idle-timeout? uint16 | | +--rw reconnect-timeout? uint16 | +--rw reconnect-strategy | +--rw start-with? enumeration | +--rw max-attempts? uint8 +--rw listen! {listen}? +--rw idle-timeout? uint16 +--rw endpoint* [name] +--rw name string +--rw (transport) +--:(ssh) {ssh-listen}? | +--rw ssh | +--rw address? inet:ip-address | +--rw port? inet:port-number | +--rw client-identity | | +--rw username? string | | +--rw (auth-type) | | +--:(password) | | | +--rw password? string | | +--:(public-key) | | | +--rw public-key | | | +--rw (local-or-keystore) | | | +--:(local) | | | | +--rw algorithm | | | | | ct:key-algorithm-ref | | | | +--rw public-key binary | | | | +--rw private-key union Watsen & Wu Expires December 6, 2018 [Page 7] Internet-Draft NETCONF Client and Server Models June 2018 | | | +--:(keystore) | | | {keystore-implemented}? | | | +--rw reference | | | ks:asymmetric-key-ref | | +--:(certificate) | | +--rw certificate {sshcmn:ssh-x509-cert\ s}? | | +--rw (local-or-keystore) | | +--:(local) | | | +--rw algorithm | | | | ct:key-algorithm-ref | | | +--rw public-key | | | | binary | | | +--rw private-key | | | | union | | | +--rw cert | | | | ct:end-entity-cert-cms\ | | | +---n certificate-expiration | | | +-- expiration-date? | | | yang:date-and-time | | +--:(keystore) | | {keystore-implemented}? | | +--rw reference | | ks:asymmetric-key-cert\ ificate-ref | +--rw server-auth | | +--rw pinned-ssh-host-keys? | | | ta:pinned-host-keys-ref | | +--rw pinned-ca-certs? | | | ta:pinned-certificates-ref | | | {sshcmn:ssh-x509-certs}? | | +--rw pinned-server-certs? | | ta:pinned-certificates-ref | | {sshcmn:ssh-x509-certs}? | +--rw transport-params | {ssh-client-transport-params-config}? | +--rw host-key | | +--rw host-key-alg* identityref | +--rw key-exchange | | +--rw key-exchange-alg* identityref | +--rw encryption | | +--rw encryption-alg* identityref | +--rw mac | +--rw mac-alg* identityref +--:(tls) {tls-listen}? +--rw tls +--rw address? inet:ip-address Watsen & Wu Expires December 6, 2018 [Page 8] Internet-Draft NETCONF Client and Server Models June 2018 +--rw port? inet:port-number +--rw client-identity | +--rw (auth-type) | +--:(certificate) | +--rw certificate | +--rw (local-or-keystore) | +--:(local) | | +--rw algorithm | | | ct:key-algorithm-ref | | +--rw public-key | | | binary | | +--rw private-key | | | union | | +--rw cert | | | ct:end-entity-cert-cms\ | | +---n certificate-expiration | | +-- expiration-date? | | yang:date-and-time | +--:(keystore) | {keystore-implemented}? | +--rw reference | ks:asymmetric-key-cert\ ificate-ref +--rw server-auth | +--rw pinned-ca-certs? | | ta:pinned-certificates-ref | +--rw pinned-server-certs? | ta:pinned-certificates-ref +--rw hello-params {tls-client-hello-params-config}? +--rw tls-versions | +--rw tls-version* identityref +--rw cipher-suites +--rw cipher-suite* identityref 3.2. Example Usage The following example illustrates configuring a NETCONF client to initiate connections, using both the SSH and TLS transport protocols, as well as listening 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-keystore]. [Note: '\' line wrapping for formatting only] Watsen & Wu Expires December 6, 2018 [Page 9] Internet-Draft NETCONF Client and Server Models June 2018 corp-fw1 corp-fw1.example.com
corp-fw1.example.com
foobar ct:secp521r1 base64encodedvalue== base64encodedvalue== explicitly-trusted-server-ca-certs explicitly-trusted-server-certs
corp-fw2.example.com
corp-fw2.example.com
foobar ct:secp521r1 base64encodedvalue== base64encodedvalue== explicitly-trusted-server-ca-certs explicitly-trusted-server-certs Watsen & Wu Expires December 6, 2018 [Page 10] Internet-Draft NETCONF Client and Server Models June 2018
last-connected
Intranet-facing listener
192.0.2.7
foobar ct:secp521r1 base64encodedvalue== base64encodedvalue== explicitly-trusted-server-ca-certs explicitly-trusted-server-certs explicitly-trusted-ssh-host-keys
3.3. YANG Module This YANG module has normative references to [RFC6242], [RFC6991], [RFC7589], [RFC8071], [I-D.ietf-netconf-ssh-client-server], and [I-D.ietf-netconf-tls-client-server]. file "ietf-netconf-client@2018-06-04.yang" module ietf-netconf-client { Watsen & Wu Expires December 6, 2018 [Page 11] Internet-Draft NETCONF Client and Server Models June 2018 yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-netconf-client"; prefix "ncc"; import ietf-inet-types { prefix inet; reference "RFC 6991: Common YANG Data Types"; } import ietf-ssh-client { prefix ss; revision-date 2018-06-04; // stable grouping definitions reference "RFC YYYY: YANG Groupings for SSH Clients and SSH Servers"; } import ietf-tls-client { prefix ts; revision-date 2018-06-04; // stable grouping definitions reference "RFC ZZZZ: 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) 2017 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 Watsen & Wu Expires December 6, 2018 [Page 12] Internet-Draft NETCONF Client and Server Models June 2018 to the license terms contained in, the Simplified BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info). This version of this YANG module is part of RFC XXXX; see the RFC itself for full legal notices."; revision "2018-06-04" { description "Initial version"; reference "RFC XXXX: NETCONF Client and Server Models"; } // Features feature initiate { description "The 'initiate' feature indicates that the NETCONF client supports initiating NETCONF connections to NETCONF servers using at least one transport (e.g., SSH, TLS, etc.)."; } 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 listen { description "The 'listen' feature indicates that the NETCONF client supports opening a port to accept NETCONF server call home connections using at least one transport (e.g., Watsen & Wu Expires December 6, 2018 [Page 13] Internet-Draft NETCONF Client and Server Models June 2018 SSH, TLS, etc.)."; } 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"; } container netconf-client { uses netconf-client; description "Top-level container for NETCONF client configuration."; } grouping netconf-client { description "Top-level grouping for NETCONF client configuration."; container initiate { if-feature initiate; presence "Enables client to initiate TCP connections"; description "Configures client initiating underlying TCP connections."; list netconf-server { key name; min-elements 1; description "List of NETCONF servers the NETCONF client is to initiate connections to in parallel."; leaf name { type string; description "An arbitrary name for the NETCONF server."; } container endpoints { Watsen & Wu Expires December 6, 2018 [Page 14] Internet-Draft NETCONF Client and Server Models June 2018 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."; } 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."; leaf address { type inet:host; description "The IP address or hostname of the endpoint. If a domain name is configured, then the DNS resolution should happen on each usage attempt. If the DNS resolution results in multiple IP addresses, the IP addresses will be tried according to local preference order until a connection has been established or until all IP addresses have failed."; } leaf port { type inet:port-number; default 830; description "The IP port for this endpoint. The NETCONF client will use the IANA-assigned well-known port for 'netconf-ssh' (830) if no value is specified."; } uses ss:ssh-client-grouping; Watsen & Wu Expires December 6, 2018 [Page 15] Internet-Draft NETCONF Client and Server Models June 2018 } } // end ssh case tls { if-feature tls-initiate; container tls { description "Specifies IP and TLS specific configuration for the connection."; leaf address { type inet:host; description "The IP address or hostname of the endpoint. If a domain name is configured, then the DNS resolution should happen on each usage attempt. If the DNS resolution results in multiple IP addresses, the IP addresses will be tried according to local preference order until a connection has been established or until all IP addresses have failed."; } leaf port { type inet:port-number; default 6513; description "The IP port for this endpoint. The NETCONF client will use the IANA-assigned well- known port for 'netconf-tls' (6513) if no value is specified."; } uses ts:tls-client-grouping { refine "client-identity/auth-type" { mandatory true; description "NETCONF/TLS clients MUST pass some authentication credentials."; } } } } // end tls } } } container connection-type { description "Indicates the kind of connection to use."; choice connection-type { default persistent-connection; Watsen & Wu Expires December 6, 2018 [Page 16] Internet-Draft NETCONF Client and Server Models June 2018 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 start trying to reconnect to it, 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."; leaf idle-timeout { type uint32; units "seconds"; default 86400; // one day; 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 client will never drop a session because it is idle. Sessions that have a notification subscription active are never dropped."; } container keep-alives { description "Configures the keep-alive policy, to proactively test the aliveness of the SSH/TLS server. An unresponsive SSH/TLS server will be dropped after approximately max-attempts * max-wait seconds."; reference "RFC 8071: NETCONF Call Home and RESTCONF Call Home, Section 3.1, item S6"; leaf max-wait { type uint16 { range "1..max"; } units seconds; default 30; description "Sets the amount of time in seconds after Watsen & Wu Expires December 6, 2018 [Page 17] Internet-Draft NETCONF Client and Server Models June 2018 which if no data has been received from the SSH/TLS server, a SSH/TLS-level message will be sent to test the aliveness of the SSH/TLS server."; } leaf max-attempts { type uint8; default 3; description "Sets the maximum number of sequential keep- alive messages that can fail to obtain a response from the SSH/TLS server before assuming the SSH/TLS server is no longer alive."; } } } } case periodic-connection { container periodic { presence "Indicates that a periodic connection is to be maintained."; description "Periodically connect to the NETCONF server, so that the NETCONF server may deliver messages pending for the NETCONF client. The NETCONF server must close the connection when it is ready to release it. Once the connection has been closed, the NETCONF client will restart its timer until the next connection."; leaf idle-timeout { type uint16; units "seconds"; default 300; // five 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. Sessions that have a notification subscription active are never dropped."; } leaf reconnect-timeout { type uint16 { range "1..max"; Watsen & Wu Expires December 6, 2018 [Page 18] Internet-Draft NETCONF Client and Server Models June 2018 } units minutes; default 60; description "Sets the maximum amount of unconnected time the NETCONF client will wait before re- establishing a connection to the NETCONF server. The NETCONF client may initiate a connection before this time if desired (e.g., to set configuration)."; } } } } } 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."; } } default first-listed; 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 { Watsen & Wu Expires December 6, 2018 [Page 19] Internet-Draft NETCONF Client and Server Models June 2018 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)."; } } } // end netconf-server } // end initiate container listen { if-feature listen; presence "Enables client to accept call-home connections"; description "Configures client accepting 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."; } choice transport { mandatory true; description "Selects between available transports."; case ssh { Watsen & Wu Expires December 6, 2018 [Page 20] Internet-Draft NETCONF Client and Server Models June 2018 if-feature ssh-listen; container ssh { description "SSH-specific listening configuration for inbound connections."; leaf address { type inet:ip-address; description "The IP address to listen on for incoming call- home connections. The NETCONF client will listen on all configured interfaces if no value is specified. INADDR_ANY (0.0.0.0) or INADDR6_ANY (0:0:0:0:0:0:0:0 a.k.a. ::) MUST be used when the server is to listen on all IPv4 or IPv6 addresses, respectively."; } leaf port { type inet:port-number; default 4334; description "The port number to listen on for call-home connections. The NETCONF client will listen on the IANA-assigned well-known port for 'netconf-ch-ssh' (4334) if no value is specified."; } uses ss:ssh-client-grouping; } } case tls { if-feature tls-listen; container tls { description "TLS-specific listening configuration for inbound connections."; leaf address { type inet:ip-address; description "The IP address to listen on for incoming call- home connections. The NETCONF client will listen on all configured interfaces if no value is specified. INADDR_ANY (0.0.0.0) or INADDR6_ANY (0:0:0:0:0:0:0:0 a.k.a. ::) MUST be used when the server is to listen on all IPv4 or IPv6 addresses, respectively."; } leaf port { type inet:port-number; Watsen & Wu Expires December 6, 2018 [Page 21] Internet-Draft NETCONF Client and Server Models June 2018 default 4335; description "The port number to listen on for call-home connections. The NETCONF client will listen on the IANA-assigned well-known port for 'netconf-ch-tls' (4335) if no value is specified."; } uses ts:tls-client-grouping { refine "client-identity/auth-type" { mandatory true; description "NETCONF/TLS clients MUST pass some authentication credentials."; } } } } } // end transport } // end endpoint } // end listen } // end netconf-client } 4. The NETCONF Server Model The NETCONF server model presented in this section supports servers both listening for connections as well as initiating call-home connections. This model supports both the SSH and TLS transport protocols, using the SSH server and TLS server groupings defined in [I-D.ietf-netconf-ssh-client-server] and [I-D.ietf-netconf-tls-client-server] respectively. All private keys and trusted certificates are held in the keystore model defined in [I-D.ietf-netconf-keystore]. YANG feature statements are used to enable implementations to advertise which parts of the model the NETCONF server supports. 4.1. Tree Diagram The following tree diagram [RFC8340] provides an overview of the data model for the "ietf-netconf-server" module. Just the container is Watsen & Wu Expires December 6, 2018 [Page 22] Internet-Draft NETCONF Client and Server Models June 2018 displayed below, but there is also a reuable grouping by the same name that the container is using. [Note: '\' line wrapping for formatting only] module: ietf-netconf-server +--rw netconf-server +--rw listen! {listen}? | +--rw idle-timeout? uint16 | +--rw endpoint* [name] | +--rw name string | +--rw (transport) | +--:(ssh) {ssh-listen}? | | +--rw ssh | | +--rw address inet:ip-address | | +--rw port? inet:port-number | | +--rw server-identity | | | +--rw host-key* [name] | | | +--rw name string | | | +--rw (host-key-type) | | | +--:(public-key) | | | | +--rw public-key | | | | +--rw (local-or-keystore) | | | | +--:(local) | | | | | +--rw algorithm | | | | | | ct:key-algorithm-re\ f | | | | | +--rw public-key binary\ | | | | | +--rw private-key union | | | | +--:(keystore) | | | | {keystore-implemented\ }? | | | | +--rw reference | | | | ks:asymmetric-key-r\ ef | | | +--:(certificate) | | | +--rw certificate | | | {sshcmn:ssh-x509-certs}? | | | +--rw (local-or-keystore) | | | +--:(local) | | | | +--rw algorithm | | | | | ct:key-algorithm-re\ f | | | | +--rw public-key | | | | | binary | | | | +--rw private-key Watsen & Wu Expires December 6, 2018 [Page 23] Internet-Draft NETCONF Client and Server Models June 2018 | | | | | union | | | | +--rw cert | | | | | ct:end-entity-cert-\ cms | | | | +---n certificate-expiratio\ n | | | | +-- expiration-date? | | | | yang:date-and-ti\ me | | | +--:(keystore) | | | {keystore-implemented\ }? | | | +--rw reference | | | ks:asymmetric-key-c\ ertificate-ref | | +--rw client-cert-auth {sshcmn:ssh-x509-certs}? | | | +--rw pinned-ca-certs? | | | | ta:pinned-certificates-ref | | | +--rw pinned-client-certs? | | | ta:pinned-certificates-ref | | +--rw transport-params | | {ssh-server-transport-params-config}? | | +--rw host-key | | | +--rw host-key-alg* identityref | | +--rw key-exchange | | | +--rw key-exchange-alg* identityref | | +--rw encryption | | | +--rw encryption-alg* identityref | | +--rw mac | | +--rw mac-alg* identityref | +--:(tls) {tls-listen}? | +--rw tls | +--rw address inet:ip-address | +--rw port? inet:port-number | +--rw server-identity | | +--rw (local-or-keystore) | | +--:(local) | | | +--rw algorithm | | | | ct:key-algorithm-ref | | | +--rw public-key binary | | | +--rw private-key union | | | +--rw cert | | | | ct:end-entity-cert-cms | | | +---n certificate-expiration | | | +-- expiration-date? | | | yang:date-and-time | | +--:(keystore) {keystore-implemented}? | | +--rw reference Watsen & Wu Expires December 6, 2018 [Page 24] Internet-Draft NETCONF Client and Server Models June 2018 | | ks:asymmetric-key-certificate-r\ ef | +--rw client-auth | | +--rw pinned-ca-certs? | | | ta:pinned-certificates-ref | | +--rw pinned-client-certs? | | | ta:pinned-certificates-ref | | +--rw cert-maps | | +--rw cert-to-name* [id] | | +--rw id uint32 | | +--rw fingerprint | | | x509c2n:tls-fingerprint | | +--rw map-type identityref | | +--rw name string | +--rw hello-params | {tls-server-hello-params-config}? | +--rw tls-versions | | +--rw tls-version* identityref | +--rw cipher-suites | +--rw cipher-suite* identityref +--rw call-home! {call-home}? +--rw netconf-client* [name] +--rw name string +--rw endpoints | +--rw endpoint* [name] | +--rw name string | +--rw (transport) | +--:(ssh) {ssh-call-home}? | | +--rw ssh | | +--rw address inet:host | | +--rw port? inet:port-number\ | | +--rw server-identity | | | +--rw host-key* [name] | | | +--rw name string | | | +--rw (host-key-type) | | | +--:(public-key) | | | | +--rw public-key | | | | +--rw (local-or-keystore) | | | | +--:(local) | | | | | +--rw algorithm | | | | | | ct:key-algori\ thm-ref | | | | | +--rw public-key | | | | | | binary | | | | | +--rw private-key | | | | | union | | | | +--:(keystore) Watsen & Wu Expires December 6, 2018 [Page 25] Internet-Draft NETCONF Client and Server Models June 2018 | | | | {keystore-imple\ mented}? | | | | +--rw reference | | | | ks:asymmetric\ -key-ref | | | +--:(certificate) | | | +--rw certificate | | | {sshcmn:ssh-x509-certs\ }? | | | +--rw (local-or-keystore) | | | +--:(local) | | | | +--rw algorithm | | | | | ct:key-algori\ thm-ref | | | | +--rw public-key | | | | | binary | | | | +--rw private-key | | | | | union | | | | +--rw cert | | | | | ct:end-entity\ -cert-cms | | | | +---n certificate-exp\ iration | | | | +-- expiration-dat\ e? | | | | yang:date-\ and-time | | | +--:(keystore) | | | {keystore-imple\ mented}? | | | +--rw reference | | | ks:asymmetric\ -key-certificate-ref | | +--rw client-cert-auth | | | {sshcmn:ssh-x509-certs}? | | | +--rw pinned-ca-certs? | | | | ta:pinned-certificates-ref | | | +--rw pinned-client-certs? | | | ta:pinned-certificates-ref | | +--rw transport-params | | {ssh-server-transport-params-confi\ g}? | | +--rw host-key | | | +--rw host-key-alg* identityref | | +--rw key-exchange | | | +--rw key-exchange-alg* identityre\ f | | +--rw encryption Watsen & Wu Expires December 6, 2018 [Page 26] Internet-Draft NETCONF Client and Server Models June 2018 | | | +--rw encryption-alg* identityref | | +--rw mac | | +--rw mac-alg* identityref | +--:(tls) {tls-call-home}? | +--rw tls | +--rw address inet:host | +--rw port? inet:port-number | +--rw server-identity | | +--rw (local-or-keystore) | | +--:(local) | | | +--rw algorithm | | | | ct:key-algorithm-ref | | | +--rw public-key | | | | binary | | | +--rw private-key | | | | union | | | +--rw cert | | | | ct:end-entity-cert-cms | | | +---n certificate-expiration | | | +-- expiration-date? | | | yang:date-and-time | | +--:(keystore) {keystore-implemented\ }? | | +--rw reference | | ks:asymmetric-key-certifi\ cate-ref | +--rw client-auth | | +--rw pinned-ca-certs? | | | ta:pinned-certificates-ref | | +--rw pinned-client-certs? | | | ta:pinned-certificates-ref | | +--rw cert-maps | | +--rw cert-to-name* [id] | | +--rw id uint32 | | +--rw fingerprint | | | x509c2n:tls-fingerprint | | +--rw map-type identityref | | +--rw name string | +--rw hello-params | {tls-server-hello-params-config}? | +--rw tls-versions | | +--rw tls-version* identityref | +--rw cipher-suites | +--rw cipher-suite* identityref +--rw connection-type | +--rw (connection-type)? | +--:(persistent-connection) | | +--rw persistent! Watsen & Wu Expires December 6, 2018 [Page 27] Internet-Draft NETCONF Client and Server Models June 2018 | | +--rw idle-timeout? uint32 | | +--rw keep-alives | | +--rw max-wait? uint16 | | +--rw max-attempts? uint8 | +--:(periodic-connection) | +--rw periodic! | +--rw idle-timeout? uint16 | +--rw reconnect-timeout? uint16 +--rw reconnect-strategy +--rw start-with? enumeration +--rw max-attempts? uint8 4.2. 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-keystore]. [Note: '\' line wrapping for formatting only] netconf/ssh
192.0.2.7
deployment-specific-certificate ct:secp521r1 base64encodedvalue== base64encodedvalue== Watsen & Wu Expires December 6, 2018 [Page 28] Internet-Draft NETCONF Client and Server Models June 2018 explicitly-trusted-client-ca-certs explicitly-trusted-client-certs
netconf/tls
192.0.2.7
ct:secp521r1 base64encodedvalue== base64encodedvalue== base64encodedvalue== explicitly-trusted-client-ca-certs explicitly-trusted-client-certs 1 11:0A:05:11:00 x509c2n:san-any 2 B3:4F:A1:8C:54 x509c2n:specified scooby-doo
config-mgr east-data-center Watsen & Wu Expires December 6, 2018 [Page 29] Internet-Draft NETCONF Client and Server Models June 2018
east.config-mgr.example.com
deployment-specific-certificate ct:secp521r1 base64encodedvalue== base64encodedvalue== explicitly-trusted-client-ca-certs explicitly-trusted-client-certs
west-data-center
west.config-mgr.example.com
deployment-specific-certificate ct:secp521r1 base64encodedvalue== base64encodedvalue== explicitly-trusted-client-ca-certs explicitly-trusted-client-certs
300 Watsen & Wu Expires December 6, 2018 [Page 30] Internet-Draft NETCONF Client and Server Models June 2018 60 last-connected 3
data-collector east-data-center
east.analytics.example.com
ct:secp521r1 base64encodedvalue== base64encodedvalue== base64encodedvalue== explicitly-trusted-client-ca-certs explicitly-trusted-client-certs 1 11:0A:05:11:00 x509c2n:san-any 2 B3:4F:A1:8C:54 x509c2n:specified scooby-doo
west-data-center
west.analytics.example.com
Watsen & Wu Expires December 6, 2018 [Page 31] Internet-Draft NETCONF Client and Server Models June 2018 ct:secp521r1 base64encodedvalue== base64encodedvalue== base64encodedvalue== explicitly-trusted-client-ca-certs explicitly-trusted-client-certs 1 11:0A:05:11:00 x509c2n:san-any 2 B3:4F:A1:8C:54 x509c2n:specified scooby-doo
300 30 3 first-listed 3
Watsen & Wu Expires December 6, 2018 [Page 32] Internet-Draft NETCONF Client and Server Models June 2018 4.3. YANG Module This YANG module has normative references to [RFC6242], [RFC6991], [RFC7407], [RFC7589], [RFC8071], [I-D.ietf-netconf-ssh-client-server], and [I-D.ietf-netconf-tls-client-server]. This YANG module imports YANG types from [RFC6991], and YANG groupings from [RFC7407], [I-D.ietf-netconf-ssh-client-server] and [I-D.ietf-netconf-ssh-client-server]. file "ietf-netconf-server@2018-06-04.yang" module ietf-netconf-server { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-netconf-server"; prefix "ncs"; 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-ssh-server { prefix ss; revision-date 2018-06-04; // stable grouping definitions reference "RFC YYYY: YANG Groupings for SSH Clients and SSH Servers"; } import ietf-tls-server { prefix ts; revision-date 2018-06-04; // stable grouping definitions reference "RFC ZZZZ: YANG Groupings for TLS Clients and TLS Servers"; } organization "IETF NETCONF (Network Configuration) Working Group"; contact Watsen & Wu Expires December 6, 2018 [Page 33] Internet-Draft NETCONF Client and Server Models June 2018 "WG Web: WG List: Author: Kent Watsen Author: Gary Wu Author: Juergen Schoenwaelder "; description "This module contains a collection of YANG definitions for configuring NETCONF servers. Copyright (c) 2017 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 (http://trustee.ietf.org/license-info). This version of this YANG module is part of RFC XXXX; see the RFC itself for full legal notices."; revision "2018-06-04" { description "Initial version"; reference "RFC XXXX: NETCONF Client and Server Models"; } // Features feature listen { description "The 'listen' feature indicates that the NETCONF server supports opening a port to accept NETCONF client connections using at least one transport (e.g., SSH, TLS, etc.)."; } feature ssh-listen { Watsen & Wu Expires December 6, 2018 [Page 34] Internet-Draft NETCONF Client and Server Models June 2018 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 "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 call-home { description "The 'call-home' feature indicates that the NETCONF server supports initiating NETCONF call home connections to NETCONF clients using at least one transport (e.g., SSH, TLS, etc.)."; reference "RFC 8071: NETCONF Call Home and RESTCONF Call Home"; } 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"; } Watsen & Wu Expires December 6, 2018 [Page 35] Internet-Draft NETCONF Client and Server Models June 2018 container netconf-server { uses netconf-server; description "Top-level container for NETCONF server configuration."; } grouping netconf-server { description "Top-level grouping for NETCONF server configuration."; container listen { if-feature listen; presence "Enables server to listen for TCP 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 "List of endpoints to listen for NETCONF connections."; leaf name { type string; description "An arbitrary name for the NETCONF listen endpoint."; } 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."; leaf address { type inet:ip-address; Watsen & Wu Expires December 6, 2018 [Page 36] Internet-Draft NETCONF Client and Server Models June 2018 mandatory true; description "The IP address to listen on for incoming connections. The NETCONF server will listen on all configured interfaces if no value is specified. INADDR_ANY (0.0.0.0) or INADDR6_ANY (0:0:0:0:0:0:0:0 a.k.a. ::) MUST be used when the server is to listen on all IPv4 or IPv6 addresses, respectively."; } leaf port { type inet:port-number; default 830; description "The local port number to listen on. If no value is specified, the IANA-assigned port value for 'netconf-ssh' (830) is used."; } uses ss:ssh-server-grouping; } } case tls { if-feature tls-listen; container tls { description "TLS-specific listening configuration for inbound connections."; leaf address { type inet:ip-address; mandatory true; description "The IP address to listen on for incoming connections. The NETCONF server will listen on all configured interfaces if no value is specified. INADDR_ANY (0.0.0.0) or INADDR6_ANY (0:0:0:0:0:0:0:0 a.k.a. ::) MUST be used when the server is to listen on all IPv4 or IPv6 addresses, respectively."; } leaf port { type inet:port-number; default 6513; description "The local port number to listen on. If no value is specified, the IANA-assigned port value for 'netconf-tls' (6513) is used."; } uses ts:tls-server-grouping { Watsen & Wu Expires December 6, 2018 [Page 37] Internet-Draft NETCONF Client and Server Models June 2018 refine "client-auth" { must 'pinned-ca-certs or pinned-client-certs'; description "NETCONF/TLS servers MUST validate client certiticates."; } augment "client-auth" { description "Augments in the cert-to-name structure."; container cert-maps { uses x509c2n:cert-to-name; description "The cert-maps container is used by a TLS- based NETCONF server to map the NETCONF client's presented X.509 certificate to 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 WWWW: NETCONF over TLS, Section 7"; } } } } } } } } container call-home { if-feature call-home; presence "Enables server to initiate TCP connections"; description "Configures call-home behavior"; list netconf-client { key name; min-elements 1; description "List of NETCONF clients the NETCONF server is to initiate call-home connections to in parallel."; leaf name { type string; description "An arbitrary name for the remote NETCONF client."; } container endpoints { description Watsen & Wu Expires December 6, 2018 [Page 38] Internet-Draft NETCONF Client and Server Models June 2018 "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."; } 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."; leaf address { type inet:host; mandatory true; description "The IP address or hostname of the endpoint. If a domain name is configured, then the DNS resolution should happen on each usage attempt. If the the DNS resolution results in multiple IP addresses, the IP addresses will be tried according to local preference order until a connection has been established or until all IP addresses have failed."; } leaf port { type inet:port-number; default 4334; description "The IP port for this endpoint. The NETCONF server will use the IANA-assigned well-known port for 'netconf-ch-ssh' (4334) if no value is specified."; } uses ss:ssh-server-grouping; } Watsen & Wu Expires December 6, 2018 [Page 39] Internet-Draft NETCONF Client and Server Models June 2018 } case tls { if-feature tls-call-home; container tls { description "Specifies TLS-specific call-home transport configuration."; leaf address { type inet:host; mandatory true; description "The IP address or hostname of the endpoint. If a domain name is configured, then the DNS resolution should happen on each usage attempt. If the the DNS resolution results in multiple IP addresses, the IP addresses will be tried according to local preference order until a connection has been established or until all IP addresses have failed."; } leaf port { type inet:port-number; default 4335; description "The IP port for this endpoint. The NETCONF server will use the IANA-assigned well-known port for 'netconf-ch-tls' (4335) if no value is specified."; } uses ts:tls-server-grouping { refine "client-auth" { must 'pinned-ca-certs or pinned-client-certs'; description "NETCONF/TLS servers MUST validate client certiticates."; } augment "client-auth" { description "Augments in the cert-to-name structure."; container cert-maps { uses x509c2n:cert-to-name; description "The cert-maps container is used by a TLS-based NETCONF server to map the NETCONF client's presented X.509 certificate to a NETCONF username. If no matching and valid cert-to-name list entry can be found, then the NETCONF Watsen & Wu Expires December 6, 2018 [Page 40] Internet-Draft NETCONF Client and Server Models June 2018 server MUST close the connection, and MUST NOT accept NETCONF messages over it."; reference "RFC WWWW: NETCONF over TLS, Section 7"; } } } } } // end tls } // end choice } // end endpoint } container connection-type { description "Indicates the kind of connection to use."; choice connection-type { default persistent-connection; 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 it, 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."; leaf idle-timeout { type uint32; units "seconds"; default 86400; // one day; 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."; } Watsen & Wu Expires December 6, 2018 [Page 41] Internet-Draft NETCONF Client and Server Models June 2018 container keep-alives { description "Configures the keep-alive policy, to proactively test the aliveness of the SSH/TLS client. An unresponsive SSH/TLS client will be dropped after approximately max-attempts * max-wait seconds."; reference "RFC 8071: NETCONF Call Home and RESTCONF Call Home, Section 3.1, item S6"; leaf max-wait { type uint16 { range "1..max"; } units seconds; default 30; description "Sets the amount of time in seconds after which if no data has been received from the SSH/TLS client, a SSH/TLS-level message will be sent to test the aliveness of the SSH/TLS client."; } leaf max-attempts { type uint8; default 3; description "Sets the maximum number of sequential keep- alive messages that can fail to obtain a response from the SSH/TLS client before assuming the SSH/TLS client is no longer alive."; } } } } case periodic-connection { container periodic { presence "Indicates that a periodic connection is to be maintained."; description "Periodically connect to the NETCONF client, so that the NETCONF client may deliver messages pending for the NETCONF server. The NETCONF client must close the connection when it is ready to release it. Once the connection has been closed, the NETCONF server will restart Watsen & Wu Expires December 6, 2018 [Page 42] Internet-Draft NETCONF Client and Server Models June 2018 its timer until the next connection."; leaf idle-timeout { type uint16; units "seconds"; default 300; // five 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. Sessions that have a notification subscription active are never dropped."; } leaf reconnect-timeout { type uint16 { range "1..max"; } units minutes; default 60; description "Sets the maximum amount of unconnected time the NETCONF server will wait before re-establishing a connection to the NETCONF client. The NETCONF server may initiate a connection before this time if desired (e.g., to deliver an event notification message)."; } } } } } 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 & Wu Expires December 6, 2018 [Page 43] Internet-Draft NETCONF Client and Server Models June 2018 } 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."; } } 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)."; } } } } } } 5. Design Considerations Editorial: this section is a hold over from before, previously called "Objectives". It was only written two support the "server" (not the "client"). The question is if it's better to add the missing "client" parts, or remove this section altogether. The primary purpose of the YANG modules defined herein is to enable the configuration of the NETCONF client and servers. This scope includes the following objectives: Watsen & Wu Expires December 6, 2018 [Page 44] Internet-Draft NETCONF Client and Server Models June 2018 5.1. Support all NETCONF transports The YANG module should support all current NETCONF transports, namely NETCONF over SSH [RFC6242], NETCONF over TLS [RFC7589], and to be extensible to support future transports as necessary. Because implementations may not support all transports, the modules should use YANG "feature" statements so that implementations can accurately advertise which transports are supported. 5.2. Enable each transport to select which keys to use Servers may have a multiplicity of host-keys or server-certificates from which subsets may be selected for specific uses. For instance, a NETCONF server may want to use one set of SSH host-keys when listening on port 830, and a different set of SSH host-keys when calling home. The data models provided herein should enable configuration of which keys to use on a per-use basis. 5.3. Support authenticating NETCONF clients certificates When a certificate is used to authenticate a NETCONF client, there is a need to configure the server to know how to authenticate the certificates. The server should be able to authenticate the client's certificate either by using path-validation to a configured trust anchor or by matching the client-certificate to one previously configured. 5.4. Support mapping authenticated NETCONF client certificates to usernames When a client certificate is used for TLS client authentication, the NETCONF server must be able to derive a username from the authenticated certificate. Thus the modules defined herein should enable this mapping to be configured. 5.5. Support both listening for connections and call home The NETCONF protocols were originally defined as having the server opening a port to listen for client connections. More recently the NETCONF working group defined support for call-home ([RFC8071]), enabling the server to initiate the connection to the client. Thus the modules defined herein should enable configuration for both listening for connections and calling home. Because implementations may not support both listening for connections and calling home, YANG "feature" statements should be used so that implementation can accurately advertise the connection types it supports. Watsen & Wu Expires December 6, 2018 [Page 45] Internet-Draft NETCONF Client and Server Models June 2018 5.6. For Call Home connections The following objectives only pertain to call home connections. 5.6.1. Support more than one NETCONF client A NETCONF server may be managed by more than one NETCONF client. For instance, a deployment may have one client for provisioning and another for fault monitoring. Therefore, when it is desired for a server to initiate call home connections, it should be able to do so to more than one client. 5.6.2. Support NETCONF clients having more than one endpoint A NETCONF client managing a NETCONF server may implement a high- availability strategy employing a multiplicity of active and/or passive endpoint. Therefore, when it is desired for a server to initiate call home connections, it should be able to connect to any of the client's endpoints. 5.6.3. Support a reconnection strategy Assuming a NETCONF client has more than one endpoint, then it becomes necessary to configure how a NETCONF server should reconnect to the client should it lose its connection to one the client's endpoints. For instance, the NETCONF server may start with first endpoint defined in a user-ordered list of endpoints or with the last endpoints it was connected to. 5.6.4. Support both persistent and periodic connections NETCONF clients may vary greatly on how frequently they need to interact with a NETCONF server, how responsive interactions need to be, and how many simultaneous connections they can support. Some clients may need a persistent connection to servers to optimize real- time interactions, while others prefer periodic interactions in order to minimize resource requirements. Therefore, when it is necessary for server to initiate connections, it should be configurable if the connection is persistent or periodic. 5.6.5. Reconnection strategy for periodic connections The reconnection strategy should apply to both persistent and periodic connections. How it applies to periodic connections becomes clear when considering that a periodic "connection" is a logical connection to a single server. That is, the periods of unconnectedness are intentional as opposed to due to external reasons. A periodic "connection" should always reconnect to the same Watsen & Wu Expires December 6, 2018 [Page 46] Internet-Draft NETCONF Client and Server Models June 2018 server until it is no longer able to, at which time the reconnection strategy guides how to connect to another server. 5.6.6. Keep-alives for persistent connections If a persistent connection is desired, it is the responsibility of the connection initiator to actively test the "aliveness" of the connection. The connection initiator must immediately work to reestablish a persistent connection as soon as the connection is lost. How often the connection should be tested is driven by NETCONF client requirements, and therefore keep-alive settings should be configurable on a per-client basis. 5.6.7. Customizations for periodic connections If a periodic connection is desired, it is necessary for the NETCONF server to know how often it should connect. This frequency determines the maximum amount of time a NETCONF client may have to wait to send data to a server. A server may connect to a client before this interval expires if desired (e.g., to send data to a client). 6. Security Considerations The YANG module defined in this document uses groupings defined in [I-D.ietf-netconf-ssh-client-server] and [I-D.ietf-netconf-tls-client-server]. Please see the Security Considerations section in those documents for concerns related those groupings. The YANG module defined in this document is designed to be accessed via YANG based management protocols, such as NETCONF [RFC6241] and RESTCONF [RFC8040]. Both of these protocols have mandatory-to- implement secure transport layers (e.g., SSH, TLS) with mutual authentication. The NETCONF access control model (NACM) [RFC6536] provides the means to restrict access for particular users to a pre-configured subset of all available protocol operations and content. There are a number of data nodes defined in this YANG module that are writable/creatable/deletable (i.e., config true, which is the default). These data nodes may be considered sensitive or vulnerable in some network environments. Write operations (e.g., edit-config) to these data nodes without proper protection can have a negative effect on network operations. These are the subtrees and data nodes and their sensitivity/vulnerability: Watsen & Wu Expires December 6, 2018 [Page 47] Internet-Draft NETCONF Client and Server Models June 2018 /: The entire data trees defined by the modules defined in this draft are sensitive to write operations. For instance, the addition or removal of references to keys, certificates, trusted anchors, etc., can dramatically alter the implemented security policy. However, no NACM annotations are applied as the data SHOULD be editable by users other than a designated 'recovery session'. Some of the readable data nodes in this YANG module may be considered sensitive or vulnerable in some network environments. It is thus important to control read access (e.g., via get, get-config, or notification) to these data nodes. These are the subtrees and data nodes and their sensitivity/vulnerability: NONE Some of the RPC operations in this YANG module may be considered sensitive or vulnerable in some network environments. It is thus important to control access to these operations. These are the operations and their sensitivity/vulnerability: NONE 7. IANA Considerations 7.1. The IETF XML Registry This document registers two URIs in 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. 7.2. The YANG Module Names Registry This document registers two YANG modules in the YANG Module Names registry [RFC7950]. Following the format in [RFC7950], the the following registrations are requested: Watsen & Wu Expires December 6, 2018 [Page 48] Internet-Draft NETCONF Client and Server Models June 2018 name: ietf-netconf-client namespace: urn:ietf:params:xml:ns:yang:ietf-netconf-client prefix: ncc reference: RFC XXXX name: ietf-netconf-server namespace: urn:ietf:params:xml:ns:yang:ietf-netconf-server prefix: ncs reference: RFC XXXX 8. References 8.1. Normative References [I-D.ietf-netconf-keystore] Watsen, K., "YANG Data Model for a "Keystore" Mechanism", draft-ietf-netconf-keystore-04 (work in progress), October 2017. [I-D.ietf-netconf-ssh-client-server] Watsen, K. and G. Wu, "YANG Groupings for SSH Clients and SSH Servers", draft-ietf-netconf-ssh-client-server-05 (work in progress), October 2017. [I-D.ietf-netconf-tls-client-server] Watsen, K. and G. Wu, "YANG Groupings for TLS Clients and TLS Servers", draft-ietf-netconf-tls-client-server-05 (work in progress), October 2017. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [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, . [RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types", RFC 6991, DOI 10.17487/RFC6991, July 2013, . Watsen & Wu Expires December 6, 2018 [Page 49] Internet-Draft NETCONF Client and Server Models June 2018 [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, . 8.2. Informative References [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, January 2004, . [RFC6536] Bierman, A. and M. Bjorklund, "Network Configuration Protocol (NETCONF) Access Control Model", RFC 6536, DOI 10.17487/RFC6536, March 2012, . [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, . Watsen & Wu Expires December 6, 2018 [Page 50] Internet-Draft NETCONF Client and Server Models June 2018 Appendix A. Change Log A.1. 00 to 01 o Renamed "keychain" to "keystore". A.2. 01 to 02 o Added to ietf-netconf-client ability to connected to a cluster of endpoints, including a reconnection-strategy. o Added to ietf-netconf-client the ability to configure connection- type and also keep-alive strategy. o Updated both modules to accomodate new groupings in the ssh/tls drafts. A.3. 02 to 03 o Refined use of tls-client-grouping to add a must statement indicating that the TLS client must specify a client-certificate. o Changed 'netconf-client' to be a grouping (not a container). A.4. 03 to 04 o Added RFC 8174 to Requirements Language Section. o Replaced refine statement in ietf-netconf-client to add a mandatory true. o Added refine statement in ietf-netconf-server to add a must statement. o Now there are containers and groupings, for both the client and server models. A.5. 04 to 05 o Now tree diagrams reference ietf-netmod-yang-tree-diagrams o Updated examples to inline key and certificates (no longer a leafref to keystore) Watsen & Wu Expires December 6, 2018 [Page 51] Internet-Draft NETCONF Client and Server Models June 2018 A.6. 05 to 06 o Fixed change log missing section issue. o Updated examples to match latest updates to the crypto-types, trust-anchors, and keystore drafts. o Reduced line length of the YANG modules to fit within 69 columns. 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, Mehmet Ersue, Balazs Kovacs, David Lamparter, Alan Luchuk, Ladislav Lhotka, Radek Krejci, Tom Petch, Juergen Schoenwaelder, Phil Shafer, Sean Turner, and Bert Wijnen. Authors' Addresses Kent Watsen Juniper Networks EMail: kwatsen@juniper.net Gary Wu Cisco Networks EMail: garywu@cisco.com Watsen & Wu Expires December 6, 2018 [Page 52]