NETCONF Working Group                                          K. Watsen
Internet-Draft                                          Juniper Networks
Intended status: Standards Track                        J. Schoenwaelder
Expires: January 7, April 11, 2016                         Jacobs University Bremen
                                                            July 6,
                                                         October 9, 2015

        NETCONF Server and RESTCONF Server Configuration Models
                   draft-ietf-netconf-server-model-07
                   draft-ietf-netconf-server-model-08

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 other related configuration
   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

   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

   o  "ZZZZ" --> the assigned RFC value for draft-thomson-httpbis-cant

   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  "2015-07-06"  "2015-10-09" --> the publication date of this draft

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

   o  Appendix B.  Change Log

   o  Appendix C.  Open Issues

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
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   Internet-Drafts are draft documents valid for a maximum of six months
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   This Internet-Draft will expire on January 7, April 11, 2016.

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   Copyright (c) 2015 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   4
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   4
     1.2.  Tree Diagrams . . . . . . . . . . . . . . . . . . . . . .   5   4
   2.  Objectives  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     2.1.  Support all NETCONF and RESTCONF transports . . . . . . .   5
     2.2.  Enable each transport to select which keys to use . . . .   5
     2.3.  Support authenticating NETCONF/RESTCONF clients
           certificates  . . . . . . . . . . . . . . . . . . . . . .   6   5
     2.4.  Support mapping authenticated NETCONF/RESTCONF client
           certificates to usernames . . . . . . . . . . . . . . . .   6   5
     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 . . . .   6
       2.6.2.  Support NETCONF/RESTCONF clients having more than one
               endpoint  . . . . . . . . . . . . . . . . . . . . . .   6
       2.6.3.  Support a reconnection strategy . . . . . . . . . . .   7   6
       2.6.4.  Support both persistent and periodic connections  . .   7   6
       2.6.5.  Reconnection strategy for periodic connections  . . .   7
       2.6.6.  Keep-alives for persistent connections  . . . . . . .   7
       2.6.7.  Customizations for periodic connections . . . . . . .   8   7
   3.  The NETCONF Server Model  High-Level Design . . . . . . . . . . . . . . . . . .   8
     3.1.  Tree Diagram . . . .   7
   4.  Solution  . . . . . . . . . . . . . . . . . .   8
     3.2.  Example Usage . . . . . . . .   8
     4.1.  The Keychain Model  . . . . . . . . . . . . . .   9
       3.2.1.  Configuring SSH Transport . . . . .   8
       4.1.1.  Tree Diagram  . . . . . . . . .  10
       3.2.2.  Configuring TLS Transport . . . . . . . . . . .   9
       4.1.2.  Example Usage . . .  11
     3.3.  YANG Model . . . . . . . . . . . . . . . . .   9
       4.1.3.  YANG Model  . . . . . .  13
   4.  The RESTCONF Server Model . . . . . . . . . . . . . . .  15
     4.2.  The SSH Server Model  . . .  26
     4.1.  Tree Diagram . . . . . . . . . . . . . . .  20
       4.2.1.  Tree Diagram  . . . . . . .  26
     4.2.  Example Usage . . . . . . . . . . . . .  21
       4.2.2.  Example Usage . . . . . . . . .  27
       4.2.1.  Configuring TLS Transport . . . . . . . . . . .  21
       4.2.3.  YANG Model  . . .  27
     4.3.  YANG Model . . . . . . . . . . . . . . . . . .  22
     4.3.  The TLS Server Model  . . . . . .  28
   5.  Security Considerations . . . . . . . . . . . .  26
       4.3.1.  Tree Diagram  . . . . . . .  37
   6.  IANA Considerations . . . . . . . . . . . . .  26
       4.3.2.  Example Usage . . . . . . . .  38
   7.  Other Considerations . . . . . . . . . . . .  27
       4.3.3.  YANG Model  . . . . . . . .  39
   8.  Acknowledgements . . . . . . . . . . . . .  27
     4.4.  The NETCONF Server Model  . . . . . . . . .  39
   9.  References . . . . . . .  31
       4.4.1.  Tree Diagram  . . . . . . . . . . . . . . . . . .  39
     9.1.  Normative References . .  31
       4.4.2.  Example Usage . . . . . . . . . . . . . . . .  39
     9.2.  Informative References . . . .  33
       4.4.3.  YANG Model  . . . . . . . . . . . . .  40
   Appendix A.  Alternative solution addressing Issue #49 . . . . .  41
     A.1.  The Keychain Model . . .  37
     4.5.  The RESTCONF Server Model . . . . . . . . . . . . . . . .  41
       A.1.1.  47
       4.5.1.  Tree Diagram  . . . . . . . . . . . . . . . . . . . .  41
       A.1.2.  47
       4.5.2.  Example Usage . . . . . . . . . . . . . . . . . . . .  42
       A.1.3.  49
       4.5.3.  YANG Model  . . . . . . . . . . . . . . . . . . . . .  45
     A.2.  The SSH Server Model  . . .  51
   5.  Security Considerations . . . . . . . . . . . . . . .  52
       A.2.1.  Tree Diagram . . . .  59
   6.  IANA Considerations . . . . . . . . . . . . . . . .  52
       A.2.2.  Example Usage . . . . .  59
   7.  Other Considerations  . . . . . . . . . . . . . . .  53
       A.2.3.  YANG Model . . . . .  60
   8.  Acknowledgements  . . . . . . . . . . . . . . . .  53
     A.3.  The TLS Server Model . . . . . .  60
   9.  References  . . . . . . . . . . . .  56
       A.3.1.  Tree Diagram . . . . . . . . . . . . .  60
     9.1.  Normative References  . . . . . . .  56
       A.3.2.  Example Usage . . . . . . . . . . .  61
     9.2.  Informative References  . . . . . . . . .  57
       A.3.3.  YANG Model . . . . . . . .  61
   Appendix A.  Change Log . . . . . . . . . . . . .  57
     A.4.  The NETCONF Server Model . . . . . . . .  62
     A.1.  00 to 01  . . . . . . . .  60
       A.4.1.  Tree Diagram . . . . . . . . . . . . . . . .  62
     A.2.  01 to 02  . . . .  60
       A.4.2.  Example Usage . . . . . . . . . . . . . . . . . . . .  62
       A.4.3.  YANG Model  .
     A.3.  02 to 03  . . . . . . . . . . . . . . . . . . . .  64
     A.5.  The RESTCONF Server Model . . . .  62
     A.4.  03 to 04  . . . . . . . . . . . .  75
       A.5.1.  Tree Diagram . . . . . . . . . . . .  62
     A.5.  04 to 05  . . . . . . . .  75
       A.5.2.  Example Usage . . . . . . . . . . . . . . . .  63
     A.6.  05 to 06  . . . .  76
       A.5.3.  YANG Model . . . . . . . . . . . . . . . . . . . . .  76
   Appendix B.  Change Log . . . . . . . . . . . . . . . . . . . . .  84
     B.1.  00 to 01  . . . . . . . . . . . . . . . . . . . . . . . .  84
     B.2.  01 to 02  . . . . . . . . . . . . . . . . . . . . . . . .  84
     B.3.  02 to 03  . . . . . . . . . . . . . . . . . . . . . . . .  84
     B.4.  03 to 04  . . . . . . . . . . . . . . . . . . . . . . . .  84
     B.5.  04 to 05  . . . . . . . . . . . . . . . . . . . . . . . .  85
     B.6.  05 to  63
     A.7.  06 to 07  . . . . . . . . . . . . . . . . . . . . . . . .  85
     B.7.  06 to  63
     A.8.  07 to 08  . . . . . . . . . . . . . . . . . . . . . . . .  86  64
   Appendix C. B.  Open Issues  . . . . . . . . . . . . . . . . . . . .  87  65

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 other related configuration parameters.

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.

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.

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 thei 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.

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 Server Model

3.1.  Tree Diagram

   module: ietf-netconf-server
      +--rw netconf-server
         +--rw session-options 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-keychain|
                     +-------------+
                         ^    ^
                         |  +--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
              <leafref>  |     +--rw (transport)    |        +--:(ssh) {ssh-listen}?  <leafref>
            +------------+    +------------+
            |                              |  +--rw ssh
     +---------------+            +------------------+
     |ietf-ssh-server|            | ietf-tls-server  |     +--rw address?     inet:ip-address
     +---------------+            +------------------+
       ^                               ^       ^
       | <uses>                        |     +--rw port?        inet:port-number       |
       |     +--rw host-keys            <augments>         |       |        +--rw host-key*   string
       |        +--:(tls) {tls-listen}?          +--------------------+       |           +--rw tls <augments>
       |              +--rw address?        inet:ip-address          |              +--rw port?           inet:port-number                            |              +--rw
   +-------------------+         +--------------------+
   |ietf-netconf-server|         |ietf-restconf-server|
   +-------------------+         +--------------------+

4.  Solution

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

4.1.  The Keychain Model

   The keychain model depicted 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.  Though private keys can only be created
      via an RPC (see bullet #3 below), the entries of the list may be
      renamed and have certificates
         | associated with them 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 request the server to generate a new private key using
      the specified algorithm and key length.

   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 set using a standard configuration change request
      (e.g., <edit-config>).

4.1.1.  Tree Diagram

   module: ietf-keychain
      +--rw certificate*   string keychain
         +--rw call-home {(ssh-call-home or tls-call-home)}? private-keys
         |  +--rw netconf-client* private-key* [name]
         |  |  +--rw name                                    string
         |     +--rw (transport)  |     |  +--:(ssh) {ssh-call-home}?  +--ro algorithm?                              enumeration
         |  |  +--ro key-length?                             uint32
         |  +--rw ssh  |  +--ro public-key?                             string
         |  |  +--rw endpoints
         | certificates
         |  |  |  +--rw endpoint* certificate* [name]
         |  |  |     |     +--rw name     string
         |  |  |     |     +--rw address    inet:host chain?   binary
         |  |  +---x generate-certificate-signing-request
         |  |     +--rw port?      inet:port-number     +---w input
         |  |     |     +--rw host-keys  +---w subject       binary
         |  |     |        +--rw host-key*   string  +---w attributes?   binary
         |  |  +--:(tls) {tls-call-home}?     +--ro output
         |  |     +--rw tls        +--ro certificate-signing-request    binary
         |  +---x generate-private-key
         |        +--rw endpoints     +---w input
         |        +---w name          string
         |        +---w algorithm     enumeration
         |        +---w key-length?   uint32
         +--rw endpoint* trusted-certificates* [name]
         |     |        |
            +--rw name                   string
         |     |        |     +--rw address    inet:host
         |     |        |     +--rw port?      inet:port-number
         |     |
            +--rw certificates
         |     |           +--rw certificate* description?           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
         +--rw ssh {(ssh-listen or ssh-call-home)}?
         |  +--rw x509 {ssh-x509-certs}?
         |     +--rw trusted-ca-certs
         |     |  +--rw trusted-ca-cert*   binary
         |     +--rw trusted-client-certs
         |        +--rw trusted-client-cert*   binary
         +--rw tls {(tls-listen or tls-call-home)}?
            +--rw client-auth
               +--rw trusted-ca-certs
               |  +--rw trusted-ca-cert*   binary
               +--rw trusted-client-certs
               |  +--rw trusted-client-cert*   binary
               +--rw cert-maps
                  +--rw cert-to-name* [id]
                     +--rw id             uint32
                     +--rw fingerprint    x509c2n:tls-fingerprint
                     +--rw map-type       identityref trusted-certificate* [name]
               +--rw name           string

3.2.
               +--rw certificate?   binary

4.1.2.  Example Usage
3.2.1.  Configuring SSH Transport

   The following example illustrates the <get> response from a NETCONF
   server that only supports SSH, both listening "generate-private-key" RPC in
   use with the RESTCONF protocol and JSON encoding.

   REQUEST
   -------

     ['\' line wrapping added for incoming
   connections as well as calling home to a single NETCONF/RESTCONF
   client having two endpoints.

<netconf-server xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-server">
  <listen>
    <endpoint>
      <name>netconf/ssh</name>
      <ssh>
        <address>11.22.33.44</address>
        <host-keys>
          <host-key>my-rsa-key</host-key>
          <host-key>my-dss-key</host-key>
        </host-keys>
      </ssh>
    </endpoint>
  </listen>
  <call-home>
    <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>my-call-home-x509-key</host-key>
        </host-keys>
      </ssh>
    </netconf-client>
  </call-home>
  <ssh>
    <x509>
      <trusted-ca-certs>
        <trusted-ca-cert>
          QW4gRWFzdGVyIGVnZywgZm9yIHRob3NlIHdobyBtaWdodCBsb29rICA6KQo=
        </trusted-ca-cert>
      </trusted-ca-certs>
      <trusted-client-certs>
        <trusted-client-cert>
          SSBhbSB0aGUgZWdnIG1hbiwgdGhleSBhcmUgdGhlIGVnZyBtZW4uCg==
        </trusted-client-cert>
        <trusted-client-cert>
          SSBhbSB0aGUgd2FscnVzLCBnb28gZ29vIGcnam9vYi4K
        </trusted-client-cert>
      </trusted-client-certs>
    </x509>
  </ssh>
</netconf-server>

3.2.2.  Configuring TLS Transport formatting only]

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

     {
       "ietf-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 <get> response from a action statement "generate-
   certificate-signing-request" action in use with the NETCONF
   server that only supports TLS, both listening for incoming
   connections as well as calling home to 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-keychain">
           <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-keychain">
          LS0tLS1CRUdJTiBDRVJUSUZJQ0FURS0tLS0tCk1JSUNrekNDQWZ5Z
          0F3SUJBZ0lKQUpRT2t3bGpNK2pjTUEwR0NTcUdTSWIzRFFFQkJRVU
          FNRFF4Q3pBSkJnTlYKQkFZVEFsVlRNUkF3RGdZRFZRUUtFd2RsZUd
          GdGNHeGxNUk13RVFZRFZRUURFd3BEVWt3Z1NYTnpkV1Z5TUI0WApE
          diR1V4RXpBUkJnTlZCQU1UQ2tOU1RDQkpjM04xWlhJd2daOHdEUVl
          KS29aSWh2Y04KQVFFQkJRQURnWTBBTUlHSkFvR0JBTXVvZmFPNEV3
          El1QWMrQ1RsTkNmc0d6cEw1Um5ydXZsOFRIcUJTdGZQY3N0Zk1KT1
          FaNzlnNlNWVldsMldzaHE1bUViCkJNNitGNzdjbTAvU25FcFE0TnV
          bXBDT2YKQWdNQkFBR2pnYXd3Z2Frd0hRWURWUjBPQkJZRUZKY1o2W
          URiR0lPNDB4ajlPb3JtREdsRUNCVTFNR1FHQTFVZApJd1JkTUZ1QU
          ZKY1o2WURiR0lPNDB4ajlPb3JtREdsRUNCVTFvVGlrTmpBME1Rc3d
          mMKTUE0R0ExVWREd0VCL3dRRUF3SUNCREFTQmdOVkhSTUJBZjhFQ0
          RBR0FRSC9BZ0VBTUEwR0NTcUdTSWIzRFFFQgpCUVVBQTRHQkFMMmx
          rWmFGNWcyaGR6MVNhZnZPbnBneHA4eG00SHRhbStadHpLazFlS3Bx
          TXp4YXJCbFpDSHlLCklVbC9GVzRtV1RQS1VDeEtFTE40NEY2Zmk2d
          c4d0tSSElkYW1WL0pGTmlQS0VXSTF4K1I1aDZmazcrQzQ1QXg1RWV
          SWHgzZjdVM2xZTgotLS0tLUVORCBDRVJUSUZJQ0FURS0tLS0tCg==
        </certificate-signing-request>
     </rpc-reply>

   The following example illustrates what a single NETCONF/RESTCONF
   client having two endpoints.  Please note 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 configurations for
   authenticating client 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-keychain">
     <!-- private keys and mappings authenticated associated certificates to NETCONF user names.

<netconf-server xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-server"
     xmlns:x509c2n="urn:ietf:params:xml:ns:yang:ietf-x509-cert-to-name">
  <listen>
    <endpoint>
      <name>netconf/tls</name>
      <tls>
        <address>11.22.33.44</address>
        <certificates>
          <certificate>fw1.east.example.com</certificate>
        </certificates>
      </tls>
    </endpoint>
  </listen>
  <call-home>
    <netconf-client>
      <name>config-mgr</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> -->
     <private-keys>
       <private-key>
         <name>ex-key-sect571r1</name>
         <algorithm>sect571r1</algorithm>
         <public-key>
           cztvaWRoc2RmZ2tqaHNkZmdramRzZnZzZGtmam5idnNvO2RmanZvO3NkZ
           mJpdmhzZGZpbHVidjtvc2lkZmhidml1bHNkYmZ2aXNiZGZpYmhzZG87Zm
           JvO3NkZ25iO29pLmR6Zgo=
         </public-key>
         <certificates>
          <certificate>IDevID Certificate</certificate>
           <certificate>
             <name>ex-key-sect571r1-cert</name>
             <data>
               LS0tLS1CRUdJTiBDRVJUSUZJQ0FURS0tLS0tCk1JSUNrekNDQWZ5Z
               0F3SUJBZ0lKQUpRT2t3bGpNK2pjTUEwR0NTcUdTSWIzRFFFQkJRVU
               FNRFF4Q3pBSkJnTlYKQkFZVEFsVlRNUkF3RGdZRFZRUUtFd2RsZUd
               GdGNHeGxNUk13RVFZRFZRUURFd3BEVWt3Z1NYTnpkV1Z5TUI0WApE
               diR1V4RXpBUkJnTlZCQU1UQ2tOU1RDQkpjM04xWlhJd2daOHdEUVl
               KS29aSWh2Y04KQVFFQkJRQURnWTBBTUlHSkFvR0JBTXVvZmFPNEV3
               El1QWMrQ1RsTkNmc0d6cEw1Um5ydXZsOFRIcUJTdGZQY3N0Zk1KT1
               FaNzlnNlNWVldsMldzaHE1bUViCkJNNitGNzdjbTAvU25FcFE0TnV
               bXBDT2YKQWdNQkFBR2pnYXd3Z2Frd0hRWURWUjBPQkJZRUZKY1o2W
               URiR0lPNDB4ajlPb3JtREdsRUNCVTFNR1FHQTFVZApJd1JkTUZ1QU
               ZKY1o2WURiR0lPNDB4ajlPb3JtREdsRUNCVTFvVGlrTmpBME1Rc3d
               mMKTUE0R0ExVWREd0VCL3dRRUF3SUNCREFTQmdOVkhSTUJBZjhFQ0
               RBR0FRSC9BZ0VBTUEwR0NTcUdTSWIzRFFFQgpCUVVBQTRHQkFMMmx
               rWmFGNWcyaGR6MVNhZnZPbnBneHA4eG00SHRhbStadHpLazFlS3Bx
               TXp4YXJCbFpDSHlLCklVbC9GVzRtV1RQS1VDeEtFTE40NEY2Zmk2d
               c4d0tSSElkYW1WL0pGTmlQS0VXSTF4K1I1aDZmazcrQzQ1QXg1RWV
               SWHgzZjdVM2xZTgotLS0tLUVORCBDRVJUSUZJQ0FURS0tLS0tCg==
             </data>
           </certificate>
         </certificates>
      </tls>
    </netconf-client>
  </call-home>
  <tls>
    <client-auth>
      <trusted-ca-certs>
        <trusted-ca-cert>
          WmdsK2gyTTg3QmtGMjhWbW1CdFFVaWc3OEgrRkYyRTFwdSt4ZVRJbVFFM
          lLQllsdWpOcjFTMnRLR05EMUc2OVJpK2FWNGw2NTdZNCtadVJMZgpRYjk
          zSFNwSDdwVXBCYnA4dmtNanFtZjJma3RqZHBxeFppUUtTbndWZTF2Zwot
          NGcEk3UE90cnNFVjRwTUNBd0VBQWFPQ0FSSXdnZ0VPCk1CMEdBMVVkRGd
          VEJiZ0JTWEdlbUEKMnhpRHVOTVkvVHFLNWd4cFJBZ1ZOYUU0cERZd05ER
          V6QVJCZ05WQkFNVENrTlNUQ0JKYzNOMVpYS0NDUUNVRHBNSll6UG8zREF
          NQmdOVkhSTUJBZjhFCkFqQUFNQTRHQTFVZER3RUIvd1FFQXdJSGdEQnBC
          Z05WSFI4RVlqQmdNRjZnSXFBZ2hoNW9kSFJ3T2k4dlpYaGgKYlhCc1pTN
          WpiMjB2WlhoaGJYQnNaUzVqY215aU9LUTJNRFF4Q3pBSkJnTlZCQVlUQW
          QmdOVkJBWVRBbFZUTVJBd0RnWURWUVFLRXdkbAplR0Z0Y0d4bE1RNHdEQ
          MkF6a3hqUDlVQWtHR0dvS1U1eUc1SVR0Wm0vK3B0R2FieXVDMjBRd2kvZ
          25PZnpZNEhONApXY0pTaUpZK2xtYWs3RTRORUZXZS9RdGp4NUlXZmdvN2
          RJSUJQFRStS0Cg==
        </trusted-ca-cert>
      </trusted-ca-certs>
      <trusted-client-certs>
        <trusted-client-cert>
       </private-key>
     </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==
        </trusted-client-cert>
        <trusted-client-cert>
         </certificate>
       </trusted-certificate>
       <trusted-certificate>
         <name>Fred Flinstone</name>
         <certificate>
           VlEVlFRREV3Vm9ZWEJ3ZVRDQm56QU5CZ2txaGtpRzl3MEJBUUVGQUFPQm
           pRQXdnWWtDCmdZRUE1RzRFSWZsS1p2bDlXTW44eUhyM2hObUFRaUhVUzV
           rRUpPQy9hSFA3eGJXQW1ra054ZStUa2hrZnBsL3UKbVhsTjhSZUd1ODhG
           NGcEk3UE90cnNFVjRwTUNBd0VBQWFPQ0FSSXdnZ0VPCk1CMEdBMVVkRGd
           VEJiZ0JTWEdlbUEKMnhpRHVOTVkvVHFLNWd4cFJBZ1ZOYUU0cERZd05ER
           V6QVJCZ05WQkFNVENrTlNUQ0JKYzNOMVpYS0NDUUNVRHBNSll6UG8zREF
           NQmdOVkhSTUJBZjhFCkFqQUFNQTRHQTFVZER3RUIvd1FFQXdJSGdEQnBC
           Z05WSFI4RVlqQmdNRjZnSXFBZ2hoNW9kSFJ3T2k4dlpYaGgKYlhCc1pTN
           WpiMjB2WlhoaGJYQnNaUzVqY215aU9LUTJNRFF4Q3pBSkJnTlZCQVlUQW
           xWVE1SQXdEZ1lEVlFRSwpFd2RsZUdGdGNHeGxNUk13RVFZRFZRUURFd3B
           EVWt3Z1NYTnpkV1Z5TUEwR0NTcUdTSWIzRFFFQkJRVUFBNEdCCkFFc3BK
           WmdsK2gyTTg3QmtGMjhWbW1CdFFVaWc3OEgrRkYyRTFwdSt4ZVRJbVFFM
           lLQllsdWpOcjFTMnRLR05EMUc2OVJpK2FWNGw2NTdZNCtadVJMZgpRYjk
           zSFNwSDdwVXBCYnA4dmtNanFtZjJma3RqZHBxeFppUUtTbndWZTF2Zwot
           QWtUOCBDRVUUZJ0RUF==
        </trusted-client-cert>
      </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>
</netconf-server>

3.3.
         </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
           Z05WSFI4RVlqQmdNRjZnSXFBZ2hoNW9kSFJ3T2k4dlpYaGgKYlhCc1pTN
           QmdOVkJBWVRBbFZUTVJBd0RnWURWUVFLRXdkbAplR0Z0Y0d4bE1RNHdEQ
           MkF6a3hqUDlVQWtHR0dvS1U1eUc1SVR0Wm0vK3B0R2FieXVDMjBRd2kvZ
           NQmdOVkhSTUJBZjhFCkFqQUFNQTRHQTFVZER3RUIvd1FFQXdJSGdEQnBC
           WmdsK2gyTTg3QmtGMjhWbW1CdFFVaWc3OEgrRkYyRTFwdSt4ZVRJbVFFM
           lLQllsdWpOcjFTMnRLR05EMUc2OVJpK2FWNGw2NTdZNCtadVJMZgpRYjk
           zSFNwSDdwVXBCYnA4dmtNanFtZjJma3RqZHBxeFppUUtTbndWZTF2Zwot
           25PZnpZNEhONApXY0pTaUpZK2xtYWs3RTRORUZXZS9RdGp4NUlXZmdvN2
           WpiMjB2WlhoaGJYQnNaUzVqY215aU9L=
         </certificate>
       </trusted-certificate>
     </trusted-certificates>

   </keychain>

4.1.3.  YANG Model

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

   <CODE BEGINS> file "ietf-netconf-server@2015-07-06.yang" "ietf-keychain@2015-10-09.yang"

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

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

  import ietf-netconf-acm {
    prefix nacm;                     // RFC 6536
  }
  import ietf-inet-types {           // RFC 6991
    prefix inet;
  }
  import ietf-x509-cert-to-name {    // RFC 7407 "urn:ietf:params:xml:ns:yang:ietf-keychain";
     prefix x509c2n;
  } "kc";

     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 defines a collection keychain to centralize management of YANG definitions for
    configuring NETCONF servers.
       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 "2015-07-06" "2015-10-09" {
       description
        "Initial version";
       reference
        "RFC VVVV: NETCONF Server and RESTCONF Server Configuration
                   Models";
     }
  // Features

  feature ssh-listen

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

  feature ssh-call-home generate a certificate signing requests.";

       container private-keys {
         description
     "The ssh-call-home feature indicates that
           "A list of private key maintained by 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 keychain.";
         list private-key {
           key name;
           description
     "The tls-listen feature indicates that the NETCONF server
      supports opening a port to accept NETCONF over TLS
      client connections.";
    reference
     "RFC 5539: Using
             "A private key.";
           leaf name {
             type string;
             description
               "An arbitrary name for the NETCONF Protocol over Transport
                Layer Security (TLS) with Mutual X.509
                Authentication"; private key.";
           }

  feature tls-call-home
           leaf algorithm {
             type enumeration {
               enum rsa { 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"; "TBD"; }

  feature ssh-x509-certs
               enum dsa { description
      "The ssh-x509-certs feature indicates that the NETCONF server
       supports RFC 6187";
    reference
      "RFC 6187: X.509v3 Certificates for Secure Shell Authentication"; "TBD"; }
  // top-level container  (groupings below)
  container netconf-server
               enum secp192r1 { description
      "Top-level container for NETCONF server configuration.";

    container session-options "TBD"; }
               enum sect163k1 {  // SHOULD WE REMOVE THIS ALTOGETHER? description
        "NETCONF session options, independent of transport
         or connection strategy.";
      leaf hello-timeout "TBD"; }
               enum sect163r2 {
        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."; "TBD"; }
               enum secp224r1 { description "TBD"; }

    container listen
               enum sect233k1 { description
        "Configures listen behavior";
      if-feature "(ssh-listen or tls-listen)";
      leaf max-sessions "TBD"; }
               enum sect233r1 {
        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."; "TBD"; }
               enum secp256r1 { description "TBD"; }
               enum sect283k1 { description "TBD"; }
               enum sect283r1 { description "TBD"; }
               enum secp384r1 { description "TBD"; }
               enum sect409k1 { description "TBD"; }
               enum sect409r1 { description "TBD"; }
               enum secp521r1 { description "TBD"; }
               enum sect571k1 { description "TBD"; }
               enum sect571r1 { description "TBD"; }
             }
             config false;
             description
               "The algorithm used by the private key.";
           }
           leaf idle-timeout key-length {
             type uint16;
        units "seconds";
        default 3600; // one hour uint32;
             config false;
             description
          "Specifies
               "The key-length used by 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 private key.";
           }
           leaf public-key {
             type string;
             config false;
             description
               "The public-key matching the server will never drop
           a session because it is idle.  Sessions that have a
           notification subscription active are never dropped."; private key.";
           }
           container certificates {
             list endpoint certificate {
               key name;
               description
          "List of endpoints to listen
                 "A certificate for NETCONF connections on."; this public key.";
               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 address-and-port-grouping {
                refine port {
                  default 830;
                }
              }
              uses host-keys-grouping;
            } certificate.";
               }
          case tls {
            if-feature tls-listen;
            container tls
               leaf chain {
                 type binary;
                 description
                "TLS-specific listening configuration for inbound
                 connections.";
              uses address-and-port-grouping {
                refine port {
                  default 6513;
                }
              }
              uses certificates-grouping;
            }
          }
        }
                   "The certificate itself, as well as an ordered
                    sequence of intermediate certificates leading
                    to a trust anchor, as specified by RFC 5246,
                    Section 7.4.2.";
                 reference
                   "RFC 5246: The Transport Layer Security (TLS)
                              Protocol Version 1.2";
               }
             }

    container call-home {
      if-feature "(ssh-call-home or tls-call-home)";
             description
        "Configures call-home behavior";
               "A list netconf-client of certificates for this public key.";
           }
           action generate-certificate-signing-request {
             description
               "Generates a certificate signing request structure for
                the associated private key name; using the passed subject
                and attribute values.";
             input {
               leaf subject {
                 type binary;
                 mandatory true;
                 description
          "List
                   "The distinguished name of NETCONF clients the NETCONF server certificate subject
                    (the entity whose public key is to initiate
           call-home connections to."; be certified).
                    This field is encoded the same as the 'subject'
                    field in the CertificationRequestInfo type defined
                    in RFC 2986, Section 4.1.";
                 reference
                   "RFC 2986: PKCS #10: Certification Request Syntax
                              Specification Version 1.7";
               }
               leaf name attributes {
                 type string; binary;
                 description
            "An arbitrary name for
                   "A collection of attributes providing additional
                    information about the remote NETCONF client."; subject of the certificate.
                    This field is encoded the same as the 'attributes'
                    field  in the CertificationRequestInfo type defined
                    in RFC 2986, Section 4.1.";
                 reference
                   "RFC 2986: PKCS #10: Certification Request Syntax
                              Specification Version 1.7";
               }
        choice transport
             }
             output {
               leaf certificate-signing-request {
                 type binary;
                 mandatory true;
                 description
            "Selects between available transports.";
          case ssh {
            if-feature ssh-call-home;
            container ssh
                   "The certificate signing request to be signed by
                    a certificate authority.  This field is encoded
                    as the CertificationRequest type defined in
                    RFC 2986, Section 4.2.";
                 reference
                   "RFC 2986: PKCS #10: Certification Request Syntax
                              Specification Version 1.7";
               }
             }
           }
         }
         action generate-private-key {
           description
                "Specifies SSH-specific call-home transport
                 configuration.";
              uses endpoints-container
             "Generates a private key using the specified algorithm and
              key length.";
           input {
                refine endpoints/endpoint/port
             leaf name {
                  default 7777;
               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 algorithm {
               type enumeration {
                 enum rsa { description "TBD"; }
              uses host-keys-grouping;
                 enum dsa { description "TBD"; }
                 enum secp192r1 { description "TBD"; }
          case tls
                 enum sect163k1 {
            if-feature tls-call-home;
            container tls description "TBD"; }
                 enum sect163r2 { description
                "Specifies TLS-specific call-home transport
                 configuration.";
              uses endpoints-container "TBD"; }
                 enum secp224r1 {
                refine endpoints/endpoint/port description "TBD"; }
                 enum sect233k1 {
                  default 8888; description "TBD"; }
                 enum sect233r1 { description "TBD"; }
              uses certificates-grouping;
                 enum secp256r1 { description "TBD"; }
                 enum sect283k1 { description "TBD"; }
                 enum sect283r1 { description "TBD"; }
        container connection-type
                 enum secp384r1 { description
           "Indicates the kind of connection to use.";
          choice connection-type "TBD"; }
                 enum sect409k1 { description
              "Selects between available connection types.";
            case persistent-connection "TBD"; }
                 enum sect409r1 {
              container persistent description "TBD"; }
                 enum secp521r1 {
                presence description "TBD"; }
                 enum sect571k1 { description "TBD"; }
                 enum sect571r1 { description "TBD"; }
               }
               mandatory 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
                 "The algorithm to NETCONF server data-transfer delay, albeit at
                  the expense of holding resources longer."; be used.";
             }
             leaf idle-timeout key-length {
               type uint32;
                  units "seconds";
                  default 86400;  // one day;
               description
                    "Specifies the maximum number of seconds
                 "For algorithms that need 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 key length specified
                  when generating the server will never drop
                     a session because it is idle.  Sessions that
                     have a notification subscription active are
                     never dropped."; key.";
             }
                container keep-alives
           }
         }
       }

       list trusted-certificates {
         key name;
         description
                    "Configures the keep-alive policy, to proactively
                     test the aliveness
           "A list 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"; lists of trusted certificates.";
         leaf max-wait name {
           type uint16 {
                      range "1..max";
                    }
                    units seconds;
                    default 30; string;
           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
             "An arbitrary name for this list of the SSH/TLS client."; trusted
              certificates.";
         }
         leaf max-attempts description {
           type uint8;
                    default 3; string;
           description
                     "Sets the number
             "An arbitrary description for this list 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.";
                  }
                }
              } trusted
              certificates.";
         }
            case periodic-connection {
              container periodic
         list trusted-certificate {
                presence true;
           key name;
           description
                 "Periodically connect to the NETCONF client, so that
                  the NETCONF client may deliver messages pending
             "A list of trusted certificates 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."; a specific use.";
           leaf idle-timeout name {
             type uint16;
                  units "seconds";
                  default 300; // five minutes string;
             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
               "An arbitrary name 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."; trusted certificate.";
           }
           leaf reconnect_timeout certificate {
             type uint16 {
                    range "1..max";
                  }
                  units minutes;
                  default 60; binary;
             description
               "The maximum amount of unconnected time the NETCONF
                    server will wait before establishing a connection
                    to the NETCONF client. binary certificate structure as specified by RFC
                5246, Section 7.4.6, i.e.,: opaque ASN.1Cert<1..2^24>;
               ";
             reference
               "RFC 5246: The NETCONF server may
                    initiate a connection before this time if desired
                    (e.g., to deliver a notification)."; Transport Layer Security (TLS)
                          Protocol Version 1.2";
           }
         }
       }
     }
   }
        container reconnect-strategy {
          description
           "The reconnection strategy guides how

   <CODE ENDS>

4.2.  The SSH Server Model

   The SSH Server model presented in this section presents two YANG
   groupings, one for a NETCONF server
            reconnects that opens a socket to an NETCONF client, after losing 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 it, even if due to configure a reboot.  The NETCONF server starts
            with the specified endpoint listening for connections
   and tries the other grouping to connect configure NETCONF call home.

   A shared characteristic between both groupings is the ability to it
            max-attempts times before trying
   configure which host key is presented to clients, the next endpoint private key for
   which is held 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 keychain configuration presented before.
   Another shared characteristic is used.   NETCONF
                   servers SHOULD be able to remember the last
                   endpoint connected ability to across reboots.";
              }
            }
            default first-listed;
            description
             "Specifies configure which of the NETCONF client's endpoints
   trusted CA or client certificates the
              NETCONF server should start with when trying to connect be used to
   authenticate clients when using X.509 based client certificates
   [RFC6187].

4.2.1.  Tree Diagram

   The following tree diagram represents the NETCONF client.";
          }
          leaf max-attempts {
            type uint8 {
              range "1..max";
            }
            default 3;
            description
             "Specifies the number times data model for the NETCONF server tries to
              connect to a specific endpoint before moving on grouping
   used to the
              next endpoint in the list (round robin).";
          }
        }
      }

    }

    container ssh {
      description
        "Configures configure an SSH properties not specific server to the listen
         or call-home use-cases";
      if-feature "(ssh-listen or ssh-call-home)";
      container x509 {
        if-feature ssh-x509-certs;
        uses trusted-certs-grouping;
      }
    }

    container tls {
      description
        "Configures TLS properties for authenticating clients.";
      if-feature "(tls-listen or tls-call-home)";
      container client-auth {
        description
          "Container TCP connections.  The
   tree diagram for TLS client authentication configuration.";
        uses trusted-certs-grouping;
        container cert-maps {
          uses x509c2n:cert-to-name;
          description
           "The cert-maps container the other grouping is not provided, but it is used by a 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
   same except without the connection, "address" and MUST NOT accept NETCONF
            messages over it.";
          reference
            "RFC WWWW: NETCONF over TLS, Section 7";
        }
      }
    }
  }

  grouping trusted-certs-grouping {
    description
      "This grouping is used by both "port" fields.

   NOTE: the ssh and tls containers.";
    container trusted-ca-certs {
      description
        "A list of Certificate Authority (CA) certificates that
         a NETCONF server can use to authenticate NETCONF client
         certificates.";
      reference
        "RFC WWWW: NETCONF over TLS, Sections 5 and 7.
         RFC 4253: The Secure Shell (SSH) Transport Layer Protocol,
                   Section 8, #3.
         RFC 6187: X.509v3 Certificates for Secure Shell
                   Authentication.";
      leaf-list trusted-ca-cert {
        type binary;
        nacm:default-deny-write;
        description
          "The binary certificate structure diagram below shows "listening-ssh-server" as specified by RFC
           5246, Section 7.4.6, i.e.,: opaque ASN.1Cert<1..2^24>;
          ";
        reference
          "RFC 5246: The Transport Layer Security (TLS)
                     Protocol Version 1.2";
      }
    }
    container trusted-client-certs {
      description
        "A list of client certificates that a NETCONF server can
         use to authenticate a NETCONF client's certificate.  A
         client's certificate is authenticated if it is an exact
         match to a configured trusted client certificate.";
      leaf-list trusted-client-cert {
        type binary;
        nacm:default-deny-write;
        description
          "The binary certificate structure, as
           specified by RFC 5246, Section 7.4.6, i.e.,:

             opaque ASN.1Cert<1..2^24>;

          ";
        reference
          "RFC 5246: The Transport Layer Security (TLS)
                     Protocol Version 1.2";
      }
    }
  }

  grouping host-keys-grouping {
    description
      "This grouping is used by both the listen and
       call-home containers";
    container host-keys {
      description
        "Parent YANG
   container for the list of host-keys.";
      leaf-list host-key {
        type string;
        min-elements 1;
        ordered-by user;
        description
          "A user-ordered list of host-keys the SSH server
           considers when composing the list of server host
           key algorithms it will send to the client in its
           SSH_MSG_KEXINIT message.  The value of the string
           is the unique identifier for a host-key configured
           on the system.  How valid values are discovered is
           outside the scope of this module, but they are
           envisioned to be the keys for a list of host-keys
           provided by another YANG module";
        reference
          "RFC 4253: The SSH Transport Layer Protocol, Section 7";
      }
    }
  }

  grouping certificates-grouping {
    description
      "This grouping is used by both the listen and
       call-home containers";
    container certificates {
      description
        "Parent container for the list of certificates.";
      leaf-list certificate {
        type string;
        min-elements 1;
        description
          "An unordered list of certificates the TLS server can pick
           from when sending its Server Certificate message.  The value
           of the string is the unique identifier for a certificate
           configured on the system.  How valid values are discovered
           is outside the scope of this module, but they are envisioned
           to be the keys for a list of certificates provided
           by another YANG module";
        reference
          "RFC 5246: The TLS Protocol, Section 7.4.2";
      }
    }
  }

  grouping address-and-port-grouping {
    description
      "This grouping is used by both the ssh and tls containers
       for listen configuration.";
    leaf address {
      type inet:ip-address;
      description
       "The IP address of the interface to listen on. The NETCONF
        server will listen on all interfaces if no value is
        specified.";
    }
    leaf port {
      type inet:port-number;
      description
       "The local port number on this interface the NETCONF server
        listens on.  The NETCONF server will use the IANA-assigned
        well-known port if no value is specified.";
    }
  }

  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 {
          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.  The RESTCONF Server Model

4.1.  Tree Diagram

   module: ietf-restconf-server
      +--rw restconf-server
         +--rw listen {tls-listen}?
         |  +--rw max-sessions?   uint16
         |  +--rw endpoint* [name]
         |     +--rw name    string
         |     +--rw (transport)
         |        +--:(tls)
         |           +--rw tls
         |              +--rw address?        inet:ip-address
         |              +--rw port?           inet:port-number
         |              +--rw certificates
         |                 +--rw certificate*   string
         +--rw call-home {tls-call-home}?
         |  +--rw restconf-client* [name]
         |     +--rw name                  string
         |     +--rw (transport)
         |     |  +--:(tls)
         |     |     +--rw tls
         |     |        +--rw endpoints
         |     |        |  +--rw endpoint* [name]
         |     |        |     +--rw name       string
         |     |        |     +--rw address    inet:host
         |     |        |     +--rw port?      inet:port-number
         |     |        +--rw certificates
         |     |           +--rw certificate*   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
         +--rw client-cert-auth {client-cert-auth}?
            +--rw trusted-ca-certs
            |  +--rw trusted-ca-cert*   binary
            +--rw trusted-client-certs
            |  +--rw trusted-client-cert*   binary
            +--rw cert-maps
               +--rw cert-to-name* [id]
                  +--rw id             uint32
                  +--rw fingerprint    x509c2n:tls-fingerprint
                  +--rw map-type       identityref
                  +--rw name           string

4.2.  Example Usage

4.2.1.  Configuring TLS Transport

   The following example illustrates the <get> response from a RESTCONF
   server that only supports TLS, both listening for incoming
   connections as well as calling home to a single RESTCONF client
   having two endpoints.

<restconf-server xmlns="urn:ietf:params:xml:ns:yang:ietf-restconf-server">
  <listen>
    <endpoint>
      <name>primary-restconf-endpoint</name>
      <tls>
        <address>11.22.33.44</address>
        <certificates>
          <certificate>fw1.east.example.com</certificate>
        </certificates>
      </tls>
    </endpoint>
  </listen>
  <call-home>
    <restconf-client>
      <name>config-mgr</name>
      <tls>
        <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>
        <certificates>
          <certificate>fw1.east.example.com</certificate>
        </certificates>
      </tls>
    </restconf-client>
  </call-home>
</restconf-server>

4.3.  YANG Model

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

<CODE BEGINS> file "ietf-restconf-server@2015-07-06.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;
  }

  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 "2015-07-06" {
    description
     "Initial version";
    reference
     "RFC VVVV: NETCONF Server and RESTCONF Server Configuration
                Models";
  }

  // Features

  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  (groupings below)
  container restconf-server {
    description
      "Top-level container for RESTCONF server configuration.";

    container listen {
      description
        "Configures listen behavior";
      if-feature tls-listen;
      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 {
          type string;
          description
            "An arbitrary name for the RESTCONF listen endpoint.";
        }
        choice transport {
          mandatory true;
          description
            "Selects between available transports.";
          case tls {
            container tls {
              description
                "TLS-specific listening configuration for inbound
                 connections.";
              leaf address {
                type inet:ip-address;
                description
                 "The IP address of the interface to listen on. The
                  RESTCONF server will listen on all interfaces if
                  no value is specified.";
              }
              leaf port {
                type inet:port-number;
                default 443;
                description
                 "The port number the RESTCONF server will listen on.";
              }
              uses certificates-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.";
          case tls {
            container tls {
              description
                "Specifies TLS-specific call-home transport
                 configuration.";
              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.  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 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;
                    default 9999;
                    description
                     "The IP port for this endpoint. The RESTCONF
                      server will use the IANA-assigned well-known
                      port if no value is specified.";
                  }

                }
              }
              uses certificates-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
                    "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).";
                }
              }
            }
          }
        }
        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).";
          }
        }
      }
    }

    container client-cert-auth {
      if-feature client-cert-auth;
      description
        "Container for TLS client certificate authentication
         configuration.";
      container trusted-ca-certs {
        description
          "A list of Certificate Authority (CA) certificates that
           a RESTCONF server can use to authenticate RESTCONF client
           certificates.";
        reference
          "RFC XXXX: RESTCONF Protocol, Sections 2.3 and 2.5.";
        leaf-list trusted-ca-cert {
          type binary;
          nacm:default-deny-write;
          description
            "The binary certificate structure as specified by RFC
             5246, Section 7.4.6, i.e.,: opaque ASN.1Cert<1..2^24>;
            ";
          reference
            "RFC 5246: The Transport Layer Security (TLS)
                       Protocol Version 1.2";
        }
      }
      container trusted-client-certs {
        description
          "A list of client certificates that a RESTCONF server can
           use to authenticate a RESTCONF client's certificate.  A
           client's certificate is authenticated if it is an exact
           match to a configured trusted client certificate.";
        leaf-list trusted-client-cert {
          type binary;
          nacm:default-deny-write;
          description
            "The binary certificate structure, as specified by RFC
             5246, Section 7.4.6, i.e.,: opaque ASN.1Cert<1..2^24>;
            ";
          reference
            "RFC 5246: The Transport Layer Security (TLS)
                       Protocol Version 1.2";
        }
      }
      container cert-maps {
        uses x509c2n:cert-to-name;
        description
         "The cert-maps container is used by a 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: RESTCONF Protocol, Section 2.5";
      }
    }
  }

  grouping certificates-grouping {
    description
      "This grouping is used by both the listen and
       call-home containers";
    container certificates {
      description
        "Parent container for the list of certificates.";
      leaf-list certificate {
        type string;
        min-elements 1;
        description
          "An unordered list of certificates the TLS server can pick
           from when sending its Server Certificate message.  The value
           of the string is the unique identifier for a certificate
           configured on the system.  How valid values are discovered
           is outside the scope of this module, but they are envisioned
           to be the keys for a list of certificates provided
           by another YANG module";
        reference
          "RFC 5246: The TLS Protocol, Section 7.4.2";
      }
    }
  }

}

<CODE ENDS>

5.  Security Considerations

   There are a number of data nodes defined in the "ietf-netconf-server"
   YANG module which are readable and/or writable that may be considered
   sensitive or vulnerable in some network environments.  Write and read
   operations to these data nodes can have a negative effect on network
   operations.  It is thus important to control write and read access to
   these data nodes.  Below are the data nodes and their sensitivity/
   vulnerability.

   netconf-server/tls/client-auth/trusted-ca-certs:

   o  This container contains certificates that a NETCONF server is to
      use as trust anchors for authenticating X.509-based client
      certificates.  Write access to this node is protected using an
      nacm:default-deny-write statement.

   netconf-server/tls/client-auth/trusted-client-certs:

   o  This container contains certificates that a NETCONF server is to
      trust directly when authenticating X.509-based client
      certificates.  Write access to this node is protected using an
      nacm:default-deny-write statement.

   restconf-server/tls/client-auth/trusted-ca-certs:

   o  This container contains certificates that a RESTCONF server is to
      use as trust anchors for authenticating X.509-based client
      certificates.  Write access to this node is protected using an
      nacm:default-deny-write statement.

   restconf-server/tls/client-auth/trusted-client-certs:

   o  This container contains certificates that a RESTCONF server is to
      trust directly when authenticating X.509-based client
      certificates.  Write access to this node is protected using an
      nacm:default-deny-write statement.

6.  IANA Considerations

   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.

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

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

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

7.  Other Considerations

   The YANG modules define herein do not themselves support virtual
   routing and forwarding (VRF).  It is expected that external modules
   will augment in VRF designations when needed.

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, 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

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC4253]  Ylonen, T. and C. Lonvick, "The Secure Shell (SSH)
              Transport Layer Protocol", RFC 4253, January 2006.

   [RFC6020]  Bjorklund, M., "YANG - A Data Modeling Language for the
              Network Configuration Protocol (NETCONF)", RFC 6020,
              October 2010.

   [RFC6187]  Igoe, K. and D. Stebila, "X.509v3 Certificates for Secure
              Shell Authentication", RFC 6187, March 2011.

   [RFC6241]  Enns, R., Bjorklund, M., Schoenwaelder, J., and A.
              Bierman, "Network Configuration Protocol (NETCONF)", RFC
              6241, June 2011.

   [RFC6242]  Wasserman, M., "Using the NETCONF Protocol over Secure
              Shell (SSH)", RFC 6242, June 2011.

   [RFC6536]  Bierman, A. and M. Bjorklund, "Network Configuration
              Protocol (NETCONF) Access Control Model", RFC 6536, March
              2012.

   [RFC6991]  Schoenwaelder, J., "Common YANG Data Types", RFC 6991,
              July 2013.

   [RFC7407]  Bjorklund, M. and J. Schoenwaelder, "A YANG Data Model for
              SNMP Configuration", RFC 7407, December 2014.

   [RFC7589]  Badra, M., Luchuk, A., and J. Schoenwaelder, "Using the
              NETCONF Protocol over Transport Layer Security (TLS) with
              Mutual X.509 Authentication", RFC 7589, June 2015.

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

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

9.2.  Informative References

   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              January 2004.

Appendix A.  Alternative solution addressing Issue #49

   Option #4 for Issue #49 proposed to define configuration for a
   keychain and on-going discussion proposed to create reusable
   groupings for SSH/TLS servers (referencing keys and certificates held
   in the keychain) that the NETCONF/RESTCONF servers would uses.  This
   relationship is illustrated by the diagram below.

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

   The following sections each of the five YANG modules above.

A.1.  The Keychain Model

A.1.1.  Tree Diagram
module: ietf-keychain
   +--rw keychain
      +--rw private-keys
      |  +--rw private-key* [name]
      |     +--rw name            string
      |     +--ro algorithm?      enumeration
      |     +--ro key-length?     uint32
      |     +--ro public-key?     string
      |     +--rw certificates
      |        +--rw certificate* [name]
      |           +--rw name     string
      |           +--rw chain?   binary
      +--rw trusted-certificates* [name]
         +--rw name                   string
         +--rw trusted-certificate* [name]
            +--rw name           string
            +--rw certificate?   binary
rpcs:
   +---x generate-certificate-signing-request
   |  +---w input
   |  |  +---w private-key?   -> /keychain/private-keys/private-key/name
   |  |  +---w subject        binary
   |  |  +---w attributes?    binary
   |  +--ro output
   |     +--ro certificate-signing-request    binary
   +---x generate-private-key
      +---w input
         +---w name          string
         +---w algorithm     enumeration
         +---w key-length    uint32

A.1.2.  Example Usage

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

     <!-- private keys and associated certificates -->
     <private-keys>
       <private-key>
         <name>TPM key</name>
         <algorithm>rsa</algorithm>
         <key-length>2048</key-length>
         <public-key>
           cztvaWRoc2RmZ2tqaHNkZmdramRzZnZzZGtmam5idnNvO2RmanZvO3NkZ
           mJpdmhzZGZpbHVidjtvc2lkZmhidml1bHNkYmZ2aXNiZGZpYmhzZG87Zm
           JvO3NkZ25iO29pLmR6Zgo=
         </public-key>
         <certificates>
           <certificate>
             <name>IDevID Certificate</name>
             <chain>
               LS0tLS1CRUdJTiBDRVJUSUZJQ0FURS0tLS0tCk1JSUNrekNDQWZ5Z
               0F3SUJBZ0lKQUpRT2t3bGpNK2pjTUEwR0NTcUdTSWIzRFFFQkJRVU
               FNRFF4Q3pBSkJnTlYKQkFZVEFsVlRNUkF3RGdZRFZRUUtFd2RsZUd
               GdGNHeGxNUk13RVFZRFZRUURFd3BEVWt3Z1NYTnpkV1Z5TUI0WApE
               diR1V4RXpBUkJnTlZCQU1UQ2tOU1RDQkpjM04xWlhJd2daOHdEUVl
               KS29aSWh2Y04KQVFFQkJRQURnWTBBTUlHSkFvR0JBTXVvZmFPNEV3
               El1QWMrQ1RsTkNmc0d6cEw1Um5ydXZsOFRIcUJTdGZQY3N0Zk1KT1
               FaNzlnNlNWVldsMldzaHE1bUViCkJNNitGNzdjbTAvU25FcFE0TnV
               bXBDT2YKQWdNQkFBR2pnYXd3Z2Frd0hRWURWUjBPQkJZRUZKY1o2W
               URiR0lPNDB4ajlPb3JtREdsRUNCVTFNR1FHQTFVZApJd1JkTUZ1QU
               ZKY1o2WURiR0lPNDB4ajlPb3JtREdsRUNCVTFvVGlrTmpBME1Rc3d
               mMKTUE0R0ExVWREd0VCL3dRRUF3SUNCREFTQmdOVkhSTUJBZjhFQ0
               RBR0FRSC9BZ0VBTUEwR0NTcUdTSWIzRFFFQgpCUVVBQTRHQkFMMmx
               rWmFGNWcyaGR6MVNhZnZPbnBneHA4eG00SHRhbStadHpLazFlS3Bx
               TXp4YXJCbFpDSHlLCklVbC9GVzRtV1RQS1VDeEtFTE40NEY2Zmk2d
               c4d0tSSElkYW1WL0pGTmlQS0VXSTF4K1I1aDZmazcrQzQ1QXg1RWV
               SWHgzZjdVM2xZTgotLS0tLUVORCBDRVJUSUZJQ0FURS0tLS0tCg==
             </chain>
           </certificate>
         </certificates>
       </private-key>
     </private-keys>

     <!-- trusted netconf/restconf client certificates -->
     <trusted-certificates>
       <name>Trusted certificates for netconf/restconf client</name>
       <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 Flinstone</name>
         <certificate>
           VlEVlFRREV3Vm9ZWEJ3ZVRDQm56QU5CZ2txaGtpRzl3MEJBUUVGQUFPQm
           pRQXdnWWtDCmdZRUE1RzRFSWZsS1p2bDlXTW44eUhyM2hObUFRaUhVUzV
           rRUpPQy9hSFA3eGJXQW1ra054ZStUa2hrZnBsL3UKbVhsTjhSZUd1ODhG
           NGcEk3UE90cnNFVjRwTUNBd0VBQWFPQ0FSSXdnZ0VPCk1CMEdBMVVkRGd
           VEJiZ0JTWEdlbUEKMnhpRHVOTVkvVHFLNWd4cFJBZ1ZOYUU0cERZd05ER
           V6QVJCZ05WQkFNVENrTlNUQ0JKYzNOMVpYS0NDUUNVRHBNSll6UG8zREF
           NQmdOVkhSTUJBZjhFCkFqQUFNQTRHQTFVZER3RUIvd1FFQXdJSGdEQnBC
           Z05WSFI4RVlqQmdNRjZnSXFBZ2hoNW9kSFJ3T2k4dlpYaGgKYlhCc1pTN
           WpiMjB2WlhoaGJYQnNaUzVqY215aU9LUTJNRFF4Q3pBSkJnTlZCQVlUQW
           xWVE1SQXdEZ1lEVlFRSwpFd2RsZUdGdGNHeGxNUk13RVFZRFZRUURFd3B
           EVWt3Z1NYTnpkV1Z5TUEwR0NTcUdTSWIzRFFFQkJRVUFBNEdCCkFFc3BK
           WmdsK2gyTTg3QmtGMjhWbW1CdFFVaWc3OEgrRkYyRTFwdSt4ZVRJbVFFM
           lLQllsdWpOcjFTMnRLR05EMUc2OVJpK2FWNGw2NTdZNCtadVJMZgpRYjk
           zSFNwSDdwVXBCYnA4dmtNanFtZjJma3RqZHBxeFppUUtTbndWZTF2Zwot
           QWtUOCBDRVUUZJ0RUF==
         </certificate>
       </trusted-certificate>
     </trusted-certificates>

     <!-- trust anchors for netconf/restconf clients -->
     <trusted-certificates>
       <name>Trust anchors for netconf/restconf clients</name>
       <trusted-certificate>
         <name>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>Trust anchors for random HTTPS servers</name>
       <trusted-certificate>
         <name>Example.com</name>
         <certificate>
           NGcEk3UE90cnNFVjRwTUNBd0VBQWFPQ0FSSXdnZ0VPCk1CMEdBMVVkRGd
           VEJiZ0JTWEdlbUEKMnhpRHVOTVkvVHFLNWd4cFJBZ1ZOYUU0cERZd05ER
           V6QVJCZ05WQkFNVENrTlNUQ0JKYzNOMVpYS0NDUUNVRHBNSll6UG8zREF
           Z05WSFI4RVlqQmdNRjZnSXFBZ2hoNW9kSFJ3T2k4dlpYaGgKYlhCc1pTN
           QmdOVkJBWVRBbFZUTVJBd0RnWURWUVFLRXdkbAplR0Z0Y0d4bE1RNHdEQ
           MkF6a3hqUDlVQWtHR0dvS1U1eUc1SVR0Wm0vK3B0R2FieXVDMjBRd2kvZ
           NQmdOVkhSTUJBZjhFCkFqQUFNQTRHQTFVZER3RUIvd1FFQXdJSGdEQnBC
           WmdsK2gyTTg3QmtGMjhWbW1CdFFVaWc3OEgrRkYyRTFwdSt4ZVRJbVFFM
           lLQllsdWpOcjFTMnRLR05EMUc2OVJpK2FWNGw2NTdZNCtadVJMZgpRYjk
           zSFNwSDdwVXBCYnA4dmtNanFtZjJma3RqZHBxeFppUUtTbndWZTF2Zwot
           25PZnpZNEhONApXY0pTaUpZK2xtYWs3RTRORUZXZS9RdGp4NUlXZmdvN2
           WpiMjB2WlhoaGJYQnNaUzVqY215aU9L=
         </certificate>
       </trusted-certificate>
     </trusted-certificates>

   </keychain>

A.1.3.  YANG Model

 <CODE BEGINS> file "ietf-keychain@2015-07-06.yang"

 module ietf-keychain {
   yang-version 1.1;

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

   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 "2015-07-06" {
     description
      "Initial version";
     reference
      "RFC VVVV: NETCONF Server and RESTCONF Server Configuration
                 Models";
   }

   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 enumeration {
             enum rsa { description "TBD"; }
             enum dsa { description "TBD"; }
             enum secp192r1 { description "TBD"; }
             enum sect163k1 { description "TBD"; }
             enum sect163r2 { description "TBD"; }
             enum secp224r1 { description "TBD"; }
             enum sect233k1 { description "TBD"; }
             enum sect233r1 { description "TBD"; }
             enum secp256r1 { description "TBD"; }
             enum sect283k1 { description "TBD"; }
             enum sect283r1 { description "TBD"; }
             enum secp384r1 { description "TBD"; }
             enum sect409k1 { description "TBD"; }
             enum sect409r1 { description "TBD"; }
             enum secp521r1 { description "TBD"; }
             enum sect571k1 { description "TBD"; }
             enum sect571r1 { description "TBD"; }
           }
           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 string;
           config false;
           description
             "The public-key matching the private key.";
         }
         container certificates {
           list certificate {
             key name;
             description
               "A certificate for this public key.";
             leaf name {
               type string;
               description
                 "An arbitrary name for the certificate.";
             }
             leaf chain {
               type binary;
               description
                 "The certificate itself, as well as an ordered
                  sequence of intermediate certificates leading
                  to a trust anchor, as specified by RFC 5246,
                  Section 7.4.2.";
               reference
                 "RFC 5246: The Transport Layer Security (TLS)
                            Protocol Version 1.2";
             }
           }
           description
             "A list of certificates for this public key.";
         }
         action generate-certificate-signing-request {
           description
             "Generates a certificate signing request structure for
              the associated private key using the passed subject
              and attribute values.";
           input {
             leaf subject {
               type binary;
               mandatory true;
               description
                 "The 'subject' field in the CertificationRequestInfo
                  defined in RFC 2986, Section 4.1.";
               reference
                 "RFC 2986: PKCS #10: Certification Request Syntax
                            Specification Version 1.7";
             }
             leaf attributes {
               type binary;
               description
                 "The 'attributes' field in the CertificationRequestInfo
                  defined in RFC 2986, Section 4.1.";
               reference
                 "RFC 2986: PKCS #10: Certification Request Syntax
                            Specification Version 1.7";
             }
           }
           output {
             leaf certificate-signing-request {
               type binary;
               mandatory true;
               description
                 "The CertificationRequestInfo structure as specified
                  by RFC 2986, Section 4.1.";
               reference
                 "RFC 2986: PKCS #10: Certification Request Syntax
                            Specification Version 1.7";
             }
           }
         }

       }
       action generate-private-key {
         description
           "Generates 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/private-key.  As such, the
                passed value must not match any existing 'name' value.";
           }
           leaf algorithm {
             type enumeration {
               enum rsa { description "TBD"; }
               enum dsa { description "TBD"; }
               enum secp192r1 { description "TBD"; }
               enum sect163k1 { description "TBD"; }
               enum sect163r2 { description "TBD"; }
               enum secp224r1 { description "TBD"; }
               enum sect233k1 { description "TBD"; }
               enum sect233r1 { description "TBD"; }
               enum secp256r1 { description "TBD"; }
               enum sect283k1 { description "TBD"; }
               enum sect283r1 { description "TBD"; }
               enum secp384r1 { description "TBD"; }
               enum sect409k1 { description "TBD"; }
               enum sect409r1 { description "TBD"; }
               enum secp521r1 { description "TBD"; }
               enum sect571k1 { description "TBD"; }
               enum sect571r1 { description "TBD"; }
             }
             mandatory true;
             description
               "The algorithm to be used.";
           }
           leaf key-length {
             type uint32;
             mandatory true;
             description
               "The key length to be used.";
           }
         }
       }
     }
     list trusted-certificates {
       key name;
       description
         "A list of lists of trusted certificates.";
       leaf name {
         type string;
         description
           "An arbitrary name for this list of trusted certificates.";
       }
       list trusted-certificate {
         key name;
         description
           "A list of trusted certificates for a specific use.";
         leaf name {
           type string;
           description
             "An arbitrary name for this trusted certificate.";
         }
         leaf certificate {
           type binary;
           description
             "The binary certificate structure as specified by RFC
              5246, Section 7.4.6, i.e.,: opaque ASN.1Cert<1..2^24>;
             ";
           reference
             "RFC 5246: The Transport Layer Security (TLS)
                        Protocol Version 1.2";
         }
       }
     }
   }

   rpc generate-certificate-signing-request {
     description
       "Generates a certificate signing request structure for
        the specified private key using the passed subject
        and attribute values.";
     input {
       leaf private-key {
         type leafref {
           path "/keychain/private-keys/private-key/name";
         }
         description
           "The private key to generate the certificate signing
            request for.";
       }
       leaf subject {
         type binary;
         mandatory true;
         description
           "The 'subject' field in the CertificationRequestInfo
            defined in RFC 2986, Section 4.1.";
         reference
           "RFC 2986: PKCS #10: Certification Request Syntax
                      Specification Version 1.7";
       }
       leaf attributes {
         type binary;
         description
           "The 'attributes' field in the CertificationRequestInfo
            defined in RFC 2986, Section 4.1.";
         reference
           "RFC 2986: PKCS #10: Certification Request Syntax
                      Specification Version 1.7";
       }
     }
     output {
       leaf certificate-signing-request {
         type binary;
         mandatory true;
         description
           "The CertificationRequestInfo structure as specified
            by RFC 2986, Section 4.1.";
         reference
           "RFC 2986: PKCS #10: Certification Request Syntax
                      Specification Version 1.7";
       }
     }
   }

   rpc generate-private-key {
     description
       "Generates 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/private-key.  As such, the
            passed value must not match any existing 'name' value.";
       }
       leaf algorithm {
         type enumeration {
           enum rsa { description "TBD"; }
           enum dsa { description "TBD"; }
           enum secp192r1 { description "TBD"; }
           enum sect163k1 { description "TBD"; }
           enum sect163r2 { description "TBD"; }
           enum secp224r1 { description "TBD"; }
           enum sect233k1 { description "TBD"; }
           enum sect233r1 { description "TBD"; }
           enum secp256r1 { description "TBD"; }
           enum sect283k1 { description "TBD"; }
           enum sect283r1 { description "TBD"; }
           enum secp384r1 { description "TBD"; }
           enum sect409k1 { description "TBD"; }
           enum sect409r1 { description "TBD"; }
           enum secp521r1 { description "TBD"; }
           enum sect571k1 { description "TBD"; }
           enum sect571r1 { description "TBD"; }
         }
         mandatory true;
         description
           "The algorithm to be used.";
       }
       leaf key-length {
         type uint32;
         mandatory true;
         description
           "The key length to be used.";
       }
     }
   }
 }

 <CODE ENDS>

A.2.  The SSH Server Model

A.2.1.  Tree Diagram

   The following tree diagram is faked, as (not a module having grouping).  This temporary container was created
   only a
   grouping in it has 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.  However, for illustrative
   purposes, a container has been added as nothing more than a "uses"
   statement of the grouping.

 module: ietf-ssh-server
    +--rw fake-ssh-server 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/private-key/name /kc:keychain/private-keys/pri
 vate-key/name
       |        +--:(certificate)
       |           +--rw certificate?   -> /kc:keychain/private-keys/private-key/certificates/certificate/name /kc:keychain/private-keys/pri
 vate-key/certificates/certificate/name {ssh-x509-certs}?
       +--rw client-cert-auth {ssh-x509-certs}?
          +--rw trusted-ca-certs?       -> /kc:keychain/trusted-certificates/name /kc:keychain/trusted-certific
 ates/name
          +--rw trusted-client-certs?   -> /kc:keychain/trusted-certificates/name

A.2.2. /kc:keychain/trusted-certific
 ates/name

4.2.2.  Example Usage

   <fake-ssh-server

   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.

   <listening-ssh-server
     xmlns="urn:ietf:params:xml:ns:yang:ietf-ssh-server">
     <port>830</port>
     <host-keys>
       <host-key>
         <name>IDevID</name>
         <certificate>
           IDevID Certificate
         </certificate>
         <name>deployment-specific-certificate</name>
         <certificate>ex-key-sect571r1-cert</certificate>
       </host-key>
     </host-keys>
     </certificates>
     <client-cert-auth>
       <trusted-ca-certs>
         Trusted certificates for netconf/restconf clients
         deployment-specific-ca-certs
       </trusted-ca-certs>
       <trusted-client-certs>
         Trust anchors for netconf/restconf clients
         explicitly-trusted-client-certs
       </trusted-client-certs>
     </client-cert-auth>
   </fake-ssh-server>

A.2.3.
   </listening-ssh-server>

4.2.3.  YANG Model

   <CODE BEGINS> file "ietf-ssh-server@2015-07-06.yang" "ietf-ssh-server@2015-10-09.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-keychain {
       prefix kc;                       // RFC VVVV
       revision-date 2015-10-09;
     }

     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 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 "2015-07-06" "2015-10-09" {
       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 ssh-server-grouping non-listening-ssh-server-grouping {
       description
         "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 hostkeys host keys the SSH server advertises
              when sending its ??? message.";
           reference
             "RFC ????: ...";
           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"; "/kc:keychain/kc:private-keys/kc:private-key/"
                      + "kc:name";
               }
               description
                 "The name of a private-key in the keychain.";
             }
             leaf certificate {
               if-feature ssh-x509-certs;
               type leafref {
                 path "/kc:keychain/kc:private-keys/kc:private-key/kc:certificates/kc:certificate/kc:name"; "/kc:keychain/kc:private-keys/kc:private-key/"
                      + "kc:certificates/kc:certificate/kc:name";
               }
               description
                 "The name of a certificate in the keychain.";
             }
           }
         }
       }

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

     // RFC Editor: please remove the following container block
     //             when publishing this document as an RFC.

     container listening-ssh-server {
       description
          "A reference
         "This container is only present to enable `pyang`
          tree diagram output, as a list of certificate authority (CA)
           certificates used grouping by the SSH server itself has
          no protocol accessible nodes to authenticate
           SSH client certificates."; output.";

          uses listening-ssh-server-grouping;
     }

      leaf trusted-client-certs {
        type leafref {
          path "/kc:keychain/kc:trusted-certificates/kc:name";

   }
        description
          "A reference

   <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 list of client certificates used by 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 authenticate SSH client certificates. configure NETCONF call home.

   A clients shared characteristic between both groupings is the ability to
   configure which server certificate is authenticated if it presented to clients, the
   private key for which is an
           exact match held in the keychain model presented in
   Section 4.1.  Another shared characteristic is the ability to a configured
   configure which trusted CA or client certificate.";
      }
    }
  }
}

<CODE ENDS>

A.3.  The TLS Server Model

A.3.1. 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 faked, the
   same except without the "address" and "port" fields.

   NOTE: the diagram below shows "listening-ssh-server" as a module having only YANG
   container (not a
   grouping in it has 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.  However, for illustrative
   purposes, a container has been added as nothing more than a "uses"
   statement of the grouping.

 module: ietf-tls-server
    +--rw fake-tls-server 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/certificates/certificate/name /kc:keychain/private-keys/private-key/cert
 ificates/certificate/name
       +--rw client-auth
          +--rw trusted-ca-certs?       -> /kc:keychain/trusted-certificates/name /kc:keychain/trusted-certific
 ates/name
          +--rw trusted-client-certs?   -> /kc:keychain/trusted-certificates/name

A.3.2. /kc:keychain/trusted-certific
 ates/name

4.3.2.  Example Usage

   <fake-tls-server

   <listening-tls-server
     xmlns="urn:ietf:params:xml:ns:yang:ietf-tls-server">
     </certificates>
     <port>6513</port>
     <certificates>
       <certificate>
         IDevID Certificate
         <name>ex-key-sect571r1-cert</name>
       </certificate>
     </certificates>
     <client-auth>
       <trusted-ca-certs>
         Trusted certificates for netconf/restconf clients
         deployment-specific-ca-certs
       </trusted-ca-certs>
       <trusted-client-certs>
         Trust anchors for netconf/restconf clients
         explicitly-trusted-client-certs
       </trusted-client-certs>
     </client-auth>
   </fake-tls-server>

A.3.3.
   </listening-tls-server>

4.3.3.  YANG Model

   <CODE BEGINS> file "ietf-tls-server@2015-07-06.yang" "ietf-tls-server@2015-10-09.yang"

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

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

     import ietf-inet-types {           // RFC 6991
       prefix inet;
     }
     import ietf-keychain {
       prefix kc;                       // RFC VVVV
       revision-date 2015-10-09;
     }

     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 "2015-07-06" "2015-10-09" {
       description
        "Initial version";
       reference
        "RFC VVVV: NETCONF Server and RESTCONF Server Configuration
                   Models";
     }
     // grouping tls-server-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.";
         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:certificates/kc:certificate/kc:name"; "/kc:keychain/kc:private-keys/kc:private-key/"
                    + "kc:certificates/kc:certificate/kc:name";
             }
             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";
           }
           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.";
      }
    }
  }
}
<CODE ENDS>

A.4.  The 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;
     }

     // RFC Editor: please remove the following container block
     //             when publishing this document as an RFC.
     container listening-tls-server {
       description
         "This container is only present to enable `pyang`
          tree diagram output, as a grouping by itself has
          no protocol accessible nodes to output.";

          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 Model

A.4.1.
   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-new 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? 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/private-key/name /kc:keychain/p
 rivate-keys/private-key/name
       |        |     |        +--:(certificate)
       |        |     |           +--rw certificate?   -> /kc:keychain/private-keys/private-key/certificates/certificate/name /kc:keychain/p
 rivate-keys/private-key/certificates/certificate/name {ssh-x509-certs}?
       |        |     +--rw client-cert-auth {ssh-x509-certs}?
       |        |        +--rw trusted-ca-certs?       -> /kc:keychain/trusted-certificates/name /kc:keychain/t

 rusted-certificates/name
       |        |        +--rw trusted-client-certs?   -> /kc:keychain/trusted-certificates/name /kc:keychain/t
 rusted-certificates/name
       |        +--:(tls) {tls-listen}?
       |           +--rw tls
       |              +--rw address?        inet:ip-address
       |              +--rw port? port            inet:port-number
       |              +--rw certificates
       |              |  +--rw certificate* [name]
       |              |     +--rw name    -> /kc:keychain/private-keys/private-key/certificates/certificate/name /kc:keychain/private-keys/p
 rivate-key/certificates/certificate/name
       |              +--rw client-auth
       |                 +--rw trusted-ca-certs?       -> /kc:keychain/trusted-certificates/name /kc:keychain/t
 rusted-certificates/name
       |                 +--rw trusted-client-certs?   -> /kc:keychain/trusted-certificates/name /kc:keychain/t
 rusted-certificates/name
       |                 +--rw cert-maps
       |                    +--rw cert-to-name* [id]
       |                       +--rw id             uint32
       |                       +--rw fingerprint    x509c2n:tls-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/private-keys/private-key/name /kc:keychain/p
 rivate-keys/private-key/name
             |  |     |        +--:(certificate)
             |  |     |           +--rw certificate?   -> /kc:keychain/private-keys/private-key/certificates/certificate/name /kc:keychain/p
 rivate-keys/private-key/certificates/certificate/name {ssh-x509-certs}?
             |  |     +--rw client-cert-auth {ssh-x509-certs}?
             |  |        +--rw trusted-ca-certs?       -> /kc:keychain/trusted-certificates/name /kc:keychain/t
 rusted-certificates/name
             |  |        +--rw trusted-client-certs?   -> /kc:keychain/trusted-certificates/name /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/private-key/certificates/certificate/name /kc:keychain/private-keys/p
 rivate-key/certificates/certificate/name
             |        +--rw client-auth
             |           +--rw trusted-ca-certs?       -> /kc:keychain/trusted-certificates/name /kc:keychain/t
 rusted-certificates/name
             |           +--rw trusted-client-certs?   -> /kc:keychain/trusted-certificates/name /kc:keychain/t
 rusted-certificates/name
             |           +--rw cert-maps
             |              +--rw cert-to-name* [id]
             |                 +--rw id             uint32
             |                 +--rw fingerprint    x509c2n:tls-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

A.4.2.

4.4.2.  Example Usage

   Configuring an SSH 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>
            Trusted netconf/restconf client certificates
               deployment-specific-ca-certs
             </trusted-ca-certs>
             <trusted-client-certs>
            Trust anchors for netconf/restconf clients
               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>
               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>
            Trusted netconf/restconf client certificates
               deployment-specific-ca-certs
             </trusted-ca-certs>
             <trusted-client-certs>
            Trust anchors for netconf/restconf clients
               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>
  </call-home>
</netconf-server>

   Configuring

       <!-- calling home to a TLS Server

<netconf-server xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-server"
     xmlns:x509c2n="urn:ietf:params:xml:ns:yang:ietf-x509-cert-to-name">
  <listen>
    <endpoint>
      <name>netconf/tls</name> TLS-based NETCONF client -->
       <netconf-client>
         <name>event-correlator</name>
         <tls>
        <address>11.22.33.44</address>
           <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>IDevID Certificate</certificate>
             <certificate>ex-key-sect571r1-cert</certificate>
           </certificates>
           <client-auth>
             <trusted-ca-certs>
            Trusted netconf/restconf client certificates
               deployment-specific-ca-certs
             </trusted-ca-certs>
             <trusted-client-certs>
            Trust anchors for netconf/restconf clients
               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>
    <netconf-client>
      <name>config-mgr</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>IDevID Certificate</certificate>
        </certificates>
      </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>

A.4.3.

4.4.3.  YANG Model

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

  <CODE BEGINS> file "ietf-netconf-server-new@2015-07-06.yang" "ietf-netconf-server@2015-10-09.yang"

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

    namespace "urn:ietf:params:xml:ns:yang:ietf-netconf-server-new"; "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 2015-10-09;
    }
    import ietf-tls-server {           // RFC VVVV
      prefix ts;
      revision-date 2015-10-09;
    }
    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 "2015-07-06" "2015-10-09" {
      description
       "Initial version";
      reference
       "RFC VVVV: NETCONF Server and RESTCONF Server Configuration
                  Models";
    }

    // Features

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

    feature 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 5539: 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";
    }

    // 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 {
      description
        "Configures listen behavior";
        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 {
          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 address-and-port-grouping ss:listening-ssh-server-grouping {
                  refine port {
                    default 830;
                  }
                }
              uses ss:ssh-server-grouping;
              }
            }
            case tls {
              if-feature tls-listen;
              container tls {
                description
                  "TLS-specific listening configuration for inbound
                   connections.";
                uses address-and-port-grouping ts:listening-tls-server-grouping {
                  refine port {
                    default 6513;
                  }
              }
                  augment "client-auth" {
                    description
                      "Augments in the cert-to-name structure.";
                    uses tls-server-grouping; cert-maps-grouping;
                  }
                }
              }
            }
          }
        }
      }

      container call-home {
        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:ssh-server-grouping; 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 tls-server-grouping; 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 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-attempts * max-wait) 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";
                      }
                      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";
                    }
                    units minutes;
                    default 60;
                    description
                   "The
                     "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 a notification)."; an event
                      notification message).";
                  }
                }
              }
            }
          }
          container reconnect-strategy {
            description
             "The reconnection strategy guides how a NETCONF server
              reconnects to an a NETCONF client, after losing a discovering its
              connection to it, even if due to a reboot. 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 {
                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 tls-server-grouping cert-maps-grouping {
      description
      "An augmentation of tls-server-grouping, as defined in
        "A grouping that defines a container around the
       ietf-tls-server module, to add
         cert-to-name structure defined in cert-maps.";
    uses ts:tls-server-grouping {
      augment "client-auth" { 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 address-and-port-grouping {
    description
      "This grouping is used by both the ssh and tls containers
       for listen configuration.";
    leaf address {
      type inet:ip-address;
      description
       "The IP address of the interface to listen on. The NETCONF
        server will listen on all interfaces if no value is
        specified.";
    }
    leaf port {
      type inet:port-number;
      description
       "The local port number on this interface the NETCONF server
        listens on.  The NETCONF server will use the IANA-assigned
        well-known port if no value is specified.";
    }
  }

    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 {
            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>

A.5.

4.5.  The RESTCONF Server Model

A.5.1.

   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?

 module: ietf-restconf-server-new 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? port            inet:port-number
       |              +--rw certificates
       |              |  +--rw certificate* [name]
       |              |     +--rw name    -> /kc:keychain/private-keys/private-key/certificates/certificate/name /kc:keychain/private-keys/p
 rivate-key/certificates/certificate/name
       |              +--rw client-auth
       |                 +--rw trusted-ca-certs?       -> /kc:keychain/trusted-certificates/name /kc:keychain/t
 rusted-certificates/name
       |                 +--rw trusted-client-certs?   -> /kc:keychain/trusted-certificates/name /kc:keychain/t
 rusted-certificates/name
       |                 +--rw cert-maps
       |                    +--rw cert-to-name* [id]
       |                       +--rw id             uint32
       |                       +--rw fingerprint    x509c2n:tls-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/private-key/certificates/certificate/name /kc:keychain/private-keys/p
 rivate-key/certificates/certificate/name
             |        +--rw client-auth
             |           +--rw trusted-ca-certs?       -> /kc:keychain/trusted-certificates/name /kc:keychain/t
 rusted-certificates/name
             |           +--rw trusted-client-certs?   -> /kc:keychain/trusted-certificates/name /kc:keychain/t
 rusted-certificates/name
             |           +--rw cert-maps
             |              +--rw cert-to-name* [id]
             |                 +--rw id             uint32
             |                 +--rw fingerprint    x509c2n:tls-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

A.5.2.

4.5.2.  Example Usage

   TBD

A.5.3.

   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>
               <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>
               </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-new@2015-07-06.yang" "ietf-restconf-server@2015-10-09.yang"

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

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

  import

  //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
    prefix ts;
    revision-date 2015-10-09;

  }

  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 "2015-07-06" "2015-10-09" {
    description
     "Initial version";
    reference
     "RFC VVVV: NETCONF Server and RESTCONF Server Configuration
                Models";
  }

  // Features

  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  (groupings below)
  container restconf-server {
    description
      "Top-level container for RESTCONF server configuration.";

    container listen {
      if-feature tls-listen;
      description
        "Configures listen behavior";
      if-feature tls-listen;
      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 {
          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.";
              leaf address
              uses ts:listening-tls-server-grouping {
                type inet:ip-address;
                description
                 "The IP address of the interface to listen on. The
                  RESTCONF server will listen on all interfaces if
                  no value is specified.";
              }
              leaf
                refine port {
                type inet:port-number;
                  default 443;
                }
                augment "client-auth" {
                  description
                 "The port number
                    "Augments in the RESTCONF server will listen on.";
              } cert-to-name structure.";
                  uses tls-server-grouping; 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.";
          case tls {
            if-feature tls-call-home;
            container tls {
              description
                "Specifies TLS-specific call-home transport
                 configuration.";
              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.  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 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 call-home transport
                 configuration.";
              uses endpoints-container {
                refine endpoints/endpoint/port {
                    type inet:port-number;
                  default 9999;
                }
              }
              uses ts:non-listening-tls-server-grouping {
                augment "client-auth" {
                  description
                     "The IP port for this endpoint. The RESTCONF
                      server will use
                    "Augments in the IANA-assigned well-known
                      port if no value is specified.";
                  } cert-to-name structure.";
                  uses cert-maps-grouping;
                }
              }
              uses tls-server-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
                    "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).";
                }

              }
            }
          }
        }
        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).";
          }
        }
      }
    }

  }

  grouping tls-server-grouping {
    description
      "An augmentation

  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
            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.  Security Considerations

   This section needs to be filled in...

6.  IANA Considerations

   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 tls-server-grouping, as defined 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.

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

      name:         ietf-keychain
      namespace:    urn:ietf:params:xml:ns:yang:ietf-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 module,
      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

7.  Other Considerations

   The YANG modules define herein do not themselves support virtual
   routing and forwarding (VRF).  It is expected that external modules
   will augment in VRF designations when needed.

8.  Acknowledgements

   The authors would like to add thank for following for lively discussions
   on list and in cert-maps.";
    uses ts:tls-server-grouping {
      augment "client-auth" {
        container cert-maps {
          uses x509c2n:cert-to-name;
          description
           "The cert-maps container is used 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, and Bert
   Wijnen.

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

9.  References
9.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to
            map Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC6020]  Bjorklund, M., "YANG - A Data Modeling Language for the NETCONF client's presented X.509 certificate to a
            NETCONF username.  If no matching
              Network Configuration Protocol (NETCONF)", RFC 6020,
              October 2010.

   [RFC6187]  Igoe, K. and valid cert-to-name
            list entry can be found, then the NETCONF server MUST
            close the connection, D. Stebila, "X.509v3 Certificates for Secure
              Shell Authentication", RFC 6187, March 2011.

   [RFC6241]  Enns, R., Bjorklund, M., Schoenwaelder, J., and MUST NOT accept A.
              Bierman, "Network Configuration Protocol (NETCONF)", RFC
              6241, June 2011.

   [RFC6242]  Wasserman, M., "Using the NETCONF
            messages Protocol over it.";
          reference
            "RFC WWWW: Secure
              Shell (SSH)", RFC 6242, June 2011.

   [RFC6991]  Schoenwaelder, J., "Common YANG Data Types", RFC 6991,
              July 2013.

   [RFC7407]  Bjorklund, M. and J. Schoenwaelder, "A YANG Data Model for
              SNMP Configuration", RFC 7407, December 2014.

   [RFC7589]  Badra, M., Luchuk, A., and J. Schoenwaelder, "Using the
              NETCONF Protocol over TLS, Section 7";
        }
      }
    }
  }

}

<CODE ENDS> Transport Layer Security (TLS) with
              Mutual X.509 Authentication", RFC 7589, June 2015.

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

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

9.2.  Informative References

   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              January 2004.

Appendix B. A.  Change Log

B.1.

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

B.2.

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

B.3.

A.3.  02 to 03

   o  fixed tree diagrams and surrounding text

B.4.

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

B.5.

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

B.6.

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).

B.7.

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).

   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.

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

Appendix C. 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