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

NETCONF Server and RESTCONF Server Configuration Models
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 related parameters.

Editorial Note (To be removed by RFC Editor)

This draft contains many placeholder values that need to be replaced with finalized values at the time of publication. This note summarizes all of the substitutions that are needed. Please note that no other RFC Editor instructions are specified anywhere else in this document.

This document contains references to other drafts in progress, both in the Normative References section, as well as in body text throughout. Please update the following references to reflect their final RFC assignments:

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

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

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

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

Status of This Memo

This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.

Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at http://datatracker.ietf.org/drafts/current/.

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This Internet-Draft will expire on April 11, 2016.

Copyright Notice

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

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

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:

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 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 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|                 
                  +-------------+                 
                      ^    ^
                      |    |
           <leafref>  |    |  <leafref>
         +------------+    +------------+ 
         |                              |
  +---------------+            +------------------+ 
  |ietf-ssh-server|            | ietf-tls-server  | 
  +---------------+            +------------------+
    ^                               ^       ^      
    | <uses>                        |       |      
    |            <augments>         |       |      
    |          +--------------------+       | <augments>     
    |          |                            |      
+-------------------+         +--------------------+
|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:

4.1.1. 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
      |  |  +---x generate-certificate-signing-request
      |  |     +---w input
      |  |     |  +---w subject       binary
      |  |     |  +---w attributes?   binary
      |  |     +--ro output
      |  |        +--ro certificate-signing-request    binary
      |  +---x generate-private-key
      |     +---w input
      |        +---w name          string
      |        +---w algorithm     enumeration
      |        +---w key-length?   uint32
      +--rw trusted-certificates* [name]
         +--rw name                   string
         +--rw description?           string
         +--rw trusted-certificate* [name]
            +--rw name           string
            +--rw certificate?   binary

4.1.2. Example Usage

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

REQUEST
-------

  ['\' line wrapping added for 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 action statement "generate-certificate-signing-request" action in use with the NETCONF protocol.

REQUEST
-------

  <rpc message-id="101"
    xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
    <action xmlns="urn:ietf:params:xml:ns:yang:1">
      <keychain xmlns="urn:ietf:params:xml:ns:yang:ietf-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 fully configured keychain object might look like. The private-key shown below is consistent with the generate-private-key and generate-certificate-signing-request examples above. This example also assumes that the resulting CA-signed certificate has been configured back onto the server. Lastly, this example shows that three lists of trusted certificates having been configured.

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

  <!-- private keys and associated certificates -->
  <private-keys>
    <private-key>
      <name>ex-key-sect571r1</name>
      <algorithm>sect571r1</algorithm>
      <public-key>
        cztvaWRoc2RmZ2tqaHNkZmdramRzZnZzZGtmam5idnNvO2RmanZvO3NkZ
        mJpdmhzZGZpbHVidjtvc2lkZmhidml1bHNkYmZ2aXNiZGZpYmhzZG87Zm
        JvO3NkZ25iO29pLmR6Zgo=
      </public-key>
      <certificates>
        <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>
    </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
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        TQzcjFZSjk0M1FQLzV5eGUKN2QxMkxCV0dxUjUrbEl5N01YL21ka2M4al
        zSFNwSDdwVXBCYnA4dmtNanFtZjJma3RqZHBxeFppUUtTbndWZTF2Zwot
        LS0tLUVORCBDRVJUSUZJQ0FURS0tLS0tCg==
      </certificate>
    </trusted-certificate>
    <trusted-certificate>
      <name>Fred Flinstone</name>
      <certificate>
        VlEVlFRREV3Vm9ZWEJ3ZVRDQm56QU5CZ2txaGtpRzl3MEJBUUVGQUFPQm
        pRQXdnWWtDCmdZRUE1RzRFSWZsS1p2bDlXTW44eUhyM2hObUFRaUhVUzV
        rRUpPQy9hSFA3eGJXQW1ra054ZStUa2hrZnBsL3UKbVhsTjhSZUd1ODhG
        NGcEk3UE90cnNFVjRwTUNBd0VBQWFPQ0FSSXdnZ0VPCk1CMEdBMVVkRGd
        VEJiZ0JTWEdlbUEKMnhpRHVOTVkvVHFLNWd4cFJBZ1ZOYUU0cERZd05ER
        V6QVJCZ05WQkFNVENrTlNUQ0JKYzNOMVpYS0NDUUNVRHBNSll6UG8zREF
        NQmdOVkhSTUJBZjhFCkFqQUFNQTRHQTFVZER3RUIvd1FFQXdJSGdEQnBC
        Z05WSFI4RVlqQmdNRjZnSXFBZ2hoNW9kSFJ3T2k4dlpYaGgKYlhCc1pTN
        WpiMjB2WlhoaGJYQnNaUzVqY215aU9LUTJNRFF4Q3pBSkJnTlZCQVlUQW
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        zSFNwSDdwVXBCYnA4dmtNanFtZjJma3RqZHBxeFppUUtTbndWZTF2Zwot
        QWtUOCBDRVUUZJ0RUF==
      </certificate>
    </trusted-certificate>
  </trusted-certificates>

  <!-- trust anchors for netconf/restconf clients -->
  <trusted-certificates>
    <name>deployment-specific-ca-certs</name>
    <description>
      Trust anchors used only to authenticate NETCONF/RESTCONF
      client connections.  Since our security policy only allows
      authentication for clients having a certificate signed by
      our CA, we only configure its certificate below.
    </description>
    <trusted-certificate>
      <name>ca.example.com</name>
      <certificate>
        WmdsK2gyTTg3QmtGMjhWbW1CdFFVaWc3OEgrRkYyRTFwdSt4ZVRJbVFFM
        lLQllsdWpOcjFTMnRLR05EMUc2OVJpK2FWNGw2NTdZNCtadVJMZgpRYjk
        zSFNwSDdwVXBCYnA4dmtNanFtZjJma3RqZHBxeFppUUtTbndWZTF2Zwot
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        V6QVJCZ05WQkFNVENrTlNUQ0JKYzNOMVpYS0NDUUNVRHBNSll6UG8zREF
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        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
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        MkF6a3hqUDlVQWtHR0dvS1U1eUc1SVR0Wm0vK3B0R2FieXVDMjBRd2kvZ
        NQmdOVkhSTUJBZjhFCkFqQUFNQTRHQTFVZER3RUIvd1FFQXdJSGdEQnBC
        WmdsK2gyTTg3QmtGMjhWbW1CdFFVaWc3OEgrRkYyRTFwdSt4ZVRJbVFFM
        lLQllsdWpOcjFTMnRLR05EMUc2OVJpK2FWNGw2NTdZNCtadVJMZgpRYjk
        zSFNwSDdwVXBCYnA4dmtNanFtZjJma3RqZHBxeFppUUtTbndWZTF2Zwot
        25PZnpZNEhONApXY0pTaUpZK2xtYWs3RTRORUZXZS9RdGp4NUlXZmdvN2
        WpiMjB2WlhoaGJYQnNaUzVqY215aU9L=
      </certificate>
    </trusted-certificate>
  </trusted-certificates>

</keychain>

4.1.3. YANG Model


<CODE BEGINS> file "ietf-keychain@2015-10-09.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 "2015-10-09" {
    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 distinguished name of the certificate subject
                 (the entity whose public key is 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 attributes {
              type binary;
              description 
                "A collection of attributes providing additional
                 information about the 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";
            }
          }
          output {
            leaf certificate-signing-request {
              type binary;
              mandatory true;
              description
                "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
          "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.  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;
            description
              "For algorithms that need a key length specified
               when generating the key.";
          }
        }
      }
    }

    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.";
      }
      leaf description {
        type string;
        description
          "An arbitrary description 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";
        }
      }
    }
  }
}


<CODE ENDS>

4.2. The SSH Server Model

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

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

A shared characteristic between both groupings is the ability to configure which host key is presented to clients, the private key for which is held in the keychain configuration presented before. Another shared characteristic is the ability to configure which trusted CA or client certificates the server should be used to authenticate clients when using X.509 based client certificates [RFC6187].

4.2.1. Tree Diagram

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

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

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

4.2.2. Example Usage

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

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

4.2.3. YANG Model


<CODE BEGINS> file "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 "2015-10-09" {
    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 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 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";
            }
            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";
            }
            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";
        }
        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
      "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-ssh-server-grouping;
  }


}



<CODE ENDS>

4.3. The TLS Server Model

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

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

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

4.3.1. Tree Diagram

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

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

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

4.3.2. Example Usage

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

4.3.3. YANG Model


<CODE BEGINS> file "ietf-tls-server@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 "2015-10-09" {
    description
     "Initial version";
    reference
     "RFC VVVV: NETCONF Server and RESTCONF Server Configuration
                Models";
  }


  // grouping
  grouping non-listening-tls-server-grouping {
    description
      "A reusable grouping for a TLS server that can be used as a
       basis for specific TLS server instances.";
    container certificates {
      description
        "The list of certificates the TLS server will present when
         establishing a TLS connection.";
      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";
          }
          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.";
      }
    }
  }


  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 supports.

4.4.1. Tree Diagram

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

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

4.4.2. Example Usage

Configuring a NETCONF Server to listen for NETCONF client connections using both the SSH and TLS transport protocols, as well as configuring call-home to two NETCONF clients, one using SSH and the other using TLS.

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

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

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

    <!-- listening for TLS connections -->
    <endpoint>
      <name>netconf/tls</name>
      <tls>
        <address>11.22.33.44</address>
        <certificates>
          <certificate>ex-key-sect571r1-cert</certificate>
        </certificates>
        <client-auth>
          <trusted-ca-certs>
            deployment-specific-ca-certs
          </trusted-ca-certs>
          <trusted-client-certs>
            explicitly-trusted-client-certs
          </trusted-client-certs>
          <cert-maps>
            <cert-to-name>
              <id>1</id>
              <fingerprint>11:0A:05:11:00</fingerprint>
              <map-type>x509c2n:san-any</map-type>
            </cert-to-name>
            <cert-to-name>
              <id>2</id>
              <fingerprint>B3:4F:A1:8C:54</fingerprint>
              <map-type>x509c2n:specified</map-type>
              <name>scooby-doo</name>
            </cert-to-name>
          </cert-maps>
        </client-auth>
      </tls>
    </endpoint>

  </listen>
  <call-home>

    <!-- calling home to an SSH-based NETCONF client -->
    <netconf-client>
      <name>config-mgr</name>
      <ssh>
        <endpoints>
          <endpoint>
            <name>east-data-center</name>
            <address>11.22.33.44</address>
          </endpoint>
          <endpoint>
            <name>west-data-center</name>
            <address>55.66.77.88</address>
          </endpoint>
        </endpoints>
        <host-keys>
          <host-key>
            <certificate>TPM key</certificate>
          </host-key>
        </host-keys>
        <client-cert-auth>
          <trusted-ca-certs>
            deployment-specific-ca-certs
          </trusted-ca-certs>
          <trusted-client-certs>
            explicitly-trusted-client-certs
          </trusted-client-certs>
        </client-cert-auth>
      </ssh>
      <connection-type>
        <periodic>
          <idle-timeout>300</idle-timeout>
          <reconnect-timeout>60</reconnect-timeout>
        </periodic>
      </connection-type>
      <reconnect-strategy>
        <start-with>last-connected</start-with>
        <max-attempts>3</max-attempts>
      </reconnect-strategy>
    </netconf-client>

    <!-- calling home to a TLS-based NETCONF client -->
    <netconf-client>
      <name>event-correlator</name>
      <tls>
        <endpoints>
          <endpoint>
            <name>east-data-center</name>
            <address>22.33.44.55</address>
          </endpoint>
          <endpoint>
            <name>west-data-center</name>
            <address>33.44.55.66</address>
          </endpoint>
        </endpoints>
        <certificates>
          <certificate>ex-key-sect571r1-cert</certificate>
        </certificates>
        <client-auth>
          <trusted-ca-certs>
            deployment-specific-ca-certs
          </trusted-ca-certs>
          <trusted-client-certs>
            explicitly-trusted-client-certs
          </trusted-client-certs>
          <cert-maps>
            <cert-to-name>
              <id>1</id>
              <fingerprint>11:0A:05:11:00</fingerprint>
              <map-type>x509c2n:san-any</map-type>
            </cert-to-name>
            <cert-to-name>
              <id>2</id>
              <fingerprint>B3:4F:A1:8C:54</fingerprint>
              <map-type>x509c2n:specified</map-type>
              <name>scooby-doo</name>
            </cert-to-name>
          </cert-maps>
        </client-auth>
      </tls>
      <connection-type>
        <persistent>
          <idle-timeout>300</idle-timeout>
          <keep-alives>
            <max-wait>30</max-wait>
            <max-attempts>3</max-attempts>
          </keep-alives>
        </persistent>
      </connection-type>
      <reconnect-strategy>
        <start-with>first-listed</start-with>
        <max-attempts>3</max-attempts>
      </reconnect-strategy>
    </netconf-client>

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

4.4.3. YANG Model

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


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

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

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

  import ietf-inet-types {           // RFC 6991
    prefix inet;
  }
  import ietf-x509-cert-to-name {    // RFC 7407
    prefix x509c2n;
  }  
  import ietf-ssh-server {           // RFC VVVV
    prefix ss;
    revision-date 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 "2015-10-09" {
    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 {
      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 ss:listening-ssh-server-grouping {
                refine port {
                  default 830;
                }
              }
            }
          }
          case tls {
            if-feature tls-listen;
            container tls {
              description
                "TLS-specific listening configuration for inbound
                 connections.";
              uses ts:listening-tls-server-grouping {
                refine port {
                  default 6513;
                }
                augment "client-auth" {
                  description
                    "Augments in the cert-to-name structure.";
                  uses cert-maps-grouping;
                }
              }
            }
          }
        }
      }
    }

    container call-home {
      if-feature "(ssh-call-home or tls-call-home)";
      description
        "Configures call-home behavior";
      list netconf-client {
        key name;
        description
          "List of NETCONF clients the NETCONF server is to initiate
           call-home connections to.";
        leaf name {
          type string;
          description
            "An arbitrary name for the remote NETCONF client.";
        }
        choice transport {
          mandatory true;
          description
            "Selects between available transports.";
          case ssh {
            if-feature ssh-call-home;
            container ssh {
              description
                "Specifies SSH-specific call-home transport
                 configuration.";
              uses endpoints-container {
                refine endpoints/endpoint/port {
                  default 7777;
                }
              }
              uses ss:non-listening-ssh-server-grouping;
            }
          }
          case tls {
            if-feature tls-call-home;
            container tls {
              description
                "Specifies TLS-specific call-home transport
                 configuration.";
              uses endpoints-container {
                refine endpoints/endpoint/port {
                  default 8888;
                }
              }
              uses ts:non-listening-tls-server-grouping {
                augment "client-auth" {
                  description
                    "Augments in the cert-to-name structure.";
                  uses cert-maps-grouping;
                }
              }
            }
          }
        }
        container connection-type {
          description
           "Indicates the kind of connection to use.";
          choice connection-type {
            description
              "Selects between available connection types.";
            case persistent-connection {
              container persistent {
                presence true;
                description
                 "Maintain a persistent connection to the NETCONF 
                  client. If the connection goes down, immediately 
                  start trying to reconnect to it, using the 
                  reconnection strategy.
    
                  This connection type minimizes any NETCONF client
                  to NETCONF server data-transfer delay, albeit at 
                  the expense of holding resources longer.";
                leaf idle-timeout {
                  type uint32;
                  units "seconds";
                  default 86400;  // one day;
                  description
                    "Specifies the maximum number of seconds that a 
                     a NETCONF session may remain idle. A NETCONF 
                     session will be dropped if it is idle for an 
                     interval longer than this number of seconds.  
                     If set to zero, then the server will never drop
                     a session because it is idle.  Sessions that 
                     have a notification subscription active are 
                     never dropped.";
                }
                container keep-alives {
                  description
                    "Configures the keep-alive policy, to proactively
                     test the aliveness of the SSH/TLS client.  An
                     unresponsive SSH/TLS client will be dropped after
                     approximately max-attempts * max-wait seconds.";
                  reference
                    "RFC YYYY: NETCONF Call Home and RESTCONF Call
                     Home, Section 3.1, item S6";
                  leaf max-wait {
                    type uint16 {
                      range "1..max";
                    }
                    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
                   "Sets the maximum amount of unconnected time the 
                    NETCONF server will wait before re-establishing
                    a connection to the NETCONF client.  The NETCONF
                    server may initiate a connection before this 
                    time if desired (e.g., to deliver an event
                    notification message).";
                }
              }
            }
          }
        }
        container reconnect-strategy {
          description
           "The reconnection strategy guides how a NETCONF server 
            reconnects to a NETCONF client, after discovering its
            connection to the client has dropped.  The NETCONF 
            server starts with the specified endpoint and tries
            to connect to it max-attempts times before trying the
            next endpoint in the list (round robin).";
          leaf start-with {
            type enumeration {
              enum first-listed {
                description
                  "Indicates that reconnections should start with
                   the first endpoint listed.";
              }
              enum last-connected { 
                description
                  "Indicates that reconnections should start with
                   the endpoint last connected to.  If no previous
                   connection has ever been established, then the
                   first endpoint configured is used.   NETCONF 
                   servers SHOULD be able to remember the last 
                   endpoint connected to across reboots.";
              }
            }
            default first-listed;
            description
             "Specifies which of the NETCONF client's endpoints the
              NETCONF server should start with when trying to connect
              to the NETCONF client.";
          }
          leaf max-attempts {
            type uint8 {
              range "1..max";
            }
            default 3;
            description
             "Specifies the number times the NETCONF server tries to
              connect to a specific endpoint before moving on to the
              next endpoint in the list (round robin).";
          }
        }
      }
    }
  }


  grouping cert-maps-grouping {
    description
      "A grouping that defines a container around the
       cert-to-name structure defined in RFC 7407.";
    container cert-maps {
      uses x509c2n:cert-to-name;
      description
       "The cert-maps container is used by a TLS-based NETCONF
        server to map the NETCONF client's presented X.509
        certificate to a NETCONF username.  If no matching and
        valid cert-to-name list entry can be found, then the
        NETCONF server MUST close the connection, and MUST NOT
        accept NETCONF messages over it.";
      reference
        "RFC WWWW: NETCONF over TLS, Section 7";
    }
  }

 
  grouping endpoints-container {
    description
      "This grouping is used by both the ssh and tls containers
       for call-home configurations.";
    container endpoints {
      description
        "Container for the list of endpoints.";
      list endpoint {
        key name;
        min-elements 1;
        ordered-by user;
        description
          "User-ordered list of endpoints for this NETCONF client.
           Defining more than one enables high-availability.";
        leaf name {
          type string;
          description
            "An arbitrary name for this endpoint.";
        }
        leaf address {
          type inet:host;
          mandatory true;
          description
           "The IP address or hostname of the endpoint.  If a 
            hostname is configured and the DNS resolution results
            in more than one IP address, the NETCONF server 
            will process the IP addresses as if they had been
            explicitly configured in place of the hostname.";
        }
        leaf port {
          type inet:port-number;
          description
           "The IP port for this endpoint. The NETCONF server will
            use the IANA-assigned well-known port if no value is 
            specified.";
        }
      }
    }
  }

}


<CODE ENDS>

4.5. The RESTCONF Server Model

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

4.5.1. Tree Diagram

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

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

4.5.2. Example Usage

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

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

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

  <!-- listening for TLS (HTTPS) connections -->
  <listen>
    <endpoint>
      <name>netconf/tls</name>
      <tls>
        <address>11.22.33.44</address>
        <certificates>
          <certificate>ex-key-sect571r1-cert</certificate>
        </certificates>
        <client-auth>
          <trusted-ca-certs>
            deployment-specific-ca-certs
          </trusted-ca-certs>
          <trusted-client-certs>
            explicitly-trusted-client-certs
          </trusted-client-certs>
          <cert-maps>
            <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@2015-10-09.yang"

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

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

  //import ietf-netconf-acm {
  //  prefix nacm;                     // RFC 6536
  //}
  import ietf-inet-types {           // RFC 6991
    prefix inet;
  }
  import ietf-x509-cert-to-name {    // RFC 7407
    prefix x509c2n;
  }
  import ietf-tls-server {           // RFC VVVV
    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 "2015-10-09" {
    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
  container restconf-server {
    description
      "Top-level container for RESTCONF server configuration.";

    container listen {
      if-feature tls-listen;
      description
        "Configures listen behavior";
      leaf max-sessions {
        type uint16;
        default 0;   // should this be 'max'?
        description
          "Specifies the maximum number of concurrent sessions
           that can be active at one time.  The value 0 indicates
           that no artificial session limit should be used.";
      }
      list endpoint {
        key name;
        description
          "List of endpoints to listen for RESTCONF connections on.";
        leaf name {
          type string;
          description
            "An arbitrary name for the RESTCONF listen endpoint.";
        }
        choice transport {
          mandatory true;
          description
            "Selects between available transports.";
          case tls {
            if-feature tls-listen;
            container tls {
              description
                "TLS-specific listening configuration for inbound
                 connections.";
              uses ts:listening-tls-server-grouping {
                refine port {
                  default 443;
                }
                augment "client-auth" {
                  description
                    "Augments in the cert-to-name structure.";
                  uses cert-maps-grouping;
                }
              }
            }
          }
        }
      }
    }

    container call-home {
      if-feature tls-call-home;
      description
        "Configures call-home behavior";
      list restconf-client {
        key name;
        description
          "List of RESTCONF clients the RESTCONF server is to 
           initiate call-home connections to.";
        leaf name {
          type string;
          description
            "An arbitrary name for the remote RESTCONF client.";
        }
        choice transport {
          mandatory true;
          description
            "Selects between TLS and any transports augmented in.";
          case tls {
            if-feature tls-call-home;
            container tls {
              description
                "Specifies TLS-specific call-home transport
                 configuration.";
              uses endpoints-container {
                refine endpoints/endpoint/port {
                  default 9999;
                }
              }
              uses ts:non-listening-tls-server-grouping {
                augment "client-auth" {
                  description
                    "Augments in the cert-to-name structure.";
                  uses cert-maps-grouping;
                }
              }
            }
          }
        }
        container connection-type {
          description
           "Indicates the RESTCONF client's preference for how the
            RESTCONF server's connection is maintained.";
          choice connection-type {
            description
              "Selects between available connection types.";
            case persistent-connection {
              container persistent {
                presence true;
                description
                 "Maintain a persistent connection to the RESTCONF 
                  client. If the connection goes down, immediately 
                  start trying to reconnect to it, using the 
                  reconnection strategy.
    
                  This connection type minimizes any RESTCONF client
                  to RESTCONF server data-transfer delay, albeit at 
                  the expense of holding resources longer.";

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

[draft-ietf-netconf-call-home] Watsen, K., "NETCONF Call Home and RESTCONF Call Home", Internet-Draft draft-ieft-netconf-call-home-02, 2014.
[draft-ietf-netconf-restconf] Bierman, A., Bjorklund, M. and K. Watsen, "RESTCONF Protocol", Internet-Draft draft-ieft-netconf-restconf-04, 2014.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997.
[RFC6020] Bjorklund, M., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, October 2010.
[RFC6187] Igoe, K. and D. Stebila, "X.509v3 Certificates for Secure Shell Authentication", RFC 6187, DOI 10.17487/RFC6187, March 2011.
[RFC6241] Enns, R., Bjorklund, M., Schoenwaelder, J. and A. Bierman, "Network Configuration Protocol (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011.
[RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011.
[RFC6991] Schoenwaelder, J., "Common YANG Data Types", RFC 6991, DOI 10.17487/RFC6991, July 2013.
[RFC7407] Bjorklund, M. and J. Schoenwaelder, "A YANG Data Model for SNMP Configuration", RFC 7407, DOI 10.17487/RFC7407, December 2014.
[RFC7589] Badra, M., Luchuk, A. and J. Schoenwaelder, "Using the NETCONF Protocol over Transport Layer Security (TLS) with Mutual X.509 Authentication", RFC 7589, DOI 10.17487/RFC7589, June 2015.

9.2. Informative References

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

Appendix A. Change Log

A.1. 00 to 01

A.2. 01 to 02

A.3. 02 to 03

A.4. 03 to 04

A.5. 04 to 05

A.6. 05 to 06

A.7. 06 to 07

A.8. 07 to 08

Appendix B. Open Issues

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

Authors' Addresses

Kent Watsen Juniper Networks EMail: kwatsen@juniper.net
Juergen Schoenwaelder Jacobs University Bremen EMail: j.schoenwaelder@jacobs-university.de