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Versions: 00 01 02 03 04 05 06 07 08 09 draft-ietf-netconf-netconf-client-server

NETCONF Working Group                                          K. Watsen
Internet-Draft                                          Juniper Networks
Intended status: Standards Track                        J. Schoenwaelder
Expires: September 17, 2016                     Jacobs University Bremen
                                                          March 16, 2016


        NETCONF Server and RESTCONF Server Configuration Models
                   draft-ietf-netconf-server-model-09

Abstract

   This draft defines a NETCONF server configuration data model and a
   RESTCONF server configuration data model.  These data models enable
   configuration of the NETCONF and RESTCONF services themselves,
   including which transports are supported, what ports the servers
   listen on, call-home parameters, client authentication, and related
   parameters.

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.  Please note
   that no other RFC Editor instructions are specified anywhere else 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  draft-ietf-netconf-restconf

   o  draft-ietf-netconf-call-home

   o  draft-ietf-rtgwg-yang-key-chain

   Artwork in this document contains shorthand references to drafts in
   progress.  Please apply the following replacements:

   o  "VVVV" --> the assigned RFC value for this draft

   o  "XXXX" --> the assigned RFC value for draft-ietf-netconf-restconf

   o  "YYYY" --> the assigned RFC value for draft-ietf-netconf-call-home





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   Artwork in this document contains placeholder values for ports
   pending IANA assignment from "draft-ietf-netconf-call-home".  Please
   apply the following replacements:

   o  "7777" --> the assigned port value for "netconf-ch-ssh"

   o  "8888" --> the assigned port value for "netconf-ch-tls"

   o  "9999" --> the assigned port value for "restconf-ch-tls"

   Artwork in this document contains placeholder values for the date of
   publication of this draft.  Please apply the following replacement:

   o  "2016-03-16" --> the publication date of this draft

   The following two Appendix sections are to be removed prior to
   publication:

   o  Appendix A.  Change Log

   o  Appendix B.  Open Issues

   Artwork in the document contains a temporary YANG containers that
   need to be removed.

   o  The "listening-ssh-server" container listed at the end of the
      artwork in Section 4.2.3 needs to be removed.  Please remove the
      ten lines starting with "container listening-ssh-server {" and
      ending with "}".

   o  The "listening-tls-server" container listed at the end of the
      artwork in Section 4.3.3 needs to be removed.  Please remove the
      ten lines starting with "container listening-tls-server {" and
      ending with "}".

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 http://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




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   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 September 17, 2016.

Copyright Notice

   Copyright (c) 2016 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
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   4
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   5
     1.2.  Tree Diagrams . . . . . . . . . . . . . . . . . . . . . .   5
   2.  Objectives  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     2.1.  Support all NETCONF and RESTCONF transports . . . . . . .   5
     2.2.  Enable each transport to select which keys to use . . . .   6
     2.3.  Support authenticating NETCONF/RESTCONF clients
           certificates  . . . . . . . . . . . . . . . . . . . . . .   6
     2.4.  Support mapping authenticated NETCONF/RESTCONF client
           certificates to usernames . . . . . . . . . . . . . . . .   6
     2.5.  Support both listening for connections and call home  . .   6
     2.6.  For Call Home connections . . . . . . . . . . . . . . . .   6
       2.6.1.  Support more than one NETCONF/RESTCONF client . . . .   7
       2.6.2.  Support NETCONF/RESTCONF clients having more than one
               endpoint  . . . . . . . . . . . . . . . . . . . . . .   7
       2.6.3.  Support a reconnection strategy . . . . . . . . . . .   7
       2.6.4.  Support both persistent and periodic connections  . .   7
       2.6.5.  Reconnection strategy for periodic connections  . . .   7
       2.6.6.  Keep-alives for persistent connections  . . . . . . .   8
       2.6.7.  Customizations for periodic connections . . . . . . .   8
   3.  High-Level Design . . . . . . . . . . . . . . . . . . . . . .   8
   4.  Solution  . . . . . . . . . . . . . . . . . . . . . . . . . .   9
     4.1.  The System Keychain Model . . . . . . . . . . . . . . . .   9
       4.1.1.  Tree Diagram  . . . . . . . . . . . . . . . . . . . .   9
       4.1.2.  Example Usage . . . . . . . . . . . . . . . . . . . .  10
       4.1.3.  YANG Model  . . . . . . . . . . . . . . . . . . . . .  18



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     4.2.  The SSH Server Model  . . . . . . . . . . . . . . . . . .  26
       4.2.1.  Tree Diagram  . . . . . . . . . . . . . . . . . . . .  27
       4.2.2.  Example Usage . . . . . . . . . . . . . . . . . . . .  27
       4.2.3.  YANG Model  . . . . . . . . . . . . . . . . . . . . .  28
     4.3.  The TLS Server Model  . . . . . . . . . . . . . . . . . .  32
       4.3.1.  Tree Diagram  . . . . . . . . . . . . . . . . . . . .  32
       4.3.2.  Example Usage . . . . . . . . . . . . . . . . . . . .  33
       4.3.3.  YANG Model  . . . . . . . . . . . . . . . . . . . . .  33
     4.4.  The NETCONF Server Model  . . . . . . . . . . . . . . . .  37
       4.4.1.  Tree Diagram  . . . . . . . . . . . . . . . . . . . .  37
       4.4.2.  Example Usage . . . . . . . . . . . . . . . . . . . .  40
       4.4.3.  YANG Model  . . . . . . . . . . . . . . . . . . . . .  43
     4.5.  The RESTCONF Server Model . . . . . . . . . . . . . . . .  53
       4.5.1.  Tree Diagram  . . . . . . . . . . . . . . . . . . . .  53
       4.5.2.  Example Usage . . . . . . . . . . . . . . . . . . . .  55
       4.5.3.  YANG Model  . . . . . . . . . . . . . . . . . . . . .  57
   5.  Design Considerations . . . . . . . . . . . . . . . . . . . .  65
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  66
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  67
     7.1.  The IETF XML Registry . . . . . . . . . . . . . . . . . .  67
     7.2.  The YANG Module Names Registry  . . . . . . . . . . . . .  67
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  68
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  68
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  68
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  70
   Appendix A.  Change Log . . . . . . . . . . . . . . . . . . . . .  71
     A.1.  00 to 01  . . . . . . . . . . . . . . . . . . . . . . . .  71
     A.2.  01 to 02  . . . . . . . . . . . . . . . . . . . . . . . .  71
     A.3.  02 to 03  . . . . . . . . . . . . . . . . . . . . . . . .  71
     A.4.  03 to 04  . . . . . . . . . . . . . . . . . . . . . . . .  71
     A.5.  04 to 05  . . . . . . . . . . . . . . . . . . . . . . . .  72
     A.6.  05 to 06  . . . . . . . . . . . . . . . . . . . . . . . .  72
     A.7.  06 to 07  . . . . . . . . . . . . . . . . . . . . . . . .  72
     A.8.  07 to 08  . . . . . . . . . . . . . . . . . . . . . . . .  73
     A.9.  08 to 09  . . . . . . . . . . . . . . . . . . . . . . . .  74
   Appendix B.  Open Issues  . . . . . . . . . . . . . . . . . . . .  74
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  74

1.  Introduction

   This draft defines a NETCONF [RFC6241] server configuration data
   model and a RESTCONF [draft-ietf-netconf-restconf] server
   configuration data model.  These data models enable configuration of
   the NETCONF and RESTCONF services themselves, including which
   transports are supported, what ports the servers listen on, call-home
   parameters, client authentication, and related parameters.





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1.1.  Terminology

   The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

1.2.  Tree Diagrams

   A simplified graphical representation of the data models is used in
   this document.  The meaning of the symbols in these diagrams is as
   follows:

   o  Brackets "[" and "]" enclose list keys.

   o  Braces "{" and "}" enclose feature names, and indicate that the
      named feature must be present for the subtree to be present.

   o  Abbreviations before data node names: "rw" means configuration
      (read-write) and "ro" state data (read-only).

   o  Symbols after data node names: "?" means an optional node, "!"
      means a presence container, and "*" denotes a list and leaf-list.

   o  Parentheses enclose choice and case nodes, and case nodes are also
      marked with a colon (":").

   o  Ellipsis ("...") stands for contents of subtrees that are not
      shown.

2.  Objectives

   The primary purpose of the YANG modules defined herein is to enable
   the configuration of the NETCONF and RESTCONF services on a network
   element.  This scope includes the following objectives:

2.1.  Support all NETCONF and RESTCONF transports

   The YANG module should support all current NETCONF and RESTCONF
   transports, namely NETCONF over SSH [RFC6242], NETCONF over TLS
   [RFC7589], and RESTCONF over TLS [draft-ietf-netconf-restconf], and
   to be extensible to support future transports as necessary.

   Because implementations may not support all transports, the module
   should use YANG "feature" statements so that implementations can
   accurately advertise which transports are supported.






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2.2.  Enable each transport to select which keys to use

   Servers may have a multiplicity of host-keys or server-certificates
   from which subsets may be selected for specific uses.  For instance,
   a NETCONF server may want to use one set of SSH host-keys when
   listening on port 830, and a different set of SSH host-keys when
   calling home.  The data models provided herein should enable
   configuration of which keys to use on a per-use basis.

2.3.  Support authenticating NETCONF/RESTCONF clients certificates

   When a certificate is used to authenticate a NETCONF or RESTCONF
   client, there is a need to configure the server to know how to
   authenticate the certificates.  The server should be able to
   authenticate the client's certificate either by using path-validation
   to a configured trust anchor or by matching the client-certificate to
   one previously configured.

2.4.  Support mapping authenticated NETCONF/RESTCONF client certificates
      to usernames

   When a client certificate is used for TLS client authentication, the
   NETCONF/RESTCONF server must be able to derive a username from the
   authenticated certificate.  Thus the modules defined herein should
   enable this mapping to be configured.

2.5.  Support both listening for connections and call home

   The NETCONF and RESTCONF protocols were originally defined as having
   the server opening a port to listen for client connections.  More
   recently the NETCONF working group defined support for call-home
   ([draft-ietf-netconf-call-home]), enabling the server to initiate the
   connection to the client, for both the NETCONF and RESTCONF
   protocols.  Thus the modules defined herein should enable
   configuration for both listening for connections and calling home.
   Because implementations may not support both listening for
   connections and calling home, YANG "feature" statements should be
   used so that implementation can accurately advertise the connection
   types it supports.

2.6.  For Call Home connections

   The following objectives only pertain to call home connections.








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2.6.1.  Support more than one NETCONF/RESTCONF client

   A NETCONF/RESTCONF server may be managed by more than one NETCONF/
   RESTCONF client.  For instance, a deployment may have one client for
   provisioning and another for fault monitoring.  Therefore, when it is
   desired for a server to initiate call home connections, it should be
   able to do so to more than one client.

2.6.2.  Support NETCONF/RESTCONF clients having more than one endpoint

   An NETCONF/RESTCONF client managing a NETCONF/RESTCONF server may
   implement a high-availability strategy employing a multiplicity of
   active and/or passive endpoint.  Therefore, when it is desired for a
   server to initiate call home connections, it should be able to
   connect to any of the client's endpoints.

2.6.3.  Support a reconnection strategy

   Assuming a NETCONF/RESTCONF client has more than one endpoint, then
   it becomes necessary to configure how a NETCONF/RESTCONF server
   should reconnect to the client should it lose its connection to one
   the client's endpoints.  For instance, the NETCONF/RESTCONF server
   may start with first endpoint defined in a user-ordered list of
   endpoints or with the last endpoints it was connected to.

2.6.4.  Support both persistent and periodic connections

   NETCONF/RESTCONF clients may vary greatly on how frequently they need
   to interact with a NETCONF/RESTCONF server, how responsive
   interactions need to be, and how many simultaneous connections they
   can support.  Some clients may need a persistent connection to
   servers to optimize real-time interactions, while others prefer
   periodic interactions in order to minimize resource requirements.
   Therefore, when it is necessary for server to initiate connections,
   it should be configurable if the connection is persistent or
   periodic.

2.6.5.  Reconnection strategy for periodic connections

   The reconnection strategy should apply to both persistent and
   periodic connections.  How it applies to periodic connections becomes
   clear when considering that a periodic "connection" is a logical
   connection to a single server.  That is, the periods of
   unconnectedness are intentional as opposed to due to external
   reasons.  A periodic "connection" should always reconnect to the same
   server until it is no longer able to, at which time the reconnection
   strategy guides how to connect to another server.




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2.6.6.  Keep-alives for persistent connections

   If a persistent connection is desired, it is the responsibility of
   the connection initiator to actively test the "aliveness" of the
   connection.  The connection initiator must immediately work to
   reestablish a persistent connection as soon as the connection is
   lost.  How often the connection should be tested is driven by
   NETCONF/RESTCONF client requirements, and therefore keep-alive
   settings should be configurable on a per-client basis.

2.6.7.  Customizations for periodic connections

   If a periodic connection is desired, it is necessary for the NETCONF/
   RESTCONF server to know how often it should connect.  This frequency
   determines the maximum amount of time a NETCONF/RESTCONF client may
   have to wait to send data to a server.  A server may connect to a
   client before this interval expires if desired (e.g., to send data to
   a client).

3.  High-Level Design

   The solution presented in this document defines a configurable
   keychain object, reusable groupings for SSH and TLS based servers,
   and, finally, the configurable NETCONF and RESTCONF server objects,
   which are the primary purpose for this draft.  Each of these are
   defined in a distinct YANG module, thus a total of five YANG modules
   are defined in this document.  The relationship between these five
   YANG modules is illustrated by the tree diagram below.

                  +--------------------+
                  |ietf-system-keychain|
                  +--------------------+
                         ^    ^
                         |    |
              <leafref>  |    |  <leafref>
            +------------+    +------------+
            |                              |
     +---------------+            +------------------+
     |ietf-ssh-server|            | ietf-tls-server  |
     +---------------+            +------------------+
       ^                               ^       ^
       | <uses>                        |       |
       |            <augments>         |       |
       |          +--------------------+       | <augments>
       |          |                            |
   +-------------------+         +--------------------+
   |ietf-netconf-server|         |ietf-restconf-server|
   +-------------------+         +--------------------+



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4.  Solution

   Each of the following five sections relate to one of the YANG modules
   depicted by the figure above.

4.1.  The System Keychain Model

   The system keychain model defined in this section provides a
   configurable object having the following characteristics:

   o  A semi-configurable list of private keys, each with one or more
      associated certificates.  Private keys MUST be either preinstalled
      (e.g., an IDevID key), be generated by request, or be loaded by
      request.  Each private key is MAY have associated certificates,
      either preinstalled or configured after creation.

   o  A configurable list of lists of trust anchor certificates.  This
      enables the server to have use-specific trust anchors.  For
      instance, one list of trust anchors might be used to authenticate
      management connections (e.g., client certificate-based
      authentication for NETCONF or RESTCONF connections), and a
      different list of trust anchors might be used for when connecting
      to a specific Internet-based service (e.g., a zero touch bootstrap
      server).

   o  An RPC to generate a certificate signing request for an existing
      private key, a passed subject, and an optional attributes.  The
      signed certificate returned from an external certificate authority
      (CA) can be later set using a standard configuration change
      request (e.g., <edit-config>).

   o  An RPC to request the server to generate a new private key using
      the specified algorithm and key length.

   o  An RPC to request the server to load a new private key.

4.1.1.  Tree Diagram














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 module: ietf-system-keychain
    +--rw keychain
       +--rw private-keys
       |  +--rw private-key* [name]
       |  |  +--rw name                                    string
       |  |  +--ro algorithm?                              kc:algorithms
       |  |  +--ro key-length?                             uint32
       |  |  +--ro public-key                              binary
       |  |  +--rw certificate-chains
       |  |  |  +--rw certificate-chain* [name]
       |  |  |     +--rw name           string
       |  |  |     +--rw certificate*   binary
       |  |  +---x generate-certificate-signing-request
       |  |     +---w input
       |  |     |  +---w subject       binary
       |  |     |  +---w attributes?   binary
       |  |     +--ro output
       |  |        +--ro certificate-signing-request    binary
       |  +---x generate-private-key
       |  |  +---w input
       |  |     +---w name          string
       |  |     +---w key-usage?    enumeration
       |  |     +---w algorithm     kc:algorithms
       |  |     +---w key-length?   uint32
       |  +---x load-private-key
       |     +---w input
       |        +---w name           string
       |        +---w private-key    binary
       +--rw trusted-certificates* [name]
          +--rw name                   string
          +--rw description?           string
          +--rw trusted-certificate* [name]
             +--rw name           string
             +--rw certificate?   binary
 notifications:
    +---n certificate-expiration
       +--ro certificate        instance-identifier
       +--ro expiration-date    yang:date-and-time

4.1.2.  Example Usage

   The following example illustrates the "generate-private-key" action
   in use with the RESTCONF protocol and JSON encoding.








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REQUEST
-------

  ['\' line wrapping added for formatting only]

  POST https://example.com/restconf/data/ietf-system-keychain:keychain/\
  private-keys/generate-private-key HTTP/1.1
  HOST: example.com
  Content-Type: application/yang.operation+json

  {
    "ietf-system-keychain:input" : {
      "name" : "ex-key-sect571r1",
      "algorithm" : "sect571r1"
    }
  }


RESPONSE
--------

  HTTP/1.1 204 No Content
  Date: Mon, 31 Oct 2015 11:01:00 GMT
  Server: example-server


   The following example illustrates the "load-private-key" action in
   use with the RESTCONF protocol and JSON encoding.























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REQUEST
-------

  ['\' line wrapping added for formatting only]

  POST https://example.com/restconf/data/ietf-system-keychain:keychain/\
  private-keys/generate-private-key HTTP/1.1
  HOST: example.com
  Content-Type: application/yang.operation+xml

  <input xmlns="urn:ietf:params:xml:ns:yang:ietf-system-keychain">
    <name>ex-key-sect571r1</name>
    <private-key>
      NGcEk3UE90cnNFVjRwTUNBd0VBQWFPQ0FSSXdnZ0VPCk1CMEdBMVVkRGd\
      VEJiZ0JTWEdlbUEKMnhpRHVOTVkvVHFLNWd4cFJBZ1ZOYUU0cERZd05ER\
      V6QVJCZ05WQkFNVENrTlNUQ0JKYzNOMVpYS0NDUUNVRHBNSll6UG8zREF\
      Z05WSFI4RVlqQmdNRjZnSXFBZ2hoNW9kSFJ3T2k4dlpYaGgKYlhCc1pTN\
      QmdOVkJBWVRBbFZUTVJBd0RnWURWUVFLRXdkbAplR0Z0Y0d4bE1RNHdEQ\
      MkF6a3hqUDlVQWtHR0dvS1U1eUc1SVR0Wm0vK3B0R2FieXVDMjBRd2kvZ\
      NQmdOVkhSTUJBZjhFCkFqQUFNQTRHQTFVZER3RUIvd1FFQXdJSGdEQnBC\
      WmdsK2gyTTg3QmtGMjhWbW1CdFFVaWc3OEgrRkYyRTFwdSt4ZVRJbVFFM\
      lLQllsdWpOcjFTMnRLR05EMUc2OVJpK2FWNGw2NTdZNCtadVJMZgpRYjk\
      zSFNwSDdwVXBCYnA4dmtNanFtZjJma3RqZHBxeFppUUtTbndWZTF2Zwot\
      25PZnpZNEhONApXY0pTaUpZK2xtYWs3RTRORUZXZS9RdGp4NUlXZmdvN2\
      WpiMjB2WlhoaGJYQnNaUzVqY215aU9L=
    </private-key>
  </input>


RESPONSE
--------

  HTTP/1.1 204 No Content
  Date: Mon, 31 Oct 2015 11:01:00 GMT
  Server: example-server


   The following example illustrates the "generate-certificate-signing-
   request" action in use with the NETCONF protocol.

   REQUEST
   -------

     <rpc message-id="101"
       xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
       <action xmlns="urn:ietf:params:xml:ns:yang:1">
         <keychain
           xmlns="urn:ietf:params:xml:ns:yang:ietf-system-keychain">



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           <private-keys>
             <private-key>
               <name>ex-key-sect571r1</name>
               <generate-certificate-signing-request>
                 <subject>
                  cztvaWRoc2RmZ2tqaHNkZmdramRzZnZzZGtmam5idnNvO2R
                  manZvO3NkZmJpdmhzZGZpbHVidjtvc2lkZmhidml1bHNlmO
                  Z2aXNiZGZpYmhzZG87ZmJvO3NkZ25iO29pLmR6Zgo=
                 </subject>
                 <attributes>
                  bwtakWRoc2RmZ2tqaHNkZmdramRzZnZzZGtmam5idnNvut4
                  arnZvO3NkZmJpdmhzZGZpbHVidjtvc2lkZmhidml1bHNkYm
                  Z2aXNiZGZpYmhzZG87ZmJvO3NkZ25iO29pLmC6Rhp=
                 </attributes>
               </generate-certificate-signing-request>
             </private-key>
           </private-keys>
         </keychain>
       </action>
     </rpc>


   RESPONSE
   --------

     <rpc-reply message-id="101"
        xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
        <certificate-signing-request
          xmlns="urn:ietf:params:xml:ns:yang:ietf-system-keychain">
          LS0tLS1CRUdJTiBDRVJUSUZJQ0FURS0tLS0tCk1JSUNrekNDQWZ5Z
          0F3SUJBZ0lKQUpRT2t3bGpNK2pjTUEwR0NTcUdTSWIzRFFFQkJRVU
          FNRFF4Q3pBSkJnTlYKQkFZVEFsVlRNUkF3RGdZRFZRUUtFd2RsZUd
          GdGNHeGxNUk13RVFZRFZRUURFd3BEVWt3Z1NYTnpkV1Z5TUI0WApE
          diR1V4RXpBUkJnTlZCQU1UQ2tOU1RDQkpjM04xWlhJd2daOHdEUVl
          KS29aSWh2Y04KQVFFQkJRQURnWTBBTUlHSkFvR0JBTXVvZmFPNEV3
          El1QWMrQ1RsTkNmc0d6cEw1Um5ydXZsOFRIcUJTdGZQY3N0Zk1KT1
          FaNzlnNlNWVldsMldzaHE1bUViCkJNNitGNzdjbTAvU25FcFE0TnV
          bXBDT2YKQWdNQkFBR2pnYXd3Z2Frd0hRWURWUjBPQkJZRUZKY1o2W
          URiR0lPNDB4ajlPb3JtREdsRUNCVTFNR1FHQTFVZApJd1JkTUZ1QU
          ZKY1o2WURiR0lPNDB4ajlPb3JtREdsRUNCVTFvVGlrTmpBME1Rc3d
          mMKTUE0R0ExVWREd0VCL3dRRUF3SUNCREFTQmdOVkhSTUJBZjhFQ0
          RBR0FRSC9BZ0VBTUEwR0NTcUdTSWIzRFFFQgpCUVVBQTRHQkFMMmx
          rWmFGNWcyaGR6MVNhZnZPbnBneHA4eG00SHRhbStadHpLazFlS3Bx
          TXp4YXJCbFpDSHlLCklVbC9GVzRtV1RQS1VDeEtFTE40NEY2Zmk2d
          c4d0tSSElkYW1WL0pGTmlQS0VXSTF4K1I1aDZmazcrQzQ1QXg1RWV
          SWHgzZjdVM2xZTgotLS0tLUVORCBDRVJUSUZJQ0FURS0tLS0tCg==
        </certificate-signing-request>
     </rpc-reply>



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   The following example illustrates what a fully configured keychain
   object might look like.  The private-key shown below is consistent
   with the generate-private-key and generate-certificate-signing-
   request examples above.  This example also assumes that the resulting
   CA-signed certificate has been configured back onto the server.
   Lastly, this example shows that three lists of trusted certificates
   having been configured.

   <keychain xmlns="urn:ietf:params:xml:ns:yang:ietf-system-keychain">

     <!-- private keys and associated certificates -->
     <private-keys>
       <private-key>
         <name>tpm-protected-key</name>
         <algorithm>sect571r1</algorithm>
         <public-key>
           cztvaWRoc2RmZ2tqaHNkZmdramRzZnZzZGtmam5idnNvO2RmanZvO3NkZ
           mJpdmhzZGZpbHVidjtvc2lkZmhidml1bHNkYmZ2aXNiZGZpYmhzZG87Zm
           JvO3NkZ25iO29pLmR6Zgo=
         </public-key>
         <certificate-chains>
           <certificate-chain>
             <name>default-idevid-chain</name>
             <certificate>
               diR1V4RXpBUkJnTlZCQU1UQ2tOU1RDQkpjM04xWlhJd2daOHdEUVl
               LS0tLS1CRUdJTiBDRVJUSUZJQ0FURS0tLS0tCk1JSUNrekNDQWZ5Z
               KS29aSWh2Y04KQVFFQkJRQURnWTBBTUlHSkFvR0JBTXVvZmFPNEV3
               0F3SUJBZ0lKQUpRT2t3bGpNK2pjTUEwR0NTcUdTSWIzRFFFQkJRVU
               FNRFF4Q3pBSkJnTlYKQkFZVEFsVlRNUkF3RGdZRFZRUUtFd2RsZUd
               GdGNHeGxNUk13RVFZRFZRUURFd3BEVWt3Z1NYTnpkV1Z5TUI0WApE
               ZKY1o2WURiR0lPNDB4ajlPb3JtREdsRUNCVTFvVGlrTmpBME1Rc3d
               mMKTUE0R0ExVWREd0VCL3dRRUF3SUNCREFTQmdOVkhSTUJBZjhFQ0
               RBR0FRSC9BZ0VBTUEwR0NTcUdTSWIzRFFFQgpCUVVBQTRHQkFMMmx
               rWmFGNWcyaGR6MVNhZnZPbnBneHA4eG00SHRhbStadHpLazFlS3Bx
               TXp4YXJCbFpDSHlLCklVbC9GVzRtV1RQS1VDeEtFTE40NEY2Zmk2d
               c4d0tSSElkYW1WL0pGTmlQS0VXSTF4K1I1aDZmazcrQzQ1QXg1RWV
               SWM2xZTgotLS0tLUVORCBDRVJUSUZJQ0FURS0tLS0tCg==
             </certificate>
             <certificate>
               KS29aSWh2Y04KQVFFQkJRQURnWTBBTUlHSkFvR0JBTXVvZmFPNEV3
               El1QWMrQ1RsTkNmc0d6cEw1Um5ydXZsOFRIcUJTdGZQY3N0Zk1KT1
               FaNzlnNlNWVldsMldzaHE1bUViCkJNNitGNzdjbTAvU25FcFE0TnV
               bXBDT2YKQWdNQkFBR2pnYXd3Z2Frd0hRWURWUjBPQkJZRUZKY1o2W
               LS0tLS1CRUdJTiBDRVJUSUZJQ0FURS0tLS0tCk1JSUNrekNDQWZ5Z
               0F3SUJBZ0lKQUpRT2t3bGpNK2pjTUEwR0NTcUdTSWIzRFFFQkJRVU
               FNRFF4Q3pBSkJnTlYKQkFZVEFsVlRNUkF3RGdZRFZRUUtFd2RsZUd
               GdGNHeGxNUk13RVFZRFZRUURFd3BEVWt3Z1NYTnpkV1Z5TUI0WApE
               diR1V4RXpBUkJnTlZCQU1UQ2tOU1RDQkpjM04xWlhJd2daOHdEUVl



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               URiR0lPNDB4ajlPb3JtREdsRUNCVTFNR1FHQTFVZApJd1JkTUZ1QU
               RBR0FRSC9BZ0VBTUEwR0NTcUdTSWIzRFFFQgpCUVVBQTRHQkFMMmx
               rWmFGNWcyaGR6MVNhZnZPbnBneHA4eG00SHRhbStadHpLazFlS3Bx
               c4d0tSSElkYW1WL0pGTmlQS0VXSTF4K1I1aDZmazcrQzQ1QXg1RWV
               SSUZJQ0FURS0tLS0tCg==
             </certificate>
           </certificate-chain>
           <certificate-chain>
             <name>my-ldevid-chain</name>
             <certificate>
               0F3SUJBZ0lKQUpRT2t3bGpNK2pjTUEwR0NTcUdTSWIzRFFFQkJRVU
               FNRFF4Q3pBSkJnTlYKQkFZVEFsVlRNUkF3RGdZRFZRUUtFd2RsZUd
               GdGNHeGxNUk13RVFZRFZRUURFd3BEVWt3Z1NYTnpkV1Z5TUI0WApE
               diR1V4RXpBUkJnTlZCQU1UQ2tOU1RDQkpjM04xWlhJd2daOHdEUVl
               LS0tLS1CRUdJTiBDRVJUSUZJQ0FURS0tLS0tCk1JSUNrekNDQWZ5Z
               KS29aSWh2Y04KQVFFQkJRQURnWTBBTUlHSkFvR0JBTXVvZmFPNEV3
               El1QWMrQ1RsTkNmc0d6cEw1Um5ydXZsOFRIcUJTdGZQY3N0Zk1KT1
               FaNzlnNlNWVldsMldzaHE1bUViCkJNNitGNzdjbTAvU25FcFE0TnV
               ZKY1o2WURiR0lPNDB4ajlPb3JtREdsRUNCVTFvVGlrTmpBME1Rc3d
               mMKTUE0R0ExVWREd0VCL3dRRUF3SUNCREFTQmdOVkhSTUJBZjhFQ0
               RBR0FRSC9BZ0VBTUEwR0NTcUdTSWIzRFFFQgpCUVVBQTRHQkFMMmx
               rWmFGNWcyaGR6MVNhZnZPbnBneHA4eG00SHRhbStadHpLazFlS3Bx
               TXp4YXJCbFpDSHlLCklVbC9GVzRtV1RQS1VDeEtFTE40NEY2Zmk2d
               c4d0tSSElkYW1WL0pGTmlQS0VXSTF4K1I1aDZmazcrQzQ1QXg1RWV
               SWM2xZTgotLS0tLUVORCBDRVJUSUZJQ0FURS0tLS0tCg==
             </certificate>
             <certificate>
               LS0tLS1CRUdJTiBDRVJUSUZJQ0FURS0tLS0tCk1JSUNrekNDQWZ5Z
               0F3SUJBZ0lKQUpRT2t3bGpNK2pjTUEwR0NTcUdTSWIzRFFFQkJRVU
               FNRFF4Q3pBSkJnTlYKQkFZVEFsVlRNUkF3RGdZRFZRUUtFd2RsZUd
               GdGNHeGxNUk13RVFZRFZRUURFd3BEVWt3Z1NYTnpkV1Z5TUI0WApE
               diR1V4RXpBUkJnTlZCQU1UQ2tOU1RDQkpjM04xWlhJd2daOHdEUVl
               KS29aSWh2Y04KQVFFQkJRQURnWTBBTUlHSkFvR0JBTXVvZmFPNEV3
               El1QWMrQ1RsTkNmc0d6cEw1Um5ydXZsOFRIcUJTdGZQY3N0Zk1KT1
               FaNzlnNlNWVldsMldzaHE1bUViCkJNNitGNzdjbTAvU25FcFE0TnV
               bXBDT2YKQWdNQkFBR2pnYXd3Z2Frd0hRWURWUjBPQkJZRUZKY1o2W
               URiR0lPNDB4ajlPb3JtREdsRUNCVTFNR1FHQTFVZApJd1JkTUZ1QU
               ZKY1o2WURiR0lPNDB4ajlPb3JtREdsRUNCVTFvVGlrTmpBME1Rc3d
               mMKTUE0R0ExVWREd0VCL3dRRUF3SUNCREFTQmdOVkhSTUJBZjhFQ0
               RBR0FRSC9BZ0VBTUEwR0NTcUdTSWIzRFFFQgpCUVVBQTRHQkFMMmx
               rWmFGNWcyaGR6MVNhZnZPbnBneHA4eG00SHRhbStadHpLazFlS3Bx
               TXp4YXJCbFpDSHlLCklVbC9GVzRtV1RQS1VDeEtFTE40NEY2Zmk2d
               c4d0tSSElkYW1WL0pGTmlQS0VXSTF4K1I1aDZmazcrQzQ1QXg1RWV
               SWHgzZjdVM2xZTgotLS0tLUVORCBDRVJUSUZJQ0FURS0tLS0tCg==
             </certificate>
           </certificate-chain>
         </certificate-chains>
       </private-key>



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     </private-keys>

     <!-- trusted netconf/restconf client certificates -->
     <trusted-certificates>
       <name>explicitly-trusted-client-certs</name>
       <description>
         Specific client authentication certificates that are to be
         explicitly trusted NETCONF/RESTCONF clients.  These are
         needed for client certificates not signed by our CA.
       </description>
       <trusted-certificate>
         <name>George Jetson</name>
         <certificate>
           QmdOVkJBWVRBbFZUTVJBd0RnWURWUVFLRXdkbAplR0Z0Y0d4bE1RNHdEQ
           MkF6a3hqUDlVQWtHR0dvS1U1eUc1SVR0Wm0vK3B0R2FieXVDMjBRd2kvZ
           25PZnpZNEhONApXY0pTaUpZK2xtYWs3RTRORUZXZS9RdGp4NUlXZmdvN2
           RV0JCU2t2MXI2SFNHeUFUVkpwSmYyOWtXbUU0NEo5akJrQmdOVkhTTUVY
           VEJiZ0JTWEdlbUEKMnhpRHVOTVkvVHFLNWd4cFJBZ1ZOYUU0cERZd05ER
           UxNQWtHQTFVRUJoTUNWVk14RURBT0JnTlZCQW9UQjJWNApZVzF3YkdVeE
           V6QVJCZ05WQkFNVENrTlNUQ0JKYzNOMVpYS0NDUUNVRHBNSll6UG8zREF
           NQmdOVkhSTUJBZjhFCkFqQUFNQTRHQTFVZER3RUIvd1FFQXdJSGdEQnBC
           Z05WSFI4RVlqQmdNRjZnSXFBZ2hoNW9kSFJ3T2k4dlpYaGgKYlhCc1pTN
           WpiMjB2WlhoaGJYQnNaUzVqY215aU9LUTJNRFF4Q3pBSkJnTlZCQVlUQW
           xWVE1SQXdEZ1lEVlFRSwpFd2RsZUdGdGNHeGxNUk13RVFZRFZRUURFd3B
           EVWt3Z1NYTnpkV1Z5TUEwR0NTcUdTSWIzRFFFQkJRVUFBNEdCCkFFc3BK
           WmdsK2gyTTg3QmtGMjhWbW1CdFFVaWc3OEgrRkYyRTFwdSt4ZVRJbVFFM
           TQzcjFZSjk0M1FQLzV5eGUKN2QxMkxCV0dxUjUrbEl5N01YL21ka2M4al
           zSFNwSDdwVXBCYnA4dmtNanFtZjJma3RqZHBxeFppUUtTbndWZTF2Zwot
           LS0tLUVORCBDRVJUSUZJQ0FURS0tLS0tCg==
         </certificate>
       </trusted-certificate>
       <trusted-certificate>
         <name>Fred Flintstone</name>
         <certificate>
           VlEVlFRREV3Vm9ZWEJ3ZVRDQm56QU5CZ2txaGtpRzl3MEJBUUVGQUFPQm
           pRQXdnWWtDCmdZRUE1RzRFSWZsS1p2bDlXTW44eUhyM2hObUFRaUhVUzV
           rRUpPQy9hSFA3eGJXQW1ra054ZStUa2hrZnBsL3UKbVhsTjhSZUd1ODhG
           NGcEk3UE90cnNFVjRwTUNBd0VBQWFPQ0FSSXdnZ0VPCk1CMEdBMVVkRGd
           VEJiZ0JTWEdlbUEKMnhpRHVOTVkvVHFLNWd4cFJBZ1ZOYUU0cERZd05ER
           V6QVJCZ05WQkFNVENrTlNUQ0JKYzNOMVpYS0NDUUNVRHBNSll6UG8zREF
           NQmdOVkhSTUJBZjhFCkFqQUFNQTRHQTFVZER3RUIvd1FFQXdJSGdEQnBC
           Z05WSFI4RVlqQmdNRjZnSXFBZ2hoNW9kSFJ3T2k4dlpYaGgKYlhCc1pTN
           WpiMjB2WlhoaGJYQnNaUzVqY215aU9LUTJNRFF4Q3pBSkJnTlZCQVlUQW
           xWVE1SQXdEZ1lEVlFRSwpFd2RsZUdGdGNHeGxNUk13RVFZRFZRUURFd3B
           EVWt3Z1NYTnpkV1Z5TUEwR0NTcUdTSWIzRFFFQkJRVUFBNEdCCkFFc3BK
           WmdsK2gyTTg3QmtGMjhWbW1CdFFVaWc3OEgrRkYyRTFwdSt4ZVRJbVFFM
           lLQllsdWpOcjFTMnRLR05EMUc2OVJpK2FWNGw2NTdZNCtadVJMZgpRYjk
           zSFNwSDdwVXBCYnA4dmtNanFtZjJma3RqZHBxeFppUUtTbndWZTF2Zwot



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           QWtUOCBDRVUUZJ0RUF==
         </certificate>
       </trusted-certificate>
     </trusted-certificates>

     <!-- trust anchors for netconf/restconf clients -->
     <trusted-certificates>
       <name>deployment-specific-ca-certs</name>
       <description>
         Trust anchors used only to authenticate NETCONF/RESTCONF
         client connections.  Since our security policy only allows
         authentication for clients having a certificate signed by
         our CA, we only configure its certificate below.
       </description>
       <trusted-certificate>
         <name>ca.example.com</name>
         <certificate>
           WmdsK2gyTTg3QmtGMjhWbW1CdFFVaWc3OEgrRkYyRTFwdSt4ZVRJbVFFM
           lLQllsdWpOcjFTMnRLR05EMUc2OVJpK2FWNGw2NTdZNCtadVJMZgpRYjk
           zSFNwSDdwVXBCYnA4dmtNanFtZjJma3RqZHBxeFppUUtTbndWZTF2Zwot
           NGcEk3UE90cnNFVjRwTUNBd0VBQWFPQ0FSSXdnZ0VPCk1CMEdBMVVkRGd
           VEJiZ0JTWEdlbUEKMnhpRHVOTVkvVHFLNWd4cFJBZ1ZOYUU0cERZd05ER
           V6QVJCZ05WQkFNVENrTlNUQ0JKYzNOMVpYS0NDUUNVRHBNSll6UG8zREF
           NQmdOVkhSTUJBZjhFCkFqQUFNQTRHQTFVZER3RUIvd1FFQXdJSGdEQnBC
           Z05WSFI4RVlqQmdNRjZnSXFBZ2hoNW9kSFJ3T2k4dlpYaGgKYlhCc1pTN
           WpiMjB2WlhoaGJYQnNaUzVqY215aU9LUTJNRFF4Q3pBSkJnTlZCQVlUQW
           QmdOVkJBWVRBbFZUTVJBd0RnWURWUVFLRXdkbAplR0Z0Y0d4bE1RNHdEQ
           MkF6a3hqUDlVQWtHR0dvS1U1eUc1SVR0Wm0vK3B0R2FieXVDMjBRd2kvZ
           25PZnpZNEhONApXY0pTaUpZK2xtYWs3RTRORUZXZS9RdGp4NUlXZmdvN2
           RJSUJQFRStS0Cg==
         </certificate>
       </trusted-certificate>
     </trusted-certificates>

     <!-- trust anchors for random HTTPS servers on Internet -->
     <trusted-certificates>
       <name>common-ca-certs</name>
       <description>
         Trusted certificates to authenticate common HTTPS servers.
         These certificates are similar to those that might be
         shipped with a web browser.
       </description>
       <trusted-certificate>
         <name>ex-certificate-authority</name>
         <certificate>
           NGcEk3UE90cnNFVjRwTUNBd0VBQWFPQ0FSSXdnZ0VPCk1CMEdBMVVkRGd
           VEJiZ0JTWEdlbUEKMnhpRHVOTVkvVHFLNWd4cFJBZ1ZOYUU0cERZd05ER
           V6QVJCZ05WQkFNVENrTlNUQ0JKYzNOMVpYS0NDUUNVRHBNSll6UG8zREF



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           Z05WSFI4RVlqQmdNRjZnSXFBZ2hoNW9kSFJ3T2k4dlpYaGgKYlhCc1pTN
           QmdOVkJBWVRBbFZUTVJBd0RnWURWUVFLRXdkbAplR0Z0Y0d4bE1RNHdEQ
           MkF6a3hqUDlVQWtHR0dvS1U1eUc1SVR0Wm0vK3B0R2FieXVDMjBRd2kvZ
           NQmdOVkhSTUJBZjhFCkFqQUFNQTRHQTFVZER3RUIvd1FFQXdJSGdEQnBC
           WmdsK2gyTTg3QmtGMjhWbW1CdFFVaWc3OEgrRkYyRTFwdSt4ZVRJbVFFM
           lLQllsdWpOcjFTMnRLR05EMUc2OVJpK2FWNGw2NTdZNCtadVJMZgpRYjk
           zSFNwSDdwVXBCYnA4dmtNanFtZjJma3RqZHBxeFppUUtTbndWZTF2Zwot
           25PZnpZNEhONApXY0pTaUpZK2xtYWs3RTRORUZXZS9RdGp4NUlXZmdvN2
           WpiMjB2WlhoaGJYQnNaUzVqY215aU9L=
         </certificate>
       </trusted-certificate>
     </trusted-certificates>

   </keychain>

   The following example illustrates a "certificate-expiration"
   notification in XML.

['\' line wrapping added for formatting only]

<notification
  xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
  <eventTime>2016-07-08T00:01:00Z</eventTime>
  <certificate-expiration
    xmlns="urn:ietf:params:xml:ns:yang:ietf-system-keychain">
    <certificate>
      /kc:keychain/kc:private-keys/kc:private-key/kc:certificate-chains\
      /kc:certificate-chain/kc:certificate[3]
    </certificate>
    <expiration-date>2016-08-08T14:18:53-05:00</expiration-date>
  </certificate-expiration>
</notification>

4.1.3.  YANG Model

   This YANG module makes extensive use of data types defined in
   [RFC5280] and [RFC5958].


<CODE BEGINS> file "ietf-system-keychain@2016-03-16.yang"

module ietf-system-keychain {
  yang-version 1.1;

  namespace "urn:ietf:params:xml:ns:yang:ietf-system-keychain";
  prefix "kc";

  import ietf-yang-types {     // RFC 6991



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    prefix yang;
  }

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

  contact
   "WG Web:   <http://tools.ietf.org/wg/netconf/>
    WG List:  <mailto:netconf@ietf.org>

    WG Chair: Mehmet Ersue
              <mailto:mehmet.ersue@nsn.com>

    WG Chair: Mahesh Jethanandani
              <mailto:mjethanandani@gmail.com>

    Editor:   Kent Watsen
              <mailto:kwatsen@juniper.net>";


  description
   "This module defines a keychain to centralize management of
    security credentials.

    Copyright (c) 2014 IETF Trust and the persons identified as
    authors of the code. All rights reserved.

    Redistribution and use in source and binary forms, with or
    without modification, is permitted pursuant to, and subject
    to the license terms contained in, the Simplified BSD
    License set forth in Section 4.c of the IETF Trust's
    Legal Provisions Relating to IETF Documents
    (http://trustee.ietf.org/license-info).

    This version of this YANG module is part of RFC VVVV; see
    the RFC itself for full legal notices.";

  revision "2016-03-16" {
    description
     "Initial version";
    reference
     "RFC VVVV: NETCONF Server and RESTCONF Server Configuration
                Models";
  }

  typedef algorithms {
    type enumeration {
      enum rsa { description "The RSA algorithm."; }



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      enum secp192r1 { description "The secp192r1 algorithm."; }
      enum secp256r1 { description "The secp256r1 algorithm."; }
      enum secp384r1 { description "The secp384r1 algorithm."; }
      enum secp521r1 { description "The secp521r1 algorithm."; }
      // what about ecdh_x25519 and ecdh_x448 in TLS 1.3?
    }
    description
      "Asymmetric key algorithms.  This list has been trimmed down
       to the minimal subset of algorithms recommended by the IETF.
       Please see the Design Consideration section in RFC VVVV for
       more information about this.";
  }

  container keychain {
    description
      "A list of private-keys and their associated certificates, as
       well as lists of trusted certificates for client certificate
       authentication.  RPCs are provided to generate a new private
       key and to generate a certificate signing requests.";

    container private-keys {
      description
        "A list of private key maintained by the keychain.";
      list private-key {
        key name;
        description
          "A private key.";
        leaf name {
          type string;
          description
            "An arbitrary name for the private key.";
        }
        leaf algorithm {
          type kc:algorithms;
          config false;
          description
            "The algorithm used by the private key.";
        }
        leaf key-length {
          type uint32;
          config false;
          description
            "The key-length used by the private key.";
        }
        leaf public-key {
          type binary;
          config false;
          mandatory true;



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          description
            "An OneAsymmetricKey 'publicKey' structure as specified
             by RFC 5958, Section 2 encoded using the ASN.1
             distinguished encoding rules (DER), as specified
             in ITU-T X.690.";
          reference
            "RFC 5958:
                Asymmetric Key Packages
             ITU-T X.690:
                Information technology - ASN.1 encoding rules:
                Specification of Basic Encoding Rules (BER),
                Canonical Encoding Rules (CER) and Distinguished
                Encoding Rules (DER).";
        }
        container certificate-chains {
          description
            "Certificate chains associated with this private key.
             More than one chain per key is enabled to support,
             for instance, a TPM-protected key that has associated
             both IDevID and LDevID certificates.";
          list certificate-chain {
            key name;
            description
              "A certificate chain for this public key.";
            leaf name {
              type string;
              description
                "An arbitrary name for the certificate chain.";
            }
            leaf-list certificate {
              type binary;
              ordered-by user;
              description
                "An X.509 v3 certificate structure as specified by RFC
                 5280, Section 4 encoded using the ASN.1 distinguished
                 encoding rules (DER), as specified in ITU-T X.690.
                 The list of certificates that run from the server
                 certificate towards the trust anchor.  The chain MAY
                 include the trust anchor certificate itself.";
              reference
                "RFC 5280:
                   Internet X.509 Public Key Infrastructure Certificate
                   and Certificate Revocation List (CRL) Profile.
                 ITU-T X.690:
                    Information technology - ASN.1 encoding rules:
                    Specification of Basic Encoding Rules (BER),
                    Canonical Encoding Rules (CER) and Distinguished
                    Encoding Rules (DER).";



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            }
          }
        }
        action generate-certificate-signing-request {
          description
            "Generates a certificate signing request structure for
             the associated private key using the passed subject and
             attribute values.  Please review both the Security
             Considerations and Design Considerations sections in
             RFC VVVV for more information regarding this action
             statement.";
          input {
            leaf subject {
              type binary;
              mandatory true;
              description
                "The 'subject' field from the CertificationRequestInfo
                 structure as specified by RFC 2986, Section 4.1 encoded
                 using the ASN.1 distinguished encoding rules (DER), as
                 specified in ITU-T X.690.";
              reference
                "RFC 2986:
                   PKCS #10: Certification Request Syntax Specification
                   Version 1.7.
                 ITU-T X.690:
                    Information technology - ASN.1 encoding rules:
                    Specification of Basic Encoding Rules (BER),
                    Canonical Encoding Rules (CER) and Distinguished
                    Encoding Rules (DER).";
            }
            leaf attributes {
              type binary;
              description
               "The 'attributes' field from the CertificationRequestInfo
                structure as specified by RFC 2986, Section 4.1 encoded
                using the ASN.1 distinguished encoding rules (DER), as
                specified in ITU-T X.690.";
              reference
                "RFC 2986:
                   PKCS #10: Certification Request Syntax Specification
                   Version 1.7.
                 ITU-T X.690:
                    Information technology - ASN.1 encoding rules:
                    Specification of Basic Encoding Rules (BER),
                    Canonical Encoding Rules (CER) and Distinguished
                    Encoding Rules (DER).";
            }
          }



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          output {
            leaf certificate-signing-request {
              type binary;
              mandatory true;
              description
                "A CertificationRequest structure as specified by RFC
                 2986, Section 4.1 encoded using the ASN.1 distinguished
                 encoding rules (DER), as specified in ITU-T X.690.";
              reference
                "RFC 2986:
                   PKCS #10: Certification Request Syntax Specification
                   Version 1.7.
                 ITU-T X.690:
                    Information technology - ASN.1 encoding rules:
                    Specification of Basic Encoding Rules (BER),
                    Canonical Encoding Rules (CER) and Distinguished
                    Encoding Rules (DER).";

            }
          }
        }
      }

      action generate-private-key {
        description
          "Requests the device to generate a private key using the
           specified algorithm and key length.";
        input {
          leaf name {
            type string;
            mandatory true;
            description
              "The name this private-key should have when listed
               in /keychain/private-keys.  As such, the passed
               value must not match any existing 'name' value.";
          }
          leaf key-usage {
            type enumeration {
              enum signing    { description "signing"; }
              enum encryption { description "encryption"; }
              // unclear if these should be somehow more
              // specific or varied.
            }
            description
              "An optional parameter further restricting the use of
               this key.  Some algorithms inherently restrict use
               (DH for signing) whereas others can support more than
               one use (RSA).  This flag forces the device to only



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               allow the key to be used for the indicated purposes.";
          }
          leaf algorithm {
            type kc:algorithms;
            mandatory true;
            description
              "The algorithm to be used when generating the key.";
          }
          leaf key-length {
            type uint32;
            description
              "For algorithms that need a key length specified
               when generating the key.";
          }
        }
      }

      action load-private-key {
        description
          "Requests the device to load a private key";
        input {
          leaf name {
            type string;
            mandatory true;
            description
              "The name this private-key should have when listed
               in /keychain/private-keys.  As such, the passed
               value must not match any existing 'name' value.";
          }
          leaf private-key {
            type binary;
            mandatory true;
              description
                "An OneAsymmetricKey structure as specified by RFC
                 5958, Section 2 encoded using the ASN.1 distinguished
                 encoding rules (DER), as specified in ITU-T X.690.
                 Note that this is the raw private with no shrouding
                 to protect it.  The strength of this private key
                 MUST NOT be greater than the strength of the secure
                 connection over which it is communicated.  Devices
                 SHOULD fail this request if ever that happens.";
              reference
                "RFC 5958:
                    Asymmetric Key Packages
                 ITU-T X.690:
                    Information technology - ASN.1 encoding rules:
                    Specification of Basic Encoding Rules (BER),
                    Canonical Encoding Rules (CER) and Distinguished



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                    Encoding Rules (DER).";
          }
        }
      }
    }

    list trusted-certificates {
      key name;
      description
        "A list of trusted certificates.  Each list SHOULD be specific
         to a purpose.  For instance, there could be one list for
         authenticating NETCONF/RESTCONF client certificates, and
         another list for authenticating manufacturer-signed data,
         and yet another list for authenticated web servers.";
      leaf name {
        type string;
        description
          "An arbitrary name for this list of trusted certificates.";
      }
      leaf description {
        type string;
        description
          "An arbitrary description for this list of trusted
           certificates.";
      }
      list trusted-certificate {
        key name;
        description
          "A trusted certificate for a specific use.";
        leaf name {
          type string;
          description
            "An arbitrary name for this trusted certificate.";
        }
        leaf certificate {
          type binary;
          description
            "An X.509 v3 certificate structure as specified by RFC
             5280, Section 4 encoded using the ASN.1 distinguished
             encoding rules (DER), as specified in ITU-T X.690.";
          reference
            "RFC 5280:
               Internet X.509 Public Key Infrastructure Certificate
               and Certificate Revocation List (CRL) Profile.
             ITU-T X.690:
                Information technology - ASN.1 encoding rules:
                Specification of Basic Encoding Rules (BER),
                Canonical Encoding Rules (CER) and Distinguished



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                Encoding Rules (DER).";
        }
      }
    }
  }
  notification certificate-expiration {
    description
      "A notification indicating that a configured certificate is
       either about to expire or has already expired.  When to send
       notifications is an implementation specific decision, but
       it is RECOMMENDED that a notification be sent once a month
       for 3 months, then once a week for four weeks, and then once
       a day thereafter.";
    leaf certificate {
      type instance-identifier;
      mandatory true;
      description
        "Identifies which certificate is expiring or is expired.";
    }
    leaf expiration-date {
      type yang:date-and-time;
      mandatory true;
      description
        "Identifies the expiration date on the certificate.";
    }
  }
}


<CODE ENDS>

4.2.  The SSH Server Model

   The SSH Server model presented in this section presents two YANG
   groupings, one for a server that opens a socket to accept TCP
   connections on, and another for a server that has had the TCP
   connection opened for it already (e.g., inetd).

   The SSH Server model (like the TLS Server model presented below) is
   provided as a grouping so that it can be used in different contexts.
   For instance, the NETCONF Server model presented in Section 4.4 uses
   one grouping to configure a NETCONF server listening for connections
   and the other grouping to configure NETCONF call home.

   A shared characteristic between both groupings is the ability to
   configure which host key is presented to clients, the private key for
   which is held in the keychain configuration presented before.
   Another shared characteristic is the ability to configure which



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   trusted CA or client certificates the server should be used to
   authenticate clients when using X.509 based client certificates
   [RFC6187].

4.2.1.  Tree Diagram

   The following tree diagram represents the data model for the grouping
   used to configure an SSH server to listen for TCP connections.  The
   tree diagram for the other grouping is not provided, but it is the
   same except without the "address" and "port" fields.

   NOTE: the diagram below shows "listening-ssh-server" as a YANG
   container (not a grouping).  This temporary container was created
   only to enable the `pyang` tool to output the tree diagram, as
   groupings by themselves have no protocol accessible nodes, and hence
   `pyang` would output an empty tree diagram.

 module: ietf-ssh-server
    +--rw listening-ssh-server
       +--rw address?            inet:ip-address
       +--rw port                inet:port-number
       +--rw host-keys
       |  +--rw host-key* [name]
       |     +--rw name           string
       |     +--rw (type)?
       |        +--:(public-key)
       |        |  +--rw public-key?    -> /kc:keychain/private-keys/pri
 vate-key/name
       |        +--:(certificate)
       |           +--rw certificate?   -> /kc:keychain/private-keys/pri
 vate-key/certificate-chains/certificate-chain/certificate {ssh-x509-cer
 ts}?
       +--rw client-cert-auth {ssh-x509-certs}?
          +--rw trusted-ca-certs?       -> /kc:keychain/trusted-certific
 ates/name
          +--rw trusted-client-certs?   -> /kc:keychain/trusted-certific
 ates/name

4.2.2.  Example Usage

   This section shows how it would appear if the temporary listening-
   ssh-server container just mentioned above were populated with some
   data.  This example is consistent with the examples presented earlier
   in this document.







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   <listening-ssh-server
     xmlns="urn:ietf:params:xml:ns:yang:ietf-ssh-server">
     <port>830</port>
     <host-keys>
       <host-key>
         <name>deployment-specific-certificate</name>
         <certificate>ex-key-sect571r1-cert</certificate>
       </host-key>
     </host-keys>
     </certificates>
     <client-cert-auth>
       <trusted-ca-certs>
         deployment-specific-ca-certs
       </trusted-ca-certs>
       <trusted-client-certs>
         explicitly-trusted-client-certs
       </trusted-client-certs>
     </client-cert-auth>
   </listening-ssh-server>

4.2.3.  YANG Model

   This YANG module has a normative reference to [RFC4253].


  <CODE BEGINS> file "ietf-ssh-server@2016-03-16.yang"

  module ietf-ssh-server {
    yang-version 1.1;

    namespace "urn:ietf:params:xml:ns:yang:ietf-ssh-server";
    prefix "ts";

    import ietf-inet-types {           // RFC 6991
      prefix inet;
    }
    import ietf-system-keychain {
      prefix kc;                       // RFC VVVV
      revision-date 2016-03-16;
    }

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

    contact
     "WG Web:   <http://tools.ietf.org/wg/netconf/>
      WG List:  <mailto:netconf@ietf.org>




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      WG Chair: Mehmet Ersue
                <mailto:mehmet.ersue@nsn.com>

      WG Chair: Mahesh Jethanandani
                <mailto:mjethanandani@gmail.com>

      Editor:   Kent Watsen
                <mailto:kwatsen@juniper.net>";


    description
     "This module defines a reusable grouping for a SSH server that
      can be used as a basis for specific SSH server instances.

      Copyright (c) 2014 IETF Trust and the persons identified as
      authors of the code. All rights reserved.

      Redistribution and use in source and binary forms, with or
      without modification, is permitted pursuant to, and subject
      to the license terms contained in, the Simplified BSD
      License set forth in Section 4.c of the IETF Trust's
      Legal Provisions Relating to IETF Documents
      (http://trustee.ietf.org/license-info).

      This version of this YANG module is part of RFC VVVV; see
      the RFC itself for full legal notices.";

    revision "2016-03-16" {
      description
       "Initial version";
      reference
       "RFC VVVV: NETCONF Server and RESTCONF Server Configuration
                  Models";
    }

    // features
    feature ssh-x509-certs {
      description
        "The ssh-x509-certs feature indicates that the NETCONF
         server supports RFC 6187";
      reference
        "RFC 6187: X.509v3 Certificates for Secure Shell
         Authentication";
    }

    // grouping
    grouping non-listening-ssh-server-grouping {
      description



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        "A reusable grouping for a SSH server that can be used as a
         basis for specific SSH server instances.";

      container host-keys {
        description
          "The list of host-keys the SSH server will present when
           establishing a SSH connection.";
        list host-key {
          key name;
          min-elements 1;
          ordered-by user;
          description
            "An ordered list of host keys the SSH server will use to
             construct its ordered list of algorithms, when sending
             its SSH_MSG_KEXINIT message, as defined in Section 7.1
             of RFC 4253.";
          reference
            "RFC 4253: The Secure Shell (SSH) Transport Layer Protocol";
          leaf name {
            type string;
            mandatory true;
            description
              "An arbitrary name for this host-key";
          }
          choice type {
            description
              "The type of host key being specified";
            leaf public-key {
              type leafref {
                path "/kc:keychain/kc:private-keys/kc:private-key/"
                     + "kc:name";
              }
              description
                "The public key is actually identified by the name of
                 its cooresponding private-key in the keychain.";
            }
            leaf certificate {
              if-feature ssh-x509-certs;
              type leafref {
                path "/kc:keychain/kc:private-keys/kc:private-key/"
                     + "kc:certificate-chains/kc:certificate-chain/"
                     + "kc:certificate";
              }
              description
                "The name of a certificate in the keychain.";
            }
          }
        }



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      }

      container client-cert-auth {
        if-feature ssh-x509-certs;
        description
          "A reference to a list of trusted certificate authority (CA)
           certificates and a reference to a list of trusted client
           certificates.";
        leaf trusted-ca-certs {
          type leafref {
            path "/kc:keychain/kc:trusted-certificates/kc:name";
          }
          description
            "A reference to a list of certificate authority (CA)
             certificates used by the SSH server to authenticate
             SSH client certificates.";
        }

        leaf trusted-client-certs {
          type leafref {
            path "/kc:keychain/kc:trusted-certificates/kc:name";
          }
          description
            "A reference to a list of client certificates used by
             the SSH server to authenticate SSH client certificates.
             A clients certificate is authenticated if it is an
             exact match to a configured trusted client certificate.";
        }
      }
    }


    grouping listening-ssh-server-grouping {
      description
        "A reusable grouping for a SSH server that can be used as a
         basis for specific SSH server instances.";
      leaf address {
        type inet:ip-address;
        description
         "The IP address of the interface to listen on. The SSH
          server will listen on all interfaces if no value is
          specified.";
      }
      leaf port {
        type inet:port-number;
        mandatory true;  // will a default augmented in work?
        description
         "The local port number on this interface the SSH server



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          listens on.";
      }
      uses non-listening-ssh-server-grouping;
    }

    container listening-ssh-server {
      description
        "This container will be removed by the RFC Editor. This
         container is currently only present in order to enable
         the `pyang` tool to generate tree diagram output of this
         module (used in the draft) as it otherwise would not
         contain any protocol accessible nodes to output.";

         uses listening-ssh-server-grouping;
    }
  }



  <CODE ENDS>

4.3.  The TLS Server Model

   The TLS Server model presented in this section presents two YANG
   groupings, one for a server that opens a socket to accept TCP
   connections on, and another for a server that has had the TCP
   connection opened for it already (e.g., inetd).

   The TLS Server model (like the SSH Server model presented above) is
   provided as a grouping so that it can be used in different contexts.
   For instance, the NETCONF Server model presented in Section 4.4 uses
   one grouping to configure a NETCONF server listening for connections
   and the other grouping to configure NETCONF call home.

   A shared characteristic between both groupings is the ability to
   configure which server certificate is presented to clients, the
   private key for which is held in the keychain model presented in
   Section 4.1.  Another shared characteristic is the ability to
   configure which trusted CA or client certificates the server should
   be used to authenticate clients.

4.3.1.  Tree Diagram

   The following tree diagram represents the data model for the grouping
   used to configure an TLS server to listen for TCP connections.  The
   tree diagram for the other grouping is not provided, but it is the
   same except without the "address" and "port" fields.




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   NOTE: the diagram below shows "listening-ssh-server" as a YANG
   container (not a grouping).  This temporary container was created
   only to enable the `pyang` tool to output the tree diagram, as
   groupings by themselves have no protocol accessible nodes, and hence
   `pyang` would output an empty tree diagram.

 module: ietf-tls-server
    +--rw listening-tls-server
       +--rw address?        inet:ip-address
       +--rw port            inet:port-number
       +--rw certificates
       |  +--rw certificate* [name]
       |     +--rw name    -> /kc:keychain/private-keys/private-key/cert
 ificate-chains/certificate-chain/certificate
       +--rw client-auth
          +--rw trusted-ca-certs?       -> /kc:keychain/trusted-certific
 ates/name
          +--rw trusted-client-certs?   -> /kc:keychain/trusted-certific
 ates/name

4.3.2.  Example Usage

   <listening-tls-server
     xmlns="urn:ietf:params:xml:ns:yang:ietf-tls-server">
     <port>6513</port>
     <certificates>
       <certificate>
         <name>ex-key-sect571r1-cert</name>
       </certificate>
     </certificates>
     <client-auth>
       <trusted-ca-certs>
         deployment-specific-ca-certs
       </trusted-ca-certs>
       <trusted-client-certs>
         explicitly-trusted-client-certs
       </trusted-client-certs>
     </client-auth>
   </listening-tls-server>

4.3.3.  YANG Model


   <CODE BEGINS> file "ietf-tls-server@2016-03-16.yang"

   module ietf-tls-server {
     yang-version 1.1;




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     namespace "urn:ietf:params:xml:ns:yang:ietf-tls-server";
     prefix "ts";

     import ietf-inet-types {           // RFC 6991
       prefix inet;
     }
     import ietf-system-keychain {
       prefix kc;                       // RFC VVVV
       revision-date 2016-03-16;
     }

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

     contact
      "WG Web:   <http://tools.ietf.org/wg/netconf/>
       WG List:  <mailto:netconf@ietf.org>

       WG Chair: Mehmet Ersue
                 <mailto:mehmet.ersue@nsn.com>

       WG Chair: Mahesh Jethanandani
                 <mailto:mjethanandani@gmail.com>

       Editor:   Kent Watsen
                 <mailto:kwatsen@juniper.net>";


     description
      "This module defines a reusable grouping for a TLS server that
       can be used as a basis for specific TLS server instances.

       Copyright (c) 2014 IETF Trust and the persons identified as
       authors of the code. All rights reserved.

       Redistribution and use in source and binary forms, with or
       without modification, is permitted pursuant to, and subject
       to the license terms contained in, the Simplified BSD
       License set forth in Section 4.c of the IETF Trust's
       Legal Provisions Relating to IETF Documents
       (http://trustee.ietf.org/license-info).

       This version of this YANG module is part of RFC VVVV; see
       the RFC itself for full legal notices.";

     revision "2016-03-16" {
       description
        "Initial version";



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       reference
        "RFC VVVV: NETCONF Server and RESTCONF Server Configuration
                   Models";
     }


     // grouping
     grouping non-listening-tls-server-grouping {
       description
         "A reusable grouping for a TLS server that can be used as a
          basis for specific TLS server instances.";
       container certificates {
         description
           "The list of certificates the TLS server will present when
            establishing a TLS connection in its Certificate message,
            as defined in Section 7.4.2 in RRC 5246.";
         reference
           "RFC 5246:
              The Transport Layer Security (TLS) Protocol Version 1.2";
         list certificate {
           key name;
           min-elements 1;
           description
             "An unordered list of certificates the TLS server can pick
              from when sending its Server Certificate message.";
           reference
             "RFC 5246: The TLS Protocol, Section 7.4.2";
           leaf name {
             type leafref {
               path "/kc:keychain/kc:private-keys/kc:private-key/"
                    + "kc:certificate-chains/kc:certificate-chain/"
                    + "kc:certificate";
             }
             description
               "The name of the certificate in the keychain.";
           }
         }
       }

       container client-auth {
         description
           "A reference to a list of trusted certificate authority (CA)
            certificates and a reference to a list of trusted client
            certificates.";
         leaf trusted-ca-certs {
           type leafref {
             path "/kc:keychain/kc:trusted-certificates/kc:name";
           }



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           description
             "A reference to a list of certificate authority (CA)
              certificates used by the TLS server to authenticate
              TLS client certificates.";
         }

         leaf trusted-client-certs {
           type leafref {
             path "/kc:keychain/kc:trusted-certificates/kc:name";
           }
           description
             "A reference to a list of client certificates used by
              the TLS server to authenticate TLS client certificates.
              A clients certificate is authenticated if it is an
              exact match to a configured trusted client certificate.";
         }
       }
     }


     grouping listening-tls-server-grouping {
       description
         "A reusable grouping for a TLS server that can be used as a
          basis for specific TLS server instances.";
       leaf address {
         type inet:ip-address;
         description
          "The IP address of the interface to listen on. The TLS
           server will listen on all interfaces if no value is
           specified.";
       }
       leaf port {
         type inet:port-number;
         mandatory true;  // will a default augmented in work?
         description
          "The local port number on this interface the TLTLS server
           listens on.";
       }
       uses non-listening-tls-server-grouping;
     }

     container listening-tls-server {
       description
         "This container will be removed by the RFC Editor. This
          container is currently only present in order to enable
          the `pyang` tool to generate tree diagram output of this
          module (used in the draft) as it otherwise would not
          contain any protocol accessible nodes to output.";



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          uses listening-tls-server-grouping;
     }
   }



   <CODE ENDS>

4.4.  The NETCONF Server Model

   The NETCONF Server model presented in this section supports servers
   both listening for connections to accept as well as initiating call-
   home connections.  This model also supports both the SSH and TLS
   transport protocols, using the SSH Server and TLS Server groupings
   presented in Section 4.2 and Section 4.3 respectively.  All private
   keys and trusted certificates are held in the keychain model
   presented in Section 4.1.  YANG feature statements are used to enable
   implementations to advertise which parts of the model the NETCONF
   server supports.

4.4.1.  Tree Diagram

   The following tree diagram uses line-wrapping in order to comply with
   xml2rfc validation.  This is annoying as I find that drafts (even txt
   drafts) look just fine with long lines - maybe xml2rfc should remove
   this warning? - or pyang could have an option to suppress printing
   leafref paths?

 module: ietf-netconf-server
    +--rw netconf-server
       +--rw session-options
       |  +--rw hello-timeout?   uint16
       +--rw listen {(ssh-listen or tls-listen)}?
       |  +--rw max-sessions?   uint16
       |  +--rw idle-timeout?   uint16
       |  +--rw endpoint* [name]
       |     +--rw name    string
       |     +--rw (transport)
       |        +--:(ssh) {ssh-listen}?
       |        |  +--rw ssh
       |        |     +--rw address?            inet:ip-address
       |        |     +--rw port                inet:port-number
       |        |     +--rw host-keys
       |        |     |  +--rw host-key* [name]
       |        |     |     +--rw name           string
       |        |     |     +--rw (type)?
       |        |     |        +--:(public-key)
       |        |     |        |  +--rw public-key?    -> /kc:keychain/p



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 rivate-keys/private-key/name
       |        |     |        +--:(certificate)
       |        |     |           +--rw certificate?   -> /kc:keychain/p
 rivate-keys/private-key/certificate-chains/certificate-chain/certificat
 e {ssh-x509-certs}?
       |        |     +--rw client-cert-auth {ssh-x509-certs}?
       |        |        +--rw trusted-ca-certs?       -> /kc:keychain/t
 rusted-certificates/name
       |        |        +--rw trusted-client-certs?   -> /kc:keychain/t
 rusted-certificates/name
       |        +--:(tls) {tls-listen}?
       |           +--rw tls
       |              +--rw address?        inet:ip-address
       |              +--rw port            inet:port-number
       |              +--rw certificates
       |              |  +--rw certificate* [name]
       |              |     +--rw name    -> /kc:keychain/private-keys/p
 rivate-key/certificate-chains/certificate-chain/certificate
       |              +--rw client-auth
       |                 +--rw trusted-ca-certs?       -> /kc:keychain/t
 rusted-certificates/name
       |                 +--rw trusted-client-certs?   -> /kc:keychain/t
 rusted-certificates/name
       |                 +--rw cert-maps
       |                    +--rw cert-to-name* [id]
       |                       +--rw id             uint32
       |                       +--rw fingerprint    x509c2n:tls-fingerpr
 int
       |                       +--rw map-type       identityref
       |                       +--rw name           string
       +--rw call-home {(ssh-call-home or tls-call-home)}?
          +--rw netconf-client* [name]
             +--rw name                  string
             +--rw (transport)
             |  +--:(ssh) {ssh-call-home}?
             |  |  +--rw ssh
             |  |     +--rw endpoints
             |  |     |  +--rw endpoint* [name]
             |  |     |     +--rw name       string
             |  |     |     +--rw address    inet:host
             |  |     |     +--rw port?      inet:port-number
             |  |     +--rw host-keys
             |  |     |  +--rw host-key* [name]
             |  |     |     +--rw name           string
             |  |     |     +--rw (type)?
             |  |     |        +--:(public-key)
             |  |     |        |  +--rw public-key?    -> /kc:keychain/p
 rivate-keys/private-key/name



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             |  |     |        +--:(certificate)
             |  |     |           +--rw certificate?   -> /kc:keychain/p
 rivate-keys/private-key/certificate-chains/certificate-chain/certificat
 e {ssh-x509-certs}?
             |  |     +--rw client-cert-auth {ssh-x509-certs}?
             |  |        +--rw trusted-ca-certs?       -> /kc:keychain/t
 rusted-certificates/name
             |  |        +--rw trusted-client-certs?   -> /kc:keychain/t
 rusted-certificates/name
             |  +--:(tls) {tls-call-home}?
             |     +--rw tls
             |        +--rw endpoints
             |        |  +--rw endpoint* [name]
             |        |     +--rw name       string
             |        |     +--rw address    inet:host
             |        |     +--rw port?      inet:port-number
             |        +--rw certificates
             |        |  +--rw certificate* [name]
             |        |     +--rw name    -> /kc:keychain/private-keys/p
 rivate-key/certificate-chains/certificate-chain/certificate
             |        +--rw client-auth
             |           +--rw trusted-ca-certs?       -> /kc:keychain/t
 rusted-certificates/name
             |           +--rw trusted-client-certs?   -> /kc:keychain/t
 rusted-certificates/name
             |           +--rw cert-maps
             |              +--rw cert-to-name* [id]
             |                 +--rw id             uint32
             |                 +--rw fingerprint    x509c2n:tls-fingerpr
 int
             |                 +--rw map-type       identityref
             |                 +--rw name           string
             +--rw connection-type
             |  +--rw (connection-type)?
             |     +--:(persistent-connection)
             |     |  +--rw persistent!
             |     |     +--rw idle-timeout?   uint32
             |     |     +--rw keep-alives
             |     |        +--rw max-wait?       uint16
             |     |        +--rw max-attempts?   uint8
             |     +--:(periodic-connection)
             |        +--rw periodic!
             |           +--rw idle-timeout?        uint16
             |           +--rw reconnect_timeout?   uint16
             +--rw reconnect-strategy
                +--rw start-with?     enumeration
                +--rw max-attempts?   uint8




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4.4.2.  Example Usage

   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 other examples presented in this
   document.

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

       <!-- listening for SSH connections -->
       <endpoint>
         <name>netconf/ssh</name>
         <ssh>
           <address>11.22.33.44</address>
           <host-keys>
             <host-key>
               <public-key>my-rsa-key</public-key>
             </host-key>
             <host-key>
               <certificate>TPM key</certificate>
             </host-key>
           </host-keys>
           <client-cert-auth>
             <trusted-ca-certs>
               deployment-specific-ca-certs
             </trusted-ca-certs>
             <trusted-client-certs>
               explicitly-trusted-client-certs
             </trusted-client-certs>
           </client-cert-auth>
         </ssh>
       </endpoint>

       <!-- listening for TLS connections -->
       <endpoint>
         <name>netconf/tls</name>
         <tls>
           <address>11.22.33.44</address>
           <certificates>
             <certificate>ex-key-sect571r1-cert</certificate>
           </certificates>
           <client-auth>
             <trusted-ca-certs>



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               deployment-specific-ca-certs
             </trusted-ca-certs>
             <trusted-client-certs>
               explicitly-trusted-client-certs
             </trusted-client-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-auth>
         </tls>
       </endpoint>

     </listen>
     <call-home>

       <!-- calling home to an SSH-based NETCONF client -->
       <netconf-client>
         <name>config-mgr</name>
         <ssh>
           <endpoints>
             <endpoint>
               <name>east-data-center</name>
               <address>11.22.33.44</address>
             </endpoint>
             <endpoint>
               <name>west-data-center</name>
               <address>55.66.77.88</address>
             </endpoint>
           </endpoints>
           <host-keys>
             <host-key>
               <certificate>TPM key</certificate>
             </host-key>
           </host-keys>
           <client-cert-auth>
             <trusted-ca-certs>
               deployment-specific-ca-certs
             </trusted-ca-certs>



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             <trusted-client-certs>
               explicitly-trusted-client-certs
             </trusted-client-certs>
           </client-cert-auth>
         </ssh>
         <connection-type>
           <periodic>
             <idle-timeout>300</idle-timeout>
             <reconnect-timeout>60</reconnect-timeout>
           </periodic>
         </connection-type>
         <reconnect-strategy>
           <start-with>last-connected</start-with>
           <max-attempts>3</max-attempts>
         </reconnect-strategy>
       </netconf-client>

       <!-- calling home to a TLS-based NETCONF client -->
       <netconf-client>
         <name>event-correlator</name>
         <tls>
           <endpoints>
             <endpoint>
               <name>east-data-center</name>
               <address>22.33.44.55</address>
             </endpoint>
             <endpoint>
               <name>west-data-center</name>
               <address>33.44.55.66</address>
             </endpoint>
           </endpoints>
           <certificates>
             <certificate>ex-key-sect571r1-cert</certificate>
           </certificates>
           <client-auth>
             <trusted-ca-certs>
               deployment-specific-ca-certs
             </trusted-ca-certs>
             <trusted-client-certs>
               explicitly-trusted-client-certs
             </trusted-client-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>



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                 <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-auth>
         </tls>
         <connection-type>
           <persistent>
             <idle-timeout>300</idle-timeout>
             <keep-alives>
               <max-wait>30</max-wait>
               <max-attempts>3</max-attempts>
             </keep-alives>
           </persistent>
         </connection-type>
         <reconnect-strategy>
           <start-with>first-listed</start-with>
           <max-attempts>3</max-attempts>
         </reconnect-strategy>
       </netconf-client>

     </call-home>
   </netconf-server>

4.4.3.  YANG Model

   This YANG module imports YANG types from [RFC6991] and [RFC7407].


  <CODE BEGINS> file "ietf-netconf-server@2016-03-16.yang"

  module ietf-netconf-server {
    yang-version 1.1;

    namespace "urn:ietf:params:xml:ns:yang:ietf-netconf-server";
    prefix "ncserver";

    import ietf-inet-types {           // RFC 6991
      prefix inet;
    }
    import ietf-x509-cert-to-name {    // RFC 7407
      prefix x509c2n;
    }
    import ietf-ssh-server {           // RFC VVVV
      prefix ss;
      revision-date 2016-03-16;



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    }
    import ietf-tls-server {           // RFC VVVV
      prefix ts;
      revision-date 2016-03-16;
    }


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

    contact
     "WG Web:   <http://tools.ietf.org/wg/netconf/>
      WG List:  <mailto:netconf@ietf.org>

      WG Chair: Mehmet Ersue
                <mailto:mehmet.ersue@nsn.com>

      WG Chair: Mahesh Jethanandani
                <mailto:mjethanandani@gmail.com>

      Editor:   Kent Watsen
                <mailto:kwatsen@juniper.net>";


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

      Copyright (c) 2014 IETF Trust and the persons identified as
      authors of the code. All rights reserved.

      Redistribution and use in source and binary forms, with or
      without modification, is permitted pursuant to, and subject
      to the license terms contained in, the Simplified BSD
      License set forth in Section 4.c of the IETF Trust's
      Legal Provisions Relating to IETF Documents
      (http://trustee.ietf.org/license-info).

      This version of this YANG module is part of RFC VVVV; see
      the RFC itself for full legal notices.";

    revision "2016-03-16" {
      description
       "Initial version";
      reference
       "RFC VVVV: NETCONF Server and RESTCONF Server Configuration
                  Models";
    }



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    // Features

    feature ssh-listen {
      description
       "The ssh-listen feature indicates that the NETCONF server
        supports opening a port to accept NETCONF over SSH
        client connections.";
      reference
       "RFC 6242: Using the NETCONF Protocol over Secure Shell (SSH)";
    }

    feature 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 YYYY: NETCONF Call Home and RESTCONF Call Home";
    }

    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 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 YYYY: NETCONF Call Home and RESTCONF Call Home";
    }

    feature ssh-x509-certs {
      description
        "The ssh-x509-certs feature indicates that the NETCONF
         server supports RFC 6187";
      reference
        "RFC 6187: X.509v3 Certificates for Secure Shell
         Authentication";
    }



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    // top-level container  (groupings below)
    container netconf-server {
      description
        "Top-level container for NETCONF server configuration.";

      container session-options {  // SHOULD WE REMOVE THIS ALTOGETHER?
        description
          "NETCONF session options, independent of transport
           or connection strategy.";
        leaf hello-timeout {
          type uint16;
          units "seconds";
          default 600;
          description
            "Specifies the maximum number of seconds that a SSH/TLS
             connection may wait for a hello message to be received.
             A connection will be dropped if no hello message is
             received before this number of seconds elapses.  If set
             to zero, then the server will wait forever for a hello
             message.";
        }
      }

      container listen {
        if-feature "(ssh-listen or tls-listen)";
        description
          "Configures listen behavior";
        leaf max-sessions {
          type uint16;
          default 0;
          description
            "Specifies the maximum number of concurrent sessions
             that can be active at one time.  The value 0 indicates
             that no artificial session limit should be used.";
        }
        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 {



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          key name;
          description
            "List of endpoints to listen for NETCONF connections on.";
          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.";
                uses ss:listening-ssh-server-grouping {
                  refine port {
                    default 830;
                  }
                }
              }
            }
            case tls {
              if-feature tls-listen;
              container tls {
                description
                  "TLS-specific listening configuration for inbound
                   connections.";
                uses ts:listening-tls-server-grouping {
                  refine port {
                    default 6513;
                  }
                  augment "client-auth" {
                    description
                      "Augments in the cert-to-name structure.";
                    uses cert-maps-grouping;
                  }
                }
              }
            }
          }
        }
      }

      container call-home {



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        if-feature "(ssh-call-home or tls-call-home)";
        description
          "Configures call-home behavior";
        list netconf-client {
          key name;
          description
            "List of NETCONF clients the NETCONF server is to initiate
             call-home connections to.";
          leaf name {
            type string;
            description
              "An arbitrary name for the remote NETCONF client.";
          }
          choice transport {
            mandatory true;
            description
              "Selects between available transports.";
            case ssh {
              if-feature ssh-call-home;
              container ssh {
                description
                  "Specifies SSH-specific call-home transport
                   configuration.";
                uses endpoints-container {
                  refine endpoints/endpoint/port {
                    default 7777;
                  }
                }
                uses ss:non-listening-ssh-server-grouping;
              }
            }
            case tls {
              if-feature tls-call-home;
              container tls {
                description
                  "Specifies TLS-specific call-home transport
                   configuration.";
                uses endpoints-container {
                  refine endpoints/endpoint/port {
                    default 8888;
                  }
                }
                uses ts:non-listening-tls-server-grouping {
                  augment "client-auth" {
                    description
                      "Augments in the cert-to-name structure.";
                    uses cert-maps-grouping;
                  }



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                }
              }
            }
          }
          container connection-type {
            description
             "Indicates the kind of connection to use.";
            choice connection-type {
              description
                "Selects between available connection types.";
              case persistent-connection {
                container persistent {
                  presence true;
                  description
                   "Maintain a persistent connection to the NETCONF
                    client. If the connection goes down, immediately
                    start trying to reconnect to it, using the
                    reconnection strategy.

                    This connection type minimizes any NETCONF client
                    to NETCONF server data-transfer delay, albeit at
                    the expense of holding resources longer.";
                  leaf idle-timeout {
                    type uint32;
                    units "seconds";
                    default 86400;  // one day;
                    description
                      "Specifies the maximum number of seconds that a
                       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.";
                  }
                  container keep-alives {
                    description
                      "Configures the keep-alive policy, to proactively
                       test the aliveness of the SSH/TLS client.  An
                       unresponsive SSH/TLS client will be dropped after
                       approximately max-attempts * max-wait seconds.";
                    reference
                      "RFC YYYY: NETCONF Call Home and RESTCONF Call
                       Home, Section 3.1, item S6";
                    leaf max-wait {
                      type uint16 {
                        range "1..max";



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                      }
                      units seconds;
                      default 30;
                      description
                       "Sets the amount of time in seconds after which
                        if no data has been received from the SSH/TLS
                        client, a SSH/TLS-level message will be sent
                        to test the aliveness of the SSH/TLS client.";
                    }
                    leaf max-attempts {
                      type uint8;
                      default 3;
                      description
                       "Sets the number of maximum number of sequential
                        keep-alive messages that can fail to obtain a
                        response from the SSH/TLS client before assuming
                        the SSH/TLS client is no longer alive.";
                    }
                  }
                }
              }
              case periodic-connection {
                container periodic {
                  presence true;
                  description
                   "Periodically connect to the NETCONF client, so that
                    the NETCONF client may deliver messages pending for
                    the NETCONF server.  The NETCONF client is expected
                    to close the connection when it is ready to release
                    it, thus starting the NETCONF server's timer until
                    next connection.";
                  leaf idle-timeout {
                    type uint16;
                    units "seconds";
                    default 300; // five minutes
                    description
                      "Specifies the maximum number of seconds that a
                       a NETCONF session may remain idle. A NETCONF
                       session will be dropped if it is idle for an
                       interval longer than this number of seconds.
                       If set to zero, then the server will never drop
                       a session because it is idle.  Sessions that
                       have a notification subscription active are
                       never dropped.";
                  }
                  leaf reconnect_timeout {
                    type uint16 {
                      range "1..max";



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                    }
                    units minutes;
                    default 60;
                    description
                     "Sets the maximum amount of unconnected time the
                      NETCONF server will wait before re-establishing
                      a connection to the NETCONF client.  The NETCONF
                      server may initiate a connection before this
                      time if desired (e.g., to deliver an event
                      notification message).";
                  }
                }
              }
            }
          }
          container reconnect-strategy {
            description
             "The reconnection strategy guides how a NETCONF server
              reconnects to a NETCONF client, after discovering its
              connection to the client has dropped.  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 {
                  description
                    "Indicates that reconnections should start with
                     the endpoint last connected to.  If no previous
                     connection has ever been established, then the
                     first endpoint configured is used.   NETCONF
                     servers SHOULD be able to remember the last
                     endpoint connected to across reboots.";
                }
              }
              default first-listed;
              description
               "Specifies which of the NETCONF client's endpoints the
                NETCONF server should start with when trying to connect
                to the NETCONF client.";
            }
            leaf max-attempts {
              type uint8 {



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                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).";
            }
          }
        }
      }
    }


    grouping cert-maps-grouping {
      description
        "A grouping that defines a container around the
         cert-to-name structure defined in RFC 7407.";
      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";
      }
    }


    grouping endpoints-container {
      description
        "This grouping is used by both the ssh and tls containers
         for call-home configurations.";
      container endpoints {
        description
          "Container for the list of endpoints.";
        list endpoint {
          key name;
          min-elements 1;
          ordered-by user;
          description
            "User-ordered list of endpoints for this NETCONF client.
             Defining more than one enables high-availability.";
          leaf name {



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            type string;
            description
              "An arbitrary name for this endpoint.";
          }
          leaf address {
            type inet:host;
            mandatory true;
            description
             "The IP address or hostname of the endpoint.  If a
              hostname is configured and the DNS resolution results
              in more than one IP address, the NETCONF server
              will process the IP addresses as if they had been
              explicitly configured in place of the hostname.";
          }
          leaf port {
            type inet:port-number;
            description
             "The IP port for this endpoint. The NETCONF server will
              use the IANA-assigned well-known port if no value is
              specified.";
          }
        }
      }
    }

  }


  <CODE ENDS>

4.5.  The RESTCONF Server Model

   The RESTCONF Server model presented in this section supports servers
   both listening for connections to accept as well as initiating call-
   home connections.  This model supports the TLS transport only, as
   RESTCONF only supports HTTPS, using the TLS Server groupings
   presented in Section 4.3.  All private keys and trusted certificates
   are held in the keychain model presented in Section 4.1.  YANG
   feature statements are used to enable implementations to advertise
   which parts of the model the RESTCONF server supports.

4.5.1.  Tree Diagram

   The following tree diagram uses line-wrapping in order to comply with
   xml2rfc validation.  This is annoying as I find that drafts (even txt
   drafts) look just fine with long lines - maybe xml2rfc should remove
   this warning? - or pyang could have an option to suppress printing
   leafref paths?



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 module: ietf-restconf-server
    +--rw restconf-server
       +--rw listen {tls-listen}?
       |  +--rw max-sessions?   uint16
       |  +--rw endpoint* [name]
       |     +--rw name    string
       |     +--rw (transport)
       |        +--:(tls) {tls-listen}?
       |           +--rw tls
       |              +--rw address?        inet:ip-address
       |              +--rw port            inet:port-number
       |              +--rw certificates
       |              |  +--rw certificate* [name]
       |              |     +--rw name    -> /kc:keychain/private-keys/p
 rivate-key/certificate-chains/certificate-chain/certificate
       |              +--rw client-auth
       |                 +--rw trusted-ca-certs?       -> /kc:keychain/t
 rusted-certificates/name
       |                 +--rw trusted-client-certs?   -> /kc:keychain/t
 rusted-certificates/name
       |                 +--rw cert-maps
       |                    +--rw cert-to-name* [id]
       |                       +--rw id             uint32
       |                       +--rw fingerprint    x509c2n:tls-fingerpr
 int
       |                       +--rw map-type       identityref
       |                       +--rw name           string
       +--rw call-home {tls-call-home}?
          +--rw restconf-client* [name]
             +--rw name                  string
             +--rw (transport)
             |  +--:(tls) {tls-call-home}?
             |     +--rw tls
             |        +--rw endpoints
             |        |  +--rw endpoint* [name]
             |        |     +--rw name       string
             |        |     +--rw address    inet:host
             |        |     +--rw port?      inet:port-number
             |        +--rw certificates
             |        |  +--rw certificate* [name]
             |        |     +--rw name    -> /kc:keychain/private-keys/p
 rivate-key/certificate-chains/certificate-chain/certificate
             |        +--rw client-auth
             |           +--rw trusted-ca-certs?       -> /kc:keychain/t
 rusted-certificates/name
             |           +--rw trusted-client-certs?   -> /kc:keychain/t
 rusted-certificates/name
             |           +--rw cert-maps



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             |              +--rw cert-to-name* [id]
             |                 +--rw id             uint32
             |                 +--rw fingerprint    x509c2n:tls-fingerpr
 int
             |                 +--rw map-type       identityref
             |                 +--rw name           string
             +--rw connection-type
             |  +--rw (connection-type)?
             |     +--:(persistent-connection)
             |     |  +--rw persistent!
             |     |     +--rw keep-alives
             |     |        +--rw max-wait?       uint16
             |     |        +--rw max-attempts?   uint8
             |     +--:(periodic-connection)
             |        +--rw periodic!
             |           +--rw reconnect-timeout?   uint16
             +--rw reconnect-strategy
                +--rw start-with?     enumeration
                +--rw max-attempts?   uint8

4.5.2.  Example Usage

   Configuring a RESTCONF Server to listen for RESTCONF client
   connections, as well as configuring call-home to one RESTCONF client.

   This example is consistent with other examples presented in this
   document.

   <restconf-server
     xmlns="urn:ietf:params:xml:ns:yang:ietf-restconf-server">

     <!-- listening for TLS (HTTPS) connections -->
     <listen>
       <endpoint>
         <name>netconf/tls</name>
         <tls>
           <address>11.22.33.44</address>
           <certificates>
             <certificate>ex-key-sect571r1-cert</certificate>
           </certificates>
           <client-auth>
             <trusted-ca-certs>
               deployment-specific-ca-certs
             </trusted-ca-certs>
             <trusted-client-certs>
               explicitly-trusted-client-certs
             </trusted-client-certs>
             <cert-maps>



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               <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-auth>
         </tls>

       </endpoint>
     </listen>

     <!-- calling home to a RESTCONF client -->
     <call-home>
       <restconf-client>
         <name>config-manager</name>
         <tls>
           <endpoints>
             <endpoint>
               <name>east-data-center</name>
               <address>22.33.44.55</address>
             </endpoint>
             <endpoint>
               <name>west-data-center</name>
               <address>33.44.55.66</address>
             </endpoint>
           </endpoints>
           <certificates>
             <certificate>ex-key-sect571r1-cert</certificate>
           </certificates>
           <client-auth>
             <trusted-ca-certs>
               deployment-specific-ca-certs
             </trusted-ca-certs>
             <trusted-client-certs>
               explicitly-trusted-client-certs
             </trusted-client-certs>
             <cert-maps>
               <cert-to-name>
                 <id>1</id>
                 <fingerprint>11:0A:05:11:00</fingerprint>
                 <map-type>x509c2n:san-any</map-type>



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               </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-auth>
         </tls>
         <connection-type>
           <periodic>
             <idle-timeout>300</idle-timeout>
             <reconnect-timeout>60</reconnect-timeout>
           </periodic>
         </connection-type>
         <reconnect-strategy>
           <start-with>last-connected</start-with>
           <max-attempts>3</max-attempts>
         </reconnect-strategy>
       </restconf-client>
     </call-home>

   </restconf-server>

4.5.3.  YANG Model

   This YANG module imports YANG types from [RFC6991] and [RFC7407].


<CODE BEGINS> file "ietf-restconf-server@2016-03-16.yang"

module ietf-restconf-server {
  yang-version 1.1;

  namespace "urn:ietf:params:xml:ns:yang:ietf-restconf-server";
  prefix "rcserver";

  //import ietf-netconf-acm {
  //  prefix nacm;                     // RFC 6536
  //}
  import ietf-inet-types {           // RFC 6991
    prefix inet;
  }
  import ietf-x509-cert-to-name {    // RFC 7407
    prefix x509c2n;
  }
  import ietf-tls-server {           // RFC VVVV



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    prefix ts;
    revision-date 2016-03-16;
  }

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

  contact
   "WG Web:   <http://tools.ietf.org/wg/netconf/>
    WG List:  <mailto:netconf@ietf.org>

    WG Chair: Mehmet Ersue
              <mailto:mehmet.ersue@nsn.com>

    WG Chair: Mahesh Jethanandani
              <mailto:mjethanandani@gmail.com>

    Editor:   Kent Watsen
              <mailto:kwatsen@juniper.net>";


  description
   "This module contains a collection of YANG definitions for
    configuring RESTCONF servers.

    Copyright (c) 2014 IETF Trust and the persons identified as
    authors of the code. All rights reserved.

    Redistribution and use in source and binary forms, with or
    without modification, is permitted pursuant to, and subject
    to the license terms contained in, the Simplified BSD
    License set forth in Section 4.c of the IETF Trust's
    Legal Provisions Relating to IETF Documents
    (http://trustee.ietf.org/license-info).

    This version of this YANG module is part of RFC VVVV; see
    the RFC itself for full legal notices.";

  revision "2016-03-16" {
    description
     "Initial version";
    reference
     "RFC VVVV: NETCONF Server and RESTCONF Server Configuration
                Models";
  }


  // Features



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  feature tls-listen {
    description
     "The listen feature indicates that the RESTCONF server
      supports opening a port to listen for incoming RESTCONF
      client connections.";
    reference
     "RFC XXXX: RESTCONF Protocol";
  }

  feature tls-call-home {
    description
     "The call-home feature indicates that the RESTCONF server
      supports initiating connections to RESTCONF clients.";
    reference
     "RFC YYYY: NETCONF Call Home and RESTCONF Call Home";
  }

  feature client-cert-auth {
    description
     "The client-cert-auth feature indicates that the RESTCONF
      server supports the ClientCertificate authentication scheme.";
    reference
     "RFC ZZZZ: Client Authentication over New TLS Connection";
  }


  // top-level container
  container restconf-server {
    description
      "Top-level container for RESTCONF server configuration.";

    container listen {
      if-feature tls-listen;
      description
        "Configures listen behavior";
      leaf max-sessions {
        type uint16;
        default 0;   // should this be 'max'?
        description
          "Specifies the maximum number of concurrent sessions
           that can be active at one time.  The value 0 indicates
           that no artificial session limit should be used.";
      }
      list endpoint {
        key name;
        description
          "List of endpoints to listen for RESTCONF connections on.";
        leaf name {



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          type string;
          description
            "An arbitrary name for the RESTCONF listen endpoint.";
        }
        choice transport {
          mandatory true;
          description
            "Selects between available transports.";
          case tls {
            if-feature tls-listen;
            container tls {
              description
                "TLS-specific listening configuration for inbound
                 connections.";
              uses ts:listening-tls-server-grouping {
                refine port {
                  default 443;
                }
                augment "client-auth" {
                  description
                    "Augments in the cert-to-name structure.";
                  uses cert-maps-grouping;
                }
              }
            }
          }
        }
      }
    }

    container call-home {
      if-feature tls-call-home;
      description
        "Configures call-home behavior";
      list restconf-client {
        key name;
        description
          "List of RESTCONF clients the RESTCONF server is to
           initiate call-home connections to.";
        leaf name {
          type string;
          description
            "An arbitrary name for the remote RESTCONF client.";
        }
        choice transport {
          mandatory true;
          description
            "Selects between TLS and any transports augmented in.";



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          case tls {
            if-feature tls-call-home;
            container tls {
              description
                "Specifies TLS-specific call-home transport
                 configuration.";
              uses endpoints-container {
                refine endpoints/endpoint/port {
                  default 9999;
                }
              }
              uses ts:non-listening-tls-server-grouping {
                augment "client-auth" {
                  description
                    "Augments in the cert-to-name structure.";
                  uses cert-maps-grouping;
                }
              }
            }
          }
        }
        container connection-type {
          description
           "Indicates the RESTCONF client's preference for how the
            RESTCONF server's connection is maintained.";
          choice connection-type {
            description
              "Selects between available connection types.";
            case persistent-connection {
              container persistent {
                presence true;
                description
                 "Maintain a persistent connection to the RESTCONF
                  client. If the connection goes down, immediately
                  start trying to reconnect to it, using the
                  reconnection strategy.

                  This connection type minimizes any RESTCONF client
                  to RESTCONF server data-transfer delay, albeit at
                  the expense of holding resources longer.";

                container keep-alives {
                  description
                    "Configures the keep-alive policy, to proactively
                     test the aliveness of the TLS client.  An
                     unresponsive TLS client will be dropped after
                     approximately (max-attempts * max-wait) seconds.";
                  reference



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                    "RFC YYYY: NETCONF Call Home and RESTCONF Call Home,
                     Section 3.1, item S6";
                  leaf max-wait {
                    type uint16 {
                      range "1..max";
                    }
                    units seconds;
                    default 30;
                    description
                     "Sets the amount of time in seconds after which
                      if no data has been received from the TLS
                      client, a TLS-level message will be sent to
                      test the aliveness of the TLS client.";
                  }
                  leaf max-attempts {
                    type uint8;
                    default 3;
                    description
                     "Sets the number of sequential keep-alive messages
                      that can fail to obtain a response from the TLS
                      client before assuming the TLS client is no
                      longer alive.";
                  }
                }
              }
            }
            case periodic-connection {
              container periodic {
                presence true;
                description
                 "Periodically connect to the RESTCONF client, so that
                  the RESTCONF client may deliver messages pending for
                  the RESTCONF server.  The RESTCONF client is expected
                  to close the connection when it is ready to release
                  it, thus starting the RESTCONF server's timer until
                  next connection.";
                leaf reconnect-timeout {
                  type uint16 {
                    range "1..max";
                  }
                  units minutes;
                  default 60;
                  description
                   "The maximum amount of unconnected time the RESTCONF
                    server will wait before re-establishing a connection
                    to the RESTCONF client.  The RESTCONF server may
                    initiate a connection before this time if desired
                    (e.g., to deliver a notification).";



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                }
              }
            }
          }
        }
        container reconnect-strategy {
          description
           "The reconnection strategy guides how a RESTCONF server
            reconnects to an RESTCONF client, after losing a connection
            to it, even if due to a reboot.  The RESTCONF server starts
            with the specified endpoint and tries to connect to it
            max-attempts times before trying the next endpoint in the
            list (round robin).";
          leaf start-with {
            type enumeration {
              enum first-listed {
                description
                  "Indicates that reconnections should start with
                   the first endpoint listed.";
              }
              enum last-connected {
                description
                  "Indicates that reconnections should start with
                   the endpoint last connected to.  If no previous
                   connection has ever been established, then the
                   first endpoint configured is used.   RESTCONF
                   servers SHOULD be able to remember the last
                   endpoint connected to across reboots.";
              }
            }
            default first-listed;
            description
             "Specifies which of the RESTCONF client's endpoints the
              RESTCONF server should start with when trying to connect
              to the RESTCONF client.";
          }
          leaf max-attempts {
            type uint8 {
              range "1..max";
            }
            default 3;
            description
             "Specifies the number times the RESTCONF server tries to
              connect to a specific endpoint before moving on to the
              next endpoint in the list (round robin).";
          }
        }
      }



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    }
  }


  grouping cert-maps-grouping {
    description
      "A grouping that defines a container around the
       cert-to-name structure defined in RFC 7407.";
    container cert-maps {
      uses x509c2n:cert-to-name;
      description
       "The cert-maps container is used by a TLS-based RESTCONF
        server to map the RESTCONF client's presented X.509
        certificate to a RESTCONF username.  If no matching and
        valid cert-to-name list entry can be found, then the
        RESTCONF server MUST close the connection, and MUST NOT
        accept RESTCONF messages over it.";
      reference
        "RFC XXXX: The RESTCONF Protocol";
    }
  }


  grouping endpoints-container {
    description
      "This grouping is used by tls container for call-home
       configurations.";
    container endpoints {
      description
        "Container for the list of endpoints.";
      list endpoint {
        key name;
        min-elements 1;
        ordered-by user;
        description
          "User-ordered list of endpoints for this RESTCONF client.
           Defining more than one enables high-availability.";
        leaf name {
          type string;
          description
            "An arbitrary name for this endpoint.";
        }
        leaf address {
          type inet:host;
          mandatory true;
          description
           "The IP address or hostname of the endpoint.  If a
            hostname is configured and the DNS resolution results



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            in more than one IP address, the RESTCONF server
            will process the IP addresses as if they had been
            explicitly configured in place of the hostname.";
        }
        leaf port {
          type inet:port-number;
          description
           "The IP port for this endpoint. The RESTCONF server will
            use the IANA-assigned well-known port if no value is
            specified.";
        }
      }
    }
  }


}


<CODE ENDS>

5.  Design Considerations

   The manner that the both local and remote endpoints have been
   specified in the ietf-netconf-server and ietf-rest-server modules
   does not directly support virtual routing and forwarding (VRF),
   though they have been specified in such a way to enable external
   modules will augment in VRF designations when needed.

   This document uses PKCS #10 [RFC2986] for the "generate-certificate-
   signing-request" action.  The use of Certificate Request Message
   Format (CRMF) [RFC4211] was considered, but is was unclear if there
   was market demand for it, and so support for CRMF has been left out
   of this specification.  If it is desired to support CRMF in the
   future, placing a "choice" statement in both the input and output
   statements, along with an "if-feature" statement on the CRMF option,
   would enable a backwards compatible solution.

   This document puts a limit of the number of elliptical curves
   supported.  This was done to match industry trends in IETF best
   practice (e.g., matching work being done in TLS 1.3).  In additional
   algorithms are needed, they MAY be augmented in by another module, or
   added directly in a future version of this document.

   Both this document and Key Chain YANG Data Model
   [draft-ietf-rtgwg-yang-key-chain] define keychain YANG modules.  The
   authors looked at this and agree that they two modules server
   different purposes and hence not worth merging into one document.  To



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   underscore this further, this document renamed its module from "ietf-
   keychain" to "ietf-system-keychain" and that other document renamed
   its module from "ietf-key-chain" to "ietf-routing-key-chain".

   For the trusted-certificates list, Trust Anchor Format [RFC5914] was
   evaluated and deemed inappropriate due to this document's need to
   also support pinning.  That is, pinning a client-certificate to
   support NETCONF over TLS client authentication.

6.  Security Considerations

   This document defines a keychain mechanism that is entrusted with the
   safe keeping of private keys, and the safe keeping of trusted
   certificates.  Nowhere in this API is there an ability to access
   (read out) a private key once it is known to the keychain.  Further,
   associated public keys and attributes (e.g., algorithm name, key
   length, etc.) are read-only.  That said, this document allows for the
   deletion of private keys and their certificates, as well the deletion
   of trusted certificates.  Access control mechanisms (e.g., NACM
   [RFC6536]) MUST be in place so as to authorize such client actions.
   Further, whilst the data model allows for private keys and trusted
   certificates in general to be deleted, implementations should be well
   aware that some privates keys (e.g., those in a TPM) and some trusted
   certificates, should never be deleted, regardless if the
   authorization mechanisms would generally allow for such actions.

   For the "generate-certificate-signing-request" action, it is
   RECOMMENDED that devices implement assert channel binding [RFC5056],
   so as to ensure that the application layer that sent the request is
   the same as the device authenticated in the secure transport layer
   was established.

   This document defines a data model that includes a list of private
   keys.  These private keys MAY be deleted using standard NETCONF or
   RESTCONF operations (e.g., <edit-config>).  Implementations SHOULD
   automatically (without explicit request) zeroize these keys in the
   most secure manner available, so as to prevent the remnants of their
   persisted storage locations from being analyzed in any meaningful
   way.

   The keychain module define within this document defines the "load-
   private-key" action enabling a device to load a client-supplied
   private key.  This is a private key with no shrouding to protect it.
   The strength of this private key MUST NOT be greater than the
   strength of the underlying secure transport connection over which it
   is communicated.  Devices SHOULD fail this request if ever the
   strength of the private key is greater then the strength of the
   underlying transport.



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   A denial of service (DoS) attack MAY occur if the NETCONF server
   limits the maximum number of NETCONF sessions it will accept (i.e.
   the 'max-sessions' field in the ietf-netconf-server module is not
   zero) and either the "hello-timeout" or "idle-timeout" fields in
   ietf-netconf-server module have been set to indicate the NETCONF
   server should wait forever (i.e. set to zero).

7.  IANA Considerations

7.1.  The IETF XML Registry

   This document registers two URIs in the IETF XML registry [RFC2119].
   Following the format in [RFC3688], the following registrations are
   requested:

      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.

      URI: urn:ietf:params:xml:ns:yang:ietf-restconf-server
      Registrant Contact: The NETCONF WG of the IETF.
      XML: N/A, the requested URI is an XML namespace.

7.2.  The YANG Module Names Registry

   This document registers five YANG modules in the YANG Module Names
   registry [RFC6020].  Following the format in [RFC6020], the the
   following registrations are requested:























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      name:         ietf-system-keychain
      namespace:    urn:ietf:params:xml:ns:yang:ietf-system-keychain
      prefix:       kc
      reference:    RFC VVVV

      name:         ietf-ssh-server
      namespace:    urn:ietf:params:xml:ns:yang:ietf-ssh-server
      prefix:       ssvr
      reference:    RFC VVVV

      name:         ietf-tls-server
      namespace:    urn:ietf:params:xml:ns:yang:ietf-tls-server
      prefix:       tsvr
      reference:    RFC VVVV

      name:         ietf-netconf-server
      namespace:    urn:ietf:params:xml:ns:yang:ietf-netconf-server
      prefix:       ncsvr
      reference:    RFC VVVV

      name:         ietf-restconf-server
      namespace:    urn:ietf:params:xml:ns:yang:ietf-restconf-server
      prefix:       rcsvr
      reference:    RFC VVVV

8.  Acknowledgements

   The authors would like to thank for following for lively discussions
   on list and in the halls (ordered by last name): Andy Bierman, Martin
   Bjorklund, Benoit Claise, Mehmet Ersue, David Lamparter, Alan Luchuk,
   Ladislav Lhotka, Radek Krejci, Tom Petch, Phil Shafer, Sean Turner,
   and Bert Wijnen.

   Juergen Schoenwaelder and was partly funded by Flamingo, a Network of
   Excellence project (ICT-318488) supported by the European Commission
   under its Seventh Framework Programme.

9.  References

9.1.  Normative References

   [draft-ietf-netconf-call-home]
              Watsen, K., "NETCONF Call Home and RESTCONF Call Home",
              draft-ieft-netconf-call-home-02 (work in progress), 2014.







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   [draft-ietf-netconf-restconf]
              Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
              Protocol", draft-ieft-netconf-restconf-04 (work in
              progress), 2014.

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

   [RFC2986]  Nystrom, M. and B. Kaliski, "PKCS #10: Certification
              Request Syntax Specification Version 1.7", RFC 2986,
              DOI 10.17487/RFC2986, November 2000,
              <http://www.rfc-editor.org/info/rfc2986>.

   [RFC4253]  Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH)
              Transport Layer Protocol", RFC 4253, DOI 10.17487/RFC4253,
              January 2006, <http://www.rfc-editor.org/info/rfc4253>.

   [RFC5280]  Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
              Housley, R., and W. Polk, "Internet X.509 Public Key
              Infrastructure Certificate and Certificate Revocation List
              (CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008,
              <http://www.rfc-editor.org/info/rfc5280>.

   [RFC5958]  Turner, S., "Asymmetric Key Packages", RFC 5958,
              DOI 10.17487/RFC5958, August 2010,
              <http://www.rfc-editor.org/info/rfc5958>.

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

   [RFC6187]  Igoe, K. and D. Stebila, "X.509v3 Certificates for Secure
              Shell Authentication", RFC 6187, DOI 10.17487/RFC6187,
              March 2011, <http://www.rfc-editor.org/info/rfc6187>.

   [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,
              <http://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,
              <http://www.rfc-editor.org/info/rfc6242>.





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   [RFC6991]  Schoenwaelder, J., Ed., "Common YANG Data Types",
              RFC 6991, DOI 10.17487/RFC6991, July 2013,
              <http://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, <http://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,
              <http://www.rfc-editor.org/info/rfc7589>.

9.2.  Informative References

   [draft-ietf-rtgwg-yang-key-chain]
              Lindem, A., Qu, Y., Yeung, D., Chen, I., Zhang, J., and Y.
              Yang, "Key Chain YANG Data Model", draft-ietf-rtgwg-yang-
              key-chain (work in progress), 2016,
              <https://tools.ietf.org/html/draft-ietf-rtgwg-yang-key-
              chain>.

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

   [RFC4211]  Schaad, J., "Internet X.509 Public Key Infrastructure
              Certificate Request Message Format (CRMF)", RFC 4211,
              DOI 10.17487/RFC4211, September 2005,
              <http://www.rfc-editor.org/info/rfc4211>.

   [RFC5056]  Williams, N., "On the Use of Channel Bindings to Secure
              Channels", RFC 5056, DOI 10.17487/RFC5056, November 2007,
              <http://www.rfc-editor.org/info/rfc5056>.

   [RFC5914]  Housley, R., Ashmore, S., and C. Wallace, "Trust Anchor
              Format", RFC 5914, DOI 10.17487/RFC5914, June 2010,
              <http://www.rfc-editor.org/info/rfc5914>.

   [RFC6536]  Bierman, A. and M. Bjorklund, "Network Configuration
              Protocol (NETCONF) Access Control Model", RFC 6536,
              DOI 10.17487/RFC6536, March 2012,
              <http://www.rfc-editor.org/info/rfc6536>.







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Appendix A.  Change Log

A.1.  00 to 01

   o  Restructured document so it flows better

   o  Added trusted-ca-certs and trusted-client-certs objects into the
      ietf-system-tls-auth module

A.2.  01 to 02

   o  removed the "one-to-many" construct

   o  removed "address" as a key field

   o  removed "network-manager" terminology

   o  moved open issues to github issues

   o  brought TLS client auth back into model

A.3.  02 to 03

   o  fixed tree diagrams and surrounding text

A.4.  03 to 04

   o  reduced the number of grouping statements

   o  removed psk-maps and associated feature statements

   o  added ability for listen/call-home instances to specify which
      host-keys/certificates (of all listed) to use

   o  clarified that last-connected should span reboots

   o  added missing "objectives" for selecting which keys to use,
      authenticating client-certificates, and mapping authenticated
      client-certificates to usernames

   o  clarified indirect client certificate authentication

   o  added keep-alive configuration for listen connections

   o  added global-level NETCONF session parameters






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A.5.  04 to 05

   o  Removed all refs to the old ietf-system-tls-auth module

   o  Removed YANG 1.1 style if-feature statements (loss some
      expressiveness)

   o  Removed the read-only (config false) lists of SSH host-keys and
      TLS certs

   o  Added an if-feature around session-options container

   o  Added ability to configure trust-anchors for SSH X.509 client
      certs

   o  Now imports by revision, per best practice

   o  Added support for RESTCONF server

   o  Added RFC Editor instructions

A.6.  05 to 06

   o  Removed feature statement on the session-options container (issue
      #21).

   o  Added NACM statements to YANG modules for sensitive nodes (issue
      #24).

   o  Fixed default RESTCONF server port value to be 443 (issue #26).

   o  Added client-cert-auth subtree to ietf-restconf-server module
      (issue #27).

   o  Updated draft-ietf-netmod-snmp-cfg reference to RFC 7407 (issue
      #28).

   o  Added description statements for groupings (issue #29).

   o  Added description for braces to tree diagram section (issue #30).

   o  Renamed feature from "rfc6187" to "ssh-x509-certs" (issue #31).

A.7.  06 to 07

   o  Replaced "application" with "NETCONF/RESTCONF client" (issue #32).

   o  Reverted back to YANG 1.1 if-feature statements (issue #34).



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   o  Removed import by revisions (issue #36).

   o  Removed groupings only used once (issue #37).

   o  Removed upper-bound on hello-timeout, idle-timeout, and max-
      sessions (issue #38).

   o  Clarified that when no listen address is configured, the NETCONF/
      RESTCONF server will listen on all addresses (issue #41).

   o  Update keep-alive reference to new section in Call Home draft
      (issue #42).

   o  Modified connection-type/persistent/keep-alives/interval-secs
      default value, removed the connection-type/periodic/linger-secs
      node, and also removed the reconnect-strategy/interval-secs node
      (issue #43).

   o  Clarified how last-connected reconnection type should work across
      reboots (issue #44).

   o  Clarified how DNS-expanded hostnames should be processed (issue
      #45).

   o  Removed text on how to implement keep-alives (now in the call-home
      draft) and removed the keep-alive configuration for listen
      connections (issue #46).

   o  Clarified text for .../periodic-connection/timeout-mins (issue
      #47).

   o  Fixed description on the "trusted-ca-certs" leaf-list (issue #48).

   o  Added optional keychain-based solution in appendix A (issue #49).

   o  Fixed description text for the interval-secs leaf (issue #50).

   o  moved idle-time into the listen, persistent, and periodic subtrees
      (issue #51).

   o  put presence statements on containers where it makes sense (issue
      #53).

A.8.  07 to 08

   o  Per WG consensus, replaced body with the keychain-based approach
      described in -07's Appendix.




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   o  Added a lot of introductory text, improved examples, and what not.

A.9.  08 to 09

   o  Renamed ietf-keychain to ietf-system-keychain to disambiguate from
      the routing area working group's keychain model (they similarly
      renamed their model from ietf-key-chain to ietf-routing-key-
      chain).

   o  Added an action statement to ietf-system-keychain to load a
      private key.

   o  Added a notification statement to ietf-system-keychain to notify
      when a certificate is nearing expiration and beyond.

   o  Converted all binary types to use ASN.1 DER encoding.

   o  Added a Design Considerations section.

   o  Filled in the Security Considerations section.

   o  Removed the Other Considerations section.

   o  Extended the Editorial Note section.

   o  Added many Normative and Informative references.

Appendix B.  Open Issues

   Please see: https://github.com/netconf-wg/server-model/issues.

Authors' Addresses

   Kent Watsen
   Juniper Networks

   EMail: kwatsen@juniper.net


   Juergen Schoenwaelder
   Jacobs University Bremen

   EMail: j.schoenwaelder@jacobs-university.de








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