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Versions: 00                                                            
I2NSF Working Group                                       P. Lingga, Ed.
Internet-Draft                                             J. Jeong, Ed.
Intended status: Standards Track                 Sungkyunkwan University
Expires: 28 February 2022                                        Y. Choi
                                                                    ETRI
                                                          27 August 2021


              I2NSF Application Interface YANG Data Model
             draft-lingga-i2nsf-application-interface-dm-00

Abstract

   This document describes an information model and a YANG data model
   for the Application Interface between an Interface to Network
   Security Functions (I2NSF) Analyzer and Security Controller in an
   I2NSF system in a Network Functions Virtualization (NFV) environment.
   The information model and YANG data model is based on the I2NSF
   Consumer-Facing Interface for enabling feedback delivery based on the
   information received from the Network Security Function (NSF).

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 28 February 2022.

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
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components



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   extracted from this document must include Simplified BSD License text
   as described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Information Model for Application Interface . . . . . . . . .   4
     3.1.  Information Model for Policy Reconfiguration  . . . . . .   5
     3.2.  YANG Tree Structure for Policy Reconfiguration  . . . . .   7
     3.3.  Information Model for Feedback Information  . . . . . . .   9
     3.4.  YANG Tree Structure for Feedback Information  . . . . . .  10
   4.  YANG Data Model of Application Interface  . . . . . . . . . .  11
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  21
   6.  XML Configuration Examples of Feedback Policy . . . . . . . .  21
     6.1.  Feedback Policy for DDoS Detection  . . . . . . . . . . .  22
     6.2.  Feedback Information for Overloaded NSF . . . . . . . . .  25
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  28
   8.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  28
   9.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .  29
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  29
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  29
     10.2.  Informative References . . . . . . . . . . . . . . . . .  30
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  31

1.  Introduction

   In Interface to Network Security Functions (I2NSF) [RFC8329], the
   Monitoring Interface [I-D.ietf-i2nsf-nsf-monitoring-data-model] is
   defined as an interface to collect information (e.g., network
   statistics, resources) from NSF(s).  The information can be received
   by a query or a report.  In a query-based, the information is
   obtained by a request from a client (I2NSF Analyzer).  But in a
   report-based, the information is provided by a server (NSFs) when the
   notification or alarm is triggered by an event.  In this model, the
   report-based collection information is used for realizing the
   Security Management Automation (SMA) in cloud-based security services
   [I-D.jeong-i2nsf-security-management-automation].  as the information
   is sent automatically by the NSFs.  Figure 1 shows the I2NSF
   Framework for Security Management Automation.










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       +------------+
       | I2NSF User |
       +------------+
              ^
              | Consumer-Facing Interface
              v
    +-------------------+     Registration     +-----------------------+
    |Security Controller|<-------------------->|Developer's Mgmt System|
    +-------------------+      Interface       +-----------------------+
              ^      ^
              |      |
              |      |  Application Interface  +-----------------------+
              |      +------------------------>|    I2NSF Analyzer     |
              |                                +-----------------+-----+
              | NSF-Facing Interface                             ^
              |                                                  |
              +--------------------------+                       |
              |                          |                       |
              v                          v                       |
       +------+---------+        +-------+--------+              |
       |      NSF-1     |  ...   |     NSF-N      |   Monitoring |
       |   (Firewall)   |        |(DDoS Mitigator)+--------------+
       +------+---------+        +-------+--------+    Interface |
              |                                                  |
              +--------------------------------------------------+


        Figure 1: I2NSF Framework for Security Management Automation

   The automatic reports by the NSFs are collected in a single instance
   (i.e., I2NSF Analyzer) to be analyzed.  By analyzing the information,
   a new security policy can be produced to further enhance the security
   of the network.  To create the automated system, the analyzer should
   be done automatically with the help of machine learning.  The
   automated analyzer is not in the scope of this document.

   The new security policy needs to be delivered from the I2NSF Analyzer
   to the Security Controller so the new policy can be listed and
   monitored properly.  For that purpose, this document introduces the
   Application Interface as the intermediary between the I2NSF Analyzer
   and the Security Controller.  Then the policy should be delivered
   directly to the NSFs by the Security Controller via the NSF-Facing
   Interface [I-D.ietf-i2nsf-nsf-facing-interface-dm].

   The purpose of this document is to provide a standard for a feedback
   interface in an I2NSF Framework called Application Interface.  With
   the provided Application Interface, the realization of Security
   Management Automation (SMA) should be possible.



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2.  Terminology

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

   This document uses the terminology described in [RFC8329].

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

3.  Information Model for Application Interface

   This document introduces Application Interface as an interface to
   deliver a report of the augmentation or generation of security policy
   rules created by I2NSF Analyzer to Security Controller
   [I-D.jeong-i2nsf-security-management-automation].  This allows
   Security Controller to actively reinforce the network with its
   security policy management.  Figure 2 shows the high-level concept of
   Application Interface such as Policy Reconfiguration and Feedback
   Information.



























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                            +-----------------+
                            |   Application   |
                            |    Interface    |
                            +--------+--------+
                                     ^
                                     |
                        +------------+-----------+
                        |                        |
               +--------+--------+       +-------+-----+
               |     Policy      |       |  Feedback   |
               | Reconfiguration |       | Information |
               +--------+--------+       +-------+-----+
                        ^                        ^
                        |                        |
                        +------------+-----------+
                                     |
                       +-------------+------------+
                       |             |            |
                 +-----+-----+ +-----+----+ +-----+-----+
                 |  NSF Name | |  Problem | |  Solution |
                 +-----------+ +----------+ +-----------+



                Figure 2: Diagram for Application Interface

   Both policy reconfiguration and feedback information provide the
   following high-level abstraction:

   *  NSF Name: It is the name or IP address of the NSF for identifying
      the NSF with problem.  The name is a unique string to identity an
      NSF, including a Fully Qualified Domain Name (FQDN).

   *  Problem: It describes the issue(s) in the NSF that needs to be
      handled.

   *  Solution: It specifies the possible solution(s) for the problem.

3.1.  Information Model for Policy Reconfiguration

   Policy reconfiguration is the rearrangement of a security policy in a
   different form or combination of the existing security policy to
   enhance the security service in the network.  A policy
   reconfiguration is generated by the I2NSF Analyzer after receiving
   and analyzing monitoring information of NSF Events from an NSF
   [I-D.ietf-i2nsf-nsf-monitoring-data-model].





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   Policy reconfiguration works together with the three I2NSF interfaces
   defined for the I2NSF Framework, i.e., NSF-Facing Interface
   [I-D.ietf-i2nsf-nsf-facing-interface-dm], NSF Monitoring Interface
   [I-D.ietf-i2nsf-nsf-monitoring-data-model], and Application
   Interface, to create a closed-loop system for reinforcing the network
   security.  Figure 3 shows an illustration of the closed-loop system
   for the I2NSF Framework.


           +------------+                            +----------+
           |  Security  | <--------------------------|  I2NSF   |
           | Controller |    Application Interface   | Analyzer |
           +------------+   (Policy Reconfiguration) +----------+
                  |                                        ^
                  |                                        |
       NSF-Facing |                +---------+             | Monitoring
        Interface |       +------->|  NSF-1  |-------+     | Interface
         (Policy  |       |        +---------+       |     |(Monitoring
    Configuration)|       |                          |     | Data &
                  |       |        +---------+       |     | Statistics)
                  +-------+------->|  NSF-2  |-------+-----+
                          |        +---------+       |
                          |             .            |
                          |             .            |
                          |             .            |
                          |        +---------+       |
                          +------->|  NSF-n  |-------+
                                   +---------+


        Figure 3: A Close Loop Architecture for Security Management
                              Automation (SMA)

   Figure 3 shows a close-loop system between Security Controller, NSF,
   and I2NSF Analyzer.  The Security Controller delivers a security
   policy to an appropriate NSF via the NSF-Facing Interface
   [I-D.ietf-i2nsf-nsf-facing-interface-dm].  The NSF will prepare for a
   security service according to the given configuration and provide a
   security service for the network.  The NSF SHOULD also provide
   monitoring information (e.g., NSF Events and System Alarms) to be
   analyzed.  This monitoring information can be delivered from the NSF
   to an I2NSF Analyzer via the Monitoring Interface
   [I-D.ietf-i2nsf-nsf-monitoring-data-model].  Then the I2NSF Analyzer
   analyzes the monitoring information for the reconfiguration of an
   existing security policy, the generation of a new security policy,
   and the feedback for security system management (e.g., the scaling-up
   or scaling-down of resources related to NSFs).  To fully automate the
   close-loop system, the I2NSF Analyzer should analyze the monitoring



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   information automatically using machine learning techniques (e.g.,
   Deep Learning [Deep-Learning]).  The results of the analysis may
   trigger the reconfiguration of an existing security policy or the
   generation of a new security policy to strengthen the network
   security.  The reconfiguration or configuration request will be
   delivered from the I2NSF Analyzer to the Security Controller via the
   Application Interface.

   To realize the close loop system, the Application Interface needs to
   properly follow the similar guidelines for the I2NSF Framework
   [RFC8329].  The Application Interface follows
   [I-D.ietf-i2nsf-nsf-facing-interface-dm] to create a security policy
   to reconfigure an existing security policy of NSF(s) or to generate a
   new security policy.

   Application Interface holds a list of security policies so that the
   (re)configuration of a security policy and the feedback information
   can be provided to the Security Controller.  Each policy consists of
   a list of rule to be enhanced on the NSF.  Note that the
   synchronization of the list of security policies should be done
   between the Security Controller and the I2NSF Analyzer and the
   specific mechanism is out of the scope of this document.  A
   (re)configured security policy rule should be able to cope with
   attacks or failures that can happen to the network in near future.
   Such a rule is reconfigured or generated by the I2NSF Analyzer to
   tackle a detected problem in the network.  It uses the Event-
   Condition-Action (ECA) model as the basis for the design of I2NSF
   Policy (Re)configuration as described in [RFC8329] and
   [I-D.ietf-i2nsf-capability-data-model].

   An example of Policy (Re)configuration is a DDoS Attack that is
   detected by a DDoS Mitigator.  The DDoS Mitigator creates monitoring
   information and delivers it to the I2NSF Analyzer.  The I2NSF
   Analyzer analyzes the information and generates a new policy to
   handle the DDoS Attack, such as a firewall rule to drop all packets
   from the source of the DDoS Attack.

3.2.  YANG Tree Structure for Policy Reconfiguration

   The YANG tree structure for policy reconfiguration is provided
   through the augmentation of the NSF-Facing Interface YANG Module
   [I-D.ietf-i2nsf-nsf-facing-interface-dm] as follows:









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     augment /nsfintf:i2nsf-security-policy:
       +--rw nsf-name?   union
       +--rw problem
          +--rw (attack-detection)?
             +--:(ddos-detected)
             |  +--rw ddos-detected
             |     +--rw attack-src-ip*     inet:ip-address
             |     +--rw attack-dst-ip*     inet:ip-prefix
             |     +--rw attack-src-port*   inet:port-number
             |     +--rw attack-dst-port*   inet:port-number
             +--:(virus-detected)
             |  +--rw virus-detected
             |     +--rw virus-name?   string
             |     +--rw file-type?    string
             |     +--rw file-name?    string
             +--:(intrusion-detected)
             |  +--rw intrusion-detected
             |     +--rw protocol?      identityref
             |     +--rw app?           identityref
             |     +--rw attack-type?   identityref
             +--:(web-attack-detected)
             |  +--rw web-attack-detected
             |     +--rw attack-type?      identityref
             |     +--rw request-method?   identityref
             |     +--rw req-uri?          string
             |     +--rw req-user-agent?   string
             |     +--rw req-cookie?       string
             |     +--rw req-host?         string
             |     +--rw response-code?    string
             +--:(voip-volte-detected)
                +--rw voip-volte-detected
                   +--rw source-voice-id*        string
                   +--rw destination-voice-id*   string
                   +--rw user-agent*             string


          Figure 4: YANG Tree Structure of Policy Reconfiguration

   The policy reconfiguration must include the following information:

      NSF Name: The name or IP address (IPv4 or IPv6) of the NSF to be
      configured.  If the given nsf-name is not IP address, the name can
      be an arbitrary string including FQDN (Fully Qualified Domain
      Name).

      Problem: The issue that is emitted by an NSF via the I2NSF
      Monitoring Interface.  The problem for policy configuration
      includes the NSF Events described in NSF Monitoring Interface YANG



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      Data Model [I-D.ietf-i2nsf-nsf-monitoring-data-model], such as
      DDoS detection, Virus detection, Intrusion detection, Web-attack
      detection, and VoIP/VoLTE violation detection.

      Solution: The solution for policy (re)configuration is the
      security policy that is reconfigured or generated to solve a
      detected attack.  The security policy can be configured using the
      NSF-Facing Interface YANG data model
      [I-D.ietf-i2nsf-nsf-facing-interface-dm].

3.3.  Information Model for Feedback Information

   Feedback information is information about problem(s) of an NSF for a
   security service such as system resource over-usage or malfunction.
   This problem cannot be handled by creating a new policy.  In the
   similar way with policy reconfiguration, the feedback information
   should be delivered from the I2NSF Analyzer to the Security
   Controller that will be able to handle the reported problem(s).

                            +------------+
                            |   I2NSF    |
                            |   User     |
                            +------+-----+
                                   ^
                                   | Report
                                   |
    +-----------+           +------+-----+   Application  +----------+
    |Developer's|<----------+  Security  |<---------------|  I2NSF   |
    |Mgmt System|  Request  | Controller |    Interface   | Analyzer |
    +-----------+           +------------+                +----------+


                 Figure 5: Handling of Feedback Information

   Figure 5 shows the handling of feedback information.  For feedback
   information, the given feedback is not a security policy, hence the
   Security Controller needs to take an action to handle the reported
   problem(s).  The action includes the reporting to the I2NSF User and
   the requesting of the system resource management of the relevant
   NSF(s) to the Developer's Management System (DMS).  DMS will
   communicate with the Management and Orchestration (MANO) Unit in the
   Network Functions Virtualization (NFV) Framework to deal with the
   system management issue(s) of the relevant NSFs
   [I-D.ietf-i2nsf-applicability].  The details of the handling process
   are out of the scope of this document.






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3.4.  YANG Tree Structure for Feedback Information

   The YANG tree structure for feedback information is provided with the
   use of the NSF Monitoring Interface YANG Module
   [I-D.ietf-i2nsf-nsf-monitoring-data-model] as follows:

   module: ietf-i2nsf-feedback-policy
     +--rw i2nsf-feedback-information* [nsf-name time]
        +--rw nsf-name    union
        +--rw time        yang:date-and-time
        +--rw problem
        |  +--rw (alarm-type)?
        |     +--:(memory-alarm)
        |     |  +--rw memory-alarm
        |     |     +--rw usage?      uint8
        |     |     +--rw message?    string
        |     |     +--rw duration?   uint32
        |     +--:(cpu-alarm)
        |     |  +--rw cpu-alarm
        |     |     +--rw usage?      uint8
        |     |     +--rw message?    string
        |     |     +--rw duration?   uint32
        |     +--:(disk-alarm)
        |     |  +--rw disk-alarm
        |     |     +--rw disk-id?    string
        |     |     +--rw usage?      uint8
        |     |     +--rw message?    string
        |     |     +--rw duration?   uint32
        |     +--:(hardware-alarm)
        |     |  +--rw hardware-alarm
        |     |     +--rw component-name?   string
        |     |     +--rw message?          string
        |     |     +--rw duration?         uint32
        |     +--:(interface-alarm)
        |        +--rw interface-alarm
        |           +--rw interface-id?      string
        |           +--rw interface-state?   enumeration
        |           +--rw message?           string
        |           +--rw duration?          uint32
        +--rw solution*   string


           Figure 6: YANG Tree Structure of Feedback Information

   Figure 6 shows the high-level abstraction of Feedback Information.
   The feedback information should include:





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   *  NSF Name: The name or IP address (IPv4 or IPv6) of the NSF that
      detected the problem.  If the given nsf-name is not IP address,
      the name can be an arbitrary string including FQDN.

   *  Time: The time of the delivery of the feedback information.

   *  Problem: The issue that is emitted by an NSF via the I2NSF
      Monitoring Interface.  The problem for feedback information
      includes the system alarms described in NSF Monitoring Interface
      YANG Data Model [I-D.ietf-i2nsf-nsf-monitoring-data-model], such
      as Memory alarm, CPU alarm, Disk alarm, Hardware alarm, and
      Interface alarm.

   *  Solution: A possible solution given as feedback is in the form of
      a free-form string (as a high-level instruction).

4.  YANG Data Model of Application Interface

   This section shows the YANG module of Application Interface.  The
   YANG module in this document is referencing to [RFC6991]
   [I-D.ietf-i2nsf-nsf-facing-interface-dm]

   <CODE BEGINS> file "ietf-i2nsf-feedback-policy@2021-08-27.yang"
   module ietf-i2nsf-feedback-policy {
     yang-version 1.1;
     namespace
       "urn:ietf:params:xml:ns:yang:ietf-i2nsf-feedback-policy";
     prefix nsffbck;

     import ietf-inet-types{
       prefix inet;
       reference "RFC 6991";
     }

     import ietf-yang-types{
       prefix yang;
       reference "RFC 6991";
     }

     import ietf-i2nsf-policy-rule-for-nsf {
       prefix nsfintf;
       reference
         "Section 4.1 of draft-ietf-i2nsf-nsf-facing-interface-dm-13";
     }

     import ietf-i2nsf-nsf-monitoring {
       prefix nsfmi;
       reference



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         "Section 7 of draft-ietf-i2nsf-nsf-monitoring-data-model-09";
     }

     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: Patrick Lingga
        <mailto:patricklink@skku.edu>

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

     description
       "This module is a YANG module for Consumer-Facing Interface.

        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).

        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.";

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

     revision "2021-08-27" {
       description "Initial revision.";
       reference
         "RFC XXXX: I2NSF Application Interface YANG Data Model";

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

     augment "/nsfintf:i2nsf-security-policy" {
       description



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       "Augment the NSF-Facing Interface Data Model for the policy
        reconfiguration";
       leaf nsf-name {
         type union {
           type string;
           type inet:ip-address;
         }
         description
           "The name or IP address (IPv4 or IPv6) of the NSF to be
            configured. If the given nsf-name is not IP address, the
            name can be an arbitrary string including FQDN (Fully
            Qualified Domain Name).";
       }

       container problem {
         description
          "Problem: The issue that is emitted by an NSF via the
           I2NSF Monitoring Interface such as DDoS detection, Virus
           detection, Intrusion detection, Web-attack detection, and
           VoIP/VoLTE violation detection.";
         choice attack-detection {
           description
             "The detected attack type";
           case ddos-detected {
             container ddos-detected {
               leaf-list attack-src-ip {
                 type inet:ip-address;
                 description
                   "The source IPv4 (or IPv6) addresses of attack
                    traffic. It can hold multiple IPv4 (or IPv6)
                    addresses.";
               }
               leaf-list attack-dst-ip {
                 type inet:ip-prefix;
                 description
                   "The destination IPv4 (or IPv6) addresses of attack
                    traffic. It can hold multiple IPv4 (or IPv6)
                    addresses.";
               }
               leaf-list attack-src-port {
                 type inet:port-number;
                 description
                   "The source ports of the DDoS attack";
               }
               leaf-list attack-dst-port {
                 type inet:port-number;
                 description
                   "The destination ports of the DDoS attack";



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               }
               description
                 "A container for DDoS Attack";
             }
             description
               "A DDoS Attack is detected";
           }
           case virus-detected {
             container virus-detected {
               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).";
                 reference
                   "IANA Website: Media Types";
               }
               leaf file-name {
                 type string;
                 description
                   "The name of file virus code is found in (if
                    applicable).";
               }
               description
                 "A Virus Attack is detected";
             }
             description
               "A virus is detected";
           }
           case intrusion-detected {
             container intrusion-detected {
               leaf protocol {
                 type identityref {
                   base nsfmi:transport-protocol;
                 }
                 description
                   "The transport protocol type for
                    nsf-detection-intrusion notification";
               }
               leaf app {
                 type identityref {
                   base nsfmi:application-protocol;
                 }



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                 description
                   "The employed application layer protocol";
               }
               leaf attack-type {
                 type identityref {
                   base nsfmi:intrusion-attack-type;
                 }
                 description
                   "The sub attack type for intrusion attack";
               }
               description
                 "An intrusion is detected";
             }
           }
           case web-attack-detected {
             container web-attack-detected {
               leaf attack-type {
                 type identityref {
                   base nsfmi:web-attack-type;
                 }
                 description
                   "Concrete web attack type, e.g., SQL injection,
                    command injection, XSS, and CSRF.";
               }
               leaf request-method {
                 type identityref {
                   base nsfmi:request-method;
                 }
                 description
                   "The HTTP request method, e.g., PUT or GET.";
                 reference
                   "RFC 7231: Hypertext Transfer Protocol (HTTP/1.1):
                    Semantics and Content - Request Methods";
               }
               leaf req-uri {
                 type string;
                 description
                   "The Requested URI";
               }
               leaf req-user-agent {
                 type string;
                 description
                   "The request user agent";
               }
               leaf req-cookie {
                 type string;
                 description
                   "The HTTP Cookie previously sent by the server with



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                    Set-Cookie";
               }
               leaf req-host {
                 type string;
                 description
                   "The domain name of the requested host";
               }
               leaf response-code {
                 type string;
                 description
                   "The HTTP Response code";
                 reference
                   "IANA Website: Hypertext Transfer Protocol (HTTP)
                    Status Code Registry";
               }
               description
                 "A web attack is detected";
             }
             description
               "A web attack is detected";
           }
           case voip-volte-detected {
             container voip-volte-detected {
               leaf-list source-voice-id {
                 type string;
                 description
                   "The detected source voice ID for VoIP and VoLTE that
                    violates the security policy.";
               }
               leaf-list destination-voice-id {
                 type string;
                 description
                   "The detected destination voice ID for VoIP and VoLTE
                    that violates the security policy.";
               }
               leaf-list user-agent {
                 type string;
                 description
                   "The detected user-agent for VoIP and VoLTE that
                    violates the security policy.";
               }
               description
                 "A violation of VoIP/VoLTE is detected";
             }
             description
               "A violation of VoIP/VoLTE is detected";
           }
         }



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       }
     }

     list i2nsf-feedback-information {
       key "nsf-name time";

       description
         "Feedback information is information about problem(s) of an
          NSF for a security service such as system resource over-usage
          or malfunction. ";

       leaf nsf-name {
         type union {
           type string;
           type inet:ip-address;
         }
         description
           "The name or IP address (IPv4 or IPv6) of the NSF to be
            configured. If the given nsf-name is not IP address, the
            name can be an arbitrary string including FQDN (Fully
            Qualified Domain Name).";
       }

       leaf time {
         type yang:date-and-time;
         description
           "The time of the feedback information delivered";
       }

       container problem {
         description
           "The issue that is emitted by an NSF via the I2NSF Monitoring
            Interface. The problem for feedback information includes the
            system alarms, such as Memory alarm, CPU alarm, Disk alarm,
            Hardware alarm, and Interface alarm.";
         choice alarm-type {
           description
             "The detected alarm type";
           case memory-alarm {
             container memory-alarm {
               leaf usage {
                 type uint8 {
                   range "0..100";
                 }
                 units "percent";
                 description
                   "The average usage for the duration of the alarm.";
               }



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               leaf message {
                 type string;
                 description
                   "A message explaining the problem.";
               }
               leaf duration {
                 type uint32;
                 description
                   "Specify the duration of the first alarm triggered
                    until the feedback information is created.";
               }
               description
                 "The container for memory-alarm";
             }
             description
               "The detected alarm type is memory-alarm";
           }
           case cpu-alarm {
             container cpu-alarm {
               leaf usage {
                 type uint8 {
                   range "0..100";
                 }
                 units "percent";
                 description
                   "The average usage for the duration of the alarm.";
               }
               leaf message {
                 type string;
                 description
                   "A message explaining the problem.";
               }
               leaf duration {
                 type uint32;
                 description
                   "Specify the duration of the first alarm triggered
                    until the feedback information is created.";
               }
               description
                 "The container for cpu-alarm";
             }
             description
               "The detected alarm type is cpu-alarm";
           }
           case disk-alarm {
             container disk-alarm {
               leaf disk-id {
                 type string;



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                 description
                   "The ID of the storage disk. It is a free form
                    identifier to identify the storage disk.";
               }
               leaf usage {
                 type uint8 {
                   range "0..100";
                 }
                 units "percent";
                 description
                   "The average usage for the duration of the alarm.";
               }
               leaf message {
                 type string;
                 description
                   "A message explaining the problem.";
               }
               leaf duration {
                 type uint32;
                 description
                   "Specify the duration of the first alarm triggered
                    until the feedback information is created.";
               }
               description
                 "The container for disk-alarm";
             }
             description
               "The detected alarm type is disk-alarm";
           }
           case hardware-alarm {
             container hardware-alarm {
               leaf component-name {
                 type string;
                 description
                   "The hardware component responsible for generating
                    the message. Applicable for Hardware Failure
                    Alarm.";
               }
               leaf message {
                 type string;
                 description
                   "A message explaining the problem.";
               }
               leaf duration {
                 type uint32;
                 description
                   "Specify the duration of the first alarm triggered
                    until the feedback information is created.";



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               }
               description
                 "The container for hardware-alarm";
             }
             description
               "The detected alarm type is hardware-alarm";
           }
           case interface-alarm {
             container interface-alarm {
               leaf interface-id {
                 type string;
                 description
                   "The interface ID responsible for generating
                    the message.";
               }
               leaf interface-state {
                 type enumeration {
                   enum down {
                     description
                       "The interface state is down.";
                   }
                   enum up {
                     description
                       "The interface state is up and not congested.";
                   }
                   enum congested {
                     description
                       "The interface state is up but congested.";
                   }
                 }
                 description
                   "The state of the interface (i.e., up, down,
                    congested). Applicable for Network Interface Failure
                    Alarm.";
               }
               leaf message {
                 type string;
                 description
                   "A message explaining the problem.";
               }
               leaf duration {
                 type uint32;
                 description
                   "Specify the duration of the first alarm triggered
                    until the feedback information is created.";
               }
               description
                 "The container for interface-alarm";



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             }
             description
               "The detected alarm type is interface-alarm";
           }
         }
       }

       leaf-list solution {
         type string;
         description
            "A possible solution given as feedback is in the form of
             a free-form string (as a high-level instruction).";
       }
     }
   }
   <CODE ENDS>

                  Figure 7: YANG for Application Interface

5.  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-feedback-policy
   Registrant Contact: The IESG.
   XML: N/A; the requested URI is an XML namespace.


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

   name: ietf-i2nsf-feedback-policy
   namespace: urn:ietf:params:xml:ns:yang:ietf-i2nsf-feedback-policy
   prefix: nsffb
   reference: RFC XXXX

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


6.  XML Configuration Examples of Feedback Policy

   This section shows XML configuration examples of feedback policy
   rules that are delivered from the I2NSF Analyzer to the Security
   Controller over the Application Interface after the I2NSF Analyzer
   analyzes the Monitoring Information.




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6.1.  Feedback Policy for DDoS Detection

   In this example, the scenario can be seen in Figure 8.

                               +---------------------------------+
     +---------------+         | Secure Network (203.0.113.0/24) |
     | DDoS Attacker |         |                                 |
     | 192.0.2.8,    | DDoS    | +---------+       +---------+   |
     | 192.0.2.9,    +-------->| |Firewall |       |Server 1 |   |
     | 192.0.2.10    | Attack  | +---------+       +---------+   |
     +---------------+         |      |                          |
                               |      v            +---------+   |
                               | +---------+       |Server 2 |   |
                               | |DDoS     | ----> +---------+   |
                               | |Mitigator|                     |
                               | +---------+       +---------+   |
                               |                   |Server 3 |   |
                               |                   +---------+   |
                               +---------------------------------+


                Figure 8: A Scenario Example of DDoS Attack

   In this scenario, a DDoS Mitigator detects a DDoS Attack and sends a
   notification to the I2NSF Analyzer as shown in Figure 9.


























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   <?xml version="1.0" encoding="UTF-8"?>
   <notification
    xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
     <eventTime>2021-08-27T09:00:01.00Z</eventTime>
     <i2nsf-nsf-event
       xmlns="urn:ietf:params:xml:ns:yang:ietf-i2nsf-nsf-monitoring">
       <i2nsf-nsf-detection-ddos>
         <attack-type
           xmlns:nsfmi="urn:ietf:params:xml:ns:yang:\
                      ietf-i2nsf-nsf-monitoring">
           nsfmi:syn-flood
         </attack-type>
         <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>
         <start-time>2021-08-27T09:00:00.00Z</start-time>
         <attack-src-ip>192.0.2.8</attack-src-ip>
         <attack-src-ip>192.0.2.9</attack-src-ip>
         <attack-src-ip>192.0.2.10</attack-src-ip>
         <attack-dst-ip>203.0.113.0/24</attack-dst-ip>
         <attack-rate>100</attack-rate>
         <message>A DDoS Attack is detected</message>
         <nsf-name>DDoS_mitigator</nsf-name>
       </i2nsf-system-detection-alarm>
     </i2nsf-event>
   </notification>


             Figure 9: A Detected DDoS Attack by DDoS Mitigator

   In the scenario shown in Figure 9, the description of the XML example
   is as follows:

   1.  The DDoS attack is detected at 9 am on August 27 in 2021.





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   2.  The sources of the attack are 192.0.2.8, 192.0.2.9, and
       192.0.2.10.

   3.  The destination of the attack is 203.0.113.0/24.

   After receiving the information, the I2NSF Analyzer analyzes the data
   and creates a new feedback policy to enforce the security of the
   network.  The I2NSF Analyzer delivers a feedback policy to the
   Security Controller as shown in Figure 10.

   <?xml version="1.0" encoding="UTF-8" ?>
   <i2nsf-security-policy
    xmlns="urn:ietf:params:xml:ns:yang:ietf-i2nsf-feedback-policy">
     <system-policy-name>
       feedback_policy_for_ddos_attack
     </system-policy-name>
     <rules>
       <rule-name>deny_ddos_attack</rule-name>
       <event>
         <start-date-time>2021-08-27T09:00:01.00Z</start-date-time>
       </event>
       <condition>
         <ipv4>
           <ipv4-range>
             <start>192.0.2.8</start>
             <end>192.0.2.10</end>
           <ipv4-range>
         </ipv4>
       </condition>
       <actions>
         <packet-action>
           <ingress-action>drop</ingress-action>
         </packet-action>
       </actions>
     </rules>
     <nsf-name>Firewall</nsf-name>
     <problem>
       <ddos-detected>
         <attack-src-ip>192.0.2.8</attack-src-ip>
         <attack-src-ip>192.0.2.9</attack-src-ip>
         <attack-src-ip>192.0.2.10</attack-src-ip>
         <attack-dst-ip>203.0.113.0/24</attack-dst-ip>
       </ddos-detected>
     </problem>
   </i2nsf-security-policy>


        Figure 10: Policy Reconfiguration for a Detected DDoS Attack



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   The policy reconfiguration in Figure 10 means the following:

   1.  The feedback policy is named as
       "feedback_policy_for_ddos_attack".

   2.  The rule is named as "deny_ddos_attack".

   3.  The rule starts from 09:00 am on August 24 in 2021.  The
       condition of the rule is from the sources of the IP addresses
       192.0.2.8, 192.0.2.9, and 192.0.2.10.

   4.  The action required is to "drop" any access from the the IP
       addresses have been identified as malicious.

   5.  The NSF to be configured is named "Firewall".

   6.  The problem that triggered the generation of the feedback is a
       DDoS attack from the sources of the IP addresses 192.0.2.8,
       192.0.2.9, and 192.0.2.10 to the protected network of
       203.0.113.0/24.

6.2.  Feedback Information for Overloaded NSF

   In this scenario, an NSF is overloaded and sends a notification to
   the I2NSF Analyzer as shown in Figure 11.


























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   <?xml version="1.0" encoding="UTF-8"?>
   <notification
    xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
     <eventTime>2021-08-27T07:43:52.181088+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:memory-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>98</usage>
         <threshold>80</threshold>
         <message>Memory Usage Exceeded the Threshold</message>
         <nsf-name>firewall</nsf-name>
         <severity>high</severity>
       </i2nsf-system-detection-alarm>
     </i2nsf-event>
   </notification>


               Figure 11: The Monitoring of an Overloaded NSF

   In the scenario shown in Figure 11, the description of the XML
   example is as follows:

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

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

   3.  The memory usage of the NSF is 98 percent.




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   4.  The memory threshold to trigger the alarm is 80 percent.

   5.  The event is delivered at 2021-08-27T07:43:52.181088+00:00.

   After receiving the information, the I2NSF Analyzer analyzes the data
   and creates a new feedback policy to solve the problem that is
   detected in the NSF.  The I2NSF Analyzer delivers a feedback
   information to the Security Controller as shown in Figure 12.

   <?xml version="1.0" encoding="UTF-8" ?>
   <i2nsf-feedback-information
    xmlns="urn:ietf:params:xml:ns:yang:ietf-i2nsf-feedback-policy">
     <time>2021-08-27T08:43:52.000000+00:00</time>
     <nsf-name>Firewall</nsf-name>
     <problem>
       <memory-alarm>
         <usage>95</usage>
         <message>Memory Usage Exceeded the Threshold</message>
         <duration>3600</duration>
       </memory-alarm>
     </problem>
     <solution>
       Add more memory capacity to the NSF
     </solution>
     <solution>
       Create a new NSF with the same security service
     </solution>
   </i2nsf-feedback-information>


           Figure 12: Feedback Information for the Overloaded NSF

   The feedback information in Figure 12 means the following:

   1.  The name of the NSF that needs to be handled is called
       "Firewall".

   2.  The feedback information is delivered at
       2021-08-27T08:43:52.000000+00:00.

   3.  The problem is that the Memory Usage Exceeded the Threshold with
       the average usage of memory as 95.

   4.  The problem persists for 3,600 seconds (1 hour) without any fix.

   5.  The proposed solution to the problem is to add more memory
       capacity in hardware to the NSF or to create a new NSF with the
       same security service.



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7.  Security Considerations

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

   The NETCONF access control model [RFC8341] provides a means of
   restricting access to specific NETCONF or RESTCONF users to a
   preconfigured subset of all available NETCONF or RESTCONF protocol
   operations and content.

   There are a number of data nodes defined in this YANG module that are
   writable/creatable/deletable (i.e., config true, which is the
   default).  These data nodes may be considered sensitive or vulnerable
   in some network environments.  Write operations (e.g., edit-config)
   to these data nodes without proper protection can have a negative
   effect on network operations.  And the data model in this document
   uses the data model from NSF-Facing Interface data model, it MUST
   follow the Security Considerations mentioned in the
   [I-D.ietf-i2nsf-nsf-facing-interface-dm].

   Some of the readable data nodes in this YANG module may be considered
   sensitive or vulnerable in some network environments.  It is thus
   important to control read access (e.g., via get, get-config, or
   notification) to these data nodes.  This document also MUST follow
   the Security Considerations about the readable data nodes mentioned
   in the [I-D.ietf-i2nsf-nsf-facing-interface-dm].

8.  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) (2020-0-00395, Standard
   Development of Blockchain based Network Management Automation
   Technology).  This work was supported in part by the IITP
   (R-20160222-002755, Cloud based Security Intelligence Technology
   Development for the Customized Security Service Provisioning).  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.








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9.  Contributors

   This document is made by the group effort of I2NSF working group.
   Many people actively contributed to this document, such as Linda
   Dunbar, Yoav Nir, Susan Hares, and Diego Lopez.  The authors
   sincerely appreciate their contributions.

   The following are co-authors of this document:

   Jeonghyeon Kim Department of Computer Science and Engineering
   Sungkyunkwan University 2066 Seo-ro Jangan-gu Suwon, Gyeonggi-do
   16419 Republic of Korea EMail: jeonghyeon12@skku.edu

   Jinyong (Tim) Kim Department of Computer Science and Engineering
   Sungkyunkwan University 2066 Seo-ro Jangan-gu Suwon, Gyeonggi-do
   16419 Republic of Korea EMail: timkim@skku.edu

   Jung-Soo Park Electronics and Telecommunications Research Institute
   218 Gajeong-Ro, Yuseong-Gu Daejeon, 34129 Republic of Korea EMail:
   pjs@etri.re.kr

   Younghan Kim School of Electronic Engineering Soongsil University
   369, Sangdo-ro, Dongjak-gu Seoul 06978 Republic of Korea EMail:
   younghak@ssu.ac.kr

10.  References

10.1.  Normative References

   [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>.

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

   [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>.





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

   [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>.

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

   [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>.

   [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>.

   [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>.

10.2.  Informative References

   [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>.






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   [I-D.ietf-i2nsf-nsf-monitoring-data-model]
              Jeong, J. (., Lingga, P., Hares, S., Xia, L. (., and H.
              Birkholz, "I2NSF NSF Monitoring Interface YANG Data
              Model", Work in Progress, Internet-Draft, draft-ietf-
              i2nsf-nsf-monitoring-data-model-08, 29 April 2021,
              <https://www.ietf.org/archive/id/draft-ietf-i2nsf-nsf-
              monitoring-data-model-08.txt>.

   [I-D.jeong-i2nsf-security-management-automation]
              Jeong, J. (., Lingga, P., and J. Park, "An Extension of
              I2NSF Framework for Security Management Automation in
              Cloud-Based Security Services", Work in Progress,
              Internet-Draft, draft-jeong-i2nsf-security-management-
              automation-02, 21 August 2021,
              <https://www.ietf.org/archive/id/draft-jeong-i2nsf-
              security-management-automation-02.txt>.

   [I-D.ietf-i2nsf-nsf-facing-interface-dm]
              Kim, J. (., Jeong, J. (., Park, J., Hares, S., and Q. Lin,
              "I2NSF Network Security Function-Facing Interface YANG
              Data Model", Work in Progress, Internet-Draft, draft-ietf-
              i2nsf-nsf-facing-interface-dm-12, 8 March 2021,
              <https://www.ietf.org/archive/id/draft-ietf-i2nsf-nsf-
              facing-interface-dm-12.txt>.

   [I-D.ietf-i2nsf-capability-data-model]
              Hares, S., Jeong, J. (., Kim, J. (., Moskowitz, R., and Q.
              Lin, "I2NSF Capability YANG Data Model", Work in Progress,
              Internet-Draft, draft-ietf-i2nsf-capability-data-model-17,
              14 August 2021, <https://www.ietf.org/archive/id/draft-
              ietf-i2nsf-capability-data-model-17.txt>.

   [I-D.ietf-i2nsf-applicability]
              Jeong, J. P., Hyun, S., Ahn, T., Hares, S., and D. R.
              Lopez, "Applicability of Interfaces to Network Security
              Functions to Network-Based Security Services", Work in
              Progress, Internet-Draft, draft-ietf-i2nsf-applicability-
              18, 16 September 2019, <https://www.ietf.org/archive/id/
              draft-ietf-i2nsf-applicability-18.txt>.

   [Deep-Learning]
              Goodfellow, I., Bengio, Y., and A. Courville, "Deep
              Learning", Publisher: The MIT Press,
              URL: https://www.deeplearningbook.org/, November 2016.

Authors' Addresses





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Internet-Draft    Application Interface YANG Data Model      August 2021


   Patrick Lingga (editor)
   Department of 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


   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
   Email: pauljeong@skku.edu
   URI:   http://iotlab.skku.edu/people-jaehoon-jeong.php


   Yunchul Choi
   Electronics and Telecommunications Research Institute
   218 Gajeong-Ro, Yuseong-Gu
   Daejeon
   305-700
   Republic of Korea

   Phone: +82 42 860 5978
   Email: cyc79@etri.re.kr















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