Using Extensible Messaging and Presence Protocol (XMPP) for Security Information Exchange
RFC 8600

Document Type RFC - Proposed Standard (June 2019; No errata)
Last updated 2019-06-21
Replaces draft-appala-mile-xmpp-grid
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Send notices to mile-chairs@ietf.org, mile@ietf.org, Takeshi Takahashi <takeshi_takahashi@nict.go.jp>
IANA IANA review state Version Changed - Review Needed
IANA action state No IANA Actions
Internet Engineering Task Force (IETF)                N. Cam-Winget, Ed.
Request for Comments: 8600                                     S. Appala
Category: Standards Track                                        S. Pope
ISSN: 2070-1721                                            Cisco Systems
                                                          P. Saint-Andre
                                                                 Mozilla
                                                               June 2019

        Using Extensible Messaging and Presence Protocol (XMPP)
                   for Security Information Exchange

Abstract

   This document describes how to use the Extensible Messaging and
   Presence Protocol (XMPP) to collect and distribute security incident
   reports and other security-relevant information between network-
   connected devices, primarily for the purpose of communication among
   Computer Security Incident Response Teams and associated entities.
   To illustrate the principles involved, this document describes such a
   usage for the Incident Object Description Exchange Format (IODEF).

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8600.

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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  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Architecture  . . . . . . . . . . . . . . . . . . . . . . . .   5
   4.  Workflow  . . . . . . . . . . . . . . . . . . . . . . . . . .   6
   5.  Service Discovery . . . . . . . . . . . . . . . . . . . . . .   8
   6.  Publish-Subscribe . . . . . . . . . . . . . . . . . . . . . .  10
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  13
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  14
     8.1.  Trust Model . . . . . . . . . . . . . . . . . . . . . . .  14
     8.2.  Threat Model  . . . . . . . . . . . . . . . . . . . . . .  16
     8.3.  Countermeasures . . . . . . . . . . . . . . . . . . . . .  20
     8.4.  Summary . . . . . . . . . . . . . . . . . . . . . . . . .  23
   9.  Privacy Considerations  . . . . . . . . . . . . . . . . . . .  24
   10. Operations and Management Considerations  . . . . . . . . . .  25
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  25
     11.1.  Normative References . . . . . . . . . . . . . . . . . .  25
     11.2.  Informative References . . . . . . . . . . . . . . . . .  27
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .  27
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  28

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1.  Introduction

   This document defines an architecture, i.e., "XMPP-Grid", as a method
   for using the Extensible Messaging and Presence Protocol (XMPP)
   [RFC6120] to collect and distribute security incident reports and
   other security-relevant information among network platforms,
   endpoints, and any other network-connected device, primarily for the
   purpose of communication among Computer Security Incident Response
   Teams and associated entities.  In effect, this document specifies an
   Applicability Statement ([RFC2026], Section 3.2) that defines how to
   use XMPP for the exchange of security notifications on a controlled-
   access network among authorized entities.

   Among other things, XMPP provides a publish-subscribe service
   [XEP-0060] that acts as a broker, enabling control-plane functions by
   which entities can discover available information to be published or
   consumed.  Although such information can take the form of any
   structured data (XML, JSON, etc.), this document illustrates the
   principles of XMPP-Grid with examples that use the Incident Object
   Description Exchange Format (IODEF) [RFC7970].  That is, while other
   security information formats can be shared using XMPP, this document
   uses IODEF as one such example format that can be published and
   consumed using XMPP.

2.  Terminology

   This document uses XMPP terminology defined in [RFC6120] and
   [XEP-0060].  Because the intended audience for this document is those
   who implement and deploy security reporting systems, mappings are
   provided for the benefit of XMPP developers and operators.

   Broker:  A specific type of controller containing control-plane
      functions; as used here, the term refers to an XMPP publish-
      subscribe service.

   Broker Flow:  A method by which security incident reports and other
      security-relevant information are published and consumed in a
      mediated fashion through a Broker.  In this flow, the Broker
      handles authorization of Consumers and Providers to Topics,
      receives messages from Providers, and delivers published messages
      to Consumers.

   Consumer:  An entity that contains functions to receive information
      from other components; as used here, the term refers to an XMPP
      publish-subscribe Subscriber.

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   Controller:  A component containing control-plane functions that
      manage and facilitate information sharing or execute on security
      functions; as used here, the term refers to an XMPP server, which
      provides core message delivery [RFC6120] used by publish-subscribe
      entities.

   Node:  The XMPP term for a Topic.

   Platform:  Any entity that connects to the XMPP-Grid in order to
      publish or consume security-relevant information.

   Provider:  An entity that contains functions to provide information
      to other components; as used here, the term refers to an XMPP
      publish-subscribe Publisher.

   Topic:  A contextual information channel created on a Broker on which
      messages generated by a Provider are propagated in real time to
      one or more Consumers.  Each Topic is limited to a specific type
      and format of security data (e.g., IODEF namespace) and provides
      an XMPP interface by which the data can be obtained.

   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.

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3.  Architecture

   The following figure illustrates the architecture of XMPP-Grid.

             +--------------------------------------+
             | +--------------------------------------+
             | | +--------------------------------------+
             | | |                                      |
             +-| |             Platforms                |
               +-|                                      |
                 +--------------------------------------+
                   /   \         /   \            /   \
                  /  C  \       /     \          /     \
                  -  o  -       -  d  -          -     -
                   ||n||A        | a  |B          |   |C
                   ||t||         | t  |           |   |
                  -  r  -       -  a  -           |   |
                  \  o  /       \     /           |   |
                   \ l /         \   /            |   |
                /|---------------------|\         |   |
         /|----/                         \--------| d |--|\
        /     /        Controller         \ ctrl  | a |    \
        \     \        & Broker           / plane | t |    /
         \|----\                         /--------| a |--|/
                \|---------------------|/         |   |
                   /   \         /   \            |   |
                  /  C  \       /     \           |   |
                  -  o  -       -  d  -           |   |
                   ||n||A        | a |B           |   |C
                   ||t||         | t |            |   |
                  -  r  -       -  a  -          -     -
                  \  o  /       \     /          \     /
                   \ l /         \   /            \   /
                 +------------------------------------+
                 |                                    |-+
                 |            Platforms               | |
                 |                                    | |-+
                 +------------------------------------+ | |
                   +------------------------------------+ |
                     +------------------------------------+

                     Figure 1: XMPP-Grid Architecture

   Platforms connect to the Controller (XMPP server) to authenticate and
   then establish appropriate authorizations to be a Provider or
   Consumer of topics of interest at the Broker.  The control-plane
   messaging is established through XMPP and is shown as "A" (control-
   plane interface) in Figure 1.  Authorized Platforms can then share

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   data either through the Broker (shown as "B" in Figure 1) or, in some
   cases, directly (shown as "C" in Figure 1).  This document focuses
   primarily on the Broker Flow for information sharing ("direct flow"
   interactions can be used for specialized purposes, such as bulk data
   transfer, but methods for doing so are outside the scope of this
   document).

4.  Workflow

   Implementations of XMPP-Grid adhere to the following workflow:

   a.  A Platform with a source of security data requests connection to
       the XMPP-Grid via a Controller.

   b.  The Controller authenticates the Platform.

   c.  The Platform establishes authorized privileges (e.g., privilege
       to publish and/or subscribe to one or more Topics) with a Broker.

   d.  The Platform can publish security incident reports and other
       security-relevant information to a Topic, subscribe to a Topic,
       query a Topic, or perform any combination of these operations.

   e.  A Provider unicasts its Topic updates to the Grid in real time
       through a Broker.  The Broker handles replication and
       distribution of the Topic to Consumers.  A Provider can publish
       the same or different data to multiple Topics.

   f.  Any Platform on the Grid can subscribe to any Topic published to
       the Grid (as permitted by the authorization policy) and (as
       Consumers) will then receive a continual, real-time stream of
       updates from the Topics to which it is subscribed.

   The general workflow is summarized in the figure below.

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   +--------------+        +------------+           +---------------+
   | IODEF Client |        | Controller |           | IODEF Service |
   |  (Consumer)  |        |  & Broker  |           |  (Provider)   |
   +--------------+        +------------+           +---------------+
           |                      |                         |
           |  Establish XMPP      |                         |
           |  Client Session      |                         |
           |  (RFC 6120)          |                         |
           |--------------------->|                         |
           |                      | Establish XMPP          |
           |                      | Client Session          |
           |                      | (RFC 6120)              |
           |                      |<------------------------|
           |                      | Request Topic Creation  |
           |                      | (XEP-0060)              |
           |                      |<------------------------|
           |                      | Topic Creation Success  |
           |                      | (XEP-0060)              |
           |                      |------------------------>|
           | Request Topic List   |                         |
           | (XEP-0030)           |                         |
           |--------------------->|                         |
           | Return Topic List    |                         |
           | (XEP-0030)           |                         |
           |<---------------------|                         |
           |                      |                         |
           | Query Each Topic     |                         |
           | (XEP-0030)           |                         |
           |--------------------->|                         |
           | Return Topic Data    |                         |
           | Including Topic Type |                         |
           | (XEP-0030)           |                         |
           |<---------------------|                         |
           |                      |                         |
           | Subscribe to IODEF   |                         |
           | Topic (XEP-0060)     |                         |
           |--------------------->|                         |
           | Subscription Success |                         |
           | (XEP-0060)           |                         |
           |<---------------------|                         |
           |                      | Publish IODEF Incident  |
           |                      | (XEP-0060)              |
           | Receive IODEF        |<------------------------|
           | Incident (XEP-0060)  |                         |
           |<---------------------|                         |
           |                      |                         |

                     Figure 2: IODEF Example Workflow

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   XMPP-Grid implementations MUST adhere to the mandatory-to-implement
   and mandatory-to-negotiate features as defined in [RFC6120].
   Similarly, implementations MUST implement the publish-subscribe
   extension [XEP-0060] to facilitate the asynchronous sharing of
   information.  Implementations SHOULD implement Service Discovery as
   defined in [XEP-0030] to facilitate the means to dynamically discover
   the available information and namespaces (Topics) to be published or
   consumed.  Care should be taken with implementations if their
   deployments allow for a large number of Topics.  The result set
   management as defined in [XEP-0059] SHOULD be used to allow the
   requesting entity to explicitly request Service Discovery result sets
   to be returned in pages or a limited size, if the discovery results
   are larger in size.  Note that the control plane may optionally also
   implement [XEP-0203] to facilitate delayed delivery of messages to
   the connected consumer as described in [XEP-0060].  Since information
   may be timely and sensitive, capability providers should communicate
   to the Controller whether its messages can be cached for delayed
   delivery during configuration; such a function is out of scope for
   this document.

   The following sections provide protocol examples for the service
   discovery and publish-subscribe parts of the workflow.

5.  Service Discovery

   Using the XMPP service discovery extension [XEP-0030], a Controller
   enables Platforms to discover what information can be consumed
   through the Broker and at which Topics.  Platforms could use
   [XEP-0059] to restrict the size of the result sets the Controller
   returns in a Service Discovery response.  As an example, the
   Controller at 'security-grid.example' might provide a Broker at
   'broker.security-grid.example', which hosts a number of Topics.  A
   Platform at 'xmpp-grid-client@mile-host.example' would query the
   Broker about its available Topics by sending an XMPP "disco#items"
   request to the Broker:

   <iq type='get'
       from='xmpp-grid-client@mile-host.example/2EBE702A97D6'
       to='broker.security-grid.example'
       id='B3C17F7B-B9EF-4ABA-B08D-805DA9F34626'>
     <query xmlns='http://jabber.org/protocol/disco#items'/>
   </iq>

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   The Broker responds with the Topics it hosts:

   <iq type='result'
       from='broker.security-grid.example'
       to='xmpp-grid-client@mile-host.example/2EBE702A97D6'
       id='B3C17F7B-B9EF-4ABA-B08D-805DA9F34626'>
     <query xmlns='http://jabber.org/protocol/disco#items'>
       <item node='NEA1'
             name='Endpoint Posture Information'
             jid='broker.security-grid.example'/>
       <item node='MILEHost'
             name='MILE Host Data'
             jid='broker.security-grid.example'/>
     </query>
   </iq>

   In order to determine the exact nature of each Topic (i.e., in order
   to find Topics that publish incidents in the IODEF format), a
   Platform would send an XMPP "disco#info" request to each Topic:

   <iq type='get'
       from='xmpp-grid-client@mile-host.example/2EBE702A97D6'
       to='broker.security-grid.example'
       id='D367D4ED-2795-489C-A83E-EAAFA07A0356'>
     <query xmlns='http://jabber.org/protocol/disco#info'
            node='MILEHost'/>
   </iq>

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   The Broker responds with the "disco#info" description, which MUST
   include an XMPP data form [XEP-0004] with a 'pubsub#type' field that
   specifies the supported namespace (in this example, the IODEF
   namespace defined in [RFC7970]):

  <iq type='result'
      from='broker.security-grid.example'
      to='xmpp-grid-client@mile-host.example/2EBE702A97D6'
      id='D367D4ED-2795-489C-A83E-EAAFA07A0356'>
    <query xmlns='http://jabber.org/protocol/disco#info'
         node='MILEHost'>
      <identity category='pubsub' type='leaf'/>
      <feature var='http://jabber.org/protocol/pubsub'/>
      <x xmlns='jabber:x:data' type='result'>
       <field var='FORM_TYPE' type='hidden'>
        <value>http://jabber.org/protocol/pubsub#meta-data</value>
       </field>
       <field var='pubsub#type' label='Payload type' type='text-single'>
        <value>urn:ietf:params:xml:ns:iodef-2.0</value>
       </field>
      </x>
    </query>
  </iq>

   The Platform discovers the Topics by obtaining the Broker's response
   and obtaining the namespaces returned in the "pubsub#type" field (in
   the foregoing example, IODEF 2.0).

6.  Publish-Subscribe

   Using the XMPP publish-subscribe extension [XEP-0060], a Consumer
   subscribes to a Topic, and a Provider publishes information to that
   Topic, which the Broker then distributes to all subscribed Consumers.

   First, a Provider would create a Topic as follows:

   <iq type='set'
       from='datasource@provider.example/F12C2EFC9BB0'
       to='broker.security-grid.example'
       id='A67507DF-2F22-4937-8D30-88D2F7DBA279'>
     <pubsub xmlns='http://jabber.org/protocol/pubsub'>
       <create node='MILEHost'/>
     </pubsub>
   </iq>

   Note: The foregoing example is the minimum protocol needed to create
   a Topic with the default node configuration on the XMPP publish-
   subscribe service specified in the 'to' address of the creation

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   request stanza.  Depending on security requirements, the Provider
   might need to request a non-default configuration for the node; see
   [XEP-0060] for detailed examples.  To also help with the Topic
   configuration, the Provider may also optionally include configuration
   parameters such as:

   <configure>
     <x xmlns='jabber:x:data' type='submit'>
       <field var='FORM_TYPE' type='hidden'>
         <value>http://jabber.org/protocol/pubsub#node_config</value>
       </field>
       <field var='pubsub#access_model'><value>authorize</value></field>
       <field var='pubsub#persist_items'><value>1</value></field>
       <field var='pubsub#send_last_published_item'>
         <value>never</value>
       </field>
     </x>
   </configure>

   The above configuration indicates the Topic is configured so that the
   Broker will a) explicitly approve subscription requests, b)
   persistently store all messages posted to the Topic, and c) not
   deliver the most recently published when an entity initially
   subscribes to the Topic.  Please refer to [XEP-0060] for a more
   detailed description of this configuration and other available
   configuration options.

   Unless an error occurs (see [XEP-0060] for various error flows), the
   Broker responds with success:

   <iq type='result'
       from='broker.security-grid.example'
       to='datasource@provider.example/F12C2EFC9BB0'
       id='A67507DF-2F22-4937-8D30-88D2F7DBA279'/>

   Second, a Consumer would subscribe as follows:

   <iq type='set'
       from='xmpp-grid-client@mile-host.example/2EBE702A97D6'
       to='broker.security-grid.example'
       id='9C6EEE9E-F09A-4418-8D68-3BA6AF852522'>
     <pubsub xmlns='http://jabber.org/protocol/pubsub'>
       <subscribe node='MILEHost'
                  jid='xmpp-grid-client@mile-host.example'/>
     </pubsub>
   </iq>

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   Unless an error occurs (see [XEP-0060] for various error flows), the
   Broker makes an appropriate authorization decision.  If access is
   granted, it responds with success:

   <iq type='result'
       from='broker.security-grid.example'
       to='xmpp-grid-client@mile-host.example/2EBE702A97D6'
       id='9C6EEE9E-F09A-4418-8D68-3BA6AF852522'>
     <pubsub xmlns='http://jabber.org/protocol/pubsub'>
       <subscription
           node='MILEHost'
           jid='xmpp-grid-client@mile-host.example'
           subscription='subscribed'/>
     </pubsub>
   </iq>

   Third, a Provider would publish an incident to the Broker using the
   MILEHost Topic as follows:

  <iq type='set'
      from='datasource@provider.example/F12C2EFC9BB0'
      to='broker.security-grid.example'
      id='2A17D283-0DAE-4A6C-85A9-C10B1B40928C'>
    <pubsub xmlns='http://jabber.org/protocol/pubsub'>
      <publish node='MILEHost'>
        <item id='8bh1g27skbga47fh9wk7'>
          <IODEF-Document version="2.00" xml:lang="en"
            xmlns="urn:ietf:params:xml:ns:iodef-2.0"
            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
            xsi:schemaLocation=
              "http://www.iana.org/assignments/xml-registry/
               schema/iodef-2.0.xsd">
            <Incident purpose="reporting" restriction="private">
              <IncidentID name="csirt.example.com">492382</IncidentID>
              <GenerationTime>2015-07-18T09:00:00-05:00</GenerationTime>
              <Contact type="organization" role="creator">
                <Email>
                  <EmailTo>contact@csirt.example.com</EmailTo>
                </Email>
              </Contact>
            </Incident>
          </IODEF-Document>
        </item>
      </publish>
    </pubsub>
  </iq>

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   (The payload in the foregoing example is from [RFC7970]; payloads for
   additional use cases can be found in [RFC8274].)

   The Broker would then deliver that incident report to all Consumers
   who are subscribed to the Topic:

  <message
      from='broker.security-grid.example'
      to='xmpp-grid-client@mile-host.example/2EBE702A97D6'
      id='37B3921D-4F7F-450F-A589-56119A88BC2E'>
    <event xmlns='http://jabber.org/protocol/pubsub#event'>
      <items node='MILEHost'>
        <item id='iah37s61s964gquqy47aksbx9453ks77'>
          <IODEF-Document version="2.00" xml:lang="en"
            xmlns="urn:ietf:params:xml:ns:iodef-2.0"
            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
            xsi:schemaLocation=
              "http://www.iana.org/assignments/xml-registry/
               schema/iodef-2.0.xsd">
            <Incident purpose="reporting" restriction="private">
              <IncidentID name="csirt.example.com">492382</IncidentID>
              <GenerationTime>2015-07-18T09:00:00-05:00</GenerationTime>
              <Contact type="organization" role="creator">
                <Email>
                  <EmailTo>contact@csirt.example.com</EmailTo>
                </Email>
              </Contact>
            </Incident>
          </IODEF-Document>
        </item>
      </items>
    </event>
  </message>

   Note that [XEP-0060] uses the XMPP "<message />" stanza for delivery
   of content.  To ensure that messages are delivered to the Consumer
   even if the Consumer is not online at the same time that the
   Publisher generates the message, an XMPP-Grid Controller MUST support
   "offline messaging" delivery semantics as specified in [RFC6121], the
   best practices of which are further explained in [XEP-0160].

7.  IANA Considerations

   This document has no actions for IANA.

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8.  Security Considerations

   An XMPP-Grid Controller serves as a controlling broker for XMPP-Grid
   Platforms such as enforcement points, policy servers, Configuration
   Management Databases (CMDBs), and sensors, using a publish-subscribe-
   search model of information exchange and lookup.  By increasing the
   ability of XMPP-Grid Platforms to learn about and respond to security
   incident reports and other security-relevant information, XMPP-Grid
   can improve the timeliness and utility of the security system.
   However, this integrated security system can also be exploited by
   attackers if they can compromise it.  Therefore, strong security
   protections for XMPP-Grid are essential.

   As XMPP is the core of this document, the security considerations of
   [RFC6120] apply.  In addition, as XMPP-Grid defines a specific
   instance, this section provides a security analysis of the XMPP-Grid
   data transfer protocol and the architectural elements that employ it,
   specifically with respect to their use of this protocol.  Three
   subsections define the trust model (which elements are trusted to do
   what), the threat model (attacks that can be mounted on the system),
   and the countermeasures (ways to address or mitigate the threats
   previously identified).

8.1.  Trust Model

   The first step in analyzing the security of the XMPP-Grid transport
   protocol is to describe the trust model and list what each
   architectural element is trusted to do.  The items listed here are
   assumptions, but provisions are made in "Threat Model" (Section 8.2)
   and "Countermeasures" (Section 8.3) for elements that fail to perform
   as they were trusted to do.

8.1.1.  Network

   The network used to carry XMPP-Grid messages (i.e., the underlying
   network transport layer over which XMPP runs) is trusted to:

   o  Perform best-effort delivery of network traffic

   The network used to carry XMPP-Grid messages is not expected
   (trusted) to:

   o  Provide confidentiality or integrity protection for messages sent
      over it

   o  Provide timely or reliable service

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8.1.2.  XMPP-Grid Platforms

   Authorized XMPP-Grid Platforms are trusted to:

   o  Preserve the confidentiality of sensitive data retrieved via the
      XMPP-Grid Controller

8.1.3.  XMPP-Grid Controller

   The XMPP-Grid Controller (including its associated Broker) is trusted
   to:

   o  Broker requests for data and enforce authorization of access to
      this data throughout its lifecycle

   o  Perform service requests in a timely and accurate manner

   o  Create and maintain accurate operational attributes

   o  Only reveal data to and accept service requests from authorized
      parties

   o  Preserve the integrity (and confidentiality against unauthorized
      parties) of the data flowing through it.

   The XMPP-Grid Controller is not expected (trusted) to:

   o  Verify the truth (correctness) of data

8.1.4.  Certification Authority

   To allow XMPP-Grid Platforms to mutually authenticate with XMPP-Grid
   Controllers, it is expected that a Certification Authority (CA) is
   employed to issue certificates.  Such a CA (or each CA, if there are
   several) is trusted to:

   o  Ensure that only proper certificates are issued and that all
      certificates are issued in accordance with the CA's policies

   o  Revoke certificates previously issued when necessary

   o  Regularly and securely distribute certificate revocation
      information

   o  Promptly detect and report any violations of this trust so that
      they can be handled

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   The CA is not expected (trusted) to:

   o  Issue certificates that go beyond the XMPP-Grid needs or other
      constraints imposed by a relying party.

8.2.  Threat Model

   To secure the XMPP-Grid data transfer protocol and the architectural
   elements that implement it, this section identifies the attacks that
   can be mounted against the protocol and elements.

8.2.1.  Network Attacks

   A variety of attacks can be mounted using the network.  For the
   purposes of this subsection, the phrase "network traffic" can be
   taken to mean messages and/or parts of messages.  Any of these
   attacks can be mounted by network elements, by parties who control
   network elements, and (in many cases) by parties who control network-
   attached devices.

   o  Network traffic can be passively monitored to glean information
      from any unencrypted traffic

   o  Even if all traffic is encrypted, valuable information can be
      gained by traffic analysis (volume, timing, source and destination
      addresses, etc.)

   o  Network traffic can be modified in transit

   o  Previously transmitted network traffic can be replayed

   o  New network traffic can be added

   o  Network traffic can be blocked, perhaps selectively

   o  A man-in-the-middle (MITM) attack can be mounted where an attacker
      interposes itself between two communicating parties and
      impersonates the other end to either or both parties

   o  Undesired network traffic can be sent in an effort to overload an
      architectural component, thus mounting a denial-of-service attack

8.2.2.  XMPP-Grid Platforms

   An unauthorized XMPP-Grid Platform (one that is not recognized by the
   XMPP-Grid Controller or is recognized but not authorized to perform
   any actions) cannot mount any attacks other than those listed in
   "Network Attacks" (Section 8.2.1).

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   An authorized XMPP-Grid Platform, on the other hand, can mount many
   attacks.  These attacks might occur because the XMPP-Grid Platform is
   controlled by a malicious, careless, or incompetent party (whether
   because its owner is malicious, careless, or incompetent or because
   the XMPP-Grid Platform has been compromised and is now controlled by
   a party other than its owner).  They might also occur because the
   XMPP-Grid Platform is running malicious software, the XMPP-Grid
   Platform is running buggy software (which can fail in a state that
   floods the network with traffic), or the XMPP-Grid Platform has been
   configured improperly.  From a security standpoint, it generally
   makes no difference why an attack is initiated.  The same
   countermeasures can be employed in any case.

   Here is a list of attacks that can be mounted by an authorized XMPP-
   Grid Platform:

   o  Cause many false alarms or otherwise overload the XMPP-Grid
      Controller or other elements in the network security system
      (including human administrators), leading to a denial of service
      or parts of the network security system being disabled.

   o  Omit important actions (such as posting incriminating data),
      resulting in incorrect access.

   o  Use confidential information obtained from the XMPP-Grid
      Controller to enable further attacks (such as using endpoint
      health check results to exploit vulnerable endpoints).

   o  Advertise data crafted to exploit vulnerabilities in the XMPP-Grid
      Controller or in other XMPP-Grid Platforms with the goal of
      compromising those systems.

   o  Issue a search request or set up a subscription that matches an
      enormous result, leading to resource exhaustion on the XMPP-Grid
      Controller, the publishing XMPP-Grid Platform, and/or the network.

   o  Establish a communication channel using another XMPP-Grid
      Platform's session-id.

   o  Advertise false data that leads to incorrect (e.g., potentially
      attacker-controlled or -induced) behavior of XMPP-Grid Platforms
      by virtue of applying correct procedures to the falsified input.

   Dependencies or vulnerabilities of authorized XMPP-Grid Platforms can
   be exploited to effect these attacks.  Another way to effect these
   attacks is to gain the ability to impersonate an XMPP-Grid Platform
   (through theft of the XMPP-Grid Platform's identity credentials or

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   through other means).  Even a clock skew between the XMPP-Grid
   Platform and XMPP-Grid Controller can cause problems if the XMPP-Grid
   Platform assumes that old XMPP-Grid Platform data should be ignored.

8.2.3.  XMPP-Grid Controllers

   An unauthorized XMPP-Grid Controller (one that is not trusted by
   XMPP-Grid Platforms) cannot mount any attacks other than those listed
   in "Network Attacks" (Section 8.2.1).

   An authorized XMPP-Grid Controller can mount many attacks.  Similar
   to the XMPP-Grid Platform case described above, these attacks might
   occur because the XMPP-Grid Controller is controlled by a malicious,
   careless, or incompetent party (either an XMPP-Grid Controller
   administrator or an attacker who has seized control of the XMPP-Grid
   Controller).  They might also occur because the XMPP-Grid Controller
   is running malicious software, the XMPP-Grid Controller is running
   buggy software (which can fail in a state that corrupts data or
   floods the network with traffic), or the XMPP-Grid Controller has
   been configured improperly.

   All of the attacks listed for XMPP-Grid Platform above can be mounted
   by the XMPP-Grid Controller.  Detection of these attacks will be more
   difficult since the XMPP-Grid Controller can create false operational
   attributes and/or logs that imply some other party created any bad
   data.

   Additional XMPP-Grid Controller attacks can include:

   o  Exposing different data to different XMPP-Grid Platforms to
      mislead investigators or cause inconsistent behavior.

   o  Mounting an even more effective denial-of-service attack than a
      single XMPP-Grid Platform could; some mechanisms include inducing
      many platforms to perform the same operation in an amplification-
      style attack, completely refusing to pass any traffic at all, or
      sending floods of traffic to (certain) platforms or other targets.

   o  Obtaining and caching XMPP-Grid Platform credentials so they can
      be used to impersonate XMPP-Grid Platforms even after a breach of
      the XMPP-Grid Controller is repaired.  Some Simple Authentication
      and Security Layer (SASL) mechanisms (including the mandatory-to-
      implement SCRAM and EXTERNAL with TLS mutual certificate-based
      authentication) do not admit this class of attack, but others
      (such as PLAIN) are susceptible.

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   o  Obtaining and caching XMPP-Grid Controller administrator
      credentials so they can be used to regain control of the XMPP-Grid
      Controller after the breach of the XMPP-Grid Controller is
      repaired.

   o  Eavesdropping, injecting, or modifying the data being transferred
      between Provider and Consumer.

   Dependencies or vulnerabilities of the XMPP-Grid Controller can be
   exploited to obtain control of the XMPP-Grid Controller and effect
   these attacks.

8.2.4.  Certification Authority

   A Certification Authority trusted to issue certificates for the XMPP-
   Grid Controller and/or XMPP-Grid Platforms can mount several attacks:

   o  Issue certificates for unauthorized parties, enabling them to
      impersonate authorized parties such as the XMPP-Grid Controller or
      an XMPP-Grid Platform.  This can lead to all the threats that can
      be mounted by the certificate's subject.

   o  Issue certificates without following all of the CA's policies.
      Because this can result in issuing certificates that can be used
      to impersonate authorized parties, this can lead to all the
      threats that can be mounted by the certificate's subject.

   o  Fail to revoke previously issued certificates that need to be
      revoked.  This can lead to undetected impersonation of the
      certificate's subject or failure to revoke authorization of the
      subject and therefore can lead to all of the threats that can be
      mounted by that subject.

   o  Fail to regularly and securely distribute certificate revocation
      information.  This can cause a relying party to accept a revoked
      certificate, leading to undetected impersonation of the
      certificate's subject or failure to revoke authorization of the
      subject and therefore can lead to all of the threats that can be
      mounted by that subject.  It can also cause a relying party to
      refuse to proceed with a transaction because timely revocation
      information is not available, even though the transaction should
      be permitted to proceed.

   o  Allow the CA's private key to be revealed to an unauthorized
      party.  This can lead to all the threats above.  Even worse, the
      actions taken with the private key will not be known to the CA.

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   o  Fail to promptly detect and report errors and violations of trust
      so that relying parties can be promptly notified.  This can cause
      the threats listed earlier in this section to persist longer than
      necessary, leading to many knock-on effects.

8.3.  Countermeasures

   Below are countermeasures for specific attack scenarios to the XMPP-
   Grid infrastructure.

8.3.1.  Securing the XMPP-Grid Data Transfer Protocol

   To address network attacks, the XMPP-Grid data transfer protocol
   described in this document requires that the XMPP-Grid messages MUST
   be carried over TLS (minimally TLS 1.2 and preferably TLS 1.3
   [RFC8446]) as described in [RFC6120] and updated by [RFC7590].  The
   XMPP-Grid Controller and XMPP-Grid Platforms SHOULD mutually
   authenticate.  The XMPP-Grid Platform MUST verify the XMPP-Grid
   Controller's certificate and determine whether the XMPP-Grid
   Controller is trusted by this XMPP-Grid Platform before completing
   the TLS handshake.  To ensure interoperability, implementations MUST
   implement at least either the SASL EXTERNAL mechanism [RFC4422] or
   the SASL SCRAM mechanism.  When using the SASL SCRAM mechanism, the
   SCRAM-SHA-256-PLUS variant SHOULD be preferred over the SCRAM-SHA-256
   variant, and SHA-256 variants [RFC7677] SHOULD be preferred over
   SHA-1 variants [RFC5802]).  XMPP-Grid Platforms and XMPP-Grid
   Controllers using certificate-based authentication SHOULD each verify
   the revocation status of the other party's certificate.  The
   selection of the XMPP-Grid Platform authentication technique to use
   in any particular deployment is left to the administrator.

   These protocol security measures provide protection against all the
   network attacks listed in Section 8.2 except denial-of-service
   attacks.  If protection against these denial-of-service attacks is
   desired, ingress filtering, rate limiting per source IP address, and
   other denial-of-service mitigation measures can be employed.  In
   addition, an XMPP-Grid Controller MAY automatically disable a
   misbehaving XMPP-Grid Platform.

8.3.2.  Securing XMPP-Grid Platforms

   XMPP-Grid Platforms can be deployed in locations that are susceptible
   to physical attacks.  Physical security measures can be taken to
   avoid compromise of XMPP-Grid Platforms, but these are not always
   practical or completely effective.  An alternative measure is to
   configure the XMPP-Grid Controller to provide read-only access for
   such systems.  The XMPP-Grid Controller SHOULD also include a full
   authorization model so that individual XMPP-Grid Platforms can be

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   configured to have only the privileges that they need.  The XMPP-Grid
   Controller MAY provide functional templates so that the administrator
   can configure a specific XMPP-Grid Platform as a DHCP [RFC2131]
   server and authorize only the operations and metadata types needed by
   a DHCP server to be permitted for that XMPP-Grid Platform.  These
   techniques can reduce the negative impacts of a compromised XMPP-Grid
   Platform without diminishing the utility of the overall system.

   To handle attacks within the bounds of this authorization model, the
   XMPP-Grid Controller MAY also include rate limits and alerts for
   unusual XMPP-Grid Platform behavior.  XMPP-Grid Controllers SHOULD
   make it easy to revoke an XMPP-Grid Platform's authorization when
   necessary.  The XMPP-Grid Controller SHOULD include auditable logs of
   XMPP-Grid Platform activities.

   To avoid compromise of XMPP-Grid Platforms, they SHOULD be hardened
   against attack and minimized to reduce their attack surface.  They
   should be well managed to minimize vulnerabilities in the underlying
   platform and in systems upon which the XMPP-Grid Platform depends.
   Personnel with administrative access should be carefully screened and
   monitored to detect problems as soon as possible.

8.3.3.  Securing XMPP-Grid Controllers

   Because of the serious consequences of XMPP-Grid Controller
   compromise, XMPP-Grid Controllers need to be especially well hardened
   against attack and minimized to reduce their attack surface.  They
   need to be well managed to minimize vulnerabilities in the underlying
   platform and in systems upon which the XMPP-Grid Controller depends.
   Network security measures such as firewalls or intrusion detection
   systems can be used to monitor and limit traffic to and from the
   XMPP-Grid Controller.  Personnel with administrative access ought to
   be carefully screened and monitored to detect problems as soon as
   possible.  Administrators SHOULD NOT use password-based
   authentication but SHOULD instead use non-reusable credentials and
   multi-factor authentication (where available).  Physical security
   measures ought to be employed to prevent physical attacks on XMPP-
   Grid Controllers.

   To ease detection of XMPP-Grid Controller compromise should it occur,
   XMPP-Grid Controller behavior should be monitored to detect unusual
   behavior (such as a reboot, a large increase in traffic, or different
   views of an information repository for similar XMPP-Grid Platforms).
   It is a matter of local policy whether XMPP-Grid Platforms log and/or
   notify administrators when peculiar XMPP-Grid Controller behavior is
   detected and whether read-only audit logs of security-relevant
   information (especially administrative actions) are maintained;
   however, such behavior is encouraged to aid in forensic analysis.

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   Furthermore, if compromise of an XMPP-Grid Controller is detected, a
   careful analysis should be performed, and any reusable credentials
   that could have been compromised should be reissued.

   To address the potential for the XMPP-Grid Controller to eavesdrop,
   modify or inject data, it would be desirable to deploy end-to-end
   encryption between the Provider and the Consumer(s).  Unfortunately,
   because there is no standardized method for encryption of one-to-many
   messages within XMPP, techniques for enforcing end-to-end encryption
   are out of scope for this specification.

8.3.4.  Broker Access Models for Topics

   The XMPP publish-subscribe specification [XEP-0060] defines five
   access models for subscribing to Topics at a Broker: open, presence,
   roster, authorize, and whitelist.  The first model allows
   uncontrolled access, and the next two models are appropriate only in
   instant-messaging applications.  Therefore, a Broker SHOULD support
   only the authorize model (under which the Topic owner needs to
   approve all subscription requests and only subscribers can retrieve
   data items) and the whitelist model (under which only preconfigured
   Platforms can subscribe or retrieve data items).  In order to ease
   the deployment burden, subscription approvals and whitelist
   management can be automated (e.g., the Topic "owner" can be a policy
   server).  The choice between "authorize" and "whitelist" as the
   default access model is a matter for local service policy.

8.3.5.  Limit on Search Result Size

   While XMPP-Grid is designed for high scalability to hundreds of
   thousands of Platforms, an XMPP-Grid Controller MAY establish a limit
   to the amount of data it is willing to return in search or
   subscription results.  Platforms could use [XEP-0059] to restrict the
   size of the result sets the Controller returns in search or
   subscription results or topics' service discovery.  This mitigates
   the threat of an XMPP-Grid Platform causing resource exhaustion by
   issuing a search or subscription that leads to an enormous result.

8.3.6.  Securing the Certification Authority

   As noted above, compromise of a Certification Authority (CA) trusted
   to issue certificates for the XMPP-Grid Controller and/or XMPP-Grid
   Platforms is a major security breach.  Many guidelines for proper CA
   security have been developed: the CA/Browser Forum's Baseline
   Requirements, the American Institute of Certified Public Accountants
   (AICPA) / Canadian Institute of Chartered Accountants (CICA) Trust

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   Service Principles, the IETF's Certificate Transparency [RFC6962],
   etc.  The CA operator and relying parties should agree on
   appropriately rigorous security practices to be used.

   Even with the most rigorous security practices, a CA can be
   compromised.  If this compromise is detected quickly, relying parties
   can remove the CA from their list of trusted CAs, and other CAs can
   revoke any certificates issued to the CA.  However, CA compromise may
   go undetected for some time, and there's always the possibility that
   a CA is being operated improperly or in a manner that is not in the
   interests of the relying parties.  For this reason, relying parties
   may wish to "pin" a small number of particularly critical
   certificates (such as the certificate for the XMPP-Grid Controller).
   Once a certificate has been pinned, the relying party will not accept
   another certificate in its place unless the Administrator explicitly
   commands it to do so.  This does not mean that the relying party will
   not check the revocation status of pinned certificates.  However, the
   Administrator can still be consulted if a pinned certificate is
   revoked, since the CA and revocation process are not completely
   trusted.  By "pinning" one or a small set of certificates, the
   relying party has identified the effective XMPP-Grid Controller(s)
   authorized for connection.

8.3.7.  End-to-End Encryption of Messages

   Because it is expected that there will be a relatively large number
   of Consumers for every Topic, for the purposes of content discovery
   and scaling, this document specifies a "one-to-many" communications
   pattern using the XMPP Publish-Subscribe extension.  Unfortunately,
   there is no standardized technology for end-to-end encryption of one-
   to-many messages in XMPP.  This implies that messages can be subject
   to eavesdropping, data injection, and data modification attacks
   within a Broker or Controller.  If it is necessary to mitigate
   against such attacks, implementers would need to select a messaging
   pattern other than [XEP-0060], most likely the basic "instant
   messaging" pattern specified in [RFC6121] with a suitable XMPP
   extension for end-to-end encryption.  The description of such an
   approach is out of scope for this document.

8.4.  Summary

   XMPP-Grid's considerable value as a broker for security-sensitive
   data exchange distribution also makes the protocol and the network
   security elements that implement it a target for attack.  Therefore,
   strong security has been included as a basic design principle within
   the XMPP-Grid design process.

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   The XMPP-Grid data transfer protocol provides strong protection
   against a variety of different attacks.  In the event that an XMPP-
   Grid Platform or XMPP-Grid Controller is compromised, the effects of
   this compromise are reduced and limited with the recommended role-
   based authorization model and other provisions, and best practices
   for managing and protecting XMPP-Grid systems have been described.
   Taken together, these measures should provide protection commensurate
   with the threat to XMPP-Grid systems, thus ensuring that they fulfill
   their promise as a network security clearinghouse.

9.  Privacy Considerations

   XMPP-Grid Platforms can publish information about endpoint health,
   network access, events (which can include information about which
   services an endpoint is accessing), roles and capabilities, and the
   identity of the end user operating the endpoint.  Any of this
   published information can be queried by other XMPP-Grid Platforms and
   could potentially be used to correlate network activity to a
   particular end user.

   Dynamic and static information brokered by an XMPP-Grid Controller,
   ostensibly for the purposes of correlation by XMPP-Grid Platforms for
   intrusion detection, could be misused by a broader set of XMPP-Grid
   Platforms that hitherto have been performing specific roles with a
   strict, well-defined separation of duties.

   Care needs to be taken by deployers of XMPP-Grid to ensure that the
   information published by XMPP-Grid Platforms does not violate
   agreements with end users or local and regional laws and regulations.
   This can be accomplished either by configuring XMPP-Grid Platforms to
   not publish certain information or by restricting access to sensitive
   data to trusted XMPP-Grid Platforms.  That is, the easiest means to
   ensure privacy or protect sensitive data is to omit or not share it
   at all.

   Similarly, care must be taken by deployers and XMPP-Grid Controller
   implementations as they implement the appropriate auditing tools.  In
   particular, any information, such as logs, must be sensitive to the
   type of information stored to ensure that the information does not
   violate privacy and agreements with end users or local and regional
   laws and regulations.

   Another consideration for deployers is to enable end-to-end
   encryption to ensure the data is protected while in transit between
   data layers and thus protected from the transport layer.  The means
   to achieve end-to-end encryption is beyond the scope of this
   document.

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10.  Operations and Management Considerations

   In order to facilitate the management of Providers and the onboarding
   of Consumers, it is helpful to generate the following ahead of time:

   o  Agreement between the operators of Provider services and the
      implementers of Consumer software regarding identifiers for common
      Topics (e.g., these could be registered with the XMPP Software
      Foundation's registry of well-known nodes for service discovery
      and publish-subscribe, located at <https://xmpp.org/registrar/
      nodes.html>).

   o  Security certificates (including appropriate certificate chains)
      for Controllers, including identification of any Providers
      associated with the Controllers (which might be located at
      subdomains).

   o  Consistent and secure access control policies for publishing and
      subscribing to Topics.

   These matters are out of scope for this document but ought to be
   addressed by the XMPP-Grid community.

11.  References

11.1.  Normative References

   [RFC2026]  Bradner, S., "The Internet Standards Process -- Revision
              3", BCP 9, RFC 2026, DOI 10.17487/RFC2026, October 1996,
              <https://www.rfc-editor.org/info/rfc2026>.

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

   [RFC4422]  Melnikov, A., Ed. and K. Zeilenga, Ed., "Simple
              Authentication and Security Layer (SASL)", RFC 4422,
              DOI 10.17487/RFC4422, June 2006,
              <https://www.rfc-editor.org/info/rfc4422>.

   [RFC5802]  Newman, C., Menon-Sen, A., Melnikov, A., and N. Williams,
              "Salted Challenge Response Authentication Mechanism
              (SCRAM) SASL and GSS-API Mechanisms", RFC 5802,
              DOI 10.17487/RFC5802, July 2010,
              <https://www.rfc-editor.org/info/rfc5802>.

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   [RFC6120]  Saint-Andre, P., "Extensible Messaging and Presence
              Protocol (XMPP): Core", RFC 6120, DOI 10.17487/RFC6120,
              March 2011, <https://www.rfc-editor.org/info/rfc6120>.

   [RFC6121]  Saint-Andre, P., "Extensible Messaging and Presence
              Protocol (XMPP): Instant Messaging and Presence",
              RFC 6121, DOI 10.17487/RFC6121, March 2011,
              <https://www.rfc-editor.org/info/rfc6121>.

   [RFC7590]  Saint-Andre, P. and T. Alkemade, "Use of Transport Layer
              Security (TLS) in the Extensible Messaging and Presence
              Protocol (XMPP)", RFC 7590, DOI 10.17487/RFC7590, June
              2015, <https://www.rfc-editor.org/info/rfc7590>.

   [RFC7677]  Hansen, T., "SCRAM-SHA-256 and SCRAM-SHA-256-PLUS Simple
              Authentication and Security Layer (SASL) Mechanisms",
              RFC 7677, DOI 10.17487/RFC7677, November 2015,
              <https://www.rfc-editor.org/info/rfc7677>.

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

   [XEP-0004] Eatmon, R., Hildebrand, J., Miller, J., Muldowney, T., and
              P. Saint-Andre, "Data Forms", XSF XEP 0004, August 2007,
              <https://xmpp.org/extensions/xep-0004.html>.

   [XEP-0030] Hildebrand, J., Millard, P., Eatmon, R., and P. Saint-
              Andre, "Service Discovery", XSF XEP 0030, October 2017,
              <https://xmpp.org/extensions/xep-0030.html>.

   [XEP-0059] Paterson, I., Saint-Andre, P., Mercier, V., and J.
              Seguineau, "Result Set Management", XSF XEP 0059,
              September 2006,
              <https://xmpp.org/extensions/xep-0059.html>.

   [XEP-0060] Millard, P., Saint-Andre, P., and R. Meijer, "Publish-
              Subscribe", XSF XEP 0060, January 2019,
              <https://xmpp.org/extensions/xep-0060.html>.

   [XEP-0203] Saint-Andre, P., "Delayed Delivery", XSF XEP 0203,
              September 2009,
              <https://xmpp.org/extensions/xep-0203.html>.

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11.2.  Informative References

   [RFC2131]  Droms, R., "Dynamic Host Configuration Protocol",
              RFC 2131, DOI 10.17487/RFC2131, March 1997,
              <https://www.rfc-editor.org/info/rfc2131>.

   [RFC6962]  Laurie, B., Langley, A., and E. Kasper, "Certificate
              Transparency", RFC 6962, DOI 10.17487/RFC6962, June 2013,
              <https://www.rfc-editor.org/info/rfc6962>.

   [RFC7970]  Danyliw, R., "The Incident Object Description Exchange
              Format Version 2", RFC 7970, DOI 10.17487/RFC7970,
              November 2016, <https://www.rfc-editor.org/info/rfc7970>.

   [RFC8274]  Kampanakis, P. and M. Suzuki, "Incident Object Description
              Exchange Format Usage Guidance", RFC 8274,
              DOI 10.17487/RFC8274, November 2017,
              <https://www.rfc-editor.org/info/rfc8274>.

   [RFC8446]  Rescorla, E., "The Transport Layer Security (TLS) Protocol
              Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
              <https://www.rfc-editor.org/info/rfc8446>.

   [XEP-0160] Saint-Andre, P., "Best Practices for Handling Offline
              Messages", XSF XEP 0160, October 2016,
              <https://xmpp.org/extensions/xep-0160.html>.

Acknowledgements

   The authors would like to acknowledge the contributions, authoring
   and/or editing of the following people: Joseph Salowey, Lisa
   Lorenzin, Clifford Kahn, Henk Birkholz, Jessica Fitzgerald-McKay,
   Steve Hanna, and Steve Venema.  In addition, we want to thank Takeshi
   Takahashi, Panos Kampanakis, Adam Montville, Chris Inacio, and Dave
   Cridland for reviewing and providing valuable comments.

Cam-Winget, et al.           Standards Track                   [Page 27]
RFC 8600                        XMPP Grid                      June 2019

Authors' Addresses

   Nancy Cam-Winget (editor)
   Cisco Systems
   3550 Cisco Way
   San Jose, CA  95134
   United States of America

   Email: ncamwing@cisco.com

   Syam Appala
   Cisco Systems
   3550 Cisco Way
   San Jose, CA  95134
   United States of America

   Email: syam1@cisco.com

   Scott Pope
   Cisco Systems
   5400 Meadows Road
   Suite 300
   Lake Oswego, OR  97035
   United States of America

   Email: scottp@cisco.com

   Peter Saint-Andre
   Mozilla

   Email: stpeter@mozilla.com

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