NETCONF M. Jethanandani
Internet-Draft VMware
Intended status: Standards Track K. Watsen
Expires: May 2, 2020 Watsen Networks
October 30, 2019

An HTTPS-based Transport for Configured Subscriptions
draft-ietf-netconf-https-notif-01

Abstract

This document defines a YANG data module for configuring HTTPS based configured subscription, as defined in Subscribed Notifications (RFC8639). The use of HTTPS maximizes transport-level interoperability, while allowing for encoding selection from text, e.g. XML or JSON, to binary.

Status of This Memo

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

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

Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress."

This Internet-Draft will expire on May 2, 2020.

Copyright Notice

Copyright (c) 2019 IETF Trust and the persons identified as the document authors. All rights reserved.

This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.


Table of Contents

1. Introduction

Subscribed Notifications defines a YANG data module for configuring subscribed notifications. It even defines a subscriptions container that contains a list of receivers. But it defers the configuration and management of those receivers to other documents. This document defines a YANG data module for configuring and managing HTTPS based receivers for the notifications. Such a configured receiver can be a third party collector, collecting events on behalf of receivers that want to correlate events from different publishers. Configured subscriptions enable a server, acting as a publisher of notifications, to proactively push notifications to external receivers without the receivers needing to first connect to the server, as is the case with dynamic subscriptions.

This document describes how to enable the transmission of YANG modeled notifications, in the configured encoding (i.e., XML, JSON) over HTTPS. It comes in the form of a HTTPS POST. The use of HTTPS maximizes transport-level interoperability, while the encoding selection pivots between implementation simplicity (XML, JSON) and throughput (text versus binary).

1.1. Note to RFC Editor

This document uses several placeholder values throughout the document. Please replace them as follows and remove this section before publication.

RFC XXXX, where XXXX is the number assigned to this document at the time of publication.

2019-10-30 with the actual date of the publication of this document.

1.2. Abbreviations

Acronym Expansion
HTTP Hyper Text Transport Protocol
TCP Transmission Control Protocol
TLS Transport Layer Security

1.3. Terminology

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.

1.3.1. Subscribed Notifications

The following terms are defined in Subscribed Notifications.

1.4. Receiver and Publisher Interaction

The interaction between the receiver and the publisher can be of type "pipelining" or send multiple notifications as part of a "bundled-message", as defined in Notification Message Headers and Bundles

1.4.1. Pipelining of messages

In the case of "pipelining", the flow of messages would look something like this.

       -------------                               --------------
       | Publisher |                               | Receiver   |
       -------------                               --------------

       Establish TCP             ------>

       Establish TLS             ------>

       Send HTTPS POST message 
       with YANG defined         ------>
       notification #1

       Send HTTPS POST message
       with YANG defined         ------>
       notification #2
                                                   Send 204 (No Content)
                                 <------           for notification #1
 
                                                   Send 204 (No Content)
                                 <------           for notification #2

       Send HTTPS POST message
       with YANG defined         ------->
       notification #3

                                                   Send 204 (No Content)
                                 <------           for notification #3

The content of the exchange would look something like this.

Request:

    POST /some/path HTTP/1.1
    Host: my-receiver.my-domain.com
    Content-Type: application/yang-data+xml

    <notification
      xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
      <eventTime>2019-03-22T12:35:00Z</eventTime>
      <foo xmlns="https://example.com/my-foobar-module">
        ...
      </foo>
    </notification>

    <notification
      xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
      <eventTime>2019-03-22T12:35:00Z</eventTime>
      <bar xmlns="https://example.com/my-foobar-module">
        ...
      </bar>
    </notification>

    <notification
      xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
      <eventTime>2019-03-22T12:35:01Z</eventTime>
      <baz xmlns="https://example.com/my-foobar-module">
        ...
      </baz>
    </notification>


Response:

      HTTP/1.1 204 No Content
      Date: Fri, 03 Mar 2019 12:35:00 GMT
      Server: my-receiver.my-domain.com


      HTTP/1.1 204 No Content
      Date: Fri, 03 Mar 2019 12:35:00 GMT
      Server: my-receiver.my-domain.com

      HTTP/1.1 204 No Content
      Date: Fri, 03 Mar 2019 12:35:01 GMT
      Server: my-receiver.my-domain.com

2. YANG module

2.1. Overview

The YANG module is a definition of a set of receivers that are interested in the notifications published by the publisher. The module contains the TCP, TLS and HTTPS parameters that are needed to communicate with the receiver. The module augments the Subscribed Notifications receiver container to create a reference to a receiver defined by the YANG module. As mentioned earlier, it uses POST method to deliver the notification. The attribute 'path' defines the absolute path for the resource on the receiver, as defined by 'path-absolute' in URI Generic Syntax. The user-id used by Network Configuration Access Control Model, is that of the receiver and is derived from the certificate presented by the receiver.

An abridged tree diagram representing the module is shown below.

module: ietf-https-notif
  +--rw receivers
     +--rw receiver* [name]
        +--rw name                 string
        +--rw tcp-params
        |  +--rw remote-address    inet:host
        |  +--rw remote-port?      inet:port-number
        |  +--rw local-address?    inet:ip-address
        |  +--rw local-port?       inet:port-number
        |  +--rw keepalives!
        |        ...
        +--rw tls-params
        |  +--rw client-identity
        |  |     ...
        |  +--rw server-authentication
        |  |     ...
        |  +--rw hello-params {tls-client-hello-params-config}?
        |  |     ...
        |  +--rw keepalives! {tls-client-keepalives}?
        |        ...
        +--rw http-params
        |  +--rw protocol-version?   enumeration
        |  +--rw client-identity
        |  |     ...
        |  +--rw proxy-server! {proxy-connect}?
        |  |     ...
        |  +--rw path?               inet:uri
        +--rw receiver-identity
           +--rw cert-maps
                 ...

  augment /sn:subscriptions/sn:subscription/sn:receivers/sn:receiver:
    +--rw receiver-ref?   -> /receivers/receiver/name

2.2. YANG module

The YANG module imports Common YANG Data Types, A YANG Data Model for SNMP Configuration, and Subscription to YANG Notifcations.

<CODE BEGINS> file "ietf-https-notif@2019-10-30.yang"
module ietf-https-notif {
  yang-version 1.1;
  namespace "urn:ietf:params:xml:ns:yang:ietf-https-notif";
  prefix "hsn";

  import ietf-inet-types {
    prefix inet;
    reference
      "RFC 6991: Common YANG Data Types.";
  }
  
  import ietf-subscribed-notifications {
    prefix sn;
    reference
      "I-D.ietf-netconf-subscribed-notifications";
  }

  import ietf-x509-cert-to-name {
    prefix x509c2n;
    reference
      "RFC 7407: A YANG Data Model for SNMP Configuration";
  }

  import ietf-tcp-client {
    prefix tcpc;
  }

  import ietf-tls-client {
    prefix tlsc;
  }
  
  import ietf-http-client {
    prefix httpc;
  }
  
  organization
    "IETF NETCONF Working Group";

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

     Authors: Mahesh Jethanandani (mjethanandani at gmail dot com)
              Kent Watsen (kent plus ietf at watsen dot net)";
  description
    "YANG module for configuring HTTPS base configuration.

     Copyright (c) 2018 IETF Trust and the persons identified as
     the document authors.  All rights reserved.
     Redistribution and use in source and binary forms, with or
     without modification, is permitted pursuant to, and subject
     to the license terms contained in, the Simplified BSD
     License set forth in Section 4.c of the IETF Trust's Legal
     Provisions Relating to IETF Documents
     (http://trustee.ietf.org/license-info).

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

  revision "2019-10-30" {
    description
      "Initial Version.";
    reference
      "RFC XXXX, YANG Data Module for HTTPS Notifications.";
  }

  identity https {
    base sn:transport;
    description
      "HTTPS transport for notifications.";
  }

  container receivers {
    list receiver {
      key "name";

      leaf name {
        type string;
        description
          "A name that uniquely identifies this receiver.";
      }

      container tcp-params {
        uses tcpc:tcp-client-grouping;
        description
          "TCP client parameters.";
      }

      container tls-params {
        description
          "TLS client parameters.";

        uses tlsc:tls-client-grouping;
      }

      container http-params {
        description
          "HTTP client parameters.";

        uses httpc:http-client-grouping;

	leaf path {
	  type inet:uri;
	  description
	    "The absolute path for the resource on the remote 
             HTTPS server. The absolute path as specified in
             RFC 3986 as 'path-absolute'.";
	  reference
	    "RFC 3986: URI Generic Syntax.";
	}
      }

      container receiver-identity {
        description
          "Specifies mechanism for identifying the receiver. The
           publisher MUST NOT include any content in a notification
           that the user is not authorized to view.";

        container cert-maps {
          uses x509c2n:cert-to-name;
          description
            "The cert-maps container is used by a TLS-based HTTP
             server to map the HTTPS client's presented X.509
             certificate to a 'local' username. If no matching and
             valid cert-to-name list entry is found, the publisher
             MUST close the connection, and MUST NOT 
             not send any notifications over it.";
          reference
            "RFC 7407: A YANG Data Model for SNMP Configuration.";
        }
      }
      description
        "All receivers interested in this notification.";
    }
    description
      "HTTPS based notifications.";
  }
  
  augment "/sn:subscriptions/sn:subscription/sn:receivers/sn:receiver" {
    leaf receiver-ref {
      type leafref {
        path "/receivers/receiver/name";
      }
      description
        "Reference to a receiver.";
    }
    description
      "Augment the subscriptions container to define the receiver.";
  }
}
<CODE ENDS>

3. Security Considerations

The YANG module specified in this document defines a schema for data that is designed to be accessed via network management protocols such as NETCONF or RESTCONF. The lowest NETCONF layer is the secure transport layer, and the mandatory-to-implement secure transport is Secure Shell (SSH). The lowest RESTCONF layer is HTTPS, and the mandatory-to-implement secure transport is TLS. The NETCONF Access Control Model (NACM) provides the means to restrict access for particular NETCONF or RESTCONF users to a preconfigured subset of all available NETCONF or RESTCONF protocol operations and content.

There are a number of data nodes defined in this YANG module that are writable/creatable/deletable (i.e., config true, which is the default). These data nodes may be considered sensitive or vulnerable in some network environments. Write operations (e.g., edit-config) to these data nodes without proper protection can have a negative effect on network operations. These are the subtrees and data nodes and their sensitivity/vulnerability:

Some of the readable data nodes in this YANG module may be considered sensitive or vulnerable in some network environments. It is thus important to control read access (e.g., via get, get-config, or notification) to these data nodes. These are the subtrees and data nodes and their sensitivity/vulnerability:

Some of the RPC operations in this YANG module may be considered sensitive or vulnerable in some network environments. It is thus important to control access to these operations. These are the operations and their sensitivity/vulnerability:

4. IANA Considerations

This document registers one URI and one YANG module.

4.1. URI Registration

URI: urn:ietf:params:xml:ns:yang:ietf-http-notif

in the IETF XML registry [RFC3688]. Following the format in RFC 3688, the following registration is requested to be made:

Registrant Contact: The IESG. XML: N/A, the requested URI is an XML namespace.

4.2. YANG Module Name Registration

This document registers one YANG module in the YANG Module Names registry YANG.

name: ietf-https-notif
namespace: urn:ietf:params:xml:ns:yang:ietf-https-notif
prefix: hn
reference: RFC XXXX

5. Examples

This section tries to show some examples in how the model can be used.

5.1. HTTPS Configured Subscription

This example shows how a HTTPS client can be configured to send notifications to a receiver at address 192.0.2.1, port 443, a 'path', with server certificates, and the corresponding trust store that is used to authenticate a connection.

[note: '\' line wrapping for formatting only]

<?xml version="1.0" encoding="UTF-8"?>
<config xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
  <receivers
      xmlns="urn:ietf:params:xml:ns:yang:ietf-https-notif"
      xmlns:x509c2n="urn:ietf:params:xml:ns:yang:ietf-x509-cert-to-n\
ame">
      <receiver>
	<name>foo</name>
	<tcp-params>
	  <remote-address>my-receiver.my-domain.com</remote-address>
	  <remote-port>443</remote-port>
	</tcp-params>
	<tls-params>
	  <server-authentication>
            <ca-certs>explicitly-trusted-server-ca-certs</ca-certs>
            <server-certs>explicitly-trusted-server-certs</server-ce\
rts>
	  </server-authentication>
	</tls-params>
	<http-params>
	  <client-identity>
	    <basic>
	      <user-id>my-name</user-id>
	      <password>my-password</password>
	    </basic>
	  </client-identity>
	  <path>/some/path</path>
	</http-params>
	<receiver-identity>
	  <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-maps>
	</receiver-identity>
      </receiver>
  </receivers>
  
  <subscriptions
      xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notificatio\
ns">
    <subscription>
      <id>6666</id>
      <stream-subtree-filter>foo</stream-subtree-filter>
      <stream>some-stream</stream>
	<receivers>
	  <receiver>
	    <name>my-receiver</name>
	    <receiver-ref
		xmlns="urn:ietf:params:xml:ns:yang:ietf-https-notif">foo</receiver\
-ref>
	  </receiver>
	</receivers>
      </subscription>
  </subscriptions>
  
  <truststore xmlns="urn:ietf:params:xml:ns:yang:ietf-truststore">
    <certificates>
       <name>explicitly-trusted-server-certs</name>
       <description>
         Specific server authentication certificates for explicitly
         trusted servers.  These are needed for server certificates
         that are not signed by a pinned CA.
       </description>
       <certificate>
         <name>Fred Flintstone</name>
         <cert>base64encodedvalue==</cert>
       </certificate>
     </certificates>
     <certificates>
       <name>explicitly-trusted-server-ca-certs</name>
       <description>
         Trust anchors (i.e. CA certs) that are used to authenticate\

         server connections.  Servers are authenticated if their
         certificate has a chain of trust to one of these CA
         certificates.
       </description>
       <certificate>
         <name>ca.example.com</name>
         <cert>base64encodedvalue==</cert>
       </certificate>
     </certificates>
  </truststore>
</config>

6. Contributors

7. Acknowledgements

8. Normative references

[I-D.ietf-netconf-notification-messages] Voit, E., Birkholz, H., Bierman, A., Clemm, A. and T. Jenkins, "Notification Message Headers and Bundles", Internet-Draft draft-ietf-netconf-notification-messages-07, August 2019.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, January 2004.
[RFC3986] Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, DOI 10.17487/RFC3986, January 2005.
[RFC6020] Bjorklund, M., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, October 2010.
[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.
[RFC7950] Bjorklund, M., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, August 2016.
[RFC8040] Bierman, A., Bjorklund, M. and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017.
[RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration Access Control Model", STD 91, RFC 8341, DOI 10.17487/RFC8341, March 2018.
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018.
[RFC8639] Voit, E., Clemm, A., Gonzalez Prieto, A., Nilsen-Nygaard, E. and A. Tripathy, "Subscription to YANG Notifications", RFC 8639, DOI 10.17487/RFC8639, September 2019.

Authors' Addresses

Mahesh Jethanandani VMware EMail: mjethanandani@gmail.com
Kent Watsen Watsen Networks USA EMail: kent+ietf@watsen.net