I2NSF NSF Monitoring Interface YANG Data Model
draft-ietf-i2nsf-nsf-monitoring-data-model-08

Document Type Active Internet-Draft (i2nsf WG)
Authors Jaehoon (Paul) Jeong  , Patrick Lingga  , Susan Hares  , Liang Xia  , Henk Birkholz 
Last updated 2021-04-29
Replaces draft-hong-i2nsf-nsf-monitoring-data-model
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Network Working Group                                      J. Jeong, Ed.
Internet-Draft                                                 P. Lingga
Intended status: Standards Track                 Sungkyunkwan University
Expires: October 31, 2021                                       S. Hares
                                                                  L. Xia
                                                                  Huawei
                                                             H. Birkholz
                                                          Fraunhofer SIT
                                                          April 29, 2021

             I2NSF NSF Monitoring Interface YANG Data Model
             draft-ietf-i2nsf-nsf-monitoring-data-model-08

Abstract

   This document proposes an information model and the corresponding
   YANG data model of an interface for monitoring Network Security
   Functions (NSFs) in the Interface to Network Security Functions
   (I2NSF) framework.  If the monitoring of NSFs is performed with the
   NSF monitoring interface in a comprehensive way, it is possible to
   detect the indication of malicious activity, anomalous behavior, the
   potential sign of denial of service attacks, or system overload in a
   timely manner.  This monitoring functionality is based on the
   monitoring information that is generated by NSFs.  Thus, this
   document describes not only an information model for the NSF
   monitoring interface along with a YANG data diagram, but also the
   corresponding YANG data model.

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 October 31, 2021.

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Copyright Notice

   Copyright (c) 2021 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
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Use Cases for NSF Monitoring Data . . . . . . . . . . . . . .   4
   4.  Classification of NSF Monitoring Data . . . . . . . . . . . .   5
     4.1.  Retention and Emission  . . . . . . . . . . . . . . . . .   6
     4.2.  Notifications and Events  . . . . . . . . . . . . . . . .   7
     4.3.  Unsolicited Poll and Solicited Push . . . . . . . . . . .   7
     4.4.  I2NSF Monitoring Terminology for Retained Information . .   8
   5.  Conveyance of NSF Monitoring Information  . . . . . . . . . .   9
     5.1.  Information Types and Acquisition Methods . . . . . . . .  10
   6.  Basic Information Model for All Monitoring Data . . . . . . .  10
   7.  Extended Information Model for Monitoring Data  . . . . . . .  11
     7.1.  System Alarms . . . . . . . . . . . . . . . . . . . . . .  11
       7.1.1.  Memory Alarm  . . . . . . . . . . . . . . . . . . . .  11
       7.1.2.  CPU Alarm . . . . . . . . . . . . . . . . . . . . . .  11
       7.1.3.  Disk Alarm  . . . . . . . . . . . . . . . . . . . . .  12
       7.1.4.  Hardware Alarm  . . . . . . . . . . . . . . . . . . .  12
       7.1.5.  Interface Alarm . . . . . . . . . . . . . . . . . . .  12
     7.2.  System Events . . . . . . . . . . . . . . . . . . . . . .  13
       7.2.1.  Access Violation  . . . . . . . . . . . . . . . . . .  13
       7.2.2.  Configuration Change  . . . . . . . . . . . . . . . .  13
       7.2.3.  Traffic flows . . . . . . . . . . . . . . . . . . . .  14
     7.3.  NSF Events  . . . . . . . . . . . . . . . . . . . . . . .  14
       7.3.1.  DDoS Detection  . . . . . . . . . . . . . . . . . . .  14
       7.3.2.  Session Table Event . . . . . . . . . . . . . . . . .  15
       7.3.3.  Virus Event . . . . . . . . . . . . . . . . . . . . .  15
       7.3.4.  Intrusion Event . . . . . . . . . . . . . . . . . . .  16
       7.3.5.  Botnet Event  . . . . . . . . . . . . . . . . . . . .  16
       7.3.6.  Web Attack Event  . . . . . . . . . . . . . . . . . .  17
     7.4.  System Logs . . . . . . . . . . . . . . . . . . . . . . .  18
       7.4.1.  Access Log  . . . . . . . . . . . . . . . . . . . . .  18

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       7.4.2.  Resource Utilization Log  . . . . . . . . . . . . . .  19
       7.4.3.  User Activity Log . . . . . . . . . . . . . . . . . .  19
     7.5.  NSF Logs  . . . . . . . . . . . . . . . . . . . . . . . .  20
       7.5.1.  DPI Log . . . . . . . . . . . . . . . . . . . . . . .  20
       7.5.2.  Vulnerability Scanning Log  . . . . . . . . . . . . .  21
     7.6.  System Counter  . . . . . . . . . . . . . . . . . . . . .  21
       7.6.1.  Interface Counter . . . . . . . . . . . . . . . . . .  21
     7.7.  NSF Counters  . . . . . . . . . . . . . . . . . . . . . .  22
       7.7.1.  Firewall Counter  . . . . . . . . . . . . . . . . . .  22
       7.7.2.  Policy Hit Counter  . . . . . . . . . . . . . . . . .  24
   8.  NSF Monitoring Management in I2NSF  . . . . . . . . . . . . .  24
   9.  Tree Structure  . . . . . . . . . . . . . . . . . . . . . . .  25
   10. YANG Data Model . . . . . . . . . . . . . . . . . . . . . . .  33
   11. I2NSF Event Stream  . . . . . . . . . . . . . . . . . . . . .  74
   12. XML Examples for I2NSF NSF Monitoring . . . . . . . . . . . .  75
     12.1.  I2NSF System Detection Alarm . . . . . . . . . . . . . .  75
     12.2.  I2NSF Interface Counters . . . . . . . . . . . . . . . .  77
   13. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  78
   14. Security Considerations . . . . . . . . . . . . . . . . . . .  79
   15. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  80
   16. Contributors  . . . . . . . . . . . . . . . . . . . . . . . .  80
   17. References  . . . . . . . . . . . . . . . . . . . . . . . . .  81
     17.1.  Normative References . . . . . . . . . . . . . . . . . .  81
     17.2.  Informative References . . . . . . . . . . . . . . . . .  84
   Appendix A.  Changes from draft-ietf-i2nsf-nsf-monitoring-data-
                model-07 . . . . . . . . . . . . . . . . . . . . . .  86
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  86

1.  Introduction

   According to [RFC8329], the interface provided by a Network Security
   Function (NSF) (e.g., Firewall, IPS, Anti-DDoS, or Anti-Virus
   function) to administrative entities (e.g., Security Controller) to
   enable remote management (i.e., configuring and monitoring) is
   referred to as an I2NSF Monitoring Interface.  Monitoring procedures
   intent to acquire vital types of data with respect to NSFs, (e.g.,
   alarms, records, and counters) via data in motion (e.g., queries,
   notifications, and events).  The monitoring of NSF plays an important
   role in an overall security framework, if it is done in a timely and
   comprehensive way.  The monitoring information generated by an NSF
   can be a good, early indication of anomalous behavior or malicious
   activity, such as denial of service attacks (DoS).

   This document defines a comprehensive information model of an NSF
   monitoring interface that provides visibility for an NSF for an NSF
   data collector (e.g., Security Controller and NSF Data Analyzer).
   Note that an NSF data collector is defined as an entity to collect
   NSF monitoring data from an NSF, such as Security Controller and NSF

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   Data Analyzer.  It specifies the information and illustrates the
   methods that enable an NSF to provide the information required in
   order to be monitored in a scalable and efficient way via the NSF
   Monitoring Interface.  The information model for the NSF monitoring
   interface presented in this document is a complementary information
   model to the information model for the security policy provisioning
   functionality of the NSF-Facing Interface specified in
   [I-D.ietf-i2nsf-nsf-facing-interface-dm].

   This document also defines a YANG [RFC7950] data model for the NSF
   monitoring interface, which is derived from the information model for
   the NSF monitoring interface.

2.  Terminology

   This document uses the terminology described in [RFC8329].

   This document follows the guidelines of [RFC8407], uses the common
   YANG types defined in [RFC6991], and adopts the Network Management
   Datastore Architecture (NMDA) [RFC8342].  The meaning of the symbols
   in tree diagrams is defined in [RFC8340].

3.  Use Cases for NSF Monitoring Data

   As mentioned earlier, monitoring plays a critical role in an overall
   security framework.  The monitoring of the NSF provides very valuable
   information to an NSF data collector (e.g., Security Controller and
   NSF data analyzer) in maintaining the provisioned security posture.
   Besides this, there are various other reasons to monitor the NSF as
   listed below:

   o  The security administrator with I2NSF User can configure a policy
      that is triggered on a specific event occurring in the NSF or the
      network [RFC8329] [I-D.ietf-i2nsf-consumer-facing-interface-dm].
      If an NSF data collector detects the specified event, it
      configures additional security functions as defined by policies.

   o  The events triggered by an NSF as a result of security policy
      violation can be used by Security Information and Event Management
      (SIEM) to detect any suspicious activity in a larger correlation
      context.

   o  The events and activity logs from an NSF can be used to build
      advanced analytics, such as behavior and predictive models to
      improve security posture in large deployments.

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   o  The NSF data collector can use events from the NSF for achieving
      high availability.  It can take corrective actions such as
      restarting a failed NSF and horizontally scaling up the NSF.

   o  The events and activity logs from the NSF can aid in the root
      cause analysis of an operational issue, so it can improve
      debugging.

   o  The activity logs from the NSF can be used to build historical
      data for operational and business reasons.

4.  Classification of NSF Monitoring Data

   In order to maintain a strong security posture, it is not only
   necessary not only to configure an NSF's security policies but also
   to continuously monitor the NSF by consuming acquirable and
   observable information.  This enables security administrators to
   assess the state of the network topology in a timely fashion.  It is
   not possible to block all the internal and external threats based on
   static security posture.  A more practical approach is supported by
   enabling dynamic security measures, for which continuous visibility
   is required.  This document defines a set of information elements
   (and their scope) that can be acquired from an NSF and can be used as
   NSF monitoring information.  In essence, these types of monitoring
   information can be leveraged to support constant visibility on
   multiple levels of granularity and can be consumed by the
   corresponding functions.

   Three basic domains about the monitoring information originating from
   a system entity [RFC4949] or an NSF are highlighted in this document.

   o  Retention and Emission

   o  Notifications and Events

   o  Unsolicited Poll and Solicited Push

   The Alarm Management Framework in [RFC3877] defines an Event as
   something that happens as a thing of of interest.  It defines a fault
   as a change in status, crossing a threshold, or an external input to
   the system.  In the I2NSF domain, I2NSF events are created and the
   scope of the Alarm Management Framework's Events is still applicable
   due to its broad definition.  The model presented in this document
   elaborates on the workflow of creating I2NSF events in the context of
   NSF monitoring and on the way initial I2NSF events are created.

   As with I2NSF components, every generic system entity can include a
   set of capabilities that creates information about the context,

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   composition, configuration, state or behavior of that system entity.
   This information is intended to be provided to other consumers of
   information and in the scope of this document, which deals with NSF
   information monitoring in an automated fashion.

4.1.  Retention and Emission

   Typically, a system entity populates standardized interface, such as
   SNMP, NETCONF, RESTCONF or CoMI to provide and emit created
   information directly via NSF Monitoring Interface.  Alternatively,
   the created information is retained inside the system entity (or a
   hierarchy of system entities in a composite device) via records or
   counters that are not exposed directly via NSF Monistoring Interface.

   Information emitted via standardized interfaces can be consumed by an
   I2NSF User that includes the capability to consume information not
   only via an I2NSF Interface (e.g., Consumer-Facing Interface
   [I-D.ietf-i2nsf-consumer-facing-interface-dm]), but also via
   interfaces complementary to the standardized interfaces a generic
   system entity provides.

   Information retained on a system entity requires a corresponding
   I2NSF User to access aggregated records of information, typically in
   the form of log-files or databases.  There are ways to aggregate
   records originating from different system entities over a network,
   for examples via Syslog Protocol [RFC5424] or Syslog over TCP
   [RFC6587].  But even if records are conveyed, the result is the same
   kind of retention in form of a bigger aggregate of records on another
   system entity.

   An I2NSF User is required to process fresh [RFC4949] records created
   by I2NSF Functions in order to provide them to other I2NSF Components
   via the corresponding I2NSF Interfaces in a timely manner.  This
   process is effectively based on homogenizing functions, which can
   access and convert specific kinds of records into information that
   can be provided and emitted via I2NSF interfaces.

   When retained or emitted, the information required to support
   monitoring processes has to be processed by an I2NSF User at some
   point in the workflow.  Typical locations of these I2NSF Users are:

   o  a system entity that creates the information

   o  a system entity that retains an aggregation of records

   o  an I2NSF Component that includes the capabilities of using
      standardized interfaces provided by other system entities that are
      not I2NSF Components

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   o  an I2NSF Component that creates the information

4.2.  Notifications and Events

   A specific task of I2NSF User is to process I2NSF Policy Rules.  The
   rules of a policy are composed of three clauses: Events, Conditions,
   and Actions.  In consequence, an I2NSF Event is specified to trigger
   an I2NSF Policy Rule.  Such an I2NSF Event is defined as any
   important occurrence over time in the system being managed, and/or in
   the environment of the system being managed, which aligns well with
   the generic definition of Event from [RFC3877].

   The model illustrated in this document introduces a complementary
   type of information that can be a conveyed notification.

   Notification:  An occurrence of a change of context, composition,
      configuration, state or behavior of a system entity that can be
      directly or indirectly observed by an I2NSF User and can be used
      as input for an event-clause in I2NSF Policy Rules.

      A notification is similar to an I2NSF Event with the exception
      that it is created by a system entity that is not an I2NSF
      Component and that its importance is yet to be assessed.
      Semantically, a notification is not an I2NSF Event in the context
      of I2NSF, although they can potentially use the exact same
      information or data model.  In respect to [RFC3877], a
      Notification is a specific subset of events, because they convey
      information about something that happens as a thing of of
      interest.  In consequence, Notifications may contain information
      with very low expressiveness or relevance.  Hence, additional
      post-processing functions, such as aggregation, correlation or
      simple anomaly detection, might have to be employed to satisfy a
      level of expressiveness that is required for an event-clause of an
      I2NSF Policy Rule.

   It is important to note that the consumer of a notification (the
   observer) assesses the importance of a notification and not the
   producer.  The producer can include metadata in a notification that
   supports the observer in assessing the importance (even metadata
   about severity), but the deciding entity is an I2NSF User.

4.3.  Unsolicited Poll and Solicited Push

   The freshness of the monitored information depends on the acquisition
   method.  Ideally, an I2NSF User is accessing every relevant
   information about the I2NSF Component and is emitting I2NSF Events to
   an NSF data collector (e.g., Security Controller and NSF data
   analyzer) in a timely manner.  Publication of events via a pubsub/

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   broker model, peer-2-peer meshes, or static defined channels are only
   a few examples on how a solicited push of I2NSF Events can be
   facilitated.  The actual mechanic implemented by an I2NSF Component
   is out of the scope of this document.

   Often, the corresponding management interfaces have to be queried in
   intervals or on-demand if required by an I2NSF Policy rule.  In some
   cases, a collection of information has to be conducted via login
   mechanics provided by a system entity.  Accessing records of
   information via this kind of unsolicited polls can introduce a
   significant latency in regard to the freshness of the monitored
   information.  The actual definition of intervals implemented by an
   I2NSF Component is also out of scope of this document.

4.4.  I2NSF Monitoring Terminology for Retained Information

   Records:  Unlike information emitted via notifications and events,
      records do not require immediate attention from an analyst but may
      be useful for visibility and retroactive cyber forensic.
      Depending on the record format, there are different qualities in
      regard to structure and detail.  Records are typically stored in
      log-files or databases on a system entity or NSF.  Records in the
      form of log-files usually include less structures but potentially
      more detailed information in regard to the changes of a system
      entity's characteristics.  In contrast, databases often use more
      strict schemas or data models, therefore enforcing a better
      structure.  However, they inhibit storing information that do not
      match those models ("closed world assumption").  Records can be
      continuously processed by I2NSF Agents that act as I2NSF Producer
      and emit events via functions specifically tailored to a certain
      type of record.  Typically, records are information generated
      either by an NSF or a system entity about operational and
      informational data, or various changes in system characteristics,
      such as user activities, network/traffic status, and network
      activity.  They are important for debugging, auditing and security
      forensic.

   Counters:  A specific representation of continuous value changes of
      information elements that potentially occur in high frequency.
      Prominent example are network interface counters, e.g., PDU amount
      or byte amount, drop counters, and error counters.  Counters are
      useful in debugging and visibility into operational behavior of an
      NSF.  An I2NSF Agent that observes the progression of counters can
      act as an I2NSF Producer and emit events in respect to I2NSF
      Policy Rules.

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5.  Conveyance of NSF Monitoring Information

   As per the use cases of NSF monitoring data, information needs to be
   conveyed to various I2NSF Consumers based on requirements imposed by
   I2NSF Capabilities and workflows.  There are multiple aspects to be
   considered in regard to the emission of monitoring information to
   requesting parties as listed below:

   o  Pull-Push Model: A set of data can be pushed by an NSF to a
      requesting party or pulled by a requesting party from an NSF.
      Specific types of information might need both the models at the
      same time if there are multiple I2NSF Consumers with varying
      requirements.  In general, any I2NSF Event including a high
      severity assessment is considered to be of great importance and
      should be processed as soon as possible (push-model).  Records, in
      contrast, are typically not as critical (pull-model).  The I2NSF
      Architecture does not mandate a specific scheme for each type of
      information and is therefore out of scope of this document.

   o  Pub-Sub Model: In order for an I2NSF Provider to push monitoring
      information to multiple appropriate I2NSF Consumers, a
      subscription can be maintained by both I2NSF Components.
      Discovery of available monitoring information can be supported by
      an I2NSF Controller that takes the role of a broker and therefore
      includes I2NSF Capabilities that support registration.

   o  Export Frequency: Monitoring information can be emitted
      immediately upon generation by an NSF to requesting I2NSF
      Consumers or can be pushed periodically.  The frequency of
      exporting the data depends upon its size and timely usefulness.
      It is out of the scope of I2NSF and left to each NSF
      implementation.

   o  Authentication: There may be a need for authentication between an
      I2NSF Producer of monitoring information and its corresponding
      I2NSF Consumer to ensure that critical information remains
      confidential.  Authentication in the scope of I2NSF can also
      require its corresponding content authorization.  This may be
      necessary, for example, if an NSF emits monitoring information to
      an I2NSF Consumer outside its administrative domain.  The I2NSF
      Architecture does not mandate when and how specific authentication
      has to be implemented.

   o  Data-Transfer Model: Monitoring information can be pushed by an
      NSF using a connection-less model that does require a persistent
      connection or streamed over a persistent connection.  An
      appropriate model depends on the I2NSF Consumer requirements and
      the semantics of the information to be conveyed.

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   o  Data Model and Interaction Model for Data in Motion: There are a
      lot of transport mechanisms such as IP, UDP, and TCP.  There are
      also open source implementations for specific set of data such as
      systems counter, e.g.  IPFIX [RFC7011] and NetFlow [RFC3954].  The
      I2NSF does not mandate any specific method for a given data set,
      so it is up to each implementation.

5.1.  Information Types and Acquisition Methods

   In this document, most defined information types defined benefit from
   high visibility with respect to value changes, e.g., alarms and
   records.  In contrast, values that change monotonically in a
   continuous way do not benefit from this high visibility.  On the
   contrary, emitting each change would result in a useless amount of
   value updates.  Hence, values, such as counter, are best acquired in
   periodic intervals.

   The mechanisms provided by YANG Push [I-D.ietf-netconf-yang-push] and
   YANG Subscribed Notifications
   [I-D.ietf-netconf-subscribed-notifications] address exactly these set
   of requirements.  YANG also enables semantically well-structured
   information, as well as subscriptions to datastores or event streams
   - by changes or periodically.

   In consequence, this information model in this document is intended
   to support data models used in solicited or unsolicited event streams
   that potentially are facilitated by a subscription mechanism.  A
   subset of information elements defined in the information model
   address this domain of application.

6.  Basic Information Model for All Monitoring Data

   As explained in the above section, there is a wealth of data
   available from the NSF that can be monitored.  Firstly, there must be
   some general information with each monitoring message sent from an
   NSF that helps a consumer to identify meta data with that message,
   which are listed as below:

   o  message: Event, Alert, Alarm, Log, Counter, etc.

   o  vendor-name: The name of the NSF vendor.

   o  nsf-name: The name (or IP) of the NSF generating the message.

   o  severity: It indicates the severity level.  There are total four
      levels, from 0 to 3.  The smaller the numeral is, the higher the
      severity is.

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7.  Extended Information Model for Monitoring Data

   This section covers the additional information associated with the
   system messages.  The extended information model is only for the
   structured data such as alarm.  Any unstructured data is specified
   with basic information model only.

7.1.  System Alarms

   Characteristics:

   o  acquisition-method: subscription

   o  emission-type: on-change

   o  dampening-type: on-repetition

7.1.1.  Memory Alarm

   The following information should be included in a Memory Alarm:

   o  event-name: mem-usage-alarm

   o  usage: specifies the size of memory used.

   o  threshold: The threshold triggering the alarm

   o  severity: The severity of the alarm such as critical, high,
      medium, low

   o  message: The memory usage exceeded the threshold

7.1.2.  CPU Alarm

   The following information should be included in a CPU Alarm:

   o  event-name: cpu-usage-alarm

   o  usage: Specifies the size of CPU used.

   o  threshold: The threshold triggering the event

   o  severity: The severity of the alarm such as critical, high,
      medium, low

   o  message: The CPU usage exceeded the threshold.

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7.1.3.  Disk Alarm

   The following information should be included in a Disk Alarm:

   o  event-name: disk-usage-alarm

   o  usage: Specifies the size of disk space used.

   o  threshold: The threshold triggering the event

   o  severity: The severity of the alarm such as critical, high,
      medium, low

   o  message: The disk usage exceeded the threshold.

7.1.4.  Hardware Alarm

   The following information should be included in a Hardware Alarm:

   o  event-name: hw-failure-alarm

   o  component-name: It indicates the HW component responsible for
      generating this alarm.

   o  severity: The severity of the alarm such as critical, high,
      medium, low

   o  message: The HW component has failed or degraded.

7.1.5.  Interface Alarm

   The following information should be included in an Interface Alarm:

   o  event-name: ifnet-state-alarm

   o  interface-name: The name of interface

   o  interface-state: up, down, congested

   o  threshold: The threshold triggering the event

   o  severity: The severity of the alarm such as critical, high,
      medium, low

   o  message: Current interface state

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7.2.  System Events

   Characteristics:

   o  acquisition-method: subscription

   o  emission-type: on-change

   o  dampening-type: on-repetition

7.2.1.  Access Violation

   The following information should be included in this event:

   o  event-name: access-denied

   o  user: Name of a user

   o  group: Group to which a user belongs

   o  login-ip-address: Login IP address of a user

   o  authentication: User authentication mode. e.g., Local
      Authentication, Third-Party Server Authentication, Authentication
      Exemption, Single Sign-On (SSO) Authentication

   o  message: access is denied.

7.2.2.  Configuration Change

   The following information should be included in this event:

   o  event-name: config-change

   o  user: Name of a user

   o  group: Group to which a user belongs

   o  login-ip-address: Login IP address of a user

   o  authentication: User authentication mode. e.g., Local
      Authentication, Third-Party Server Authentication, Authentication
      Exemption, SSO Authentication

   o  message: Configuration is modified.

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7.2.3.  Traffic flows

   The following information should be included in this event:

   o  src-ip: The source IPv4 or IPv6 address of the flows

   o  dst-ip: The destination IPv4 or IPv6 address of the flows

   o  src-port: The source port of the flows

   o  dst-port: The destination port of the flows

   o  protocol: The protocol of the packet flows.

   o  arrival-rate: Arrival rate of the same flow.

7.3.  NSF Events

   Characteristics:

   o  acquisition-method: subscription

   o  emission-type: on-change

   o  dampening-type: on-repetition

7.3.1.  DDoS Detection

   The following information should be included in a DDoS Event:

   o  event-name: detection-ddos

   o  attack-type: Any one of SYN flood, ACK flood, SYN-ACK flood, FIN/
      RST flood, TCP Connection flood, UDP flood, ICMP flood, HTTPS
      flood, HTTP flood, DNS query flood, DNS reply flood, SIP flood,
      and etc.

   o  dst-ip: The IP address of a victim under attack

   o  dst-port: The port number that the attack traffic aims at.

   o  start-time: The time stamp indicating when the attack started

   o  end-time: The time stamp indicating when the attack ended.  If the
      attack is still undergoing when sending out the alarm, this field
      can be empty.

   o  attack-rate: The PPS of attack traffic

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   o  attack-speed: the bps of attack traffic

   o  rule-name: The name of the rule being triggered

   o  profile: Security profile that traffic matches.

7.3.2.  Session Table Event

   The following information should be included in a Session
   Table Event:

   o  event-name: session-table

   o  current-session: The number of concurrent sessions

   o  maximum-session: The maximum number of sessions that the session
      table can support

   o  threshold: The threshold triggering the event

   o  message: The number of session table exceeded the threshold.

7.3.3.  Virus Event

   The following information should be included in a Virus Event:

   o  event-name: detection-virus

   o  virus: Type of the virus. e.g., trojan, worm, macro virus type

   o  virus-name: Name of the virus

   o  dst-ip: The destination IP address of the packet where the virus
      is found

   o  src-ip: The source IP address of the packet where the virus is
      found

   o  src-port: The source port of the packet where the virus is found

   o  dst-port: The destination port of the packet where the virus is
      found

   o  src-zone: The source security zone of the packet where the virus
      is found

   o  dst-zone: The destination security zone of the packet where the
      virus is found

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   o  file-type: The type of the file where the virus is hided within

   o  file-name: The name of the file where the virus is hided within

   o  raw_info: The information describing the packet triggering the
      event.

   o  rule_name: The name of the rule being triggered

7.3.4.  Intrusion Event

   The following information should be included in an Intrusion Event:

   o  event-name: The name of event. e.g., detection-intrusion

   o  attack-type: Attack type, e.g., brutal force and buffer overflow

   o  src-ip: The source IP address of the packet

   o  dst-ip: The destination IP address of the packet

   o  src-port:The source port number of the packet

   o  dst-port: The destination port number of the packet

   o  src-zone: The source security zone of the packet

   o  dst-zone: The destination security zone of the packet

   o  protocol: The employed transport layer protocol. e.g.,TCP and UDP

   o  app: The employed application layer protocol. e.g.,HTTP and FTP

   o  rule-name: The name of the rule being triggered

   o  raw-info: The information describing the packet triggering the
      event

7.3.5.  Botnet Event

   The following information should be included in a Botnet Event:

   o  event-name: The name of event. e.g., detection-botnet

   o  botnet-name: The name of the detected botnet

   o  src-ip: The source IP address of the packet

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   o  dst-ip: The destination IP address of the packet

   o  src-port: The source port number of the packet

   o  dst-port: The destination port number of the packet

   o  src-zone: The source security zone of the packet

   o  dst-zone: The destination security zone of the packet

   o  protocol: The employed transport layer protocol. e.g.,TCP and UDP

   o  role: The role of the communicating parties within the botnet:

      1.  The packet from the zombie host to the attacker

      2.  The packet from the attacker to the zombie host

      3.  The packet from the IRC/WEB server to the zombie host

      4.  The packet from the zombie host to the IRC/WEB server

      5.  The packet from the attacker to the IRC/WEB server

      6.  The packet from the IRC/WEB server to the attacker

      7.  The packet from the zombie host to the victim

   o  rule-name: The name of the rule being triggered

   o  raw-info: The information describing the packet triggering the
      event.

7.3.6.  Web Attack Event

   The following information should be included in a Web Attack Alarm:

   o  event-name: The name of event. e.g., detection-web-attack

   o  attack-type: Concrete web attack type. e.g., SQL injection,
      command injection, XSS, CSRF

   o  src-ip: The source IP address of the packet

   o  dst-ip: The destination IP address of the packet

   o  src-port: The source port number of the packet

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   o  dst-port: The destination port number of the packet

   o  src-zone: The source security zone of the packet

   o  dst-zone: The destination security zone of the packet

   o  request-method: The method of requirement.  For instance, "PUT"
      and "GET" in HTTP

   o  req-uri: Requested URI

   o  rsp-code: Response code

   o  req-clientapp: The client application

   o  req-cookies: Cookies

   o  req-host: The domain name of the requested host

   o  uri-category: Matched URI category

   o  filtering-type: URL filtering type. e.g., Blacklist, Whitelist,
      User-Defined, Predefined, Malicious Category, and Unknown

   o  rule-name: The name of the rule being triggered

   o  profile: Security profile that traffic matches

7.4.  System Logs

   Characteristics:

   o  acquisition-method: subscription

   o  emission-type: on-change

   o  dampening-type: on-repetition

7.4.1.  Access Log

   Access logs record administrators' login, logout, and operations on a
   device.  By analyzing them, security vulnerabilities can be
   identified.  The following information should be included in an
   operation report:

   o  Administrator: Administrator that operates on the device

   o  login-ip-address: IP address used by an administrator to log in

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   o  login-mode: Specifies the administrator logs in mode e.g. root,
      user

   o  operation-type: The operation type that the administrator execute,
      e.g., login, logout, and configuration.

   o  result: Command execution result

   o  content: Operation performed by an administrator after login.

7.4.2.  Resource Utilization Log

   Running reports record the device system's running status, which is
   useful for device monitoring.  The following information should be
   included in running report:

   o  system-status: The current system's running status

   o  cpu-usage: Specifies the CPU usage.

   o  memory-usage: Specifies the memory usage.

   o  disk-usage: Specifies the disk usage.

   o  disk-left: Specifies the available disk space left.

   o  session-number: Specifies total concurrent sessions.

   o  process-number: Specifies total number of systems processes.

   o  in-traffic-rate: The total inbound traffic rate in pps

   o  out-traffic-rate: The total outbound traffic rate in pps

   o  in-traffic-speed: The total inbound traffic speed in bps

   o  out-traffic-speed: The total outbound traffic speed in bps

7.4.3.  User Activity Log

   User activity logs provide visibility into users' online records
   (such as login time, online/lockout duration, and login IP addresses)
   and the actions that users perform.  User activity reports are
   helpful to identify exceptions during a user's login and network
   access activities.

   o  user: Name of a user

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   o  group: Group to which a user belongs

   o  login-ip-addr: Login IP address of a user

   o  authentication: User authentication mode. e.g., Local
      Authentication, Third-Party Server Authentication, Authentication
      Exemption, SSO Authentication

   o  access: User access mode. e.g., PPP, SVN, LOCAL

   o  online-duration: Online duration

   o  logout-duration: Logout duration

   o  additional-info: Additional Information for login:

      1.  type: User activities. e.g., Successful User Login, Failed
          Login attempts, User Logout, Successful User Password Change,
          Failed User Password Change, User Lockout, User Unlocking,
          Unknown

      2.  cause: Cause of a failed user activity

7.5.  NSF Logs

   Characteristics:

   o  acquisition-method: subscription

   o  emission-type: on-change

   o  dampening-type: on-repetition

7.5.1.  DPI Log

   DPI Logs provide statistics on uploaded and downloaded files and
   data, sent and received emails, and alert and block records on
   websites.  It is helpful to learn risky user behaviors and why access
   to some URLs is blocked or allowed with an alert record.

   o  attack-type: DPI action types. e.g., File Blocking, Data
      Filtering, and Application Behavior Control

   o  src-user: User source who generates the policy

   o  policy-name: Security policy name that traffic matches

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   o  action: Action defined in the file blocking rule, data filtering
      rule, or application behavior control rule that traffic matches.

7.5.2.  Vulnerability Scanning Log

   Vulnerability scanning logs record the victim host and its related
   vulnerability information that should to be fixed.  The following
   information should be included in the report:

   o  victim-ip: IP address of the victim host which has vulnerabilities

   o  vulnerability-id: The vulnerability id

   o  level: The vulnerability level. e.g., high, middle, and low

   o  OS: The operating system of the victim host

   o  service: The service which has vulnerability in the victim host

   o  protocol: The protocol type. e.g., TCP and UDP

   o  port-num: The port number

   o  vulnerability-info: The information about the vulnerability

   o  fix-suggestion: The fix suggestion to the vulnerability.

7.6.  System Counter

   Characteristics:

   o  acquisition-method: subscription or query

   o  emission-type: periodical

   o  dampening-type: none

7.6.1.  Interface Counter

   Interface counters provide visibility into traffic into and out of an
   NSF, and bandwidth usage.

   o  interface-name: Network interface name configured in NSF

   o  in-total-traffic-pkts: Total inbound packets

   o  out-total-traffic-pkts: Total outbound packets

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   o  in-total-traffic-bytes: Total inbound bytes

   o  out-total-traffic-bytes: Total outbound bytes

   o  in-drop-traffic-pkts: Total inbound drop packets

   o  out-drop-traffic-pkts: Total outbound drop packets

   o  in-drop-traffic-bytes: Total inbound drop bytes

   o  out-drop-traffic-bytes: Total outbound drop bytes

   o  in-traffic-average-rate: Inbound traffic average rate in pps

   o  in-traffic-peak-rate: Inbound traffic peak rate in pps

   o  in-traffic-average-speed: Inbound traffic average speed in bps

   o  in-traffic-peak-speed: Inbound traffic peak speed in bps

   o  out-traffic-average-rate: Outbound traffic average rate in pps

   o  out-traffic-peak-rate: Outbound traffic peak rate in pps

   o  out-traffic-average-speed: Outbound traffic average speed in bps

   o  out-traffic-peak-speed: Outbound traffic peak speed in bps

7.7.  NSF Counters

   Characteristics:

   o  acquisition-method: subscription or query

   o  emission-type: periodical

   o  dampening-type: none

7.7.1.  Firewall Counter

   Firewall counters provide visibility into traffic signatures,
   bandwidth usage, and how the configured security and bandwidth
   policies have been applied.

   o  src-zone: Source security zone of traffic

   o  dst-zone: Destination security zone of traffic

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   o  src-region: Source region of traffic

   o  dst-region: Destination region of traffic

   o  src-ip: Source IP address of traffic

   o  src-user: User who generates traffic

   o  dst-ip: Destination IP address of traffic

   o  src-port: Source port of traffic

   o  dst-port: Destination port of traffic

   o  protocol: Protocol type of traffic

   o  app: Application type of traffic

   o  policy-id: Security policy id that traffic matches

   o  policy-name: Security policy name that traffic matches

   o  in-interface: Inbound interface of traffic

   o  out-interface: Outbound interface of traffic

   o  total-traffic: Total traffic volume

   o  in-traffic-average-rate: Inbound traffic average rate in pps

   o  in-traffic-peak-rate: Inbound traffic peak rate in pps

   o  in-traffic-average-speed: Inbound traffic average speed in bps

   o  in-traffic-peak-speed: Inbound traffic peak speed in bps

   o  out-traffic-average-rate: Outbound traffic average rate in pps

   o  out-traffic-peak-rate: Outbound traffic peak rate in pps

   o  out-traffic-average-speed: Outbound traffic average speed in bps

   o  out-traffic-peak-speed: Outbound traffic peak speed in bps.

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7.7.2.  Policy Hit Counter

   Policy Hit Counters record the security policy that traffic matches
   and its hit count.  It can check if policy configurations are
   correct.

   o  src-zone: Source security zone of traffic

   o  dst-zone: Destination security zone of traffic

   o  src-region: Source region of the traffic

   o  dst-region: Destination region of the traffic

   o  src-ip: Source IP address of traffic

   o  src-user: User who generates traffic

   o  dst-ip: Destination IP address of traffic

   o  src-port: Source port of traffic

   o  dst-port: Destination port of traffic

   o  protocol: Protocol type of traffic

   o  app: Application type of traffic

   o  policy-id: Security policy id that traffic matches

   o  policy-name: Security policy name that traffic matches

   o  hit-times: The hit times that the security policy matches the
      specified traffic.

8.  NSF Monitoring Management in I2NSF

   A standard model for monitoring data is required for an administrator
   to check the monitoring data generated by an NSF.  The administrator
   can check the monitoring data through the following process.  When
   the NSF monitoring data that is under the standard format is
   generated, the NSF forwards it to an NSF data collector via the I2NSF
   NSF Monitoring Interface.  The NSF data collector delivers it to
   I2NSF Consumer or Developer's Management System (DMS) so that the
   administrator can know the state of the I2NSF framework.

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   In order to communicate with other components, an I2NSF framework
   [RFC8329] requires the interfaces.  The three main interfaces in
   I2NSF framework are used for sending monitoring data as follows:

   o  I2NSF Consumer-Facing Interface
      [I-D.ietf-i2nsf-consumer-facing-interface-dm]: When an I2NSF User
      makes a security policy and forwards it to the Security Controller
      via Consumer-Facing Interface, it can specify the threat-feed for
      threat prevention, the custom list, the malicious code scan group,
      and the event map group.  They can be used as an event to be
      monitored by an NSF.

   o  I2NSF Registration Interface
      [I-D.ietf-i2nsf-registration-interface-dm]: The Network Functions
      Virtualization (NFV) architecture provides the lifecycle
      management of a Virtual Network Function (VNF) via the Ve-Vnfm
      interface.  The role of Ve-Vnfm is to request VNF lifecycle
      management (e.g., the instantiation and de-instantiation of an
      NSF, and load balancing among NSFs), exchange configuration
      information, and exchange status information for a network
      service.  In the I2NSF framework, the DMS manages data about
      resource states and network traffic for the lifecycle management
      of an NSF.  Therefore, the generated monitoring data from NSFs are
      delivered from the NSF data collector to the DMS via either
      Registration Interface or a new interface (e.g., NSF Monitoring
      Interface).  These data are delivered from the DMS to the VNF
      Manager in the Management and Orchestration (MANO) in the NFV
      system [I-D.ietf-i2nsf-applicability].

   o  I2NSF NSF Monitoring Interface [RFC8329]: After a high-level
      security policy from I2NSF User is translated by security policy
      translator [I-D.yang-i2nsf-security-policy-translation] in the
      Security Controller, the translated security policy (i.e., low-
      level policy) is applied to an NSF via NSF-Facing Interface.  The
      monitoring data model for an NSF specifies the list of events that
      can trigger Event-Condition-Action (ECA) policies via NSF
      Monitoring Interface.

9.  Tree Structure

   The tree structure of the NSF monitoring YANG module is provided
   below:

 module: ietf-i2nsf-nsf-monitoring
   +--ro i2nsf-counters
   |  +--ro system-interface* [interface-name]
   |  |  +--ro acquisition-method?            identityref
   |  |  +--ro emission-type?                 identityref

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   |  |  +--ro dampening-type?                identityref
   |  |  +--ro interface-name                 string
   |  |  +--ro in-total-traffic-pkts?         yang:counter32
   |  |  +--ro out-total-traffic-pkts?        yang:counter32
   |  |  +--ro in-total-traffic-bytes?        uint64
   |  |  +--ro out-total-traffic-bytes?       uint64
   |  |  +--ro in-drop-traffic-pkts?          yang:counter32
   |  |  +--ro out-drop-traffic-pkts?         yang:counter32
   |  |  +--ro in-drop-traffic-bytes?         uint64
   |  |  +--ro out-drop-traffic-bytes?        uint64
   |  |  +--ro total-traffic?                 yang:counter32
   |  |  +--ro in-traffic-average-rate?       uint32
   |  |  +--ro in-traffic-peak-rate?          uint32
   |  |  +--ro in-traffic-average-speed?      uint32
   |  |  +--ro in-traffic-peak-speed?         uint32
   |  |  +--ro out-traffic-average-rate?      uint32
   |  |  +--ro out-traffic-peak-rate?         uint32
   |  |  +--ro out-traffic-average-speed?     uint32
   |  |  +--ro out-traffic-peak-speed?        uint32
   |  |  +--ro message?                       string
   |  |  +--ro vendor-name?                   string
   |  |  +--ro nsf-name?                      string
   |  |  +--ro severity?                      severity
   |  +--ro nsf-firewall* [policy-name]
   |  |  +--ro acquisition-method?       identityref
   |  |  +--ro emission-type?            identityref
   |  |  +--ro dampening-type?           identityref
   |  |  +--ro policy-name
     -> /nsfi:i2nsf-security-policy/system-policy/system-policy-name
   |  |  +--ro src-user?                     string
   |  |  +--ro total-traffic?                yang:counter32
   |  |  +--ro in-traffic-average-rate?      uint32
   |  |  +--ro in-traffic-peak-rate?         uint32
   |  |  +--ro in-traffic-average-speed?     uint32
   |  |  +--ro in-traffic-peak-speed?        uint32
   |  |  +--ro out-traffic-average-rate?     uint32
   |  |  +--ro out-traffic-peak-rate?        uint32
   |  |  +--ro out-traffic-average-speed?    uint32
   |  |  +--ro out-traffic-peak-speed?       uint32
   |  |  +--ro message?                      string
   |  |  +--ro vendor-name?                  string
   |  |  +--ro nsf-name?                     string
   |  |  +--ro severity?                     severity
   |  +--ro nsf-policy-hits* [policy-name]
   |     +--ro acquisition-method?   identityref
   |     +--ro emission-type?        identityref
   |     +--ro dampening-type?       identityref
   |     +--ro policy-name

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     -> /nsfi:i2nsf-security-policy/system-policy/system-policy-name
   |     +--ro src-user?             string
   |     +--ro message?              string
   |     +--ro vendor-name?          string
   |     +--ro nsf-name?             string
   |     +--ro severity?             severity
   |     +--ro hit-times?            yang:counter32
   +--rw i2nsf-monitoring-configuration
      +--rw i2nsf-system-detection-alarm
      |  +--rw enabled?        boolean
      |  +--rw system-alarm* [alarm-type]
      |     +--rw alarm-type          enumeration
      |     +--rw threshold?          uint8
      |     +--rw dampening-period?   uint32
      +--rw i2nsf-system-detection-event
      |  +--rw enabled?            boolean
      |  +--rw dampening-period?   uint32
      +--rw i2nsf-traffic-flows
      |  +--rw dampening-period?   uint32
      |  +--rw enabled?            boolean
      +--rw i2nsf-nsf-detection-ddos {i2nsf-nsf-detection-ddos}?
      |  +--rw enabled?            boolean
      |  +--rw dampening-period?   uint32
      +--rw i2nsf-nsf-detection-session-table-configuration
      |  +--rw enabled?            boolean
      |  +--rw dampening-period?   uint32
      +--rw i2nsf-nsf-detection-virus {i2nsf-nsf-detection-virus}?
      |  +--rw enabled?            boolean
      |  +--rw dampening-period?   uint32
      +--rw i2nsf-nsf-detection-intrusion
         {i2nsf-nsf-detection-intrusion}?
      |  +--rw enabled?            boolean
      |  +--rw dampening-period?   uint32
      +--rw i2nsf-nsf-detection-botnet {i2nsf-nsf-detection-botnet}?
      |  +--rw enabled?            boolean
      |  +--rw dampening-period?   uint32
      +--rw i2nsf-nsf-detection-web-attack
         {i2nsf-nsf-detection-web-attack}?
      |  +--rw enabled?            boolean
      |  +--rw dampening-period?   uint32
      +--rw i2nsf-nsf-system-access-log
      |  +--rw enabled?            boolean
      |  +--rw dampening-period?   uint32
      +--rw i2nsf-system-res-util-log
      |  +--rw enabled?            boolean
      |  +--rw dampening-period?   uint32
      +--rw i2nsf-system-user-activity-log
      |  +--rw enabled?            boolean

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      |  +--rw dampening-period?   uint32
      +--rw i2nsf-nsf-log-dpi {i2nsf-nsf-log-dpi}?
      |  +--rw enabled?            boolean
      |  +--rw dampening-period?   uint32
      +--rw i2nsf-nsf-log-vuln-scan {i2nsf-nsf-log-vuln-scan}?
      |  +--rw enabled?            boolean
      |  +--rw dampening-period?   uint32
      +--rw i2nsf-counter
         +--rw period?   uint16

   notifications:
     +---n i2nsf-event
     |  +--ro (sub-event-type)?
     |     +--:(i2nsf-system-detection-alarm)
     |     |  +--ro i2nsf-system-detection-alarm
     |     |     +--ro alarm-category?       identityref
     |     |     +--ro component-name?       string
     |     |     +--ro interface-name?       string
     |     |     +--ro interface-state?      enumeration
     |     |     +--ro acquisition-method?   identityref
     |     |     +--ro emission-type?        identityref
     |     |     +--ro dampening-type?       identityref
     |     |     +--ro usage?                uint8
     |     |     +--ro threshold?            uint8
     |     |     +--ro message?              string
     |     |     +--ro vendor-name?          string
     |     |     +--ro nsf-name?             string
     |     |     +--ro severity?             severity
     |     +--:(i2nsf-system-detection-event)
     |     |  +--ro i2nsf-system-detection-event
     |     |     +--ro event-category?       identityref
     |     |     +--ro acquisition-method?   identityref
     |     |     +--ro emission-type?        identityref
     |     |     +--ro dampening-type?       identityref
     |     |     +--ro user                  string
     |     |     +--ro group                 string
     |     |     +--ro login-ip-addr         inet:ip-address
     |     |     +--ro authentication?       identityref
     |     |     +--ro message?              string
     |     |     +--ro vendor-name?          string
     |     |     +--ro nsf-name?             string
     |     |     +--ro severity?             severity
     |     +--:(i2nsf-traffic-flows)
     |     |  +--ro i2nsf-traffic-flows
     |     |     +--ro src-ip?               inet:ip-address
     |     |     +--ro dst-ip?               inet:ip-address
     |     |     +--ro protocol?             identityref
     |     |     +--ro src-port?             inet:port-number

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     |     |     +--ro dst-port?             inet:port-number
     |     |     +--ro arrival-rate?         uint32
     |     |     +--ro acquisition-method?   identityref
     |     |     +--ro emission-type?        identityref
     |     |     +--ro dampening-type?       identityref
     |     |     +--ro message?              string
     |     |     +--ro vendor-name?          string
     |     |     +--ro nsf-name?             string
     |     |     +--ro severity?             severity
     |     +--:(i2nsf-nsf-detection-session-table)
     |        +--ro i2nsf-nsf-detection-session-table
     |           +--ro current-session?   uint32
     |           +--ro maximum-session?   uint32
     |           +--ro threshold?         uint32
     |           +--ro message?           string
     |           +--ro vendor-name?       string
     |           +--ro nsf-name?          string
     |           +--ro severity?          severity
     +---n i2nsf-log
     |  +--ro (sub-logs-type)?
     |     +--:(i2nsf-nsf-system-access-log)
     |     |  +--ro i2nsf-nsf-system-access-log
     |     |     +--ro login-ip              inet:ip-address
     |     |     +--ro administrator?        string
     |     |     +--ro login-mode?           login-mode
     |     |     +--ro operation-type?       operation-type
     |     |     +--ro result?               string
     |     |     +--ro content?              string
     |     |     +--ro acquisition-method?   identityref
     |     |     +--ro emission-type?        identityref
     |     |     +--ro dampening-type?       identityref
     |     |     +--ro message?              string
     |     |     +--ro vendor-name?          string
     |     |     +--ro nsf-name?             string
     |     |     +--ro severity?             severity
     |     +--:(i2nsf-system-res-util-log)
     |     |  +--ro i2nsf-system-res-util-log
     |     |     +--ro system-status?        string
     |     |     +--ro cpu-usage?            uint8
     |     |     +--ro memory-usage?         uint8
     |     |     +--ro disk-usage?           uint8
     |     |     +--ro disk-left?            uint8
     |     |     +--ro session-num?          uint8
     |     |     +--ro process-num?          uint8
     |     |     +--ro in-traffic-rate?      uint32
     |     |     +--ro out-traffic-rate?     uint32
     |     |     +--ro in-traffic-speed?     uint32
     |     |     +--ro out-traffic-speed?    uint32

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     |     |     +--ro acquisition-method?   identityref
     |     |     +--ro emission-type?        identityref
     |     |     +--ro dampening-type?       identityref
     |     |     +--ro message?              string
     |     |     +--ro vendor-name?          string
     |     |     +--ro nsf-name?             string
     |     |     +--ro severity?             severity
     |     +--:(i2nsf-system-user-activity-log)
     |        +--ro i2nsf-system-user-activity-log
     |           +--ro acquisition-method?   identityref
     |           +--ro emission-type?        identityref
     |           +--ro dampening-type?       identityref
     |           +--ro user                  string
     |           +--ro group                 string
     |           +--ro login-ip-addr         inet:ip-address
     |           +--ro authentication?       identityref
     |           +--ro message?              string
     |           +--ro vendor-name?          string
     |           +--ro nsf-name?             string
     |           +--ro severity?             severity
     |           +--ro access?               identityref
     |           +--ro online-duration?      string
     |           +--ro logout-duration?      string
     |           +--ro additional-info?      string
     +---n i2nsf-nsf-event
        +--ro (sub-event-type)?
           +--:(i2nsf-nsf-detection-ddos) {i2nsf-nsf-detection-ddos}?
           |  +--ro i2nsf-nsf-detection-ddos
           |     +--ro dst-ip?               inet:ip-address
           |     +--ro dst-port?             inet:port-number
           |     +--ro rule-name
            -> /nsfi:i2nsf-security-policy/system-policy/rules/rule-name
           |     +--ro raw-info?             string
           |     +--ro attack-type?          identityref
           |     +--ro start-time            yang:date-and-time
           |     +--ro end-time              yang:date-and-time
           |     +--ro attack-src-ip?        inet:ip-address
           |     +--ro attack-dst-ip?        inet:ip-address
           |     +--ro attack-rate?          uint32
           |     +--ro attack-speed?         uint32
           |     +--ro action?               log-action
           |     +--ro acquisition-method?   identityref
           |     +--ro emission-type?        identityref
           |     +--ro dampening-type?       identityref
           |     +--ro message?              string
           |     +--ro vendor-name?          string
           |     +--ro nsf-name?             string
           |     +--ro severity?             severity

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           +--:(i2nsf-nsf-detection-virus) {i2nsf-nsf-detection-virus}?
           |  +--ro i2nsf-nsf-detection-virus
           |     +--ro dst-ip?               inet:ip-address
           |     +--ro dst-port?             inet:port-number
           |     +--ro rule-name
            -> /nsfi:i2nsf-security-policy/system-policy/rules/rule-name
           |     +--ro raw-info?             string
           |     +--ro src-ip?               inet:ip-address
           |     +--ro src-port?             inet:port-number
           |     +--ro src-zone?             string
           |     +--ro dst-zone?             string
           |     +--ro virus?                identityref
           |     +--ro virus-name?           string
           |     +--ro file-type?            string
           |     +--ro file-name?            string
           |     +--ro os?                   string
           |     +--ro action?               log-action
           |     +--ro acquisition-method?   identityref
           |     +--ro emission-type?        identityref
           |     +--ro dampening-type?       identityref
           |     +--ro message?              string
           |     +--ro vendor-name?          string
           |     +--ro nsf-name?             string
           |     +--ro severity?             severity
           +--:(i2nsf-nsf-detection-intrusion)
               {i2nsf-nsf-detection-intrusion}?
           |  +--ro i2nsf-nsf-detection-intrusion
           |     +--ro dst-ip?               inet:ip-address
           |     +--ro dst-port?             inet:port-number
           |     +--ro rule-name
            -> /nsfi:i2nsf-security-policy/system-policy/rules/rule-name
           |     +--ro raw-info?             string
           |     +--ro src-ip?               inet:ip-address
           |     +--ro src-port?             inet:port-number
           |     +--ro src-zone?             string
           |     +--ro dst-zone?             string
           |     +--ro protocol?             identityref
           |     +--ro app?                  string
           |     +--ro attack-type?          identityref
           |     +--ro action?               log-action
           |     +--ro attack-rate?          uint32
           |     +--ro attack-speed?         uint32
           |     +--ro acquisition-method?   identityref
           |     +--ro emission-type?        identityref
           |     +--ro dampening-type?       identityref
           |     +--ro message?              string
           |     +--ro vendor-name?          string
           |     +--ro nsf-name?             string

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           |     +--ro severity?             severity
           +--:(i2nsf-nsf-detection-botnet)
             {i2nsf-nsf-detection-botnet}?
           |  +--ro i2nsf-nsf-detection-botnet
           |     +--ro dst-ip?               inet:ip-address
           |     +--ro dst-port?             inet:port-number
           |     +--ro rule-name
            -> /nsfi:i2nsf-security-policy/system-policy/rules/rule-name
           |     +--ro raw-info?             string
           |     +--ro src-ip?               inet:ip-address
           |     +--ro src-port?             inet:port-number
           |     +--ro src-zone?             string
           |     +--ro dst-zone?             string
           |     +--ro attack-type?          identityref
           |     +--ro protocol?             identityref
           |     +--ro botnet-name?          string
           |     +--ro role?                 string
           |     +--ro action?               log-action
           |     +--ro botnet-pkt-num?       uint8
           |     +--ro os?                   string
           |     +--ro acquisition-method?   identityref
           |     +--ro emission-type?        identityref
           |     +--ro dampening-type?       identityref
           |     +--ro message?              string
           |     +--ro vendor-name?          string
           |     +--ro nsf-name?             string
           |     +--ro severity?             severity
           +--:(i2nsf-nsf-detection-web-attack)
               {i2nsf-nsf-detection-web-attack}?
           |  +--ro i2nsf-nsf-detection-web-attack
           |     +--ro dst-ip?               inet:ip-address
           |     +--ro dst-port?             inet:port-number
           |     +--ro rule-name
            -> /nsfi:i2nsf-security-policy/system-policy/rules/rule-name
           |     +--ro raw-info?             string
           |     +--ro src-ip?               inet:ip-address
           |     +--ro src-port?             inet:port-number
           |     +--ro src-zone?             string
           |     +--ro dst-zone?             string
           |     +--ro attack-type?          identityref
           |     +--ro request-method?       identityref
           |     +--ro req-uri?              string
           |     +--ro uri-category?         string
           |     +--ro filtering-type*       identityref
           |     +--ro rsp-code?             string
           |     +--ro req-clientapp?        string
           |     +--ro req-cookies?          string
           |     +--ro req-host?             string

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           |     +--ro acquisition-method?   identityref
           |     +--ro emission-type?        identityref
           |     +--ro dampening-type?       identityref
           |     +--ro action?               log-action
           |     +--ro message?              string
           |     +--ro vendor-name?          string
           |     +--ro nsf-name?             string
           |     +--ro severity?             severity
           +--:(i2nsf-nsf-log-vuln-scan) {i2nsf-nsf-log-vuln-scan}?
           |  +--ro i2nsf-nsf-log-vuln-scan
           |     +--ro vulnerability-id?     uint8
           |     +--ro victim-ip?            inet:ip-address
           |     +--ro protocol?             identityref
           |     +--ro port-num?             inet:port-number
           |     +--ro level?                severity
           |     +--ro os?                   string
           |     +--ro vulnerability-info?   string
           |     +--ro fix-suggestion?       string
           |     +--ro service?              string
           |     +--ro acquisition-method?   identityref
           |     +--ro emission-type?        identityref
           |     +--ro dampening-type?       identityref
           |     +--ro message?              string
           |     +--ro vendor-name?          string
           |     +--ro nsf-name?             string
           |     +--ro severity?             severity
           +--:(i2nsf-nsf-log-dpi) {i2nsf-nsf-log-dpi}?
              +--ro i2nsf-nsf-log-dpi
                 +--ro attack-type?          dpi-type
                 +--ro acquisition-method?   identityref
                 +--ro emission-type?        identityref
                 +--ro dampening-type?       identityref
                 +--ro policy-name
         -> /nsfi:i2nsf-security-policy/system-policy/system-policy-name
                 +--ro src-user?             string
                 +--ro message?              string
                 +--ro vendor-name?          string
                 +--ro nsf-name?             string
                 +--ro severity?             severity

              Figure 1: Information Model for NSF Monitoring

10.  YANG Data Model

   This section describes a YANG module of I2NSF NSF Monitoring.  This
   YANG module imports from [RFC6991], and makes references to
   [RFC0768][RFC0791] [RFC0792][RFC0793][RFC0956]
   [RFC0959][RFC2616][RFC4443] [RFC8200][RFC8632][RFC8641].

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 <CODE BEGINS> file "ietf-i2nsf-nsf-monitoring@2021-04-29.yang"

 module ietf-i2nsf-nsf-monitoring {
   yang-version 1.1;
   namespace
     "urn:ietf:params:xml:ns:yang:ietf-i2nsf-nsf-monitoring";
   prefix
     nsfmi;
   import ietf-inet-types{
     prefix inet;
     reference
       "Section 4 of RFC 6991";
   }
   import ietf-yang-types {
     prefix yang;
     reference
       "Section 3 of RFC 6991";
   }
   import ietf-i2nsf-policy-rule-for-nsf {
     prefix nsfi;
     reference
       "Section 4.1 of draft-ietf-i2nsf-nsf-facing-interface-dm-12";
   }
   organization
     "IETF I2NSF (Interface to Network Security Functions)
      Working Group";
   contact
     "WG Web: <http://tools.ietf.org/wg/i2nsf>
      WG List: <mailto:i2nsf@ietf.org>

      Editor: Jaehoon Paul Jeong
      <mailto:pauljeong@skku.edu>

      Editor: Patrick Lingga
      <mailto:patricklink@skku.edu>";

   description
     "This module is a YANG module for I2NSF NSF Monitoring.

      Copyright (c) 2021 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
      (https://trustee.ietf.org/license-info).

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      This version of this YANG module is part of RFC XXXX
      (https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself
      for full legal notices.";

   revision "2021-04-29" {
     description "Latest revision";
     reference
       "RFC XXXX: I2NSF NSF Monitoring Interface YANG Data Model";

     // RFC Ed.: replace XXXX with an actual RFC number and remove
     // this note.
   }

   /*
    * Typedefs
    */

   typedef severity {
     type enumeration {
       enum critical {
         description
           "The 'critical' severity level indicates that
            an immediate corrective action is required.
            A 'critical' severity is reported when a service
            becomes totally out of service and must be restored.";
       }
       enum high {
         description
           "The 'high' severity level indicates that
            an urgent corrective action is required.
            A 'high' severity is reported when there is
            a severe degradation in the capability of the
            service and its full capability must be restored.";
       }
       enum middle {
         description
           "The 'middle' severity level indicates the
            existence of a non-service-affecting fault
            condition and corrective action should be done
            to prevent a more serious fault. The 'middle'
            severity is reported when the detected problem
            is not degrading the capability of the service but
            might happen if not prevented.";
       }
       enum low {
         description
           "The 'low' severity level indicates the detection
            of a potential fault before any effect is felt.

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            The 'low' severity is reported when an action should
            be done before a fault happen.";
       }
     }
     description
       "An indicator representing severity level. The severity level
        starting from the highest are critical, high, middle, and
        low.";
     reference
       "RFC 8632: A YANG Data Model for Alarm Management -
        The severity levels are defined.";
   }

   typedef log-action {
     type enumeration {
       enum allow {
         description
           "If action is allowed";
       }
       enum alert {
         description
           "If action is alert";
       }
       enum block {
         description
           "If action is block";
       }
       enum discard {
         description
           "If action is discarded";
       }
       enum declare {
         description
           "If action is declared";
       }
       enum block-ip {
         description
           "If action is block-ip";
       }
       enum block-service{
         description
           "If action is block-service";
       }
     }
     description
       "The type representing action for logging.";
   }

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   typedef dpi-type{
     type enumeration {
       enum file-blocking{
         description
           "DPI for blocking file";
       }
       enum data-filtering{
         description
           "DPI for filtering data";
       }
       enum application-behavior-control{
         description
           "DPI for controlling application behavior";
       }
     }
     description
       "The type of deep packet inspection.";
   }

   typedef operation-type{
     type enumeration {
       enum login{
         description
           "Login operation";
       }
       enum logout{
         description
           "Logout operation";
       }
       enum configuration{
         description
           "Configuration operation";
       }
     }
     description
       "The type of operation done by a user
        during a session.";
   }

   typedef login-mode{
     type enumeration {
       enum root{
         description
           "Root login-mode";
       }
       enum user{
         description
           "User login-mode";

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       }
       enum guest{
         description
           "Guest login-mode";
       }
     }
     description
       "The authorization login-mode done by a user.";
   }

   /*
    * Identity
    */

   identity characteristics {
     description
       "Base identity for monitoring information
        characteristics";
   }
   identity acquisition-method {
     base characteristics;
     description
       "The type of acquisition-method. It can be multiple
        types at once.";
   }
   identity subscription {
     base acquisition-method;
     description
       "The acquisition-method type is subscription.";
   }
   identity query {
     base acquisition-method;
     description
       "The acquisition-method type is query.";
   }
   identity emission-type {
     base characteristics;
     description
       "The type of emission-type.";
   }
   identity periodical {
     base emission-type;
     description
       "The emission-type type is periodical.";
   }
   identity on-change {
     base emission-type;
     description

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       "The emission-type type is on-change.";
   }
   identity dampening-type {
     base characteristics;
     description
       "The type of dampening-type.";
   }
   identity no-dampening {
     base dampening-type;
     description
       "The dampening-type is no-dampening.";
   }
   identity on-repetition {
     base dampening-type;
     description
       "The dampening-type is on-repetition.";
   }
   identity none {
     base dampening-type;
     description
       "The dampening-type is none.";
   }
   identity authentication-mode {
     description
       "User authentication mode types:
        e.g., Local Authentication,
        Third-Party Server Authentication,
        Authentication Exemption, or Single Sign-On (SSO)
        Authentication.";
   }
   identity local-authentication {
     base authentication-mode;
     description
       "Authentication-mode : local authentication.";
   }
   identity third-party-server-authentication {
     base authentication-mode;
     description
       "If authentication-mode is
        third-party-server-authentication";
   }
   identity exemption-authentication {
     base authentication-mode;
     description
       "If authentication-mode is
        exemption-authentication";
   }
   identity sso-authentication {

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     base authentication-mode;
     description
       "If authentication-mode is
        sso-authentication";
   }
   identity alarm-type {
     description
       "Base identity for detectable alarm types";
   }
   identity mem-usage-alarm {
     base alarm-type;
     description
       "A memory alarm is alerted.";
   }
   identity cpu-usage-alarm {
     base alarm-type;
     description
       "A CPU alarm is alerted.";
   }
   identity disk-usage-alarm {
     base alarm-type;
     description
       "A disk alarm is alerted.";
   }
   identity hw-failure-alarm {
     base alarm-type;
     description
       "A hardware alarm is alerted.";
   }
   identity ifnet-state-alarm {
     base alarm-type;
     description
       "An interface alarm is alerted.";
   }
   identity event-type {
     description
       "Base identity for detectable event types";
   }
   identity access-denied {
     base event-type;
     description
       "The system event is access-denied.";
   }
   identity config-change {
     base event-type;
     description
       "The system event is config-change.";
   }

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   identity attack-type {
     description
       "The root ID of attack-based notification
        in the notification taxonomy";
   }
   identity system-attack-type {
     base attack-type;
     description
       "This ID is intended to be used
        in the context of system events.";
   }
   identity nsf-attack-type {
     base attack-type;
     description
       "This ID is intended to be used
        in the context of NSF event.";
   }
   identity botnet-attack-type {
     base nsf-attack-type;
     description
       "This indicates that this attack type is botnet.
        The usual semantic and taxonomy is missing
        and a name is used.";
   }
   identity virus-type {
     base nsf-attack-type;
     description
       "The type of virus. It caan be multiple types at once.
        This attack type is associated with a detected
        system-log virus-attack.";
   }
   identity trojan {
     base virus-type;
     description
       "The detected virus type is trojan.";
   }
   identity worm {
     base virus-type;
     description
       "The detected virus type is worm.";
   }
   identity macro {
     base virus-type;
     description
       "The detected virus type is macro.";
   }
   identity intrusion-attack-type {
     base nsf-attack-type;

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     description
       "The attack type is associated with a detected
        system-log intrusion.";
   }
   identity brute-force {
     base intrusion-attack-type;
     description
       "The intrusion type is brute-force.";
   }
   identity buffer-overflow {
     base intrusion-attack-type;
     description
       "The intrusion type is buffer-overflow.";
   }
   identity web-attack-type {
     base nsf-attack-type;
     description
       "The attack type is associated with a detected
        system-log web-attack.";
   }
   identity command-injection {
     base web-attack-type;
     description
       "The detected web attack type is command injection.";
   }
   identity xss {
     base web-attack-type;
     description
       "The detected web attack type is XSS.";
   }
   identity csrf {
     base web-attack-type;
     description
       "The detected web attack type is CSRF.";
   }
   identity flood-type {
     base nsf-attack-type;
     description
       "Base identity for detectable flood types";
   }
   identity syn-flood {
     base flood-type;
     description
       "A SYN flood is detected.";
   }
   identity ack-flood {
     base flood-type;
     description

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       "An ACK flood is detected.";
   }
   identity syn-ack-flood {
     base flood-type;
     description
       "A SYN-ACK flood is detected.";
   }
   identity fin-rst-flood {
     base flood-type;
     description
       "A FIN-RST flood is detected.";
   }
   identity tcp-con-flood {
     base flood-type;
     description
       "A TCP connection flood is detected.";
   }
   identity udp-flood {
     base flood-type;
     description
       "A UDP flood is detected.";
   }
   identity icmp-flood {
     base flood-type;
     description
       "Either an ICMPv4 or ICMPv6 flood is detected.";
   }
   identity icmpv4-flood {
     base flood-type;
     description
       "An ICMPv4 flood is detected.";
   }
   identity icmpv6-flood {
     base flood-type;
     description
       "An ICMPv6 flood is detected.";
   }
   identity http-flood {
     base flood-type;
     description
       "An HTTP flood is detected.";
   }
   identity https-flood {
     base flood-type;
     description
       "An HTTPS flood is detected.";
   }
   identity dns-query-flood {

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     base flood-type;
     description
       "A DNS query flood is detected.";
   }
   identity dns-reply-flood {
     base flood-type;
     description
      "A DNS reply flood is detected.";
   }
   identity sip-flood {
     base flood-type;
     description
       "An SIP flood is detected.";
   }

   identity req-method {
     description
       "A set of request types (if applicable).
        For instance, PUT or GET in HTTP.";
   }
   identity put-req {
     base req-method;
     description
       "The detected request type is PUT.";
   }
   identity get-req {
     base req-method;
     description
       "The detected request type is GET.";
   }
   identity filter-type {
     description
       "The type of filter used to detect an attack,
        for example, a web-attack.  It can be applicable to
        more than web-attacks.  It can be more than one type.";
   }
   identity whitelist {
     base filter-type;
     description
       "The applied filter type is whitelist.";
   }
   identity blacklist {
     base filter-type;
     description
       "The applied filter type is blacklist.";
   }
   identity user-defined {
    base filter-type;

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     description
       "The applied filter type is user-defined.";
   }
   identity malicious-category {
     base filter-type;
     description
       "The applied filter is malicious category.";
   }
   identity unknown-filter {
     base filter-type;
     description
       "The applied filter is unknown.";
   }

   identity access-mode {
     description
       "Base identity for detectable access mode.";
   }
   identity ppp {
     base access-mode;
     description
       "Access-mode: ppp";
   }
   identity svn {
     base access-mode;
     description
       "Access-mode: svn";
   }
   identity local {
     base access-mode;
     description
       "Access-mode: local";
   }

   identity protocol-type {
     description
       "An identity used to enable type choices in leaves
        and leaflists with respect to protocol metadata.";
   }
   identity tcp {
     base ipv4;
     base ipv6;
     description
       "TCP protocol type.";
     reference
       "RFC 793: Transmission Control Protocol";
   }
   identity udp {

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     base ipv4;
     base ipv6;
     description
       "UDP protocol type.";
     reference
       "RFC 768: User Datagram Protocol";
   }
   identity icmp {
     base ipv4;
     base ipv6;
     description
       "General ICMP protocol type.";
     reference
       "RFC 792: Internet Control Message Protocol
        RFC 4443: Internet Control Message Protocol
        (ICMPv6) for the Internet Protocol Version 6
        (IPv6) Specification";
   }
   identity icmpv4 {
     base ipv4;
     description
       "ICMPv4 protocol type.";
     reference
       "RFC 791: Internet Protocol
        RFC 792: Internet Control Message Protocol";
   }
   identity icmpv6 {
     base ipv6;
     description
       "ICMPv6 protocol type.";
     reference
       "RFC 8200: Internet Protocol, Version 6 (IPv6)
        RFC 4443: Internet Control Message Protocol (ICMPv6)
        for the Internet Protocol Version 6 (IPv6)
        Specification";
   }
   identity ip {
     base protocol-type;
     description
       "General IP protocol type.";
     reference
       "RFC 791: Internet Protocol
        RFC 8200: Internet Protocol, Version 6 (IPv6)";
   }
   identity ipv4 {
     base ip;
     description
       "IPv4 protocol type.";

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     reference
       "RFC 791: Internet Protocol";
   }
   identity ipv6 {
     base ip;
     description
       "IPv6 protocol type.";
     reference
       "RFC 8200: Internet Protocol, Version 6 (IPv6)";
   }
   identity http {
     base tcp;
     description
       "HTPP protocol type.";
     reference
       "RFC 2616: Hypertext Transfer Protocol";
   }
   identity ftp {
     base tcp;
     description
       "FTP protocol type.";
     reference
       "RFC 959: File Transfer Protocol";
   }

   /*
    * Grouping
    */

   grouping common-monitoring-data {
     description
       "A set of common monitoring data that is needed
       as the basic information.";
     leaf message {
       type string;
       description
         "This is a freetext annotation for
          monitoring a notification's content.";
     }
     leaf vendor-name {
       type string;
       description
         "The name of the NSF vendor";
     }
     leaf nsf-name {
       type string;
       description
         "The name (or IP) of the NSF generating the message.";

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     }
     leaf severity {
       type severity;
       description
         "The severity of the alarm such as critical, high,
          middle, low.";
     }
   }
   grouping characteristics {
     description
       "A set of characteristics of a notification.";
     leaf acquisition-method {
       type identityref {
         base acquisition-method;
       }
       description
         "The acquisition-method for characteristics";
     }
     leaf emission-type {
       type identityref {
         base emission-type;
       }
      description
         "The emission-type for characteristics";
     }
     leaf dampening-type {
       type identityref {
         base dampening-type;
       }
       description
         "The dampening-type for characteristics";
     }
   }
   grouping i2nsf-system-alarm-type-content {
     description
       "A set of contents for alarm type notification.";
     leaf usage {
       type uint8 {
         range "0..100";
       }
       units "percent";
       description
         "Specifies the used percentage";
     }
     leaf threshold {
       type uint8 {
         range "0..100";
       }

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       units "percent";
       description
         "The threshold percentage triggering the alarm or
          the event";
     }
   }
   grouping i2nsf-system-event-type-content {
     description
       "System event metadata associated with system events
        caused by user activity.";
     leaf user {
       type string;
       mandatory true;
       description
         "The name of a user";
     }
     leaf group {
       type string;
       mandatory true;
       description
         "The group to which a user belongs.";
     }
     leaf login-ip-addr {
       type inet:ip-address;
       mandatory true;
       description
         "The login IPv4 (or IPv6) address of a user.";
     }
     leaf authentication {
       type identityref {
         base authentication-mode;
       }
       description
         "The authentication-mode for authentication";
     }
   }
   grouping i2nsf-nsf-event-type-content {
     description
       "A set of common IPv4 (or IPv6)-related NSF event
        content elements";
     leaf dst-ip {
       type inet:ip-address;
       description
         "The destination IPv4 (IPv6) address of the packet";
     }
     leaf dst-port {
       type inet:port-number;
       description

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         "The destination port of the packet";
     }
     leaf rule-name {
       type leafref {
         path
           "/nsfi:i2nsf-security-policy/nsfi:system-policy"
          +"/nsfi:rules/nsfi:rule-name";
       }
       mandatory true;
       description
         "The name of the rule being triggered";
     }
     leaf raw-info {
       type string;
       description
         "The information describing the packet
          triggering the event.";
     }
   }
   grouping i2nsf-nsf-event-type-content-extend {
     description
       "A set of extended common IPv4 (or IPv6)-related NSF
        event content elements";
     uses i2nsf-nsf-event-type-content;
     leaf src-ip {
       type inet:ip-address;
       description
         "The source IPv4 (or IPv6) address of the packet";
     }
     leaf src-port {
       type inet:port-number;
       description
         "The source port of the packet";
     }
     leaf src-zone {
       type string {
         length "1..100";
         pattern "[0-9a-zA-Z ]*";
       }
       description
         "The source security zone of the packet";
     }
     leaf dst-zone {
       type string {
         length "1..100";
         pattern "[0-9a-zA-Z ]*";
       }
       description

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         "The destination security zone of the packet";
     }
   }
   grouping log-action {
     description
       "A grouping for logging action.";
     leaf action {
       type log-action;
       description
         "Action type: allow, alert, block, discard, declare,
          block-ip, block-service";
     }
   }
   grouping attack-rates {
     description
       "A set of traffic rates for monitoring attack traffic
        data";
     leaf attack-rate {
       type uint32;
       units "pps";
       description
         "The PPS rate of attack traffic";
     }
     leaf attack-speed {
       type uint32;
       units "bps";
       description
         "The BPS speed of attack traffic";
     }
   }
   grouping traffic-rates {
     description
       "A set of traffic rates for statistics data";
     leaf total-traffic {
       type yang:counter32;
       description
         "Total traffic";
     }
     leaf in-traffic-average-rate {
       type uint32;
       units "pps";
       description
         "Inbound traffic average rate in packets per second (pps)";
     }
     leaf in-traffic-peak-rate {
       type uint32;
       units "pps";
       description

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         "Inbound traffic peak rate in packets per second (pps)";
     }
     leaf in-traffic-average-speed {
       type uint32;
       units "bps";
       description
         "Inbound traffic average speed in bits per second (bps)";
     }
     leaf in-traffic-peak-speed {
       type uint32;
       units "bps";
       description
         "Inbound traffic peak speed in bits per second (bps)";
     }
     leaf out-traffic-average-rate {
       type uint32;
       units "pps";
       description
         "Outbound traffic average rate in packets per second (pps)";
     }
     leaf out-traffic-peak-rate {
       type uint32;
       units "pps";
       description
        "Outbound traffic peak rate in packets per Second (pps)";
     }
     leaf out-traffic-average-speed {
       type uint32;
       units "bps";
       description
         "Outbound traffic average speed in bits per second (bps)";
     }
     leaf out-traffic-peak-speed {
       type uint32;
       units "bps";
       description
         "Outbound traffic peak speed in bits per second (bps)";
     }
   }
   grouping i2nsf-system-counter-type-content{
     description
       "A set of counters for an interface traffic data.";
     leaf interface-name {
       type string;
       description
         "Network interface name configured in an NSF";
     }
     leaf in-total-traffic-pkts {

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       type yang:counter32;
       description
         "Total inbound packets";
     }
     leaf out-total-traffic-pkts {
       type yang:counter32;
       description
         "Total outbound packets";
     }
     leaf in-total-traffic-bytes {
       type uint64;
       units "bytes";
       description
         "Total inbound bytes";
     }
     leaf out-total-traffic-bytes {
       type uint64;
       units "bytes";
       description
         "Total outbound bytes";
     }
     leaf in-drop-traffic-pkts {
       type yang:counter32;
       description
         "Total inbound drop packets";
     }
     leaf out-drop-traffic-pkts {
       type yang:counter32;
       description
         "Total outbound drop packets";
     }
     leaf in-drop-traffic-bytes {
       type uint64;
       units "bytes";
       description
         "Total inbound drop bytes";
     }
     leaf out-drop-traffic-bytes {
       type uint64;
       units "bytes";
       description
         "Total outbound drop bytes";
     }
     uses traffic-rates;
   }
   grouping i2nsf-nsf-counters-type-content{
     description
       "A set of contents of a policy in an NSF.";

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     leaf policy-name {
       type leafref {
         path
           "/nsfi:i2nsf-security-policy/nsfi:system-policy"
          +"/nsfi:system-policy-name";
       }
       mandatory true;
       description
         "The name of the policy being triggered";
     }
     leaf src-user{
       type string;
       description
         "User who generates the policy";
     }
   }

   grouping enable-notification {
     description
       "A grouping for enabling or disabling notification";
     leaf enabled {
       type boolean;
       default "true";
       description
         "Enables or Disables the notification.
          If 'true', then the notification is enabled.
          If 'false, then the notification is disabled.";
     }
   }

   grouping dampening {
     description
       "A grouping for dampening period of notification.";
     leaf dampening-period {
       type uint32;
       units "centiseconds";
       default "0";
       description
         "Specifies the minimum interval between the assembly of
          successive update records for a single receiver of a
          subscription. Whenever subscribed objects change and
          a dampening-period interval (which may be zero) has
          elapsed since the previous update record creation for
          a receiver, any subscribed objects and properties
          that have changed since the previous update record
          will have their current values marshalled and placed
          in a new update record. But if the subscribed objects change
          when the dampening-period is active, it should update the

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          record without sending the notification until the dampening-
          period is finished. If multiple changes happen during the
          active dampening-period, it should update the record with the
          latest data. And at the end of the dampening-period, it should
          send the record as a notification with the latest updated
          record and restart the countdown.";
       reference
         "RFC 8641:  Subscription to YANG Notifications for
          Datastore Updates - Section 5.";
     }
   }

   /*
    * Feature Nodes
    */

   feature i2nsf-nsf-detection-ddos {
     description
       "This feature means it supports I2NSF nsf-detection-ddos
        notification";
   }
   feature i2nsf-nsf-detection-virus {
     description
       "This feature means it supports I2NSF nsf-detection-virus
        notification";
   }
   feature i2nsf-nsf-detection-intrusion {
     description
       "This feature means it supports I2NSF nsf-detection-intrusion
        notification";
   }
   feature i2nsf-nsf-detection-botnet {
     description
       "This feature means it supports I2NSF nsf-detection-botnet
        notification";
   }
   feature i2nsf-nsf-detection-web-attack {
     description
       "This feature means it supports I2NSF nsf-detection-web-attack
        notification";
   }
   feature i2nsf-nsf-log-dpi {
     description
       "This feature means it supports I2NSF nsf-log-dpi
        notification";
   }
   feature i2nsf-nsf-log-vuln-scan {
     description

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       "This feature means it supports I2NSF nsf-log-vuln-scan
        notification";
   }

   /*
    * Notification nodes
    */

   notification i2nsf-event {
     description
       "Notification for I2NSF Event.";
     choice sub-event-type {
       description
         "This choice must be augmented with cases for each allowed
          sub-event. Only 1 sub-event will be instantiated in each
          i2nsf-event message. Each case is expected to define one
          container with all the sub-event fields.";
       case i2nsf-system-detection-alarm {
         container i2nsf-system-detection-alarm{
           description
             "This notification is sent, when a system alarm
              is detected.";
           leaf alarm-category {
             type identityref {
              base alarm-type;
             }
             description
               "The alarm category for
                system-detection-alarm notification";
           }
           leaf component-name {
             type string;
             description
               "The hardware component responsible for generating
                the message. Applicable for Hardware Failure
                Alarm.";
           }
           leaf interface-name {
             type string;
             description
               "The interface name responsible for generating
                the message. Applicable for Network Interface
                Failure Alarm.";
           }
           leaf interface-state {
             type enumeration {

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               enum down {
                 description
                   "The interface state is down.";
               }
               enum up {
                 description
                   "The interface state is up.";
               }
               enum congested {
                 description
                   "The interface state is congested.";
               }
             }
             description
               "The state of the interface (i.e., up, down, congested).
               Applicable for Network Interface Failure Alarm.";
           }
           uses characteristics;
           uses i2nsf-system-alarm-type-content;
           uses common-monitoring-data;
         }
       }

       case i2nsf-system-detection-event {
         container i2nsf-system-detection-event {
           description
             "This notification is sent when a security-sensitive
              authentication action fails.";
           leaf event-category {
            type identityref {
               base event-type;
             }
             description
               "The event category for system-detection-event";
           }
           uses characteristics;
           uses i2nsf-system-event-type-content;
           uses common-monitoring-data;
         }
       }

       case i2nsf-traffic-flows {
         container i2nsf-traffic-flows {
           description
             "This notification is sent to inform about the traffic
              flows.";
           leaf src-ip {
             type inet:ip-address;

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             description
               "The source IPv4 (or IPv6) address of the packet";
           }
           leaf dst-ip {
             type inet:ip-address;
             description
               "The destination IPv4 (or IPv6) address of the packet";
           }
           leaf protocol {
             type identityref {
               base protocol-type;
             }
             description
               "The protocol type for nsf-detection-intrusion
                notification";
           }
           leaf src-port {
             type inet:port-number;
             description
               "The source port of the packet";
           }
           leaf dst-port {
             type inet:port-number;
             description
               "The destination port of the packet";
           }
           leaf arrival-rate {
             type uint32;
             units "pps";
             description
               "The arrival rate of the packet in packets
               per second";
           }
           uses characteristics;
           uses common-monitoring-data;
         }
       }

       case i2nsf-nsf-detection-session-table {
         container i2nsf-nsf-detection-session-table {
           description
             "This notification is sent, when a session table
              event is detected.";
           leaf current-session {
             type uint32;
             description
               "The number of concurrent sessions";
           }

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           leaf maximum-session {
             type uint32;
             description
               "The maximum number of sessions that the session
                table can support";
           }
           leaf threshold {
             type uint32;
             description
               "The threshold triggering the event";
           }
           uses common-monitoring-data;
         }
       }
     }
   }

   notification i2nsf-log {
     description
       "Notification for I2NSF log. The notification is generated
        from the logs of the NSF.";
     choice sub-logs-type {
       description
         "This choice must be augmented with cases for each allowed
          sub-logs. Only 1 sub-event will be instantiated in each
          i2nsf-logs message. Each case is expected to define one
          container with all the sub-logs fields.";
       case i2nsf-nsf-system-access-log {
         container i2nsf-nsf-system-access-log {
           description
             "The notification is sent, if there is a new system
              log entry about a system access event.";
           leaf login-ip {
             type inet:ip-address;
             mandatory true;
             description
               "Login IP address of a user";
           }
           leaf administrator {
             type string;
             description
               "Administrator that maintains the device";
           }
           leaf login-mode {
             type login-mode;
             description
               "Specifies the administrator log-in mode";
           }

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           leaf operation-type {
             type operation-type;
             description
               "The operation type that the administrator executes";
           }
           leaf result {
             type string;
             description
               "Command execution result";
           }
           leaf content {
             type string;
             description
               "The Operation performed by an administrator after
                login";
           }
           uses characteristics;
           uses common-monitoring-data;
         }
       }

       case i2nsf-system-res-util-log {
         container i2nsf-system-res-util-log {
           description
             "This notification is sent, if there is a new log
              entry representing resource utilization updates.";
           leaf system-status {
              type string;
              description
               "The current systems running status";
           }
           leaf cpu-usage {
             type uint8;
             description
               "Specifies the relative size of CPU usage with
                respect to platform resources";
           }
           leaf memory-usage {
             type uint8;
             description
               "Specifies the size of memory usage.";
           }
           leaf disk-usage {
             type uint8;
             description
               "Specifies the size of disk usage";
           }
           leaf disk-left {

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             type uint8;
             description
               "Specifies the size of disk left";
           }
           leaf session-num {
             type uint8;
             description
               "The total number of sessions";
           }
           leaf process-num {
             type uint8;
             description
               "The total number of process";
           }
           leaf in-traffic-rate {
             type uint32;
             units "pps";
             description
               "The total inbound traffic rate in pps";
           }
           leaf out-traffic-rate {
             type uint32;
             units "pps";
             description
                "The total outbound traffic rate in pps";
           }
           leaf in-traffic-speed {
             type uint32;
             units "bps";
             description
               "The total inbound traffic speed in bps";
           }
           leaf out-traffic-speed {
             type uint32;
             units "bps";
             description
               "The total outbound traffic speed in bps";
           }
           uses characteristics;
           uses common-monitoring-data;
         }
       }

       case i2nsf-system-user-activity-log {
         container i2nsf-system-user-activity-log {
           description
             "This notification is sent, if there is a new user
              activity log entry.";

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           uses characteristics;
           uses i2nsf-system-event-type-content;
           uses common-monitoring-data;
           leaf access {
             type identityref {
               base access-mode;
             }
             description
               "The access type for system-user-activity-log
                notification";
           }
           leaf online-duration {
             type string;
             description
               "Online duration";
           }
           leaf logout-duration {
             type string;
             description
               "Lockout duration";
           }
           leaf additional-info {
             type string;
             description
               "User activities, e.g., Successful User Login,
                Failed Login attempts, User Logout, Successful User
                Password Change, Failed User Password Change, User
                Lockout, User Unlocking, and Unknown.";
           }
         }
       }
     }
   }

   notification i2nsf-nsf-event {
     description
       "Notification for I2NSF NSF Event. This notification is
        used for a specific NSF that supported such feature.";
     choice sub-event-type {
       description
       "This choice must be augmented with cases for each allowed
        sub-event. Only 1 sub-event will be instantiated in each
        i2nsf-event message. Each case is expected to define one
        container with all the sub-event fields.";
       case i2nsf-nsf-detection-ddos {
         if-feature "i2nsf-nsf-detection-ddos";
         container i2nsf-nsf-detection-ddos {
           description

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             "This notification is sent, when a specific flood type
              is detected.";
           uses i2nsf-nsf-event-type-content;
           leaf attack-type {
             type identityref {
               base flood-type;
             }
             description
               "Any one of Syn flood, ACK flood, SYN-ACK flood,
                FIN/RST flood, TCP Connection flood, UDP flood,
                ICMP (i.e., ICMPv4 or ICMPv6) flood, HTTP flood,
                HTTPS flood, DNS query flood, DNS reply flood, SIP
                flood, etc.";
           }
           leaf start-time {
             type yang:date-and-time;
             mandatory true;
             description
               "The time stamp indicating when the attack started";
           }
           leaf end-time {
             type yang:date-and-time;
             mandatory true;
             description
               "The time stamp indicating when the attack ended";
           }
           leaf attack-src-ip {
             type inet:ip-address;
             description
               "The source IPv4 (or IPv6) addresses of attack
                traffic. If there are a large number of IPv4
                (or IPv6) addresses, then pick a certain number
                of resources according to different rules.";
           }
           leaf attack-dst-ip {
             type inet:ip-address;
             description
               "The destination IPv4 (or IPv6) addresses of attack
                traffic. If there are a large number of IPv4
                (or IPv6) addresses, then pick a certain number
                of resources according to different rules.";
           }
           uses attack-rates;
           uses log-action;
           uses characteristics;
           uses common-monitoring-data;
         }
       }

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       case i2nsf-nsf-detection-virus {
         if-feature "i2nsf-nsf-detection-virus";
         container i2nsf-nsf-detection-virus {
           description
             "This notification is sent, when a virus is detected.";
           uses i2nsf-nsf-event-type-content-extend;
           leaf virus {
             type identityref {
               base virus-type;
             }
            description
               "The virus type for nsf-detection-virus notification";
           }
           leaf virus-name {
             type string;
             description
               "The name of the detected virus";
           }
           leaf file-type {
             type string;
             description
               "The type of file virus code is found in (if
                applicable).";
           }
           leaf file-name {
             type string;
             description
               "The name of file virus code is found in (if
                applicable).";
           }
           leaf os {
             type string;
             description
               "Simple OS information";
           }
           uses log-action;
           uses characteristics;
           uses common-monitoring-data;
         }
       }
       case i2nsf-nsf-detection-intrusion {
         if-feature "i2nsf-nsf-detection-intrusion";
         container i2nsf-nsf-detection-intrusion {
           description
             "This notification is sent, when an intrusion event
              is detected.";
           uses i2nsf-nsf-event-type-content-extend;
           leaf protocol {

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             type identityref {
               base protocol-type;
             }
             description
               "The protocol type for nsf-detection-intrusion
                notification";
           }
           leaf app {
             type string;
             description
               "The employed application layer protocol";
           }
           leaf attack-type {
             type identityref {
               base intrusion-attack-type;
             }
             description
               "The sub attack type for intrusion attack";
           }
           uses log-action;
           uses attack-rates;
           uses characteristics;
           uses common-monitoring-data;
         }
       }
       case i2nsf-nsf-detection-botnet {
         if-feature "i2nsf-nsf-detection-botnet";
         container i2nsf-nsf-detection-botnet {
           description
             "This notification is sent, when a botnet event is
              detected.";
           uses i2nsf-nsf-event-type-content-extend;
           leaf attack-type {
             type identityref {
               base botnet-attack-type;
             }
            description
               "The attack type for botnet attack";
           }
           leaf protocol {
             type identityref {
               base protocol-type;
             }
             description
               "The protocol type for nsf-detection-botnet
                notification";
           }
           leaf botnet-name {

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             type string;
             description
               "The name of the detected botnet";
           }
           leaf role {
             type string;
             description
               "The role of the communicating
                parties within the botnet";
           }
           uses log-action;
           leaf botnet-pkt-num{
             type uint8;
             description
               "The number of the packets sent to or from the detected
                botnet";
           }
           leaf os{
             type string;
             description
               "Simple OS information";
           }
           uses characteristics;
           uses common-monitoring-data;
         }
       }
       case i2nsf-nsf-detection-web-attack {
         if-feature "i2nsf-nsf-detection-web-attack";
         container i2nsf-nsf-detection-web-attack {
           description
             "This notification is sent, when an attack event is
              detected.";
           uses i2nsf-nsf-event-type-content-extend;
           leaf attack-type {
             type identityref {
               base web-attack-type;
             }
             description
               "Concrete web attack type, e.g., SQL injection,
                command injection, XSS, and CSRF.";
           }
           leaf request-method {
             type identityref {
               base req-method;
             }
             description
               "The method of requirement. For instance, PUT or
                GET in HTTP.";

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           }
           leaf req-uri {
             type string;
             description
               "Requested URI";
           }
           leaf uri-category {
             type string;
             description
               "Matched URI category";
           }
           leaf-list filtering-type {
             type identityref {
               base filter-type;
             }
             description
               "URL filtering type, e.g., Blacklist, Whitelist,
                User-Defined, Predefined, Malicious Category,
                and Unknown";
           }
           leaf rsp-code {
             type string;
             description
               "Response code";
           }
           leaf req-clientapp {
             type string;
             description
               "The client application";
           }
           leaf req-cookies {
             type string;
             description
               "Cookies";
           }
           leaf req-host {
             type string;
             description
               "The domain name of the requested host";
           }
           uses characteristics;
           uses log-action;
           uses common-monitoring-data;
         }
       }
       case i2nsf-nsf-log-vuln-scan {
         if-feature "i2nsf-nsf-log-vuln-scan";
         container i2nsf-nsf-log-vuln-scan {

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           description
             "This notification is sent, if there is a new
              vulnerability-scan report in the NSF log.";
           leaf vulnerability-id {
             type uint8;
             description
               "The vulnerability ID";
           }
           leaf victim-ip {
             type inet:ip-address;
             description
               "IPv4 (or IPv6) address of the victim host which
                has vulnerabilities";
           }
           leaf protocol {
             type identityref {
               base protocol-type;
             }
             description
               "The protocol type for nsf-log-vuln-scan
                notification";
           }
           leaf port-num {
             type inet:port-number;
               description
                 "The port number";
           }
           leaf level {
             type severity;
             description
               "The vulnerability severity";
           }
           leaf os {
             type string;
             description
               "simple OS information";
           }
           leaf vulnerability-info {
             type string;
             description
               "The information about the vulnerability";
           }
           leaf fix-suggestion {
             type string;
             description
               "The fix suggestion to the vulnerability";
           }
           leaf service {

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             type string;
             description
               "The service which has vulnerability in the victim
                host";
           }
           uses characteristics;
           uses common-monitoring-data;
         }
       }
       case i2nsf-nsf-log-dpi {
         if-feature "i2nsf-nsf-log-dpi";
         container i2nsf-nsf-log-dpi {
           description
             "This notification is sent, if there is a new DPI
              event in the NSF log.";
           leaf attack-type {
             type dpi-type;
             description
               "The type of the DPI";
           }
           uses characteristics;
           uses i2nsf-nsf-counters-type-content;
           uses common-monitoring-data;
         }
       }
     }
   }
   /*
    * Data nodes
    */
   container i2nsf-counters {
     config false;
     description
       "This is probably better covered by an import as this
        will not be notifications.  Counters are not very
        suitable as telemetry, maybe via periodic
        subscriptions, which would still violate the principle
        of least surprise.";
     list system-interface {
       key interface-name;
       description
         "Interface counters provide the visibility of traffic into and
          out of an NSF, and bandwidth usage.";
       uses characteristics;
       uses i2nsf-system-counter-type-content;
       uses common-monitoring-data;
     }
     list nsf-firewall {

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       key policy-name;
       description
         "Firewall counters provide the visibility of traffic
          signatures, bandwidth usage, and how the configured security
          and bandwidth policies have been applied.";
       uses characteristics;
       uses i2nsf-nsf-counters-type-content;
       uses traffic-rates;
       uses common-monitoring-data;
     }
     list nsf-policy-hits {
       key policy-name;
       description
         "Policy Hit Counters record the number of hits that traffic
          packets match a security policy. It can check if policy
          configurations are correct or not.";
       uses characteristics;
       uses i2nsf-nsf-counters-type-content;
       uses common-monitoring-data;
       leaf hit-times {
         type yang:counter32;
         description
           "The number of times a policy is hit";
       }
     }
   }

   container i2nsf-monitoring-configuration {
     description
       "The container for configuring I2NSF monitoring.";
     container i2nsf-system-detection-alarm {
       description
         "The container for configuring I2NSF system-detection-alarm
          notification";
       uses enable-notification;
       list system-alarm {
         key alarm-type;
         description
           "Configuration for system alarm (i.e., CPU, Memory,
            and Disk Usage)";
         leaf alarm-type {
           type enumeration {
             enum CPU {
               description
                 "To configure the CPU usage threshold to trigger the
                  CPU-USAGE-ALARM";
             }
             enum Memory {

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               description
                 "To configure the Memory usage threshold to trigger the
                  MEM-USAGE-ALARM";
             }
             enum Disk {
               description
                 "To configure the Disk (storage) usage threshold to
                  trigger the DISK-USAGE-ALARM";
             }
           }
           description
             "Type of alarm to be configured";
         }
         leaf threshold {
           type uint8 {
             range "1..100";
           }
           units "percent";
           description
             "The configuration for threshold percentage to trigger
              the alarm. The alarm will be triggered if the usage
              is exceeded the threshold.";
         }
         uses dampening;
       }
     }
     container i2nsf-system-detection-event {
       description
         "The container for configuring I2NSF system-detection-event
          notification";
       uses enable-notification;
       uses dampening;
     }
     container i2nsf-traffic-flows {
       description
         "The container for configuring I2NSF traffic-flows
          notification";
       uses dampening;
       uses enable-notification;
     }
     container i2nsf-nsf-detection-ddos {
       if-feature "i2nsf-nsf-detection-ddos";
       description
         "The container for configuring I2NSF nsf-detection-ddos
          notification";
       uses enable-notification;
       uses dampening;
     }

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     container i2nsf-nsf-detection-session-table-configuration {
       description
         "The container for configuring I2NSF nsf-detection-session-
          table notification";
       uses enable-notification;
       uses dampening;
     }
     container i2nsf-nsf-detection-virus {
       if-feature "i2nsf-nsf-detection-virus";
       description
         "The container for configuring I2NSF nsf-detection-virus
          notification";
       uses enable-notification;
       uses dampening;
     }
     container i2nsf-nsf-detection-intrusion {
       if-feature "i2nsf-nsf-detection-intrusion";
       description
         "The container for configuring I2NSF nsf-detection-intrusion
          notification";
       uses enable-notification;
       uses dampening;
     }
     container i2nsf-nsf-detection-botnet {
       if-feature "i2nsf-nsf-detection-botnet";
       description
         "The container for configuring I2NSF nsf-detection-botnet
          notification";
       uses enable-notification;
       uses dampening;
     }
     container i2nsf-nsf-detection-web-attack {
       if-feature "i2nsf-nsf-detection-web-attack";
       description
         "The container for configuring I2NSF nsf-detection-web-attack
          notification";
       uses enable-notification;
       uses dampening;
     }
     container i2nsf-nsf-system-access-log {
       description
         "The container for configuring I2NSF system-access-log
          notification";
       uses enable-notification;
       uses dampening;
     }
     container i2nsf-system-res-util-log {
       description

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         "The container for configuring I2NSF system-res-util-log
          notification";
       uses enable-notification;
       uses dampening;
     }
     container i2nsf-system-user-activity-log {
       description
         "The container for configuring I2NSF system-user-activity-log
          notification";
       uses enable-notification;
       uses dampening;
     }
     container i2nsf-nsf-log-dpi {
       if-feature "i2nsf-nsf-log-dpi";
       description
         "The container for configuring I2NSF nsf-log-dpi
          notification";
       uses enable-notification;
       uses dampening;
     }
     container i2nsf-nsf-log-vuln-scan {
       if-feature "i2nsf-nsf-log-vuln-scan";
       description
         "The container for configuring I2NSF nsf-log-vuln-scan
          notification";
       uses enable-notification;
       uses dampening;
     }
     container i2nsf-counter {
       description
         "This is used to configure the counters
          for monitoring an NSF";
       leaf period {
         type uint16;
         units "minutes";
         default 0;
         description
           "The configuration for the period interval of reporting
            the counter. If 0, then the counter period is disabled.
            If value is not 0, then the counter will be reported
            following the period value.";
       }
     }
   }
 }
 <CODE ENDS>

                    Figure 2: Data Model of Monitoring

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11.  I2NSF Event Stream

   This section discusses the NETCONF event stream for I2NSF NSF
   Monitoring subscription.  The YANG module in this document supports
   "ietf-subscribed-notifications" YANG module [RFC8639] for
   subscription.  The reserved event stream name for this document is
   "I2NSF-Monitoring".  The NETCONF Server (e.g., an NSF) MUST support
   "I2NSF-Monitoring" event stream for an NSF data collector (e.g.,
   Security Controller and NSF data analyzer).  The "I2NSF-Monitoring"
   event stream contains all I2NSF events described in this document.
   The following example shows the capabilities of the event streams of
   an NSF (e.g., "NETCONF" and "I2NSF-Monitoring" event streams) by the
   subscription of an NSF data collector; note that this example XML
   file is delivered by an NSF to an NSF data collector:

   <?xml version="1.0" encoding="UTF-8"?>
   <rpc-reply message-id="1"
              xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
     <data>
       <netconf xmlns="urn:ietf:params:xml:ns:netmod:notification">
         <streams>
           <stream>
             <name>NETCONF</name>
             <description>Default NETCONF Event Stream</description>
             <replaySupport>false</replaySupport>
           </stream>
           <stream>
             <name>I2NSF-Monitoring</name>
             <description>I2NSF Monitoring Event Stream</description>
             <replaySupport>true</replaySupport>
             <replayLogCreationTime>
               2021-04-29T09:37:39+00:00
             </replayLogCreationTime>
           </stream>
         </streams>
       </netconf>
     </data>
   </rpc-reply>

   Figure 3: Example of NETCONF Server supporting I2NSF-Monitoring Event
                                  Stream

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12.  XML Examples for I2NSF NSF Monitoring

   This section shows the XML examples of I2NSF NSF Monitoring data
   delivered via Monitoring Interface from an NSF.

12.1.  I2NSF System Detection Alarm

   The following example shows an alarm triggered by Memory Usage of the
   server; note that this example XML file is delivered by an NSF to an
   NSF data collector:

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  <?xml version="1.0" encoding="UTF-8"?>
  <notification xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
    <eventTime>2021-04-29T07:43:52.181088+00:00</eventTime>
    <i2nsf-event
      xmlns="urn:ietf:params:xml:ns:yang:ietf-i2nsf-nsf-monitoring">
      <i2nsf-system-detection-alarm>
        <alarm-category
          xmlns:nsfmi="urn:ietf:params:xml:ns:yang:\
                     ietf-i2nsf-nsf-monitoring">
          nsfmi:mem-usage-alarm
        </alarm-category>
        <acquisition-method
          xmlns:nsfmi="urn:ietf:params:xml:ns:yang:\
                       ietf-i2nsf-nsf-monitoring">
          nsfmi:subscription
        </acquisition-method>
        <emission-type
          xmlns:nsfmi="urn:ietf:params:xml:ns:yang:\
                       ietf-i2nsf-nsf-monitoring">
          nsfmi:on-change
        </emission-type>
        <dampening-type
          xmlns:nsfmi="urn:ietf:params:xml:ns:yang:\
                       ietf-i2nsf-nsf-monitoring">
          nsfmi:on-repetition
        </dampening-type>
        <usage>91</usage>
        <threshold>90</threshold>
        <message>Memory Usage Exceeded the Threshold</message>
        <nsf-name>time_based_firewall</nsf-name>
        <severity>high</severity>
      </i2nsf-system-detection-alarm>
    </i2nsf-event>
  </notification>

   Figure 4: Example of I2NSF System Detection Alarm triggered by Memory
                                   Usage

   The XML data above shows:

   1.  The NSF that sends the information is named
       "time_based_firewall".

   2.  The memory usage of the NSF triggered the alarm.

   3.  The monitoring information is received by subscription method.

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   4.  The monitoring information is emitted "on-change".

   5.  The monitoring information is dampened "on-repetition".

   6.  The memory usage of the NSF is 91 percent.

   7.  The memory threshold to trigger the alarm is 90 percent.

   8.  The severity level of the notification is high.

12.2.  I2NSF Interface Counters

   To get the I2NSF system interface counters information by query,
   NETCONF Client (e.g., NSF data collector) needs to initiate GET
   connection with NETCONF Server (e.g., NSF).  The following XML file
   can be used to get the state data and filter the information.

   <?xml version="1.0" encoding="UTF-8"?>
   <rpc xmlns="urn:ietf:params:xml:ns:netconf:base:1.0" message-id="1">
     <get>
       <filter
         xmlns="urn:ietf:params:xml:ns:yang:ietf-i2nsf-nsf-monitoring">
         <i2nsf-counters>
           <system-interface/>
         </i2nsf-counters>
       </filter>
     </get>
   </rpc>

    Figure 5: XML Example for NETCONF GET with System Interface Filter

   The following XML file shows the reply from the NETCONF Server (e.g.,
   NSF):

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   <?xml version="1.0" encoding="UTF-8"?>
   <rpc-reply message-id="1"
              xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
     <data>
       <i2nsf-counters
         xmlns="urn:ietf:params:xml:ns:yang:ietf-i2nsf-nsf-monitoring">
         <system-interface>
           <interface-name>ens3</interface-name>
           <acquisition-method
             xmlns:nsfmi="urn:ietf:params:xml:ns:yang:\
                          ietf-i2nsf-nsf-monitoring">
             nsfmi:query
           </acquisition-method>
           <in-total-traffic-bytes>549050</in-total-traffic-bytes>
           <out-total-traffic-bytes>814956</out-total-traffic-bytes>
           <in-drop-traffic-bytes>0</in-drop-traffic-bytes>
           <out-drop-traffic-bytes>5078</out-drop-traffic-bytes>
           <nsf-name>time_based_firewall</nsf-name>
         </system-interface>
         <system-interface>
           <interface-name>lo</interface-name>
           <acquisition-method
             xmlns:nsfmi="urn:ietf:params:xml:ns:yang:\
                          ietf-i2nsf-nsf-monitoring">
             nsfmi:query
           </acquisition-method>
           <in-total-traffic-bytes>48487</in-total-traffic-bytes>
           <out-total-traffic-bytes>48487</out-total-traffic-bytes>
           <in-drop-traffic-bytes>0</in-drop-traffic-bytes>
           <out-drop-traffic-bytes>0</out-drop-traffic-bytes>
           <nsf-name>time_based_firewall</nsf-name>
         </system-interface>
       </i2nsf-counters>
     </data>
   </rpc-reply>

   Figure 6: Example of I2NSF System Interface Counters XML Information

13.  IANA Considerations

   This document requests IANA to register the following URI in the
   "IETF XML Registry" [RFC3688]:

   URI: urn:ietf:params:xml:ns:yang:ietf-i2nsf-nsf-monitoring
   Registrant Contact: The IESG.
   XML: N/A; the requested URI is an XML namespace.

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   This document requests IANA to register the following YANG module in
   the "YANG Module Names" registry [RFC7950][RFC8525]:

   name: ietf-i2nsf-nsf-monitoring
   namespace: urn:ietf:params:xml:ns:yang:ietf-i2nsf-nsf-monitoring
   prefix: nsfmi
   reference: RFC XXXX

   // RFC Ed.: replace XXXX with an actual RFC number and remove
   // this note.

14.  Security Considerations

   The YANG module described in this document defines a schema for data
   that is designed to be accessed via network management protocols such
   as NETCONF [RFC6241] or RESTCONF [RFC8040].  The lowest NETCONF layer
   is the secure transport layer, and the mandatory-to-implement secure
   transport is Secure Shell (SSH) [RFC6242].  The lowest RESTCONF layer
   is HTTPS, and the mandatory-to-implement secure transport is TLS
   [RFC8446].

   The NETCONF access control model [RFC8341] 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.

   All data nodes defined in the YANG module which can be created,
   modified and deleted (i.e., config true, which is the default) are
   considered sensitive.  Write operations (e.g., edit-config) applied
   to these data nodes without proper protection can negatively affect
   framework operations.  The monitoring YANG module should be protected
   by the secure communication channel, to ensure its confidentiality
   and integrity.  In another side, the NSF and NSF data collector can
   all be faked, which lead to undesirable results (i.e., leakage of an
   NSF's important operational information, and faked NSF sending false
   information to mislead the NSF data collector).  The mutual
   authentication is essential to protected against this kind of attack.
   The current mainstream security technologies (i.e., TLS, DTLS, IPsec,
   and X.509 PKI) can be employed appropriately to provide the above
   security functions.

   In addition, to defend against the DDoS attack caused by a lot of
   NSFs sending massive notifications to the NSF data collector, the
   rate limiting or similar mechanisms should be considered in both an
   NSF and NSF data collector, whether in advance or just in the process
   of DDoS attack.

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15.  Acknowledgments

   This work was supported by Institute of Information & Communications
   Technology Planning & Evaluation (IITP) grant funded by the Korea
   MSIT (Ministry of Science and ICT) (R-20160222-002755, Cloud based
   Security Intelligence Technology Development for the Customized
   Security Service Provisioning).  This work was supported in part by
   the IITP (2020-0-00395, Standard Development of Blockchain based
   Network Management Automation Technology).  This work was supported
   in part by the MSIT under the Information Technology Research Center
   (ITRC) support program (IITP-2021-2017-0-01633) supervised by the
   IITP.

16.  Contributors

   This document is made by the group effort of I2NSF working group.
   Many people actively contributed to this document.  The authors
   sincerely appreciate their contributions.

   The following are co-authors of this document:

   Chaehong Chung
   Department of Electronic, Electrical and Computer Engineering
   Sungkyunkwan University
   2066 Seo-ro Jangan-gu
   Suwon, Gyeonggi-do 16419
   Republic of Korea

   EMail: darkhong@skku.edu

   Jinyong (Tim) Kim
   Department of Electronic, Electrical and Computer Engineering
   Sungkyunkwan University
   2066 Seo-ro Jangan-gu
   Suwon, Gyeonggi-do 16419
   Republic of Korea

   EMail: timkim@skku.edu

   Dongjin Hong
   Department of Electronic, Electrical and Computer Engineering
   Sungkyunkwan University
   2066 Seo-ro Jangan-gu
   Suwon, Gyeonggi-do 16419
   Republic of Korea

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   EMail: dong.jin@skku.edu

   Dacheng Zhang
   Huawei

   EMail: dacheng.zhang@huawei.com

   Yi Wu
   Aliababa Group

   EMail: anren.wy@alibaba-inc.com

   Rakesh Kumar
   Juniper Networks
   1133 Innovation Way
   Sunnyvale, CA 94089
   USA

   EMail: rkkumar@juniper.net

   Anil Lohiya
   Juniper Networks

   EMail: alohiya@juniper.net

17.  References

17.1.  Normative References

   [RFC0768]  Postel, J., "User Datagram Protocol", STD 6, RFC 768,
              DOI 10.17487/RFC0768, August 1980,
              <https://www.rfc-editor.org/info/rfc768>.

   [RFC0791]  Postel, J., "Internet Protocol", STD 5, RFC 791,
              DOI 10.17487/RFC0791, September 1981,
              <https://www.rfc-editor.org/info/rfc791>.

   [RFC0792]  Postel, J., "Internet Control Message Protocol", STD 5,
              RFC 792, DOI 10.17487/RFC0792, September 1981,
              <https://www.rfc-editor.org/info/rfc792>.

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   [RFC0793]  Postel, J., "Transmission Control Protocol", STD 7,
              RFC 793, DOI 10.17487/RFC0793, September 1981,
              <https://www.rfc-editor.org/info/rfc793>.

   [RFC0956]  Mills, D., "Algorithms for synchronizing network clocks",
              RFC 956, DOI 10.17487/RFC0956, September 1985,
              <https://www.rfc-editor.org/info/rfc956>.

   [RFC0959]  Postel, J. and J. Reynolds, "File Transfer Protocol",
              STD 9, RFC 959, DOI 10.17487/RFC0959, October 1985,
              <https://www.rfc-editor.org/info/rfc959>.

   [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>.

   [RFC2616]  Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
              Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
              Transfer Protocol -- HTTP/1.1", RFC 2616,
              DOI 10.17487/RFC2616, June 1999,
              <https://www.rfc-editor.org/info/rfc2616>.

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

   [RFC3877]  Chisholm, S. and D. Romascanu, "Alarm Management
              Information Base (MIB)", RFC 3877, DOI 10.17487/RFC3877,
              September 2004, <https://www.rfc-editor.org/info/rfc3877>.

   [RFC3954]  Claise, B., Ed., "Cisco Systems NetFlow Services Export
              Version 9", RFC 3954, DOI 10.17487/RFC3954, October 2004,
              <https://www.rfc-editor.org/info/rfc3954>.

   [RFC4443]  Conta, A., Deering, S., and M. Gupta, Ed., "Internet
              Control Message Protocol (ICMPv6) for the Internet
              Protocol Version 6 (IPv6) Specification", STD 89,
              RFC 4443, DOI 10.17487/RFC4443, March 2006,
              <https://www.rfc-editor.org/info/rfc4443>.

   [RFC4949]  Shirey, R., "Internet Security Glossary, Version 2",
              FYI 36, RFC 4949, DOI 10.17487/RFC4949, August 2007,
              <https://www.rfc-editor.org/info/rfc4949>.

   [RFC5424]  Gerhards, R., "The Syslog Protocol", RFC 5424,
              DOI 10.17487/RFC5424, March 2009,
              <https://www.rfc-editor.org/info/rfc5424>.

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   [RFC6241]  Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
              and A. Bierman, Ed., "Network Configuration Protocol
              (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
              <https://www.rfc-editor.org/info/rfc6241>.

   [RFC6242]  Wasserman, M., "Using the NETCONF Protocol over Secure
              Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011,
              <https://www.rfc-editor.org/info/rfc6242>.

   [RFC6587]  Gerhards, R. and C. Lonvick, "Transmission of Syslog
              Messages over TCP", RFC 6587, DOI 10.17487/RFC6587, April
              2012, <https://www.rfc-editor.org/info/rfc6587>.

   [RFC6991]  Schoenwaelder, J., Ed., "Common YANG Data Types",
              RFC 6991, DOI 10.17487/RFC6991, July 2013,
              <https://www.rfc-editor.org/info/rfc6991>.

   [RFC7011]  Claise, B., Ed., Trammell, B., Ed., and P. Aitken,
              "Specification of the IP Flow Information Export (IPFIX)
              Protocol for the Exchange of Flow Information", STD 77,
              RFC 7011, DOI 10.17487/RFC7011, September 2013,
              <https://www.rfc-editor.org/info/rfc7011>.

   [RFC7950]  Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
              RFC 7950, DOI 10.17487/RFC7950, August 2016,
              <https://www.rfc-editor.org/info/rfc7950>.

   [RFC8040]  Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
              Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
              <https://www.rfc-editor.org/info/rfc8040>.

   [RFC8200]  Deering, S. and R. Hinden, "Internet Protocol, Version 6
              (IPv6) Specification", STD 86, RFC 8200,
              DOI 10.17487/RFC8200, July 2017,
              <https://www.rfc-editor.org/info/rfc8200>.

   [RFC8329]  Lopez, D., Lopez, E., Dunbar, L., Strassner, J., and R.
              Kumar, "Framework for Interface to Network Security
              Functions", RFC 8329, DOI 10.17487/RFC8329, February 2018,
              <https://www.rfc-editor.org/info/rfc8329>.

   [RFC8340]  Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
              BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
              <https://www.rfc-editor.org/info/rfc8340>.

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   [RFC8341]  Bierman, A. and M. Bjorklund, "Network Configuration
              Access Control Model", STD 91, RFC 8341,
              DOI 10.17487/RFC8341, March 2018,
              <https://www.rfc-editor.org/info/rfc8341>.

   [RFC8342]  Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K.,
              and R. Wilton, "Network Management Datastore Architecture
              (NMDA)", RFC 8342, DOI 10.17487/RFC8342, March 2018,
              <https://www.rfc-editor.org/info/rfc8342>.

   [RFC8407]  Bierman, A., "Guidelines for Authors and Reviewers of
              Documents Containing YANG Data Models", BCP 216, RFC 8407,
              DOI 10.17487/RFC8407, October 2018,
              <https://www.rfc-editor.org/info/rfc8407>.

   [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>.

   [RFC8525]  Bierman, A., Bjorklund, M., Schoenwaelder, J., Watsen, K.,
              and R. Wilton, "YANG Library", RFC 8525,
              DOI 10.17487/RFC8525, March 2019,
              <https://www.rfc-editor.org/info/rfc8525>.

   [RFC8632]  Vallin, S. and M. Bjorklund, "A YANG Data Model for Alarm
              Management", RFC 8632, DOI 10.17487/RFC8632, September
              2019, <https://www.rfc-editor.org/info/rfc8632>.

   [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,
              <https://www.rfc-editor.org/info/rfc8639>.

   [RFC8641]  Clemm, A. and E. Voit, "Subscription to YANG Notifications
              for Datastore Updates", RFC 8641, DOI 10.17487/RFC8641,
              September 2019, <https://www.rfc-editor.org/info/rfc8641>.

17.2.  Informative References

   [I-D.ietf-i2nsf-applicability]
              Jeong, J., Hyun, S., Ahn, T., Hares, S., and D. Lopez,
              "Applicability of Interfaces to Network Security Functions
              to Network-Based Security Services", draft-ietf-i2nsf-
              applicability-18 (work in progress), September 2019.

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   [I-D.ietf-i2nsf-capability]
              Xia, L., Strassner, J., Basile, C., and D. Lopez,
              "Information Model of NSFs Capabilities", draft-ietf-
              i2nsf-capability-05 (work in progress), April 2019.

   [I-D.ietf-i2nsf-consumer-facing-interface-dm]
              Jeong, J., Chung, C., Ahn, T., Kumar, R., and S. Hares,
              "I2NSF Consumer-Facing Interface YANG Data Model", draft-
              ietf-i2nsf-consumer-facing-interface-dm-13 (work in
              progress), March 2021.

   [I-D.ietf-i2nsf-nsf-facing-interface-dm]
              Kim, J., Jeong, J., J., J., PARK, P., Hares, S., and Q.
              Lin, "I2NSF Network Security Function-Facing Interface
              YANG Data Model", draft-ietf-i2nsf-nsf-facing-interface-
              dm-12 (work in progress), March 2021.

   [I-D.ietf-i2nsf-registration-interface-dm]
              Hyun, S., Jeong, J., Roh, T., Wi, S., J., J., and P. PARK,
              "I2NSF Registration Interface YANG Data Model", draft-
              ietf-i2nsf-registration-interface-dm-10 (work in
              progress), February 2021.

   [I-D.ietf-netconf-subscribed-notifications]
              Voit, E., Clemm, A., Prieto, A., Nilsen-Nygaard, E., and
              A. Tripathy, "Subscription to YANG Event Notifications",
              draft-ietf-netconf-subscribed-notifications-26 (work in
              progress), May 2019.

   [I-D.ietf-netconf-yang-push]
              Clemm, A. and E. Voit, "Subscription to YANG Datastores",
              draft-ietf-netconf-yang-push-25 (work in progress), May
              2019.

   [I-D.yang-i2nsf-security-policy-translation]
              Jeong, J., Lingga, P., Yang, J., and C. Chung, "Security
              Policy Translation in Interface to Network Security
              Functions", draft-yang-i2nsf-security-policy-
              translation-08 (work in progress), February 2021.

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Appendix A.  Changes from draft-ietf-i2nsf-nsf-monitoring-data-model-07

   The following changes are made from draft-ietf-i2nsf-nsf-monitoring-
   data-model-07:

   o  This version is revised according to the comments from both Tom
      Petch and Andy Bierman.

Authors' Addresses

   Jaehoon (Paul) Jeong (editor)
   Department of Computer Science and Engineering
   Sungkyunkwan University
   2066 Seobu-Ro, Jangan-Gu
   Suwon, Gyeonggi-Do  16419
   Republic of Korea

   Phone: +82 31 299 4957
   Fax:   +82 31 290 7996
   EMail: pauljeong@skku.edu
   URI:   http://iotlab.skku.edu/people-jaehoon-jeong.php

   Patrick Lingga
   Department of Electronic, Electrical and Computer Engineering
   Sungkyunkwan University
   2066 Seobu-Ro, Jangan-Gu
   Suwon, Gyeonggi-Do  16419
   Republic of Korea

   Phone: +82 31 299 4957
   EMail: patricklink@skku.edu

   Susan Hares
   Huawei
   7453 Hickory Hill
   Saline, MI  48176
   USA

   Phone: +1-734-604-0332
   EMail: shares@ndzh.com

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   Liang (Frank) Xia
   Huawei
   101 Software Avenue, Yuhuatai District
   Nanjing, Jiangsu
   China

   EMail: Frank.xialiang@huawei.com

   Henk Birkholz
   Fraunhofer Institute for Secure Information Technology
   Rheinstrasse 75
   Darmstadt  64295
   Germany

   EMail: henk.birkholz@sit.fraunhofer.de

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