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Versions: (draft-ietf-netconf-server-model) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15

NETCONF Working Group                                          K. Watsen
Internet-Draft                                           Watsen Networks
Intended status: Standards Track                            June 7, 2019
Expires: December 9, 2019


                    NETCONF Client and Server Models
              draft-ietf-netconf-netconf-client-server-13

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-tcp-client-server

   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  "AAAA" --> the assigned RFC value for I-D.ietf-netconf-tcp-client-
      server

   o  "YYYY" --> the assigned RFC value for I-D.ietf-netconf-ssh-client-
      server





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   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:

   o  "2019-06-07" --> the publication date of this draft

   The following Appendix section is to be removed prior to publication:

   o  Appendix B.  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 9, 2019.

Copyright Notice

   Copyright (c) 2019 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.








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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  The NETCONF Client Model  . . . . . . . . . . . . . . . . . .   4
     3.1.  Tree Diagram  . . . . . . . . . . . . . . . . . . . . . .   4
     3.2.  Example Usage . . . . . . . . . . . . . . . . . . . . . .   5
     3.3.  YANG Module . . . . . . . . . . . . . . . . . . . . . . .   8
   4.  The NETCONF Server Model  . . . . . . . . . . . . . . . . . .  18
     4.1.  Tree Diagram  . . . . . . . . . . . . . . . . . . . . . .  18
     4.2.  Example Usage . . . . . . . . . . . . . . . . . . . . . .  20
     4.3.  YANG Module . . . . . . . . . . . . . . . . . . . . . . .  25
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  37
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  38
     6.1.  The IETF XML Registry . . . . . . . . . . . . . . . . . .  38
     6.2.  The YANG Module Names Registry  . . . . . . . . . . . . .  38
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  38
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .  38
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  40
   Appendix A.  Expanded Tree Diagrams . . . . . . . . . . . . . . .  41
     A.1.  Expanded Tree Diagram for 'ietf-netconf-client' . . . . .  41
     A.2.  Expanded Tree Diagram for 'ietf-netconf-server' . . . . .  49
   Appendix B.  Change Log . . . . . . . . . . . . . . . . . . . . .  59
     B.1.  00 to 01  . . . . . . . . . . . . . . . . . . . . . . . .  59
     B.2.  01 to 02  . . . . . . . . . . . . . . . . . . . . . . . .  59
     B.3.  02 to 03  . . . . . . . . . . . . . . . . . . . . . . . .  59
     B.4.  03 to 04  . . . . . . . . . . . . . . . . . . . . . . . .  60
     B.5.  04 to 05  . . . . . . . . . . . . . . . . . . . . . . . .  60
     B.6.  05 to 06  . . . . . . . . . . . . . . . . . . . . . . . .  60
     B.7.  06 to 07  . . . . . . . . . . . . . . . . . . . . . . . .  60
     B.8.  07 to 08  . . . . . . . . . . . . . . . . . . . . . . . .  61
     B.9.  08 to 09  . . . . . . . . . . . . . . . . . . . . . . . .  61
     B.10. 09 to 10  . . . . . . . . . . . . . . . . . . . . . . . .  61
     B.11. 10 to 11  . . . . . . . . . . . . . . . . . . . . . . . .  61
     B.12. 11 to 12  . . . . . . . . . . . . . . . . . . . . . . . .  61
     B.13. 12 to 13  . . . . . . . . . . . . . . . . . . . . . . . .  62
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .  62
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  62

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].





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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
   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, 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
   client supports.

3.1.  Tree Diagram

   The following tree diagram [RFC8340] provides an overview of the data
   model for the "ietf-netconf-client" module.

   This tree diagram only shows the nodes defined in this module; it
   does show the nodes defined by "grouping" statements used by this
   module.

   Please see Appendix A.1 for a tree diagram that illustrates what the
   module looks like with all the "grouping" statements expanded.

   module: ietf-netconf-client
     +--rw netconf-client
        +---u netconf-client-grouping

     grouping netconf-client-grouping
       +-- initiate! {ssh-initiate or tls-initiate}?
       |  +-- netconf-server* [name]
       |     +-- name?                 string
       |     +-- endpoints
       |     |  +-- endpoint* [name]
       |     |     +-- name?        string
       |     |     +-- (transport)
       |     |        +--:(ssh) {ssh-initiate}?
       |     |        |  +-- ssh
       |     |        |     +-- tcp-client-parameters
       |     |        |     |  +---u tcpc:tcp-client-grouping
       |     |        |     +-- ssh-client-parameters



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       |     |        |        +---u sshc:ssh-client-grouping
       |     |        +--:(tls) {tls-initiate}?
       |     |           +-- tls
       |     |              +-- tcp-client-parameters
       |     |              |  +---u tcpc:tcp-client-grouping
       |     |              +-- tls-client-parameters
       |     |                 +---u tlsc:tls-client-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
             +-- (transport)
                +--:(ssh) {ssh-listen}?
                |  +-- ssh
                |     +-- tcp-server-parameters
                |     |  +---u tcps:tcp-server-grouping
                |     +-- ssh-client-parameters
                |        +---u sshc:ssh-client-grouping
                +--:(tls) {tls-listen}?
                   +-- tls
                      +-- tcp-server-parameters
                      |  +---u tcps:tcp-server-grouping
                      +-- tls-client-parameters
                         +---u tlsc:tls-client-grouping

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
   of [I-D.ietf-netconf-trust-anchors] and Section 3.2 of
   [I-D.ietf-netconf-keystore].




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   =========== NOTE: '\' line wrapping per BCP XX (RFC XXXX) ===========

   <netconf-client
     xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-client">

     <!-- NETCONF servers to initiate connections to -->
     <initiate>
       <netconf-server>
         <name>corp-fw1</name>
         <endpoints>
           <endpoint>
             <name>corp-fw1.example.com</name>
             <ssh>
               <tcp-client-parameters>
                 <remote-address>corp-fw1.example.com</remote-address>
                 <keepalives>
                   <idle-time>15</idle-time>
                   <max-probes>3</max-probes>
                   <probe-interval>30</probe-interval>
                 </keepalives>
               </tcp-client-parameters>
               <ssh-client-parameters>
                 <client-identity>
                   <username>foobar</username>
                   <public-key>
                     <local-definition>
                       <algorithm xmlns:ct="urn:ietf:params:xml:ns:yang\
   :ietf-crypto-types">ct:rsa2048</algorithm>
                       <private-key>base64encodedvalue==</private-key>
                       <public-key>base64encodedvalue==</public-key>
                     </local-definition>
                   </public-key>
                 </client-identity>
                 <server-authentication>
                   <ca-certs>explicitly-trusted-server-ca-certs</ca-cer\
   ts>
                   <server-certs>explicitly-trusted-server-certs</serve\
   r-certs>
                 </server-authentication>
                 <keepalives>
                   <max-wait>30</max-wait>
                   <max-attempts>3</max-attempts>
                 </keepalives>
               </ssh-client-parameters>
             </ssh>
           </endpoint>
           <endpoint>
             <name>corp-fw2.example.com</name>



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             <ssh>
               <tcp-client-parameters>
                 <remote-address>corp-fw2.example.com</remote-address>
                 <keepalives>
                   <idle-time>15</idle-time>
                   <max-probes>3</max-probes>
                   <probe-interval>30</probe-interval>
                 </keepalives>
               </tcp-client-parameters>
               <ssh-client-parameters>
                 <client-identity>
                   <username>foobar</username>
                   <public-key>
                     <local-definition>
                       <algorithm xmlns:ct="urn:ietf:params:xml:ns:yang\
   :ietf-crypto-types">ct:rsa2048</algorithm>
                       <private-key>base64encodedvalue==</private-key>
                       <public-key>base64encodedvalue==</public-key>
                     </local-definition>
                   </public-key>
                 </client-identity>
                 <server-authentication>
                   <ca-certs>explicitly-trusted-server-ca-certs</ca-cer\
   ts>
                   <server-certs>explicitly-trusted-server-certs</serve\
   r-certs>
                 </server-authentication>
                 <keepalives>
                   <max-wait>30</max-wait>
                   <max-attempts>3</max-attempts>
                 </keepalives>
               </ssh-client-parameters>
             </ssh>
           </endpoint>
         </endpoints>
         <connection-type>
           <persistent/>
         </connection-type>
         <reconnect-strategy>
           <start-with>last-connected</start-with>
         </reconnect-strategy>
       </netconf-server>
     </initiate>

     <!-- endpoints to listen for NETCONF Call Home connections on -->
     <listen>
       <endpoint>
         <name>Intranet-facing listener</name>



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         <ssh>
           <tcp-server-parameters>
             <local-address>192.0.2.7</local-address>
           </tcp-server-parameters>
           <ssh-client-parameters>
             <client-identity>
               <username>foobar</username>
               <public-key>
                 <local-definition>
                   <algorithm xmlns:ct="urn:ietf:params:xml:ns:yang:iet\
   f-crypto-types">ct:rsa2048</algorithm>
                   <private-key>base64encodedvalue==</private-key>
                   <public-key>base64encodedvalue==</public-key>
                 </local-definition>
               </public-key>
             </client-identity>
             <server-authentication>
               <ca-certs>explicitly-trusted-server-ca-certs</ca-certs>
               <server-certs>explicitly-trusted-server-certs</server-ce\
   rts>
               <ssh-host-keys>explicitly-trusted-ssh-host-keys</ssh-hos\
   t-keys>
             </server-authentication>
           </ssh-client-parameters>
         </ssh>
       </endpoint>
     </listen>
   </netconf-client>

3.3.  YANG Module

   This YANG module has normative references to [RFC6242], [RFC6991],
   [RFC7589], [RFC8071], [I-D.kwatsen-netconf-tcp-client-server],
   [I-D.ietf-netconf-ssh-client-server], and
   [I-D.ietf-netconf-tls-client-server].

   <CODE BEGINS> file "ietf-netconf-client@2019-06-07.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";
     }




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     import ietf-tcp-client {
       prefix tcpc;
       reference
         "RFC AAAA: YANG Groupings for TCP Clients and TCP Servers";
     }
     import ietf-tcp-server {
       prefix tcps;
       reference
         "RFC AAAA: YANG Groupings for TCP Clients and TCP Servers";
     }

     import ietf-ssh-client {
       prefix sshc;
       revision-date 2019-06-07; // stable grouping definitions
       reference
         "RFC BBBB: YANG Groupings for SSH Clients and SSH Servers";
     }

     import ietf-tls-client {
       prefix tlsc;
       revision-date 2019-06-07; // stable grouping definitions
       reference
         "RFC CCCC: YANG Groupings for TLS Clients and TLS Servers";
     }

     organization
       "IETF NETCONF (Network Configuration) Working Group";

     contact
       "WG Web:   <http://datatracker.ietf.org/wg/netconf/>
        WG List:  <mailto:netconf@ietf.org>
        Author:   Kent Watsen <mailto:kent+ietf@watsen.net>
        Author:   Gary Wu <mailto:garywu@cisco.com>";

     description
       "This module contains a collection of YANG definitions
        for configuring NETCONF clients.

        Copyright (c) 2019 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).




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        This version of this YANG module is part of RFC XXXX
        (https://www.rfc-editor.org/info/rfcXXXX); 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 2019-06-07 {
       description
         "Initial version";
       reference
         "RFC XXXX: 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 {



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       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

     grouping netconf-client-grouping {
       description
         "Top-level grouping for NETCONF client configuration.";
       container initiate {
         if-feature "ssh-initiate or tls-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 {
             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;



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                 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' (443) 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;
                     }
                   }
                 }
                 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



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                              specified.";
                         }
                       }
                     }
                     container tls-client-parameters {
                       description
                         "A wrapper around the TLS client parameters
                          to avoid name collisions.";
                       uses tlsc:tls-client-grouping {
                         refine "client-identity"
                                                       + "/auth-type" {
                           mandatory true;
                           description
                             "NETCONF/TLS clients MUST pass some
                              authentication credentials.";
                         }
                       }
                     }
                   }
                 }
               } // choice transport
             } // 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
                      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 {



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                 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.";
                   }
                   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.



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                        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";
               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";
               }



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               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 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 {
               if-feature "ssh-listen";
               container ssh {
                 description
                   "SSH-specific listening configuration for inbound
                    connections.";



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                 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;
                 }
               }
             }
             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 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 {
                   description
                     "A wrapper around the TLS client parameters
                      to avoid name collisions.";
                   uses tlsc:tls-client-grouping {
                     refine "client-identity/auth-type" {



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                       mandatory true;
                       description
                         "NETCONF/TLS clients MUST pass some
                           authentication credentials.";
                     }
                   }
                 }
               }
             }
           } // transport
         } // endpoint
       } // listen
     } // netconf-client

     // Protocol accessible node, for servers that implement this
     // module.

     container netconf-client {
       uses netconf-client-grouping;
       description
         "Top-level container for NETCONF client configuration.";
     }
   }
   <CODE ENDS>

4.  The NETCONF Server Model

   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.

4.1.  Tree Diagram

   The following tree diagram [RFC8340] provides an overview of the data
   model for the "ietf-netconf-server" module.

   This tree diagram only shows the nodes defined in this module; it
   does show the nodes defined by "grouping" statements used by this
   module.

   Please see Appendix A.2 for a tree diagram that illustrates what the
   module looks like with all the "grouping" statements expanded.

   module: ietf-netconf-server



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     +--rw netconf-server
        +---u netconf-server-grouping

     grouping netconf-server-grouping
       +-- listen! {ssh-listen or tls-listen}?
       |  +-- idle-timeout?   uint16
       |  +-- endpoint* [name]
       |     +-- name?        string
       |     +-- (transport)
       |        +--:(ssh) {ssh-listen}?
       |        |  +-- ssh
       |        |     +-- tcp-server-parameters
       |        |     |  +---u tcps:tcp-server-grouping
       |        |     +-- ssh-server-parameters
       |        |        +---u sshs:ssh-server-grouping
       |        +--:(tls) {tls-listen}?
       |           +-- tls
       |              +-- tcp-server-parameters
       |              |  +---u tcps:tcp-server-grouping
       |              +-- tls-server-parameters
       |                 +---u tlss:tls-server-grouping
       +-- call-home! {ssh-call-home or tls-call-home}?
          +-- netconf-client* [name]
             +-- name?                 string
             +-- endpoints
             |  +-- endpoint* [name]
             |     +-- name?        string
             |     +-- (transport)
             |        +--:(ssh) {ssh-call-home}?
             |        |  +-- ssh
             |        |     +-- tcp-client-parameters
             |        |     |  +---u tcpc:tcp-client-grouping
             |        |     +-- ssh-server-parameters
             |        |        +---u sshs:ssh-server-grouping
             |        +--:(tls) {tls-call-home}?
             |           +-- tls
             |              +-- tcp-client-parameters
             |              |  +---u tcpc:tcp-client-grouping
             |              +-- tls-server-parameters
             |                 +---u tlss:tls-server-grouping
             +-- connection-type
             |  +-- (connection-type)
             |     +--:(persistent-connection)
             |     |  +-- persistent!
             |     +--:(periodic-connection)
             |        +-- periodic!
             |           +-- period?         uint16
             |           +-- anchor-time?    yang:date-and-time



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             |           +-- idle-timeout?   uint16
             +-- reconnect-strategy
                +-- start-with?     enumeration
                +-- 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
   of [I-D.ietf-netconf-trust-anchors] and Section 3.2 of
   [I-D.ietf-netconf-keystore].

   =========== NOTE: '\' line wrapping per BCP XX (RFC XXXX) ===========

   <netconf-server
     xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-server"
     xmlns:x509c2n="urn:ietf:params:xml:ns:yang:ietf-x509-cert-to-name">

     <!-- endpoints to listen for NETCONF connections on -->
     <listen>
       <endpoint> <!-- listening for SSH connections -->
         <name>netconf/ssh</name>
         <ssh>
           <tcp-server-parameters>
             <local-address>192.0.2.7</local-address>
           </tcp-server-parameters>
           <ssh-server-parameters>
             <server-identity>
               <host-key>
                 <name>deployment-specific-certificate</name>
                 <public-key>
                   <local-definition>
                     <algorithm xmlns:ct="urn:ietf:params:xml:ns:yang:i\
   etf-crypto-types">ct:rsa2048</algorithm>
                     <private-key>base64encodedvalue==</private-key>
                     <public-key>base64encodedvalue==</public-key>
                   </local-definition>
                 </public-key>
               </host-key>
             </server-identity>
             <client-authentication>
               <supported-authentication-methods>
                 <publickey/>
               </supported-authentication-methods>



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               <client-auth-defined-elsewhere/>
             </client-authentication>
           </ssh-server-parameters>
         </ssh>
       </endpoint>
       <endpoint> <!-- listening for TLS sessions -->
         <name>netconf/tls</name>
         <tls>
           <tcp-server-parameters>
             <local-address>192.0.2.7</local-address>
           </tcp-server-parameters>
           <tls-server-parameters>
             <server-identity>
               <local-definition>
                 <algorithm xmlns:ct="urn:ietf:params:xml:ns:yang:ietf-\
   crypto-types">ct:rsa2048</algorithm>
                 <private-key>base64encodedvalue==</private-key>
                 <public-key>base64encodedvalue==</public-key>
                 <cert>base64encodedvalue==</cert>
               </local-definition>
             </server-identity>
             <client-authentication>
               <required/>
               <ca-certs>explicitly-trusted-client-ca-certs</ca-certs>
               <client-certs>explicitly-trusted-client-certs</client-ce\
   rts>
               <cert-maps>
                 <cert-to-name>
                   <id>1</id>
                   <fingerprint>11:0A:05:11:00</fingerprint>
                   <map-type>x509c2n:san-any</map-type>
                 </cert-to-name>
                 <cert-to-name>
                   <id>2</id>
                   <fingerprint>B3:4F:A1:8C:54</fingerprint>
                   <map-type>x509c2n:specified</map-type>
                   <name>scooby-doo</name>
                 </cert-to-name>
               </cert-maps>
             </client-authentication>
           </tls-server-parameters>
         </tls>
       </endpoint>
     </listen>

     <!-- calling home to SSH and TLS based NETCONF clients -->
     <call-home>
       <netconf-client> <!-- SSH-based client -->



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         <name>config-mgr</name>
         <endpoints>
           <endpoint>
             <name>east-data-center</name>
             <ssh>
               <tcp-client-parameters>
                 <remote-address>east.config-mgr.example.com</remote-ad\
   dress>
               </tcp-client-parameters>
               <ssh-server-parameters>
                 <server-identity>
                   <host-key>
                     <name>deployment-specific-certificate</name>
                     <public-key>
                       <local-definition>
                         <algorithm xmlns:ct="urn:ietf:params:xml:ns:ya\
   ng:ietf-crypto-types">ct:rsa2048</algorithm>
                         <private-key>base64encodedvalue==</private-key>
                         <public-key>base64encodedvalue==</public-key>
                       </local-definition>
                     </public-key>
                   </host-key>
                 </server-identity>
                 <client-authentication>
                   <supported-authentication-methods>
                     <publickey/>
                   </supported-authentication-methods>
                   <client-auth-defined-elsewhere/>
                 </client-authentication>
               </ssh-server-parameters>
             </ssh>
           </endpoint>
           <endpoint>
             <name>west-data-center</name>
             <ssh>
               <tcp-client-parameters>
                 <remote-address>west.config-mgr.example.com</remote-ad\
   dress>
               </tcp-client-parameters>
               <ssh-server-parameters>
                 <server-identity>
                   <host-key>
                     <name>deployment-specific-certificate</name>
                     <public-key>
                       <local-definition>
                         <algorithm xmlns:ct="urn:ietf:params:xml:ns:ya\
   ng:ietf-crypto-types">ct:rsa2048</algorithm>
                         <private-key>base64encodedvalue==</private-key>



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                         <public-key>base64encodedvalue==</public-key>
                       </local-definition>
                     </public-key>
                   </host-key>
                 </server-identity>
                 <client-authentication>
                   <supported-authentication-methods>
                     <publickey/>
                   </supported-authentication-methods>
                   <client-auth-defined-elsewhere/>
                 </client-authentication>
               </ssh-server-parameters>
             </ssh>
           </endpoint>
         </endpoints>
         <connection-type>
           <periodic>
             <idle-timeout>300</idle-timeout>
             <period>60</period>
           </periodic>
         </connection-type>
         <reconnect-strategy>
           <start-with>last-connected</start-with>
           <max-attempts>3</max-attempts>
         </reconnect-strategy>
       </netconf-client>
       <netconf-client> <!-- TLS-based client -->
         <name>data-collector</name>
         <endpoints>
           <endpoint>
             <name>east-data-center</name>
             <tls>
               <tcp-client-parameters>
                 <remote-address>east.analytics.example.com</remote-add\
   ress>
                 <keepalives>
                   <idle-time>15</idle-time>
                   <max-probes>3</max-probes>
                   <probe-interval>30</probe-interval>
                 </keepalives>
               </tcp-client-parameters>
               <tls-server-parameters>
                 <server-identity>
                   <local-definition>
                     <algorithm xmlns:ct="urn:ietf:params:xml:ns:yang:i\
   etf-crypto-types">ct:rsa2048</algorithm>
                     <private-key>base64encodedvalue==</private-key>
                     <public-key>base64encodedvalue==</public-key>



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                     <cert>base64encodedvalue==</cert>
                   </local-definition>
                 </server-identity>
                 <client-authentication>
                   <required/>
                   <ca-certs>explicitly-trusted-client-ca-certs</ca-cer\
   ts>
                   <client-certs>explicitly-trusted-client-certs</clien\
   t-certs>
                   <cert-maps>
                     <cert-to-name>
                       <id>1</id>
                       <fingerprint>11:0A:05:11:00</fingerprint>
                       <map-type>x509c2n:san-any</map-type>
                     </cert-to-name>
                     <cert-to-name>
                       <id>2</id>
                       <fingerprint>B3:4F:A1:8C:54</fingerprint>
                       <map-type>x509c2n:specified</map-type>
                       <name>scooby-doo</name>
                     </cert-to-name>
                   </cert-maps>
                 </client-authentication>
                 <keepalives>
                   <max-wait>30</max-wait>
                   <max-attempts>3</max-attempts>
                 </keepalives>
               </tls-server-parameters>
             </tls>
           </endpoint>
           <endpoint>
             <name>west-data-center</name>
             <tls>
               <tcp-client-parameters>
                 <remote-address>west.analytics.example.com</remote-add\
   ress>
                 <keepalives>
                   <idle-time>15</idle-time>
                   <max-probes>3</max-probes>
                   <probe-interval>30</probe-interval>
                 </keepalives>
               </tcp-client-parameters>
               <tls-server-parameters>
                 <server-identity>
                   <local-definition>
                     <algorithm xmlns:ct="urn:ietf:params:xml:ns:yang:i\
   etf-crypto-types">ct:rsa2048</algorithm>
                     <private-key>base64encodedvalue==</private-key>



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                     <public-key>base64encodedvalue==</public-key>
                     <cert>base64encodedvalue==</cert>
                   </local-definition>
                 </server-identity>
                 <client-authentication>
                   <required/>
                   <ca-certs>explicitly-trusted-client-ca-certs</ca-cer\
   ts>
                   <client-certs>explicitly-trusted-client-certs</clien\
   t-certs>
                   <cert-maps>
                     <cert-to-name>
                       <id>1</id>
                       <fingerprint>11:0A:05:11:00</fingerprint>
                       <map-type>x509c2n:san-any</map-type>
                     </cert-to-name>
                     <cert-to-name>
                       <id>2</id>
                       <fingerprint>B3:4F:A1:8C:54</fingerprint>
                       <map-type>x509c2n:specified</map-type>
                       <name>scooby-doo</name>
                     </cert-to-name>
                   </cert-maps>
                 </client-authentication>
                 <keepalives>
                   <max-wait>30</max-wait>
                   <max-attempts>3</max-attempts>
                 </keepalives>
               </tls-server-parameters>
             </tls>
           </endpoint>
         </endpoints>
         <connection-type>
           <persistent/>
         </connection-type>
         <reconnect-strategy>
           <start-with>first-listed</start-with>
           <max-attempts>3</max-attempts>
         </reconnect-strategy>
       </netconf-client>
     </call-home>
   </netconf-server>

4.3.  YANG Module

   This YANG module has normative references to [RFC6242], [RFC6991],
   [RFC7407], [RFC7589], [RFC8071],
   [I-D.kwatsen-netconf-tcp-client-server],



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   [I-D.ietf-netconf-ssh-client-server], and
   [I-D.ietf-netconf-tls-client-server].

   <CODE BEGINS> file "ietf-netconf-server@2019-06-07.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";
     }

     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 AAAA: YANG Groupings for TCP Clients and TCP Servers";
     }

     import ietf-tcp-server {
       prefix tcps;
       reference
         "RFC AAAA: YANG Groupings for TCP Clients and TCP Servers";
     }

     import ietf-ssh-server {
       prefix sshs;
       revision-date 2019-06-07; // stable grouping definitions
       reference
         "RFC BBBB: YANG Groupings for SSH Clients and SSH Servers";
     }

     import ietf-tls-server {
       prefix tlss;
       revision-date 2019-06-07; // stable grouping definitions
       reference
         "RFC CCCC: YANG Groupings for TLS Clients and TLS Servers";
     }

     organization



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       "IETF NETCONF (Network Configuration) Working Group";

     contact
       "WG Web:   <http://datatracker.ietf.org/wg/netconf/>
        WG List:  <mailto:netconf@ietf.org>
        Author:   Kent Watsen <mailto:kent+ietf@watsen.net>
        Author:   Gary Wu <mailto:garywu@cisco.com>
        Author:   Juergen Schoenwaelder
                  <mailto:j.schoenwaelder@jacobs-university.de>";
     description
       "This module contains a collection of YANG definitions
        for configuring NETCONF servers.

        Copyright (c) 2019 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 XXXX
        (https://www.rfc-editor.org/info/rfcXXXX); 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 2019-06-07 {
       description
         "Initial version";
       reference
         "RFC XXXX: 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.";



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       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 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
         "Top-level grouping for NETCONF server configuration.";
       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";



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           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.";
                 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.";
                     }
                   }
                 }
                 container ssh-server-parameters {
                   description
                     "A wrapper around the SSH server parameters



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                      to avoid name collisions.";
                   uses sshs:ssh-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 client-certs';
                       description
                         "NETCONF/TLS servers MUST validate client
                          certificates.";
                     }
                     augment "client-authentication" {
                       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,



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                            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 "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
              initiate call-home connections to in parallel.";
           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.";
               }
               choice transport {



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                 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.";
                         }
                       }
                     }
                     container ssh-server-parameters {
                       description
                         "A wrapper around the SSH server parameters
                          to avoid name collisions.";
                       uses sshs:ssh-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



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                              '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" {
                           /* commented out since auth could be external
                         must 'ca-certs or client-certs';
                         */
                           description
                             "NETCONF/TLS servers MUST validate client
                              certificates.";
                         }
                         augment "client-authentication" {
                           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";
                           }
                         }
                       }
                     }
                   }
                 } // tls
               } // choice
             } // endpoint
           } // endpoints
           container connection-type {
             description
               "Indicates the NETCONF server's preference for how the
                NETCONF connection is maintained.";



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             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.";
                 } // container persistent
               } // case persistent-connection
               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 <close-session> 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.";
                   }
                   leaf anchor-time {



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                     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.";
                   }
                 } // container periodic
               } // 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.";
                 }
                 enum last-connected {



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                   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-grouping

     // Protocol accessible node, for servers that implement this
     // module.

     container netconf-server {
       uses netconf-server-grouping;
       description
         "Top-level container for NETCONF server configuration.";
     }
   }
   <CODE ENDS>






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5.  Security Considerations

   The YANG module defined in this document uses groupings defined in
   [I-D.kwatsen-netconf-tcp-client-server],
   [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 modules defined in this document 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.

   There are a number of data nodes defined in the YANG modules that are
   writable/creatable/deletable (i.e., config true, which is the
   default).  Some of 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:

      None of the subtrees or data nodes in the modules defined in this
   document need to be protected from write operations.

   Some of the readable data nodes in the YANG modules 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 of the subtrees or data nodes in the modules defined in this
   document need to be protected from read operations.

   Some of the RPC operations in the YANG modules 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:

      The modules defined in this document do not define any 'RPC' or
   'action' statements.





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6.  IANA Considerations

6.1.  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.

6.2.  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 XXXX

      name:         ietf-netconf-server
      namespace:    urn:ietf:params:xml:ns:yang:ietf-netconf-server
      prefix:       ncs
      reference:    RFC XXXX

7.  References

7.1.  Normative References

   [I-D.ietf-netconf-keystore]
              Watsen, K., "YANG Data Model for a Centralized Keystore
              Mechanism", draft-ietf-netconf-keystore-09 (work in
              progress), April 2019.

   [I-D.ietf-netconf-ssh-client-server]
              Watsen, K., Wu, G., and L. Xia, "YANG Groupings for SSH
              Clients and SSH Servers", draft-ietf-netconf-ssh-client-
              server-13 (work in progress), April 2019.






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   [I-D.ietf-netconf-tls-client-server]
              Watsen, K., Wu, G., and L. Xia, "YANG Groupings for TLS
              Clients and TLS Servers", draft-ietf-netconf-tls-client-
              server-12 (work in progress), April 2019.

   [I-D.kwatsen-netconf-tcp-client-server]
              Watsen, K. and M. Scharf, "YANG Groupings for TCP Clients
              and TCP Servers", draft-kwatsen-netconf-tcp-client-
              server-02 (work in progress), April 2019.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC6020]  Bjorklund, M., Ed., "YANG - A Data Modeling Language for
              the Network Configuration Protocol (NETCONF)", RFC 6020,
              DOI 10.17487/RFC6020, October 2010,
              <https://www.rfc-editor.org/info/rfc6020>.

   [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,
              <https://www.rfc-editor.org/info/rfc6241>.

   [RFC6242]  Wasserman, M., "Using the NETCONF Protocol over Secure
              Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011,
              <https://www.rfc-editor.org/info/rfc6242>.

   [RFC6991]  Schoenwaelder, J., Ed., "Common YANG Data Types",
              RFC 6991, DOI 10.17487/RFC6991, July 2013,
              <https://www.rfc-editor.org/info/rfc6991>.

   [RFC7407]  Bjorklund, M. and J. Schoenwaelder, "A YANG Data Model for
              SNMP Configuration", RFC 7407, DOI 10.17487/RFC7407,
              December 2014, <https://www.rfc-editor.org/info/rfc7407>.

   [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,
              <https://www.rfc-editor.org/info/rfc7589>.

   [RFC7950]  Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
              RFC 7950, DOI 10.17487/RFC7950, August 2016,
              <https://www.rfc-editor.org/info/rfc7950>.





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   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

7.2.  Informative References

   [I-D.ietf-netconf-trust-anchors]
              Watsen, K., "YANG Data Model for Global Trust Anchors",
              draft-ietf-netconf-trust-anchors-04 (work in progress),
              April 2019.

   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              DOI 10.17487/RFC3688, January 2004,
              <https://www.rfc-editor.org/info/rfc3688>.

   [RFC8040]  Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
              Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
              <https://www.rfc-editor.org/info/rfc8040>.

   [RFC8071]  Watsen, K., "NETCONF Call Home and RESTCONF Call Home",
              RFC 8071, DOI 10.17487/RFC8071, February 2017,
              <https://www.rfc-editor.org/info/rfc8071>.

   [RFC8340]  Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
              BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
              <https://www.rfc-editor.org/info/rfc8340>.

   [RFC8341]  Bierman, A. and M. Bjorklund, "Network Configuration
              Access Control Model", STD 91, RFC 8341,
              DOI 10.17487/RFC8341, March 2018,
              <https://www.rfc-editor.org/info/rfc8341>.




















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Appendix A.  Expanded Tree Diagrams

A.1.  Expanded Tree Diagram for 'ietf-netconf-client'

   The following tree diagram [RFC8340] provides an overview of the data
   model for the "ietf-netconf-client" module.

   This tree diagram shows all the nodes defined in this module,
   including those defined by "grouping" statements used by this module.

   Please see Section 3.1 for a tree diagram that illustrates what the
   module looks like without all the "grouping" statements expanded.

   =========== NOTE: '\' line wrapping per BCP XX (RFC XXXX) ===========

   module: ietf-netconf-client
     +--rw netconf-client
        +--rw initiate! {ssh-initiate or tls-initiate}?
        |  +--rw netconf-server* [name]
        |     +--rw name                  string
        |     +--rw endpoints
        |     |  +--rw endpoint* [name]
        |     |     +--rw name         string
        |     |     +--rw (transport)
        |     |        +--:(ssh) {ssh-initiate}?
        |     |        |  +--rw ssh
        |     |        |     +--rw tcp-client-parameters
        |     |        |     |  +--rw remote-address    inet:host
        |     |        |     |  +--rw remote-port?      inet:port-number
        |     |        |     |  +--rw local-address?    inet:ip-address
        |     |        |     |  |       {local-binding-supported}?
        |     |        |     |  +--rw local-port?       inet:port-number
        |     |        |     |  |       {local-binding-supported}?
        |     |        |     |  +--rw keepalives!
        |     |        |     |          {keepalives-supported}?
        |     |        |     |     +--rw idle-time         uint16
        |     |        |     |     +--rw max-probes        uint16
        |     |        |     |     +--rw probe-interval    uint16
        |     |        |     +--rw ssh-client-parameters
        |     |        |        +--rw client-identity
        |     |        |        |  +--rw username?            string
        |     |        |        |  +--rw (auth-type)
        |     |        |        |     +--:(password)
        |     |        |        |     |  +--rw password?      string
        |     |        |        |     +--:(public-key)
        |     |        |        |     |  +--rw public-key
        |     |        |        |     |     +--rw (local-or-keystore)
        |     |        |        |     |        +--:(local)



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        |     |        |        |     |        |        {local-definiti\
   ons-supported}?
        |     |        |        |     |        |  +--rw local-definition
        |     |        |        |     |        |     +--rw algorithm
        |     |        |        |     |        |     |       asymmetric\
   -key-algorithm-ref
        |     |        |        |     |        |     +--rw public-key
        |     |        |        |     |        |     |       binary
        |     |        |        |     |        |     +--rw private-key
        |     |        |        |     |        |             union
        |     |        |        |     |        +--:(keystore)
        |     |        |        |     |                 {keystore-suppo\
   rted}?
        |     |        |        |     |           +--rw keystore-refere\
   nce?
        |     |        |        |     |                   ks:asymmetric\
   -key-ref
        |     |        |        |     +--:(certificate)
        |     |        |        |        +--rw certificate
        |     |        |        |                {sshcmn:ssh-x509-certs\
   }?
        |     |        |        |           +--rw (local-or-keystore)
        |     |        |        |              +--:(local)
        |     |        |        |              |        {local-definiti\
   ons-supported}?
        |     |        |        |              |  +--rw local-definition
        |     |        |        |              |     +--rw algorithm
        |     |        |        |              |     |       asymmetric\
   -key-algorithm-ref
        |     |        |        |              |     +--rw public-key
        |     |        |        |              |     |       binary
        |     |        |        |              |     +--rw private-key
        |     |        |        |              |     |       union
        |     |        |        |              |     +--rw cert?
        |     |        |        |              |     |       end-entity\
   -cert-cms
        |     |        |        |              |     +---n certificate-\
   expiration
        |     |        |        |              |     |  +-- expiration-\
   date
        |     |        |        |              |     |          yang:da\
   te-and-time
        |     |        |        |              |     +---x generate-cer\
   tificate-signing-request
        |     |        |        |              |        +---w input
        |     |        |        |              |        |  +---w subject
        |     |        |        |              |        |  |       bina\
   ry



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        |     |        |        |              |        |  +---w attrib\
   utes?
        |     |        |        |              |        |          bina\
   ry
        |     |        |        |              |        +--ro output
        |     |        |        |              |           +--ro certif\
   icate-signing-request
        |     |        |        |              |                   bina\
   ry
        |     |        |        |              +--:(keystore)
        |     |        |        |                       {keystore-suppo\
   rted}?
        |     |        |        |                 +--rw keystore-refere\
   nce?
        |     |        |        |                         ks:asymmetric\
   -key-certificate-ref
        |     |        |        +--rw server-authentication
        |     |        |        |  +--rw ssh-host-keys?
        |     |        |        |  |       ts:host-keys-ref
        |     |        |        |  |       {ts:ssh-host-keys}?
        |     |        |        |  +--rw ca-certs?
        |     |        |        |  |       ts:certificates-ref
        |     |        |        |  |       {sshcmn:ssh-x509-certs,ts:x5\
   09-certificates}?
        |     |        |        |  +--rw server-certs?
        |     |        |        |          ts:certificates-ref
        |     |        |        |          {sshcmn:ssh-x509-certs,ts:x5\
   09-certificates}?
        |     |        |        +--rw transport-params
        |     |        |        |       {ssh-client-transport-params-co\
   nfig}?
        |     |        |        |  +--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
        |     |        |        +--rw keepalives!
        |     |        |                {ssh-client-keepalives}?
        |     |        |           +--rw max-wait?       uint16
        |     |        |           +--rw max-attempts?   uint8
        |     |        +--:(tls) {tls-initiate}?
        |     |           +--rw tls
        |     |              +--rw tcp-client-parameters



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        |     |              |  +--rw remote-address    inet:host
        |     |              |  +--rw remote-port?      inet:port-number
        |     |              |  +--rw local-address?    inet:ip-address
        |     |              |  |       {local-binding-supported}?
        |     |              |  +--rw local-port?       inet:port-number
        |     |              |  |       {local-binding-supported}?
        |     |              |  +--rw keepalives!
        |     |              |          {keepalives-supported}?
        |     |              |     +--rw idle-time         uint16
        |     |              |     +--rw max-probes        uint16
        |     |              |     +--rw probe-interval    uint16
        |     |              +--rw tls-client-parameters
        |     |                 +--rw client-identity
        |     |                 |  +--rw (auth-type)
        |     |                 |     +--:(certificate)
        |     |                 |        +--rw certificate
        |     |                 |           +--rw (local-or-keystore)
        |     |                 |              +--:(local)
        |     |                 |              |        {local-definiti\
   ons-supported}?
        |     |                 |              |  +--rw local-definition
        |     |                 |              |     +--rw algorithm
        |     |                 |              |     |       asymmetric\
   -key-algorithm-ref
        |     |                 |              |     +--rw public-key
        |     |                 |              |     |       binary
        |     |                 |              |     +--rw private-key
        |     |                 |              |     |       union
        |     |                 |              |     +--rw cert?
        |     |                 |              |     |       end-entity\
   -cert-cms
        |     |                 |              |     +---n certificate-\
   expiration
        |     |                 |              |     |  +-- expiration-\
   date
        |     |                 |              |     |          yang:da\
   te-and-time
        |     |                 |              |     +---x generate-cer\
   tificate-signing-request
        |     |                 |              |        +---w input
        |     |                 |              |        |  +---w subject
        |     |                 |              |        |  |       bina\
   ry
        |     |                 |              |        |  +---w attrib\
   utes?
        |     |                 |              |        |          bina\
   ry
        |     |                 |              |        +--ro output



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        |     |                 |              |           +--ro certif\
   icate-signing-request
        |     |                 |              |                   bina\
   ry
        |     |                 |              +--:(keystore)
        |     |                 |                       {keystore-suppo\
   rted}?
        |     |                 |                 +--rw keystore-refere\
   nce?
        |     |                 |                         ks:asymmetric\
   -key-certificate-ref
        |     |                 +--rw server-authentication
        |     |                 |  +--rw ca-certs?
        |     |                 |  |       ts:certificates-ref
        |     |                 |  |       {ts:x509-certificates}?
        |     |                 |  +--rw server-certs?
        |     |                 |          ts:certificates-ref
        |     |                 |          {ts:x509-certificates}?
        |     |                 +--rw hello-params
        |     |                 |       {tls-client-hello-params-config\
   }?
        |     |                 |  +--rw tls-versions
        |     |                 |  |  +--rw tls-version*   identityref
        |     |                 |  +--rw cipher-suites
        |     |                 |     +--rw cipher-suite*   identityref
        |     |                 +--rw keepalives!
        |     |                         {tls-client-keepalives}?
        |     |                    +--rw max-wait?       uint16
        |     |                    +--rw max-attempts?   uint8
        |     +--rw connection-type
        |     |  +--rw (connection-type)
        |     |     +--:(persistent-connection)
        |     |     |  +--rw persistent!
        |     |     +--:(periodic-connection)
        |     |        +--rw periodic!
        |     |           +--rw period?         uint16
        |     |           +--rw anchor-time?    yang:date-and-time
        |     |           +--rw idle-timeout?   uint16
        |     +--rw reconnect-strategy
        |        +--rw start-with?     enumeration
        |        +--rw max-attempts?   uint8
        +--rw listen! {ssh-listen or tls-listen}?
           +--rw idle-timeout?   uint16
           +--rw endpoint* [name]
              +--rw name         string
              +--rw (transport)
                 +--:(ssh) {ssh-listen}?
                 |  +--rw ssh



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                 |     +--rw tcp-server-parameters
                 |     |  +--rw local-address
                 |     |  |       inet:ip-address
                 |     |  +--rw local-port?
                 |     |  |       inet:port-number
                 |     |  +--rw keepalives! {keepalives-supported}?
                 |     |  |  +--rw idle-time         uint16
                 |     |  |  +--rw max-probes        uint16
                 |     |  |  +--rw probe-interval    uint16
                 |     |  +--rw external-endpoint-values!
                 |     |          {external-endpoints}?
                 |     |     +--rw address    inet:ip-address
                 |     |     +--rw port?      inet:port-number
                 |     +--rw ssh-client-parameters
                 |        +--rw client-identity
                 |        |  +--rw username?            string
                 |        |  +--rw (auth-type)
                 |        |     +--:(password)
                 |        |     |  +--rw password?      string
                 |        |     +--:(public-key)
                 |        |     |  +--rw public-key
                 |        |     |     +--rw (local-or-keystore)
                 |        |     |        +--:(local)
                 |        |     |        |        {local-definitions-su\
   pported}?
                 |        |     |        |  +--rw local-definition
                 |        |     |        |     +--rw algorithm
                 |        |     |        |     |       asymmetric-key-a\
   lgorithm-ref
                 |        |     |        |     +--rw public-key
                 |        |     |        |     |       binary
                 |        |     |        |     +--rw private-key
                 |        |     |        |             union
                 |        |     |        +--:(keystore)
                 |        |     |                 {keystore-supported}?
                 |        |     |           +--rw keystore-reference?
                 |        |     |                   ks:asymmetric-key-r\
   ef
                 |        |     +--:(certificate)
                 |        |        +--rw certificate
                 |        |                {sshcmn:ssh-x509-certs}?
                 |        |           +--rw (local-or-keystore)
                 |        |              +--:(local)
                 |        |              |        {local-definitions-su\
   pported}?
                 |        |              |  +--rw local-definition
                 |        |              |     +--rw algorithm
                 |        |              |     |       asymmetric-key-a\



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   lgorithm-ref
                 |        |              |     +--rw public-key
                 |        |              |     |       binary
                 |        |              |     +--rw private-key
                 |        |              |     |       union
                 |        |              |     +--rw cert?
                 |        |              |     |       end-entity-cert-\
   cms
                 |        |              |     +---n certificate-expira\
   tion
                 |        |              |     |  +-- expiration-date
                 |        |              |     |          yang:date-and\
   -time
                 |        |              |     +---x generate-certifica\
   te-signing-request
                 |        |              |        +---w input
                 |        |              |        |  +---w subject
                 |        |              |        |  |       binary
                 |        |              |        |  +---w attributes?
                 |        |              |        |          binary
                 |        |              |        +--ro output
                 |        |              |           +--ro certificate-\
   signing-request
                 |        |              |                   binary
                 |        |              +--:(keystore)
                 |        |                       {keystore-supported}?
                 |        |                 +--rw keystore-reference?
                 |        |                         ks:asymmetric-key-c\
   ertificate-ref
                 |        +--rw server-authentication
                 |        |  +--rw ssh-host-keys?   ts:host-keys-ref
                 |        |  |       {ts:ssh-host-keys}?
                 |        |  +--rw ca-certs?        ts:certificates-ref
                 |        |  |       {sshcmn:ssh-x509-certs,ts:x509-cer\
   tificates}?
                 |        |  +--rw server-certs?    ts:certificates-ref
                 |        |          {sshcmn:ssh-x509-certs,ts:x509-cer\
   tificates}?
                 |        +--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



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                 |        +--rw keepalives! {ssh-client-keepalives}?
                 |           +--rw max-wait?       uint16
                 |           +--rw max-attempts?   uint8
                 +--:(tls) {tls-listen}?
                    +--rw tls
                       +--rw tcp-server-parameters
                       |  +--rw local-address
                       |  |       inet:ip-address
                       |  +--rw local-port?
                       |  |       inet:port-number
                       |  +--rw keepalives! {keepalives-supported}?
                       |  |  +--rw idle-time         uint16
                       |  |  +--rw max-probes        uint16
                       |  |  +--rw probe-interval    uint16
                       |  +--rw external-endpoint-values!
                       |          {external-endpoints}?
                       |     +--rw address    inet:ip-address
                       |     +--rw port?      inet:port-number
                       +--rw tls-client-parameters
                          +--rw client-identity
                          |  +--rw (auth-type)
                          |     +--:(certificate)
                          |        +--rw certificate
                          |           +--rw (local-or-keystore)
                          |              +--:(local)
                          |              |        {local-definitions-su\
   pported}?
                          |              |  +--rw local-definition
                          |              |     +--rw algorithm
                          |              |     |       asymmetric-key-a\
   lgorithm-ref
                          |              |     +--rw public-key
                          |              |     |       binary
                          |              |     +--rw private-key
                          |              |     |       union
                          |              |     +--rw cert?
                          |              |     |       end-entity-cert-\
   cms
                          |              |     +---n certificate-expira\
   tion
                          |              |     |  +-- expiration-date
                          |              |     |          yang:date-and\
   -time
                          |              |     +---x generate-certifica\
   te-signing-request
                          |              |        +---w input
                          |              |        |  +---w subject
                          |              |        |  |       binary



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                          |              |        |  +---w attributes?
                          |              |        |          binary
                          |              |        +--ro output
                          |              |           +--ro certificate-\
   signing-request
                          |              |                   binary
                          |              +--:(keystore)
                          |                       {keystore-supported}?
                          |                 +--rw keystore-reference?
                          |                         ks:asymmetric-key-c\
   ertificate-ref
                          +--rw server-authentication
                          |  +--rw ca-certs?       ts:certificates-ref
                          |  |       {ts:x509-certificates}?
                          |  +--rw server-certs?   ts:certificates-ref
                          |          {ts:x509-certificates}?
                          +--rw hello-params
                          |       {tls-client-hello-params-config}?
                          |  +--rw tls-versions
                          |  |  +--rw tls-version*   identityref
                          |  +--rw cipher-suites
                          |     +--rw cipher-suite*   identityref
                          +--rw keepalives! {tls-client-keepalives}?
                             +--rw max-wait?       uint16
                             +--rw max-attempts?   uint8

A.2.  Expanded Tree Diagram for 'ietf-netconf-server'

   The following tree diagram [RFC8340] provides an overview of the data
   model for the "ietf-netconf-server" module.

   This tree diagram shows all the nodes defined in this module,
   including those defined by "grouping" statements used by this module.

   Please see Section 4.1 for a tree diagram that illustrates what the
   module looks like without all the "grouping" statements expanded.

   =========== NOTE: '\' line wrapping per BCP XX (RFC XXXX) ===========

   module: ietf-netconf-server
     +--rw netconf-server
        +--rw listen! {ssh-listen or tls-listen}?
        |  +--rw idle-timeout?   uint16
        |  +--rw endpoint* [name]
        |     +--rw name         string
        |     +--rw (transport)
        |        +--:(ssh) {ssh-listen}?
        |        |  +--rw ssh



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        |        |     +--rw tcp-server-parameters
        |        |     |  +--rw local-address
        |        |     |  |       inet:ip-address
        |        |     |  +--rw local-port?
        |        |     |  |       inet:port-number
        |        |     |  +--rw keepalives! {keepalives-supported}?
        |        |     |  |  +--rw idle-time         uint16
        |        |     |  |  +--rw max-probes        uint16
        |        |     |  |  +--rw probe-interval    uint16
        |        |     |  +--rw external-endpoint-values!
        |        |     |          {external-endpoints}?
        |        |     |     +--rw address    inet:ip-address
        |        |     |     +--rw port?      inet:port-number
        |        |     +--rw ssh-server-parameters
        |        |        +--rw server-identity
        |        |        |  +--rw host-key* [name]
        |        |        |     +--rw name                 string
        |        |        |     +--rw (host-key-type)
        |        |        |        +--:(public-key)
        |        |        |        |  +--rw public-key
        |        |        |        |     +--rw (local-or-keystore)
        |        |        |        |        +--:(local)
        |        |        |        |        |        {local-definitions\
   -supported}?
        |        |        |        |        |  +--rw local-definition
        |        |        |        |        |     +--rw algorithm
        |        |        |        |        |     |       asymmetric-ke\
   y-algorithm-ref
        |        |        |        |        |     +--rw public-key
        |        |        |        |        |     |       binary
        |        |        |        |        |     +--rw private-key
        |        |        |        |        |             union
        |        |        |        |        +--:(keystore)
        |        |        |        |                 {keystore-supporte\
   d}?
        |        |        |        |           +--rw keystore-reference?
        |        |        |        |                   ks:asymmetric-ke\
   y-ref
        |        |        |        +--:(certificate)
        |        |        |           +--rw certificate
        |        |        |                   {sshcmn:ssh-x509-certs}?
        |        |        |              +--rw (local-or-keystore)
        |        |        |                 +--:(local)
        |        |        |                 |        {local-definitions\
   -supported}?
        |        |        |                 |  +--rw local-definition
        |        |        |                 |     +--rw algorithm
        |        |        |                 |     |       asymmetric-ke\



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   y-algorithm-ref
        |        |        |                 |     +--rw public-key
        |        |        |                 |     |       binary
        |        |        |                 |     +--rw private-key
        |        |        |                 |     |       union
        |        |        |                 |     +--rw cert?
        |        |        |                 |     |       end-entity-ce\
   rt-cms
        |        |        |                 |     +---n certificate-exp\
   iration
        |        |        |                 |     |  +-- expiration-date
        |        |        |                 |     |          yang:date-\
   and-time
        |        |        |                 |     +---x generate-certif\
   icate-signing-request
        |        |        |                 |        +---w input
        |        |        |                 |        |  +---w subject
        |        |        |                 |        |  |       binary
        |        |        |                 |        |  +---w attribute\
   s?
        |        |        |                 |        |          binary
        |        |        |                 |        +--ro output
        |        |        |                 |           +--ro certifica\
   te-signing-request
        |        |        |                 |                   binary
        |        |        |                 +--:(keystore)
        |        |        |                          {keystore-supporte\
   d}?
        |        |        |                    +--rw keystore-reference?
        |        |        |                            ks:asymmetric-ke\
   y-certificate-ref
        |        |        +--rw client-authentication
        |        |        |  +--rw supported-authentication-methods
        |        |        |  |  +--rw publickey?   empty
        |        |        |  |  +--rw passsword?   empty
        |        |        |  |  +--rw hostbased?   empty
        |        |        |  |  +--rw none?        empty
        |        |        |  |  +--rw other*       string
        |        |        |  +--rw (local-or-external)
        |        |        |     +--:(local)
        |        |        |     |        {local-client-auth-supported}?
        |        |        |     |  +--rw users
        |        |        |     |     +--rw user* [name]
        |        |        |     |        +--rw name              string
        |        |        |     |        +--rw password?
        |        |        |     |        |       ianach:crypt-hash
        |        |        |     |        +--rw authorized-key* [name]
        |        |        |     |           +--rw name         string



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        |        |        |     |           +--rw algorithm    string
        |        |        |     |           +--rw key-data     binary
        |        |        |     +--:(external)
        |        |        |              {external-client-auth-supporte\
   d}?
        |        |        |        +--rw client-auth-defined-elsewhere?
        |        |        |                empty
        |        |        +--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
        |        |        +--rw keepalives! {ssh-server-keepalives}?
        |        |           +--rw max-wait?       uint16
        |        |           +--rw max-attempts?   uint8
        |        +--:(tls) {tls-listen}?
        |           +--rw tls
        |              +--rw tcp-server-parameters
        |              |  +--rw local-address
        |              |  |       inet:ip-address
        |              |  +--rw local-port?
        |              |  |       inet:port-number
        |              |  +--rw keepalives! {keepalives-supported}?
        |              |  |  +--rw idle-time         uint16
        |              |  |  +--rw max-probes        uint16
        |              |  |  +--rw probe-interval    uint16
        |              |  +--rw external-endpoint-values!
        |              |          {external-endpoints}?
        |              |     +--rw address    inet:ip-address
        |              |     +--rw port?      inet:port-number
        |              +--rw tls-server-parameters
        |                 +--rw server-identity
        |                 |  +--rw (local-or-keystore)
        |                 |     +--:(local)
        |                 |     |        {local-definitions-supported}?
        |                 |     |  +--rw local-definition
        |                 |     |     +--rw algorithm
        |                 |     |     |       asymmetric-key-algorithm-\
   ref
        |                 |     |     +--rw public-key
        |                 |     |     |       binary
        |                 |     |     +--rw private-key
        |                 |     |     |       union



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        |                 |     |     +--rw cert?
        |                 |     |     |       end-entity-cert-cms
        |                 |     |     +---n certificate-expiration
        |                 |     |     |  +-- expiration-date
        |                 |     |     |          yang:date-and-time
        |                 |     |     +---x generate-certificate-signin\
   g-request
        |                 |     |        +---w input
        |                 |     |        |  +---w subject       binary
        |                 |     |        |  +---w attributes?   binary
        |                 |     |        +--ro output
        |                 |     |           +--ro certificate-signing-r\
   equest
        |                 |     |                   binary
        |                 |     +--:(keystore) {keystore-supported}?
        |                 |        +--rw keystore-reference?
        |                 |                ks:asymmetric-key-certificat\
   e-ref
        |                 +--rw client-authentication!
        |                 |  +--rw (required-or-optional)
        |                 |  |  +--:(required)
        |                 |  |  |  +--rw required?
        |                 |  |  |          empty
        |                 |  |  +--:(optional)
        |                 |  |     +--rw optional?
        |                 |  |             empty
        |                 |  +--rw (local-or-external)
        |                 |  |  +--:(local)
        |                 |  |  |        {local-client-auth-supported}?
        |                 |  |  |  +--rw ca-certs?
        |                 |  |  |  |       ts:certificates-ref
        |                 |  |  |  |       {ts:x509-certificates}?
        |                 |  |  |  +--rw client-certs?
        |                 |  |  |          ts:certificates-ref
        |                 |  |  |          {ts:x509-certificates}?
        |                 |  |  +--:(external)
        |                 |  |           {external-client-auth-supporte\
   d}?
        |                 |  |     +--rw client-auth-defined-elsewhere?
        |                 |  |             empty
        |                 |  +--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



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        |                 |       {tls-server-hello-params-config}?
        |                 |  +--rw tls-versions
        |                 |  |  +--rw tls-version*   identityref
        |                 |  +--rw cipher-suites
        |                 |     +--rw cipher-suite*   identityref
        |                 +--rw keepalives! {tls-server-keepalives}?
        |                    +--rw max-wait?       uint16
        |                    +--rw max-attempts?   uint8
        +--rw call-home! {ssh-call-home or tls-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 tcp-client-parameters
              |        |     |  +--rw remote-address    inet:host
              |        |     |  +--rw remote-port?      inet:port-number
              |        |     |  +--rw local-address?    inet:ip-address
              |        |     |  |       {local-binding-supported}?
              |        |     |  +--rw local-port?       inet:port-number
              |        |     |  |       {local-binding-supported}?
              |        |     |  +--rw keepalives!
              |        |     |          {keepalives-supported}?
              |        |     |     +--rw idle-time         uint16
              |        |     |     +--rw max-probes        uint16
              |        |     |     +--rw probe-interval    uint16
              |        |     +--rw ssh-server-parameters
              |        |        +--rw server-identity
              |        |        |  +--rw host-key* [name]
              |        |        |     +--rw name                 string
              |        |        |     +--rw (host-key-type)
              |        |        |        +--:(public-key)
              |        |        |        |  +--rw public-key
              |        |        |        |     +--rw (local-or-keystore)
              |        |        |        |        +--:(local)
              |        |        |        |        |        {local-defin\
   itions-supported}?
              |        |        |        |        |  +--rw local-defini\
   tion
              |        |        |        |        |     +--rw algorithm
              |        |        |        |        |     |       asymmet\
   ric-key-algorithm-ref
              |        |        |        |        |     +--rw public-key
              |        |        |        |        |     |       binary
              |        |        |        |        |     +--rw private-k\



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   ey
              |        |        |        |        |             union
              |        |        |        |        +--:(keystore)
              |        |        |        |                 {keystore-su\
   pported}?
              |        |        |        |           +--rw keystore-ref\
   erence?
              |        |        |        |                   ks:asymmet\
   ric-key-ref
              |        |        |        +--:(certificate)
              |        |        |           +--rw certificate
              |        |        |                   {sshcmn:ssh-x509-ce\
   rts}?
              |        |        |              +--rw (local-or-keystore)
              |        |        |                 +--:(local)
              |        |        |                 |        {local-defin\
   itions-supported}?
              |        |        |                 |  +--rw local-defini\
   tion
              |        |        |                 |     +--rw algorithm
              |        |        |                 |     |       asymmet\
   ric-key-algorithm-ref
              |        |        |                 |     +--rw public-key
              |        |        |                 |     |       binary
              |        |        |                 |     +--rw private-k\
   ey
              |        |        |                 |     |       union
              |        |        |                 |     +--rw cert?
              |        |        |                 |     |       end-ent\
   ity-cert-cms
              |        |        |                 |     +---n certifica\
   te-expiration
              |        |        |                 |     |  +-- expirati\
   on-date
              |        |        |                 |     |          yang\
   :date-and-time
              |        |        |                 |     +---x generate-\
   certificate-signing-request
              |        |        |                 |        +---w input
              |        |        |                 |        |  +---w sub\
   ject
              |        |        |                 |        |  |       b\
   inary
              |        |        |                 |        |  +---w att\
   ributes?
              |        |        |                 |        |          b\
   inary
              |        |        |                 |        +--ro output



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              |        |        |                 |           +--ro cer\
   tificate-signing-request
              |        |        |                 |                   b\
   inary
              |        |        |                 +--:(keystore)
              |        |        |                          {keystore-su\
   pported}?
              |        |        |                    +--rw keystore-ref\
   erence?
              |        |        |                            ks:asymmet\
   ric-key-certificate-ref
              |        |        +--rw client-authentication
              |        |        |  +--rw supported-authentication-metho\
   ds
              |        |        |  |  +--rw publickey?   empty
              |        |        |  |  +--rw passsword?   empty
              |        |        |  |  +--rw hostbased?   empty
              |        |        |  |  +--rw none?        empty
              |        |        |  |  +--rw other*       string
              |        |        |  +--rw (local-or-external)
              |        |        |     +--:(local)
              |        |        |     |        {local-client-auth-suppo\
   rted}?
              |        |        |     |  +--rw users
              |        |        |     |     +--rw user* [name]
              |        |        |     |        +--rw name
              |        |        |     |        |       string
              |        |        |     |        +--rw password?
              |        |        |     |        |       ianach:crypt-hash
              |        |        |     |        +--rw authorized-key*
              |        |        |     |                [name]
              |        |        |     |           +--rw name
              |        |        |     |           |       string
              |        |        |     |           +--rw algorithm
              |        |        |     |           |       string
              |        |        |     |           +--rw key-data
              |        |        |     |                   binary
              |        |        |     +--:(external)
              |        |        |              {external-client-auth-su\
   pported}?
              |        |        |        +--rw client-auth-defined-else\
   where?
              |        |        |                empty
              |        |        +--rw transport-params
              |        |        |       {ssh-server-transport-params-co\
   nfig}?
              |        |        |  +--rw host-key
              |        |        |  |  +--rw host-key-alg*   identityref



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              |        |        |  +--rw key-exchange
              |        |        |  |  +--rw key-exchange-alg*
              |        |        |  |          identityref
              |        |        |  +--rw encryption
              |        |        |  |  +--rw encryption-alg*
              |        |        |  |          identityref
              |        |        |  +--rw mac
              |        |        |     +--rw mac-alg*   identityref
              |        |        +--rw keepalives!
              |        |                {ssh-server-keepalives}?
              |        |           +--rw max-wait?       uint16
              |        |           +--rw max-attempts?   uint8
              |        +--:(tls) {tls-call-home}?
              |           +--rw tls
              |              +--rw tcp-client-parameters
              |              |  +--rw remote-address    inet:host
              |              |  +--rw remote-port?      inet:port-number
              |              |  +--rw local-address?    inet:ip-address
              |              |  |       {local-binding-supported}?
              |              |  +--rw local-port?       inet:port-number
              |              |  |       {local-binding-supported}?
              |              |  +--rw keepalives!
              |              |          {keepalives-supported}?
              |              |     +--rw idle-time         uint16
              |              |     +--rw max-probes        uint16
              |              |     +--rw probe-interval    uint16
              |              +--rw tls-server-parameters
              |                 +--rw server-identity
              |                 |  +--rw (local-or-keystore)
              |                 |     +--:(local)
              |                 |     |        {local-definitions-suppo\
   rted}?
              |                 |     |  +--rw local-definition
              |                 |     |     +--rw algorithm
              |                 |     |     |       asymmetric-key-algo\
   rithm-ref
              |                 |     |     +--rw public-key
              |                 |     |     |       binary
              |                 |     |     +--rw private-key
              |                 |     |     |       union
              |                 |     |     +--rw cert?
              |                 |     |     |       end-entity-cert-cms
              |                 |     |     +---n certificate-expiration
              |                 |     |     |  +-- expiration-date
              |                 |     |     |          yang:date-and-ti\
   me
              |                 |     |     +---x generate-certificate-\
   signing-request



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              |                 |     |        +---w input
              |                 |     |        |  +---w subject
              |                 |     |        |  |       binary
              |                 |     |        |  +---w attributes?
              |                 |     |        |          binary
              |                 |     |        +--ro output
              |                 |     |           +--ro certificate-sig\
   ning-request
              |                 |     |                   binary
              |                 |     +--:(keystore)
              |                 |              {keystore-supported}?
              |                 |        +--rw keystore-reference?
              |                 |                ks:asymmetric-key-cert\
   ificate-ref
              |                 +--rw client-authentication!
              |                 |  +--rw (required-or-optional)
              |                 |  |  +--:(required)
              |                 |  |  |  +--rw required?
              |                 |  |  |          empty
              |                 |  |  +--:(optional)
              |                 |  |     +--rw optional?
              |                 |  |             empty
              |                 |  +--rw (local-or-external)
              |                 |  |  +--:(local)
              |                 |  |  |        {local-client-auth-suppo\
   rted}?
              |                 |  |  |  +--rw ca-certs?
              |                 |  |  |  |       ts:certificates-ref
              |                 |  |  |  |       {ts:x509-certificates}?
              |                 |  |  |  +--rw client-certs?
              |                 |  |  |          ts:certificates-ref
              |                 |  |  |          {ts:x509-certificates}?
              |                 |  |  +--:(external)
              |                 |  |           {external-client-auth-su\
   pported}?
              |                 |  |     +--rw client-auth-defined-else\
   where?
              |                 |  |             empty
              |                 |  +--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\



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   }?
              |                 |  +--rw tls-versions
              |                 |  |  +--rw tls-version*   identityref
              |                 |  +--rw cipher-suites
              |                 |     +--rw cipher-suite*   identityref
              |                 +--rw keepalives!
              |                         {tls-server-keepalives}?
              |                    +--rw max-wait?       uint16
              |                    +--rw max-attempts?   uint8
              +--rw connection-type
              |  +--rw (connection-type)
              |     +--:(persistent-connection)
              |     |  +--rw persistent!
              |     +--:(periodic-connection)
              |        +--rw periodic!
              |           +--rw period?         uint16
              |           +--rw anchor-time?    yang:date-and-time
              |           +--rw idle-timeout?   uint16
              +--rw reconnect-strategy
                 +--rw start-with?     enumeration
                 +--rw max-attempts?   uint8

Appendix B.  Change Log

B.1.  00 to 01

   o  Renamed "keychain" to "keystore".

B.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 accommodate new groupings in the ssh/tls
      drafts.

B.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).






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B.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.

B.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)

B.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.

B.7.  06 to 07

   o  Removed "idle-timeout" from "persistent" connection config.

   o  Added "random-selection" for reconnection-strategy's "starts-with"
      enum.

   o  Replaced "connection-type" choice default (persistent) with
      "mandatory true".

   o  Reduced the periodic-connection's "idle-timeout" from 5 to 2
      minutes.

   o  Replaced reconnect-timeout with period/anchor-time combo.








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B.8.  07 to 08

   o  Modified examples to be compatible with new crypto-types algs

B.9.  08 to 09

   o  Corrected use of "mandatory true" for "address" leafs.

   o  Updated examples to reflect update to groupings defined in the
      keystore draft.

   o  Updated to use groupings defined in new TCP and HTTP drafts.

   o  Updated copyright date, boilerplate template, affiliation, and
      folding algorithm.

B.10.  09 to 10

   o  Reformatted YANG modules.

B.11.  10 to 11

   o  Adjusted for the top-level "demux container" added to groupings
      imported from other modules.

   o  Added "must" expressions to ensure that keepalives are not
      configured for "periodic" connections.

   o  Updated the boilerplate text in module-level "description"
      statement to match copyeditor convention.

   o  Moved "expanded" tree diagrams to the Appendix.

B.12.  11 to 12

   o  Removed the "Design Considerations" section.

   o  Removed the 'must' statement limiting keepalives in periodic
      connections.

   o  Updated models and examples to reflect removal of the "demux"
      containers in the imported models.

   o  Updated the "periodic-connnection" description statements to be
      more like the RESTCONF draft, especially where it described
      dropping the underlying TCP connection.





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   o  Updated text to better reference where certain examples come from
      (e.g., which Section in which draft).

   o  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.

   o  Replaced the 'listen', 'initiate', and 'call-home' features with
      boolean expressions.

B.13.  12 to 13

   o  Updated to reflect changes in trust-anchors drafts (e.g., s/trust-
      anchors/truststore/g + s/pinned.//)

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, Alan Luchuk, Ladislav Lhotka, 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





















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