Internet-Draft I2NSF Capability YANG Data Model January 2022
Hares, et al. Expires 1 August 2022 [Page]
Workgroup:
I2NSF Working Group
Internet-Draft:
draft-ietf-i2nsf-capability-data-model-23
Published:
Intended Status:
Standards Track
Expires:
Authors:
S. Hares, Ed.
Huawei
J. Jeong, Ed.
Sungkyunkwan University
J. Kim
Sungkyunkwan University
R. Moskowitz
HTT Consulting
Q. Lin
Huawei

I2NSF Capability YANG Data Model

Abstract

This document defines an information model and the corresponding YANG data model for the capabilities of various Network Security Functions (NSFs) in the Interface to Network Security Functions (I2NSF) framework to centrally manage the capabilities of the various NSFs.

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 1 August 2022.

▲

Table of Contents

1. Introduction

As the industry becomes more sophisticated and network devices (e.g., Internet-of-Things (IoT) devices, autonomous vehicles, and smartphones using Voice over IP (VoIP) and Voice over LTE (VoLTE)) require advanced security protection in various scenarios, security service providers have a lot of problems described in [RFC8192] to provide such network devices with efficient and reliable security services in network infrastructure. To resolve these problems, this document specifies the information and data models of the capabilities of Network Security Functions (NSFs) in a framework of the Interface to Network Security Functions (I2NSF) [RFC8329].

NSFs produced by multiple security vendors provide various security capabilities to customers. Multiple NSFs can be combined together to provide security services over the given network traffic, regardless of whether the NSFs are implemented as physical or virtual functions. Security Capabilities describe the functions that Network Security Functions (NSFs) can provide for security policy enforcement. Security Capabilities are independent of the actual security policy that will implement the functionality of the NSF.

Every NSF should be described with the set of capabilities it offers. Security Capabilities enable security functionality to be described in a vendor-neutral manner. Security Capabilities are a market enabler, providing a way to define customized security protection by unambiguously describing the security features offered by a given NSF. Note that this YANG data model forms the basis of the NSF Monitoring Interface YANG data model [I-D.ietf-i2nsf-nsf-monitoring-data-model] and the NSF-Facing Interface YANG data model [I-D.ietf-i2nsf-nsf-facing-interface-dm].

This document provides an information model and the corresponding YANG data model [RFC6020][RFC7950] that defines the capabilities of NSFs to centrally manage the capabilities of those NSFs. The NSFs can register their own capabilities into a Network Operator Management (Mgmt) System (i.e., Security Controller) with this YANG data model through the registration interface [RFC8329]. With the database of the capabilities of those NSFs that are maintained centrally, those NSFs can be more easily managed [RFC8329].

This YANG data model uses an "Event-Condition-Action" (ECA) policy model that is used as the basis for the design of I2NSF Policy as described in [RFC8329] and Section 3.1. The "ietf-i2nsf-capability" YANG module defined in this document provides the following features:

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

3. Information Model of I2NSF NSF Capability

This section provides the I2NSF Capability Information Model (CapIM). A CapIM is a formalization of the functionality that an NSF advertises. This enables the precise specification of what an NSF can do in terms of security policy enforcement, so that computer-based tasks can unambiguously refer to, use, configure, and manage NSFs. Capabilities are defined in a vendor- and technology-independent manner (i.e., regardless of the differences among vendors and individual products).

Network security experts can refer to categories of security controls and understand each other. For instance, network security experts agree on what is meant by the terms "NAT", "filtering", and "VPN concentrator". As a further example, network security experts unequivocally refer to "packet filters" as devices that allow or deny packet forwarding based on various conditions (e.g., source and destination IP addresses, source and destination ports, and IP protocol type fields) [Alshaer].

However, more information is required in case of other devices, like stateful firewalls or application layer filters. These devices filter packets or communications, but there are differences in the packets and communications that they can categorize and the states they maintain. Network engineers deal with these differences by asking more questions to determine the specific category and functionality of the device. Machines can follow a similar approach, which is commonly referred to as question-answering [Hirschman]. In this context, the CapIM and the derived data model can provide important and rich information sources.

Analogous considerations can be applied for channel protection protocols, where we all understand that they will protect packets by means of symmetric algorithms whose keys could have been negotiated with asymmetric cryptography, but they may work at different layers and support different algorithms and protocols. To ensure protection, these protocols apply integrity, optionally confidentiality, anti-reply protections, and authentication.

The CapIM is intended to clarify these ambiguities by providing a formal description of NSF functionality. The set of functions that are advertised MAY be restricted according to the privileges of the user or application that is viewing those functions. I2NSF Capabilities enable unambiguous specification of the security capabilities available in a (virtualized) networking environment, and their automatic processing by means of computer-based techniques.

This CapIM includes enabling a security controller in an I2NSF framework [RFC8329] to properly identify and manage NSFs, and allow NSFs to properly declare their functionality through a Developer's Management System (DMS) [RFC8329], so that they can be used in the correct way.

3.1. Design Principles and ECA Policy Model

This document defines an information model for representing NSF capabilities. Some basic design principles for security capabilities and the systems that manage them are:

  • Independence: Each security capability (e.g., events, conditions, and actions) SHOULD be an independent function, with minimum overlap or dependency on other capabilities. This enables each security capability to be utilized and assembled with other security capabilities together freely. More importantly, changes to one capability SHOULD NOT affect other capabilities. This follows the Single Responsibility Principle [Martin] [OODSRP].
  • Abstraction: Each capability MUST be defined in a vendor- independent manner.
  • Advertisement: Registration Interface [I-D.ietf-i2nsf-registration-interface-dm] MUST be used to advertise and register the capabilities of each NSF. This same interface MUST be used by other I2NSF Components to determine what Capabilities are currently available to them.
  • Execution: NSF-Facing Interface [I-D.ietf-i2nsf-nsf-facing-interface-dm] and NSF Monitoring Interface [I-D.ietf-i2nsf-nsf-monitoring-data-model] MUST be used to configure the use of a capability into an NSF and monitor the NSF, respectively. These provide a standardized ability to describe its functionality, and report its processing results, respectively. These facilitate multi-vendor interoperability.
  • Automation: The system MUST have the ability to auto-discover, auto-negotiate, and auto-update its security capabilities (i.e., without human intervention). These features are especially useful for the management of a large number of NSFs. They are essential for adding smart services (e.g., refinement, analysis, capability reasoning, and optimization) to the security scheme employed. These features are supported by many design patterns, including the Observer Pattern [OODOP], the Mediator Pattern [OODMP], and a set of Message Exchange Patterns [Hohpe]. Registration Interface [I-D.ietf-i2nsf-registration-interface-dm] can register the capabilities of NSFs with the security controller from the request of Developer's Management System providing NSFs and the corresponding security capabilities. Also, this interface can send a query to Developer's Management System in order to find an NSF to satisfy the requested security capability from the security controller that receives a security policy.
  • Scalability: The management system SHOULD have the capability to scale up/down or scale in/out. Thus, it can meet various performance requirements derived from changeable network traffic or service requests. In addition, security capabilities that are affected by scalability changes SHOULD support reporting statistics to the security controller to assist its decision on whether it needs to invoke scaling or not. NSF Monitoring Interface [I-D.ietf-i2nsf-nsf-monitoring-data-model] can observe the performance of NSFs to let the security controller decide scalability changes of the NSFs.

Based on the above principles, this document defines a capability model that enables an NSF to register (and hence advertise) its set of capabilities that other I2NSF Components can use. These capabilities MUST have their access control restricted by a policy; this is out of scope for this document. The set of capabilities provided by a given set of NSFs unambiguously defines the security services offered by the set of NSFs used. The security controller can compare the requirements of users and applications with the set of capabilities that are currently available in order to choose which capabilities of which NSFs are needed to meet those requirements. Note that this choice is independent of vendor, and instead relies specifically on the capabilities (i.e., the description) of the functions provided.

Furthermore, NSFs are subject to the updates of security capabilities and software to cope with newly found security attacks or threats, hence new capabilities may be created, and/or existing capabilities may be updated (e.g., by updating its signature and algorithm). New capabilities may be sent to and stored in a centralized repository, or stored separately in a vendor's local repository. In either case, Registration Interface can facilitate this update process to Developer's Management System to let the security controller update its repository for NSFs and their security capabilities.

The "Event-Condition-Action" (ECA) policy model in [RFC8329] is used as the basis for the design of the capability model; The following three terms define the structure and behavior of an I2NSF imperative policy rule:

  • Event: An Event is defined as any important occurrence in time of a change in the system being managed, and/or in the environment of the system being managed. When used in the context of I2NSF Policy Rules, it is used to determine whether the condition clause of an I2NSF Policy Rule can be evaluated or not. Examples of an I2NSF Event include time and user actions (e.g., logon, logoff, and actions that violate an ACL).
  • Condition: A condition is defined as a set of attributes, features, and/or values that are to be compared with a set of known attributes, features, and/or values in order to determine whether or not the set of actions in that (imperative) I2NSF Policy Rule can be executed or not. Examples of I2NSF conditions include matching attributes of a packet or flow, and comparing the internal state of an NSF with a desired state.
  • Action: An action is used to control and monitor aspects of NSFs to handle packets or flows when the event and condition clauses are satisfied. NSFs provide security functions by executing various Actions. Examples of I2NSF actions include providing intrusion detection and/or protection, web filtering (i.e., URL filtering) and flow filtering, and deep packet inspection for packets and flows.

An I2NSF Policy Rule is made up of three clauses: an Event clause, a Condition clause, and an Action clause. This structure is also called an ECA (Event-Condition-Action) Policy Rule. A Boolean clause is a logical statement that evaluates to either TRUE or FALSE. It may be made up of one or more terms; if more than one term is present, then each term in the Boolean clause is combined using logical connectives (i.e., AND, OR, and NOT).

An I2NSF ECA Policy Rule has the following semantics:

  • IF <event-clause> is TRUE

    • IF <condition-clause> is TRUE

      • THEN execute <action-clause> [constrained by metadata]
    • END-IF
  • END-IF

Technically, the "Policy Rule" is really a container that aggregates the above three clauses, as well as metadata, which describe the characteristics and behaviors of a capability (or an NSF). Aggregating metadata enables a business logic to be used to prescribe a behavior. For example, suppose a particular ECA Policy Rule contains three actions (A1, A2, and A3, in that order). Action A2 has a priority of 10; actions A1 and A3 have no priority specified. Then, metadata may be used to restrict the set of actions that can be executed when the event and condition clauses of this ECA Policy Rule are evaluated to be TRUE; two examples are: (1) only the first action (A1) is executed, and then the policy rule returns to its caller, or (2) all actions are executed, starting with the highest priority.

The above ECA policy model is very general and easily extensible.

For example, when an NSF has both url filtering capability and packet filtering capability for protocol headers, it means that it can match the URL as well as the Ethernet header, IP header, and Transport header for packet filtering. The condition capability for url filtering and packet filtering is not tightly linked to the action capability due to the independence of our ECA design principle. The action capability only lists the type of action that the NSF can take to handle the matched packets.

3.2. Conflict, Resolution Strategy and Default Action

Formally, two I2NSF Policy Rules conflict with each other if:

  • the Event Clauses of each evaluate to TRUE;
  • the Condition Clauses of each evaluate to TRUE;
  • the Action Clauses affect the same object in different ways.

For example, if we have two Policy Rules called R1 and R2 in the same Policy:

  • R1: During 8am-6pm, if traffic is external, then run through firewall
  • R2: During 7am-8pm, run anti-virus

There is no conflict between the two policy rules R1 and R2, since the actions are different. However, consider these two rules called R3 and R4:

  • R3: During 9am-6pm, allow John to access social networking service websites
  • R4: During 9am-6pm, disallow all users to access social networking service websites

The two policy rules R3 and R4 are now in conflict, between the hours of 9am and 6pm, because the actions of R3 and R4 are different and apply to the same user (i.e., John).

Conflicts theoretically compromise the correct functioning of devices. However, NSFs have been designed to cope with these issues. Since conflicts are originated by simultaneously matching rules, an additional process decides the action to be applied, e.g., among the actions which the matching rule would have enforced. This process is described by means of a resolution strategy for conflicts. The finding and handling of conflicted matching rules is performed by resolution strategies in the security controller. The implementation of such resolution strategies is out of scope for I2NSF.

On the other hand, it may happen that, if an event is caught, none of the policy rules matches the condition. Note that a packet or flow is handled only when it matches both the event and condition of a policy rule according to the ECA policy model. As a simple case, no condition in the rules may match a packet arriving at the border firewall. In this case, the packet is usually dropped, that is, the firewall has a default behavior of packet dropping in order to manage the cases that are not covered by specific rules.

Therefore, this document introduces two further capabilities for an NSF to handle security policy conflicts with resolution strategies and enforce a default action if no rules match.

  • Resolution Strategies: They can be used to specify how to resolve conflicts that occur between the actions of the same or different policy rules that are matched and contained in this particular NSF;
  • Default Action: It provides the default behavior to be executed when there are no other alternatives. This action can be either an explicit action or a set of actions.

4. Overview of YANG Data Model

This section provides an overview of how the YANG data model can be used in the I2NSF framework described in [RFC8329]. Figure 1 shows the capabilities (e.g., firewall and web filter) of NSFs in the I2NSF Framework. As shown in this figure, a Developer's Management System (DMS) can register NSFs and their capabilities with a Security Controller. To register NSFs in this way, the DMS utilizes the standardized capability YANG data model in this document through the I2NSF Registration Interface [RFC8329]. That is, this Registration Interface uses the YANG module described in this document to describe the capabilities of an NSF that is registered with the Security Controller. As described in [RFC8192], with the usage of Registration Interface and the YANG module in this document, the NSFs manufactured by multiple vendors can be managed together by the Security Controller in a centralized way and be updated dynamically by each vendor as the NSF has software or hardware updates.

In Figure 1, a new NSF at a Developer's Management System has capabilities of Firewall (FW) and Web Filter (WF), which are denoted as (Cap = {FW, WF}), to support Event-Condition-Action (ECA) policy rules where 'E', 'C', and 'A' mean "Event", "Condition", and "Action", respectively. The condition involves IPv4 or IPv6 datagrams, and the action includes "Allow" and "Deny" for those datagrams.

Note that the NSF-Facing Interface [RFC8329] is used by the Security Controller to configure the security policy rules of NSFs (e.g., firewall and Distributed-Denial-of-Service (DDoS) attack mitigator) with the capabilities of the NSFs registered with the Security Controller.

      +------------------------------------------------------+
      |  I2NSF User (e.g., Overlay Network Mgmt, Enterprise  |
      |  Network Mgmt, another network domain's mgmt, etc.)  |
      +--------------------+---------------------------------+
          I2NSF            ^
 Consumer-Facing Interface |
                           |
                           v                 I2NSF
         +-----------------+------------+  Registration +-------------+
         | Network Operator Mgmt System |   Interface   | Developer's |
         | (i.e., Security Controller)  |<------------->| Mgmt System |
         +-----------------+------------+               +-------------+
                           ^                                New NSF
                           |                          Cap = {FW, WF}
             I2NSF         |                          E = {}
      NSF-Facing Interface |                          C = {IPv4, IPv6}
                           |                          A = {Allow, Deny}
                           v
      +---------------+----+------------+-----------------+
      |               |                 |                 |
  +---+---+       +---+---+         +---+---+         +---+---+
  | NSF-1 |  ...  | NSF-m |         | NSF-1 |   ...   | NSF-n |
  +-------+       +-------+         +-------+         +-------+
    NSF-1           NSF-m             NSF-1             NSF-n
 Cap = {FW, WF}    Cap = {FW, WF}    Cap = {FW, WF}    Cap = {FW, WF}
 E = {}            E = {user}        E = {dev}         E = {time}
 C = {IPv4}        C = {IPv6}        C = {IPv4, IPv6}  C = {IPv4}
 A = {Allow, Deny} A = {Allow, Deny} A = {Allow, Deny} A = {Allow, Deny}

  Developer's Mgmt System A           Developer's Mgmt System B
Figure 1: Capabilities of NSFs in I2NSF Framework

A use case of an NSF with the capabilities of firewall and web filter is described as follows.

5. YANG Tree Diagram

This section shows a YANG tree diagram of capabilities of network security functions, as defined in the Section 3.

5.1. Network Security Function (NSF) Capabilities

This section explains a YANG tree diagram of NSF capabilities and its features. Figure 2 shows a YANG tree diagram of NSF capabilities. The NSF capabilities in the tree include time capabilities, event capabilities, condition capabilities, action capabilities, resolution strategy capabilities, and default action capabilities. Those capabilities can be tailored or extended according to a vendor's specific requirements. Refer to the NSF capabilities information model for detailed discussion in Section 3.


module: ietf-i2nsf-capability
  +--rw nsf* [nsf-name]
     +--rw nsf-name                            string
     +--rw directional-capabilities*           identityref
     +--rw event-capabilities
     |  +--rw system-event-capability*   identityref
     |  +--rw system-alarm-capability*   identityref
     |  +--rw time-capabilities*         identityref
     +--rw condition-capabilities
     |  +--rw generic-nsf-capabilities
     |  |  +--rw ethernet-capability*   identityref
     |  |  +--rw ipv4-capability*       identityref
     |  |  +--rw ipv6-capability*       identityref
     |  |  +--rw icmpv4-capability*     identityref
     |  |  +--rw icmpv6-capability*     identityref
     |  |  +--rw tcp-capability*        identityref
     |  |  +--rw udp-capability*        identityref
     |  |  +--rw sctp-capability*       identityref
     |  |  +--rw dccp-capability*       identityref
     |  +--rw advanced-nsf-capabilities
     |  |  +--rw anti-ddos-capability*              identityref
     |  |  +--rw ips-capability*                    identityref
     |  |  +--rw anti-virus-capability*             identityref
     |  |  +--rw url-filtering-capability*          identityref
     |  |  +--rw voip-volte-filtering-capability*   identityref
     |  +--rw context-capabilities
     |     +--rw application-filter-capabilities*   identityref
     |     +--rw device-type-capabilities*          identityref
     |     +--rw user-condition-capabilities*       identityref
     |     +--rw geographic-capabilities*           identityref
     +--rw action-capabilities
     |  +--rw ingress-action-capability*   identityref
     |  +--rw egress-action-capability*    identityref
     |  +--rw log-action-capability*       identityref
     +--rw resolution-strategy-capabilities*   identityref
     +--rw default-action-capabilities*        identityref
Figure 2: YANG Tree Diagram of Capabilities of Network Security Functions

The data model in this document provides identities for the capabilities of NSFs. Every identity in the data model represents the capability of an NSF. Each identity is explained in the description of the identity.

Event capabilities are used to specify the capabilities that describe an event that would trigger the evaluation of the condition clause of the I2NSF Policy Rule. The defined event capabilities are system event, system alarm, and time. Time capabilities are used to specify the capabilities which describe when to execute the I2NSF policy rule. The time capabilities are defined in terms of absolute time and periodic time. The absolute time means the exact time to start or end. The periodic time means repeated time like day, week, month, or year.

Condition capabilities are used to specify capabilities of a set of attributes, features, and/or values that are to be compared with a set of known attributes, features, and/or values in order to determine whether a set of actions needs to be executed or not so that an imperative I2NSF policy rule can be executed. In this document, two kinds of condition capabilities are used to classify different capabilities of NSFs such as generic-nsf-capabilities and advanced-nsf-capabilities. First, the generic-nsf-capabilities define NSFs that operate on packet header for layer 2 (i.e., Ethernet capability), layer 3 (i.e., IPv4 capability, IPv6 capability, ICMPv4 capability, and ICMPv6 capability.), and layer 4 (i.e., TCP capability, UDP capability, SCTP capability, and DCCP capability). Second, the advanced-nsf-capabilities define NSFs that operate on features different from the generic-nsf-capabilities, e.g., the payload, cross flow state, application layer, traffic statistics, network behavior, etc. This document defines the advanced-nsf into two categories such as content-security-control and attack-mitigation-control.

The advanced-nsf can be extended with other types of NSFs. This document only provides five advanced-nsf capabilities, i.e., IPS capability, URL-Filtering capability, Antivirus capability, VoIP/VoLTE Filter capability, and Anti-DDoS capability. Note that VoIP and VoLTE are merged into a single capability in this document because VoIP and VoLTE use the Session Initiation Protocol (SIP) [RFC3261] for a call setup. See Section 3.1 for more information about the condition in the ECA policy model.

The context capabilities provide extra information for the condition. The given context conditions are application filter, target, user condition, and geographic location. The application filter capability is capability in matching the packet based on the application protocol, such as HTTP, HTTPS, FTP, etc. The device type capability is capability in matching the type of the destination devices, such as PC, IoT, Network Infrastructure devices, etc. The user condition is capability in matching the users of the network by mapping each user ID to an IP address. Users can be combined into one group. The geographic location capability is capability in matching the geographical location of a source or destination of a packet.

Action capabilities are used to specify the capabilities that describe the control and monitoring aspects of flow-based NSFs when the event and condition clauses are satisfied. The action capabilities are defined as ingress-action capability, egress-action capability, and log-action capability. See Section 3.1 for more information about the action in the ECA policy model. Also, see Section 7.2 (NSF-Facing Flow Security Policy Structure) in [RFC8329] for more information about the ingress and egress actions. In addition, see Section 9.1 (Flow-Based NSF Capability Characterization) in [RFC8329] and Section 7.5 (NSF Logs) in [I-D.ietf-i2nsf-nsf-monitoring-data-model] for more information about logging at NSFs.

Resolution strategy capabilities are used to specify the capabilities that describe conflicts that occur between the actions of the same or different policy rules that are matched and contained in this particular NSF. The resolution strategy capabilities are defined as First Matching Rule (FMR), Last Matching Rule (LMR), Prioritized Matching Rule (PMR), Prioritized Matching Rule with Errors (PMRE), and Prioritized Matching Rule with No Errors (PMRN). See Section 3.2 for more information about the resolution strategy.

Default action capabilities are used to specify the capabilities that describe how to execute I2NSF policy rules when no rule matches a packet. The default action capabilities are defined as pass, drop, reject, rate-limit, and mirror. See Section 3.2 for more information about the default action.

6. YANG Data Model of I2NSF NSF Capability

This section introduces a YANG module for NSFs' capabilities, as defined in the Section 3.

It makes references to

<CODE BEGINS> file "ietf-i2nsf-capability@2022-01-28.yang"

module ietf-i2nsf-capability {
  yang-version 1.1;
  namespace
    "urn:ietf:params:xml:ns:yang:ietf-i2nsf-capability";
  prefix
    nsfcap;

  organization
    "IETF I2NSF (Interface to Network Security Functions)
     Working Group";

  contact
    "WG Web: <https://datatracker.ietf.org/wg/i2nsf/>
     WG List: <mailto:i2nsf@ietf.org>

     Editor: Susan Hares
     <mailto:shares@ndzh.com>

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

     Editor: Jinyong (Tim) Kim
     <mailto:timkim@skku.edu>

     Editor: Robert Moskowitz
     <mailto:rgm@htt-consult.com>

     Editor: Qiushi Lin
     <mailto:linqiushi@huawei.com>

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

  description
    "This module is a YANG module for I2NSF Network Security
     Functions (NSFs)'s Capabilities.

     Copyright (c) 2022 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 "2022-01-28"{
    description "Initial revision.";
    reference
      "RFC XXXX: I2NSF Capability YANG Data Model";

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

  /*
   * Identities
   */

  identity event {
    description
      "Base identity for I2NSF events.";
    reference
      "draft-ietf-i2nsf-nsf-monitoring-data-model-09: I2NSF NSF
       Monitoring YANG Data Model - Event";
  }

  identity system-event {
    base event;
    description
      "Identity for system event";
    reference
      "draft-ietf-i2nsf-nsf-monitoring-data-model-09: I2NSF NSF
       Monitoring YANG Data Model - System event";
  }

  identity system-alarm {
    base event;
    description
      "Identity for system alarm";
    reference
      "draft-ietf-i2nsf-nsf-monitoring-data-model-09: I2NSF NSF
       Monitoring YANG Data Model - System alarm";
  }

  identity time {
    base event;
    description
      "Identity for time capabilities";
  }

  identity access-violation {
    base system-event;
    description
      "Identity for access violation event";
    reference
      "draft-ietf-i2nsf-nsf-monitoring-data-model-09: I2NSF NSF
       Monitoring YANG Data Model - System event for access
       violation";
  }

  identity configuration-change {
    base system-event;
    description
      "Identity for configuration change event";
    reference
      "draft-ietf-i2nsf-nsf-monitoring-data-model-09: I2NSF NSF
       Monitoring YANG Data Model - System event for configuration
       change";
  }

  identity memory-alarm {
    base system-alarm;
    description
      "Identity for memory alarm. Alarm when memory usage
      exceeds a threshold.";
    reference
      "draft-ietf-i2nsf-nsf-monitoring-data-model-09: I2NSF NSF
       Monitoring YANG Data Model - System alarm for memory";
  }

  identity cpu-alarm {
    base system-alarm;
    description
      "Identity for CPU alarm. Alarm when CPU usage
      exceeds a threshold.";
    reference
      "draft-ietf-i2nsf-nsf-monitoring-data-model-09: I2NSF NSF
       Monitoring YANG Data Model - System alarm for CPU";
  }

  identity disk-alarm {
    base system-alarm;
    description
      "Identity for disk alarm. Alarm when disk usage
      exceeds a threshold.";
    reference
      "draft-ietf-i2nsf-nsf-monitoring-data-model-09: I2NSF NSF
       Monitoring YANG Data Model - System alarm for disk";
  }

  identity hardware-alarm {
    base system-alarm;
    description
      "Identity for hardware alarm. Alarm when a hardware failure
      or hardware degradation occurs.";
    reference
      "draft-ietf-i2nsf-nsf-monitoring-data-model-09: I2NSF NSF
       Monitoring YANG Data Model - System alarm for hardware";
  }

  identity interface-alarm {
    base system-alarm;
    description
      "Identity for interface alarm. Alarm when interface usage
      exceeds a threshold.";
    reference
      "draft-ietf-i2nsf-nsf-monitoring-data-model-09: I2NSF NSF
       Monitoring YANG Data Model - System alarm for interface";
  }

  identity absolute-time {
    base time;
    description
      "absolute time capabilities.
       If a network security function has the absolute time
       capability, the network security function supports
       rule execution according to absolute time.";
  }

  identity periodic-time {
    base time;
    description
      "periodic time capabilities.
       If a network security function has the periodic time
       capability, the network security function supports
       rule execution according to periodic time.";
  }

  identity device-type {
    description
      "Identity for device type condition capability. The capability
       for matching the destination device type.";
  }

  identity computer {
    base device-type;
    description
      "Identity for computer such as personal computer (PC)
       and server";
  }

  identity mobile-phone {
    base device-type;
    description
      "Identity for mobile-phone such as smartphone and
       cellphone";
  }

  identity voip-volte-phone {
    base device-type;
    description
      "Identity for voip-volte-phone";
  }

  identity tablet {
    base device-type;
    description
      "Identity for tablet";
  }

  identity network-infrastructure-device {
    base device-type;
    description
      "Identity for network infrastructure devices
       such as switch, router, and access point";
  }

  identity iot {
    base device-type;
    description
      "Identity for Internet of Things (IoT) devices
       such as sensors, actuators, and low-power
       low-capacity computing devices";
  }

  identity ot {
    base device-type;
    description
      "Identity for Operational Technology (OT) devices
       also known as industrial control systems such as
       programmable logic controllers (PLCs), digital
       oscilloscopes, and building management systems (BMS)";
  }

  identity vehicle {
    base device-type;
    description
      "Identity for vehicle that connects to and shares
       data through the Internet";
  }

  identity user-condition {
    description
      "Base identity for user condition capability. This is the
       capability of mapping user(s) into their corresponding IP
       address";
  }

  identity user {
    base user-condition;
    description
      "Identity for user condition capability.
       A user (e.g., employee) can be mapped to an IP address of
       a computing device (e.g., computer, laptop, and virtual
       machine) which the user is using.";
  }

  identity group {
    base user-condition;
    description
      "Identity for group condition capability.
       A group (e.g., employees) can be mapped to multiple IP
       addresses of computing devices (e.g., computers, laptops,
       and virtual machines) which the group is using.";
  }

  identity geographic-location {
    description
      "Identity for geographic location condition capability";
    reference
      "RFC 8805: A Format for Self-Published IP Geolocation Feeds -
       An access control for a geographical location (i.e.,
       geolocation) that has the corresponding IP prefix.";
  }

  identity source-location {
    base geographic-location;
    description
      "Identity for source geographic location condition capability";
    reference
      "RFC 8805: A Format for Self-Published IP Geolocation Feeds -
       An access control for a geographical location (i.e.,
       geolocation) that has the corresponding IP prefix.";
  }

  identity destination-location {
    base geographic-location;
    description
      "Identity for destination geographic location condition
       capability";
    reference
      "RFC 8805: A Format for Self-Published IP Geolocation Feeds -
       An access control for a geographical location (i.e.,
       geolocation) that has the corresponding IP prefix.";
  }

  identity directional {
    description
      "Base identity for directional traffic flow capability";
    reference
      "RFC 5103: Bidirectional Flow Export Using IP Flow Information
       Export (IPFIX) - Terminology Unidirectional and Bidirectional
       Flow";
  }

  identity unidirectional {
    base directional;
    description
      "Identity for unidirectional traffic flow.";
    reference
      "RFC 5103: Bidirectional Flow Export Using IP Flow Information
       Export (IPFIX) - Terminology Unidirectional Flow";
  }

  identity bidirectional {
    base directional;
    description
      "Identity for bidirectional traffic flow.";
    reference
      "RFC 5103: Bidirectional Flow Export Using IP Flow Information
       Export (IPFIX) - Terminology Bidirectional Flow";
  }

  identity protocol {
    description
      "Base identity for protocols";
  }

  identity ethernet {
    base protocol;
    description
      "Base identity for Ethernet protocol.";
  }

  identity source-mac-address {
    base ethernet;
    description
      "Identity for the capability of matching Media Access Control
       (MAC) source address(es) condition capability.";
    reference
      "IEEE 802.3 - 2018: IEEE Standard for Ethernet";
  }

  identity destination-mac-address {
    base ethernet;
    description
      "Identity for the capability of matching Media Access Control
       (MAC) destination address(es) condition capability.";
    reference
      "IEEE 802.3 - 2018: IEEE Standard for Ethernet";
  }

  identity ether-type {
    base ethernet;
    description
      "Identity for the capability of matching the EtherType in
       Ethernet II and Length in Ethernet 802.3 of a packet.";
    reference
      "IEEE 802.3 - 2018: IEEE Standard for Ethernet";
  }

  identity ip {
    base protocol;
    description
      "Base identity for internet/network layer protocol,
       e.g., IPv4, IPv6, and ICMP.";
  }

  identity ipv4 {
    base ip;
    description
      "Base identity for IPv4 condition capability";
    reference
      "RFC 791: Internet Protocol";
  }

  identity ipv6 {
    base ip;
    description
      "Base identity for IPv6 condition capabilities";
    reference
      "RFC 8200: Internet Protocol, Version 6 (IPv6)
       Specification";
  }

  identity dscp {
    base ipv4;
    base ipv6;
    description
      "Identity for the capability of matching IPv4 annd IPv6
       Differentiated Services Codepoint (DSCP) condition";
    reference
      "RFC 791: Internet Protocol - Type of Service
       RFC 2474: Definition of the Differentiated
       Services Field (DS Field) in the IPv4 and
       IPv6 Headers
       RFC 8200: Internet Protocol, Version 6 (IPv6)
       Specification - Traffic Class";
  }

  identity ecn {
    base ipv4;
    base ipv6;
    description
      "Identity for the capability of matching IPv4 annd IPv6
       Explicit Congestion Notification (ECN) condition";
    reference
      "RFC 3168: The Addition of Explicit Congestion
       Notification (ECN) to IP.";
  }

  identity total-length {
    base ipv4;
    base ipv6;
    description
      "Identity for the capability of matching IPv4 Total Length
       header field or IPv6 Payload Length header field.

       IPv4 Total Length is the length of datagram, measured in
       octets, including internet header and data.

       IPv6 Payload Length is the length of the IPv6 payload, i.e.,
       the rest of the packet following the IPv6 header, measured in
       octets.";
    reference
      "RFC 791: Internet Protocol - Total Length
       RFC 8200: Internet Protocol, Version 6 (IPv6)
       Specification - Payload Length";
  }

  identity ttl {
    base ipv4;
    base ipv6;
    description
      "Identity for the capability of matching IPv4 Time-To-Live
       (TTL) or IPv6 Hop Limit.";
    reference
      "RFC 791: Internet Protocol - Time To Live (TTL)
       RFC 8200: Internet Protocol, Version 6 (IPv6)
       Specification - Hop Limit";
  }

  identity next-header {
    base ipv4;
    base ipv6;
    description
      "Identity for the capability of matching IPv4 Protocol Field or
       equivalent to IPv6 Next Header.";
    reference
      "IANA Website: Assigned Internet Protocol Numbers
       - Protocol Number for IPv4
       RFC 791: Internet Protocol - Protocol
       RFC 8200: Internet Protocol, Version 6 (IPv6)
       Specification - Next Header";
  }

  identity source-address {
    base ipv4;
    base ipv6;
    description
      "Identity for the capability of matching IPv4 or IPv6 source
       address(es) condition capability.";
    reference
      "RFC 791: Internet Protocol - Address
       RFC 8200: Internet Protocol, Version 6 (IPv6)
       Specification - Source Address";
  }

  identity destination-address {
    base ipv4;
    base ipv6;
    description
      "Identity for the capability of matching IPv4 or IPv6
       destination address(es) condition capability.";
    reference
      "RFC 791: Internet Protocol - Address
       RFC 8200: Internet Protocol, Version 6 (IPv6)
       Specification - Destination Address";
  }

  identity flow-direction {
    base ipv4;
    base ipv6;
    description
      "Identity for flow direction of matching IPv4/IPv6 source
       or destination address(es) condition capability where a flow's
       direction is either unidirectional or bidirectional";
    reference
      "RFC 791: Internet Protocol
       RFC 8200: Internet Protocol, Version 6 (IPv6)
       Specification";
  }

  identity header-length {
    base ipv4;
    description
      "Identity for matching IPv4 header-length (IHL)
      condition capability";
    reference
      "RFC 791: Internet Protocol - Header Length";
  }

  identity identification {
    base ipv4;
    description
      "Identity for IPv4 identification condition capability.
       IPv4 ID field is used for fragmentation and reassembly.";
    reference
      "RFC 791: Internet Protocol - Identification
       RFC 6864: Updated Specification of the IPv4 ID Field -
       Fragmentation and Reassembly";
  }

  identity fragment-flags {
    base ipv4;
    description
      "Identity for IPv4 fragment flags condition capability";
    reference
      "RFC 791: Internet Protocol - Fragmentation Flags";
  }

  identity fragment-offset {
    base ipv4;
    description
      "Identity for matching IPv4 fragment offset
      condition capability";
    reference
      "RFC 791: Internet Protocol - Fragmentation Offset";
  }

  identity flow-label {
    base ipv6;
    description
      "Identity for matching IPv6 flow label
      condition capability";
    reference
      "RFC 8200: Internet Protocol, Version 6 (IPv6)
       Specification - Flow Label
       RFC 6437: IPv6 Flow Label Specification";
  }

  identity header-order {
    base ipv6;
    description
      "Identity for IPv6 extension header order condition
      capability";
    reference
      "RFC 8200: Internet Protocol, Version 6 (IPv6)
       Specification - Extension Header Order";
  }

  identity hop-by-hop {
    base ipv6;
    description
      "Identity for IPv6 hop by hop options header
      condition capability";
    reference
      "RFC 8200: Internet Protocol, Version 6 (IPv6)
      Specification - Hop-by-Hop Options Header";
  }

  identity routing-header {
    base ipv6;
    description
      "Identity for IPv6 routing header condition
      capability";
    reference
      "RFC 8200: Internet Protocol, Version 6 (IPv6)
      Specification - Routing Header";
  }

  identity fragment-header {
    base ipv6;
    description
      "Identity for IPv6 fragment header condition
      capability";
    reference
      "RFC 8200: Internet Protocol, Version 6 (IPv6)
      Specification - Fragment Header";
  }

  identity destination-options {
    base ipv6;
    description
      "Identity for IPv6 destination options condition
      capability";
    reference
      "RFC 8200: Internet Protocol, Version 6 (IPv6)
      Specification - Destination Options";
  }

  identity icmp {
    base protocol;
    description
      "Base identity for ICMPv4 and ICMPv6 condition capability";
    reference
      "RFC 792: Internet Control Message Protocol
       RFC 4443: Internet Control Message Protocol (ICMPv6)
       for the Internet Protocol Version 6 (IPv6) Specification
       - ICMPv6";
  }

  identity icmpv4 {
    base icmp;
    description
      "Base identity for ICMPv4 condition capability";
    reference
      "RFC 792: Internet Control Message Protocol";
  }

  identity icmpv6 {
    base icmp;
    description
      "Base identity for ICMPv6 condition capability";
    reference
      "RFC 4443: Internet Control Message Protocol (ICMPv6)
       for the Internet Protocol Ver sion 6 (IPv6) Specification
       - ICMPv6";
  }

  identity type {
    base icmpv4;
    base icmpv6;
    description
      "Identity for ICMPv4 and ICMPv6 type condition capability";
    reference
      "RFC 792: Internet Control Message Protocol
       RFC 4443: Internet Control Message Protocol (ICMPv6)
       for the Internet Protocol Version 6 (IPv6) Specification
       - ICMPv6";
  }

  identity code {
    base icmpv4;
    base icmpv6;
    description
      "Identity for ICMPv4 and ICMPv6 code condition capability";
    reference
      "RFC 792: Internet Control Message Protocol
       RFC 4443: Internet Control Message Protocol (ICMPv6)
       for the Internet Protocol Version 6 (IPv6) Specification
       - ICMPv6";
  }

  identity transport-protocol {
    base protocol;
    description
      "Base identity for Layer 4 protocol condition capabilities,
       e.g., TCP, UDP, SCTP, and DCCP";
  }

  identity tcp {
    base transport-protocol;
    description
      "Base identity for TCP condition capabilities";
    reference
      "draft-ietf-tcpm-rfc793bis-25: Transmission Control Protocol
       (TCP) Specification";
  }

  identity udp {
    base transport-protocol;
    description
      "Base identity for UDP condition capabilities";
    reference
      "RFC 768: User Datagram Protocol";
  }

  identity sctp {
    base transport-protocol;
    description
      "Identity for SCTP condition capabilities";
    reference
      "RFC 4960: Stream Control Transmission Protocol";
  }

  identity dccp {
    base transport-protocol;
    description
      "Identity for DCCP condition capabilities";
    reference
      "RFC 4340: Datagram Congestion Control Protocol";
  }

  identity source-port-number {
    base tcp;
    base udp;
    base sctp;
    base dccp;
    description
      "Identity for matching TCP, UDP, SCTP, and DCCP source port
       number condition capability";
    reference
      "draft-ietf-tcpm-rfc793bis-25: Transmission Control Protocol
       (TCP) Specification
       RFC 768: User Datagram Protocol
       RFC 4960: Stream Control Transmission Protocol
       RFC 4340: Datagram Congestion Control Protocol";
  }

  identity destination-port-number {
    base tcp;
    base udp;
    base sctp;
    base dccp;
    description
      "Identity for matching TCP, UDP, SCTP, and DCCP destination
       port number condition capability";
    reference
      "draft-ietf-tcpm-rfc793bis-25: Transmission Control Protocol
       (TCP) Specification";
  }

  identity flags {
    base tcp;
    description
      "Identity for TCP control bits (flags) condition capability";
    reference
      "draft-ietf-tcpm-rfc793bis-25: Transmission Control Protocol
       (TCP) Specification - TCP Header Flags
       RFC 3168: The Addition of Explicit Congestion Notification
       (ECN) to IP - ECN-Echo (ECE) Flag and Congestion Window
       Reduced (CWR) Flag
       draft-ietf-tcpm-accurate-ecn-15: More Accurate ECN Feedback
       in TCP - ECN-Echo (ECE) Flag and Congestion Window Reduced
       (CWR) Flag";
  }

  identity options {
    base tcp;
    description
      "Identity for TCP options condition capability";
    reference
      "draft-ietf-tcpm-rfc793bis-25: Transmission Control Protocol
       (TCP) Specification
       RFC 6691: TCP Options and Maximum Segment Size
       RFC 7323: TCP Extensions for High Performance";
  }

  identity length {
    base tcp;
    base udp;
    description
      "Identity for matching TCP or UDP length condition capability.
       TCP length is the Data Offset header field where it represents
       the size of the TCP header, expressed in 32-bit words.
       The UDP length is the length in octets of this user datagram
       including this header and the datagram.
       The UDP length can be smaller than the IP transport
       length for UDP transport layer options.";
    reference
      "draft-ietf-tcpm-rfc793bis-25: Transmission Control Protocol
       (TCP) Specification - Data Offset
       RFC 768: User Datagram Protocol - Length
       draft-ietf-tsvwg-udp-options: Transport Options for UDP";
  }

  identity reserved {
    base tcp;
    description
      "Identity for TCP header reserved field condition capability.
       The set of control bits reserved for future used. The control
       bits are also known as flags. Must be zero in generated
       segments and must be ignored in received segments, if
       corresponding future features are unimplemented by the
       sending or receiving host.";
    reference
      "draft-ietf-tcpm-rfc793bis-25: Transmission Control Protocol
       (TCP) Specification";
  }

  identity window-size {
    base tcp;
    description
      "Identity for TCP header Window field condition capability.
       The number of data octets beginning with the one indicated
       in the acknowledgment field that the sender of this segment
       is willing to accept.";
    reference
      "draft-ietf-tcpm-rfc793bis-25: Transmission Control Protocol
       (TCP) Specification";
  }

  identity urgent-pointer {
    base tcp;
    description
      "Identity for TCP Urgent Pointer header field condition
       capability. The Urgent Pointer field in TCP describes the
       current value of urgent pointer as a positive offset from
       the sequence number in this segment. The urgent pointer
       points to the sequence number of the octet following the
       urgent data. This field is only be interpreted in segments
       with the URG control bit set.";
    reference
      "draft-ietf-tcpm-rfc793bis-25: Transmission Control Protocol
       (TCP) Specification";
  }

  identity chunk-type {
    base sctp;
    description
      "Identity for SCTP chunk type condition capability";
    reference
      "RFC 4960: Stream Control Transmission Protocol - Chunk Type";
  }

  identity service-code {
    base dccp;
    description
      "Identity for DCCP Service Code condition capabilitiy";
    reference
      "RFC 4340: Datagram Congestion Control Protocol
       RFC 5595: The Datagram Congestion Control Protocol (DCCP)
       Service Codes
       RFC 6335: Internet Assigned Numbers Authority (IANA)
       Procedures for the Management of the Service Name and
       Transport Protocol Port Number Registry - Service Code";
  }

  identity application-protocol {
    base protocol;
    description
      "Base identity for Application protocol";
  }

  identity http {
    base application-protocol;
    description
      "The identity for Hypertext Transfer Protocol.";
    reference
      "RFC 7230: Hypertext Transfer Protocol (HTTP/1.1): Message
       Syntax and Routing
       RFC 7231: Hypertext Transfer Protocol (HTTP/1.1): Semantics
       and Content";
  }

  identity https {
    base application-protocol;
    description
      "The identity for Hypertext Transfer Protocol Secure.";
    reference
      "RFC 2818: HTTP over TLS (HTTPS)
       RFC 7230: Hypertext Transfer Protocol (HTTP/1.1): Message
       Syntax and Routing
       RFC 7231: Hypertext Transfer Protocol (HTTP/1.1): Semantics
       and Content";
  }

  identity ftp {
    base application-protocol;
    description
      "The identity for File Transfer Protocol.";
    reference
      "RFC 959: File Transfer Protocol (FTP)";
  }

  identity ssh {
    base application-protocol;
    description
      "The identity for Secure Shell (SSH) protocol.";
    reference
      "RFC 4250: The Secure Shell (SSH) Protocol";
  }

  identity telnet {
    base application-protocol;
    description
      "The identity for telnet.";
    reference
      "RFC 854: Telnet Protocol";
  }

  identity smtp {
    base application-protocol;
    description
      "The identity for Simple Mail Transfer Protocol.";
    reference
      "RFC 5321: Simple Mail Transfer Protocol (SMTP)";
  }

  identity pop3 {
    base application-protocol;
    description
      "The identity for Post Office Protocol 3. This includes
       POP3 over TLS";
    reference
      "RFC 1939: Post Office Protocol - Version 3 (POP3)";
  }

  identity imap {
    base application-protocol;
    description
      "The identity for Internet Message Access Protocol. This
       includes IMAP over TLS";
    reference
      "RFC 9051: Internet Message Access Protocol (IMAP) - Version
       4rev2";
  }

  identity action {
    description
      "Base identity for action capability";
  }

  identity log-action {
    base action;
    description
      "Base identity for log-action capability";
  }

  identity ingress-action {
    base action;
    description
      "Base identity for ingress-action capability";
    reference
      "RFC 8329: Framework for Interface to Network Security
       Functions - Section 7.2";
  }

  identity egress-action {
    base action;
    description
      "Base identity for egress-action capability";
    reference
      "RFC 8329: Framework for Interface to Network Security
       Functions - Section 7.2";
  }

  identity default-action {
    base action;
    description
      "Base identity for default-action capability";
  }

  identity rule-log {
    base log-action;
    description
      "Identity for rule log-action capability.
       Log the received packet based on the rule";
  }

  identity session-log {
    base log-action;
    description
      "Identity for session log-action capability.
       Log the received packet based on the session.";
  }

  identity pass {
    base ingress-action;
    base egress-action;
    base default-action;
    description
      "Identity for pass action capability. The pass action allows
       packet or flow to go through the NSF entering or exiting the
       internal network.";
  }

  identity drop {
    base ingress-action;
    base egress-action;
    base default-action;
    description
      "Identity for drop action capability. The drop action denies
       a packet to go through the NSF entering or exiting the
       internal network without sending any response back to the
       source.";
  }

  identity reject {
    base ingress-action;
    base egress-action;
    base default-action;
    description
      "Identity for reject action capability. The reject action
       denies a packet to go through the NSF entering or exiting the
       internal network and send a response back to the source.
       The response depends on the packet and implementation.
       For example, a TCP packet is rejected with TCP RST response
       or a UDP packet may be rejected with ICMP message Type 3
       Code 3 response, i.e., Destination Unreachable: Destination
       port unreachable.";
  }

  identity mirror {
    base ingress-action;
    base egress-action;
    base default-action;
    description
      "Identity for mirror action capability. The mirror action
       copies packet and send it to the monitoring entity while still
       allow the packet or flow to go through the NSF.";
  }

  identity rate-limit {
    base ingress-action;
    base egress-action;
    base default-action;
    description
      "Identity for rate limiting action capability. The rate limit
       action limits the number of packets or flows that can go
       through the NSF by dropping packets or flows (randomly or
       systematically).";
  }

  identity invoke-signaling {
    base egress-action;
    description
      "Identity for invoke signaling action capability";
  }

  identity tunnel-encapsulation {
    base egress-action;
    description
      "Identity for tunnel encapsulation action capability";
  }

  identity forwarding {
    base egress-action;
    description
      "Identity for forwarding action capability";
  }

  identity transformation {
    base egress-action;
    description
      "Identity for transformation action capability";
  }

  identity resolution-strategy {
    description
      "Base identity for resolution strategy capability";
  }

  identity fmr {
    base resolution-strategy;
    description
      "Identity for First Matching Rule (FMR) resolution
       strategy capability";
  }

  identity lmr {
    base resolution-strategy;
    description
      "Identity for Last Matching Rule (LMR) resolution
       strategy capability";
  }

  identity pmr {
    base resolution-strategy;
    description
      "Identity for Prioritized Matching Rule (PMR) resolution
       strategy capability";
  }

  identity pmre {
    base resolution-strategy;
    description
      "Identity for Prioritized Matching Rule with Errors (PMRE)
       resolution strategy capability";
  }

  identity pmrn {
    base resolution-strategy;
    description
      "Identity for Prioritized Matching Rule with No Errors (PMRN)
       resolution strategy capability";
  }

  identity advanced-nsf {
    description
      "Base identity for advanced Network Security Function (NSF)
       capability.";
  }

  identity content-security-control {
    base advanced-nsf;
    description
      "Base identity for content security control. Content security
       control is an NSF that evaluates a packet's payload such as
       Intrusion Prevention System (IPS), URL-Filtering, Antivirus,
       and VoIP/VoLTE Filter.";
  }

  identity attack-mitigation-control {
    base advanced-nsf;
    description
      "Base identity for attack mitigation control. Attack mitigation
       control is an NSF that mitigates an attack such as anti-DDoS
       or DDoS-mitigator.";
  }

  identity ips {
    base content-security-control;
    description
      "Base identity for IPS (Intrusion Prevention System) capability
       that prevents malicious activity within a network";
  }

  identity url-filtering {
    base content-security-control;
    description
      "Base identity for url filtering capability that limits access
       by comparing the web traffic's URL with the URLs for web
       filtering in a database";
  }

  identity anti-virus {
    base content-security-control;
    description
      "Base identity for anti-virus capability to protect the network
       by detecting and removing viruses.";
  }

  identity voip-volte-filtering {
    base content-security-control;
    description
      "Base identity for advanced NSF VoIP/VoLTE Security Service
       capability to filter the VoIP/VoLTE packets or flows.";
    reference
      "RFC 3261: SIP: Session Initiation Protocol";
  }

  identity anti-ddos {
    base attack-mitigation-control;
    description
      "Base identity for advanced NSF Anti-DDoS Attack or DDoS
       Mitigator capability.";
  }

  identity packet-rate {
    base anti-ddos;
    description
      "Identity for advanced NSF Anti-DDoS detecting Packet Rate
       Capability where a packet rate is defined as the arrival rate
       of Packets toward a victim destination node.  The NSF with
       this capability can detect the incoming packet rate and create
       an alert if the rate exceeds the threshold.";

  }

  identity flow-rate {
    base anti-ddos;
    description
      "Identity for advanced NSF Anti-DDoS detecting Flow Rate
       Capability where a flow rate is defined as the arrival rate of
       flows towards a victim destination node.  The NSF with this
       capability can detect the incoming flow rate and create an
       alert if the rate exceeds the threshold.";
  }

  identity byte-rate {
    base anti-ddos;
    description
      "Identity for advanced NSF Anti-DDoS detecting Byte Rate
       Capability where a byte rate is defined as the arrival rate of
       Bytes toward a victim destination node.  The NSF with this
       capability can detect the incoming byte rate and create an
       alert if the rate exceeds the threshold.";
  }

  identity signature-set {
    base ips;
    description
      "Identity for the capability of IPS to set the signature.
       Signature is a set of rules to detect an intrusive activity.";
    reference
      "RFC 4766:  Intrusion Detection Message Exchange Requirements -
       Section 2.2.13";
  }

  identity exception-signature {
    base ips;
    description
      "Identity for the capability of IPS to exclude signatures from
       detecting the intrusion.";
    reference
      "RFC 4766:  Intrusion Detection Message Exchange Requirements -
       Section 2.2.13";
  }

  identity detect {
    base anti-virus;
    description
      "Identity for advanced NSF Antivirus capability to detect
       viruses using a security profile. The security profile is used
       to scan threats, such as virus, malware, and spyware. The NSF
       should be able to update the security profile.";
  }

  identity exception-files {
    base anti-virus;
    description
      "Identity for advanced NSF Antivirus capability to exclude a
       certain file type or name from detection.";
  }

  identity pre-defined {
    base url-filtering;
    description
      "Identity for pre-defined URL Database condition capability
       where URL database is a public database for URL filtering.";
  }

  identity user-defined {
    base url-filtering;
    description
      "Identity for user-defined URL Database condition capability
       that allows a user's manual addition of URLs for URL
       filtering.";
  }

  identity call-id {
    base voip-volte-filtering;
    description
      "Identity for advanced NSF VoIP/VoLTE Call Identifier (ID)
       capability.";
  }

  identity user-agent {
    base voip-volte-filtering;
    description
      "Identity for advanced NSF VoIP/VoLTE User Agent capability.";
  }

  /*
   *  Grouping
   */

  grouping nsf-capabilities {
    description
      "Network Security Function (NSF) Capabilities";
    reference
      "RFC 8329: Framework for Interface to Network Security
       Functions - I2NSF Flow Security Policy Structure.";

    leaf-list directional-capabilities {
      type identityref {
        base directional;
      }
      description
        "The capability of an NSF for handling directional traffic
         flow (i.e., unidirectional or bidirectional traffic flow).";
    }

    container event-capabilities {
      description
        "Capabilities of events.
         If a network security function has the event capabilities,
         the network security function supports rule execution
         according to system event and system alarm.";

      reference
        "RFC 8329: Framework for Interface to Network Security
         Functions - Section 7.
         draft-ietf-i2nsf-nsf-monitoring-data-model-09: I2NSF
         NSF Monitoring YANG Data Model - System Alarm and
         System Events.";

      leaf-list system-event-capability {
        type identityref {
          base system-event;
        }
        description
          "System event capabilities";
      }

      leaf-list system-alarm-capability {
        type identityref {
          base system-alarm;
        }
        description
          "System alarm capabilities";
      }

      leaf-list time-capabilities {
        type identityref {
          base time;
        }
        description
          "The capabilities for activating the policy within a
           specific time.";
      }
    }

    container condition-capabilities {
      description
        "Conditions capabilities.";
      container generic-nsf-capabilities {
        description
          "Conditions capabilities.
           If a network security function has the condition
           capabilities, the network security function
           supports rule execution according to conditions of
           IPv4, IPv6, TCP, UDP, SCTP, DCCP, ICMP, or ICMPv6.";
        reference
          "RFC 768: User Datagram Protocol - UDP.
           RFC 791: Internet Protocol - IPv4.
           RFC 792: Internet Control Message Protocol - ICMP.
           RFC 4443: Internet Control Message Protocol (ICMPv6)
           for the Internet Protocol Version 6 (IPv6) Specification
           - ICMPv6.
           RFC 4960: Stream Control Transmission Protocol - SCTP.
           RFC 8200: Internet Protocol, Version 6 (IPv6)
           Specification - IPv6.
           RFC 8329: Framework for Interface to Network Security
           Functions - I2NSF Flow Security Policy Structure.
           draft-ietf-tcpm-rfc793bis-25: Transmission Control
           Protocol (TCP) Specification";

        leaf-list ethernet-capability {
          type identityref {
            base ethernet;
          }
          description
            "Media Access Control (MAC) capabilities";
          reference
            "IEEE 802.3: IEEE Standard for Ethernet";
        }

        leaf-list ipv4-capability {
          type identityref {
            base ipv4;
          }
          description
            "IPv4 packet capabilities";
          reference
            "RFC 791: Internet Protocol";
        }

        leaf-list ipv6-capability {
          type identityref {
            base ipv6;
          }
          description
            "IPv6 packet capabilities";
          reference
            "RFC 8200: Internet Protocol, Version 6 (IPv6)
             Specification - IPv6";
        }

        leaf-list icmpv4-capability {
          type identityref {
            base icmpv4;
          }
          description
            "ICMPv4 packet capabilities";
          reference
            "RFC 792: Internet Control Message Protocol - ICMP";
        }

        leaf-list icmpv6-capability {
          type identityref {
            base icmpv6;
          }
          description
            "ICMPv6 packet capabilities";
          reference
            "RFC 4443: Internet Control Message Protocol (ICMPv6)
             for the Internet Protocol Version 6 (IPv6) Specification
             - ICMPv6";
        }

        leaf-list tcp-capability {
          type identityref {
            base tcp;
          }
          description
            "TCP packet capabilities";
          reference
            "draft-ietf-tcpm-rfc793bis-25: Transmission Control
             Protocol (TCP) Specification";
        }

        leaf-list udp-capability {
          type identityref {
            base udp;
          }
          description
            "UDP packet capabilities";
          reference
            "RFC 768: User Datagram Protocol - UDP";
        }

        leaf-list sctp-capability {
          type identityref {
            base sctp;
          }
          description
            "SCTP packet capabilities";
          reference
            "RFC 4960: Stream Control Transmission Protocol - SCTP";
        }

        leaf-list dccp-capability {
          type identityref {
            base dccp;
          }
          description
            "DCCP packet capabilities";
          reference
            "RFC 4340: Datagram Congestion Control Protocol - DCCP";
        }
      }

      container advanced-nsf-capabilities {
        description
          "Advanced Network Security Function (NSF) capabilities,
           such as Anti-DDoS, IPS, and VoIP/VoLTE.
           This container contains the leaf-lists of advanced
           NSF capabilities";

        leaf-list anti-ddos-capability {
          type identityref {
            base anti-ddos;
          }
          description
            "Anti-DDoS Attack capabilities";
        }

        leaf-list ips-capability {
          type identityref {
            base ips;
          }
          description
            "IPS capabilities";
        }

        leaf-list anti-virus-capability {
          type identityref {
            base anti-virus;
          }
          description
            "Anti-Virus capabilities";
        }

        leaf-list url-filtering-capability {
          type identityref {
            base url-filtering;
          }
          description
            "URL Filtering capabilities";
        }

        leaf-list voip-volte-filtering-capability {
          type identityref {
            base voip-volte-filtering;
         }
          description
            "VoIP/VoLTE capabilities";
        }
      }

      container context-capabilities {
        description
          "Security context capabilities";
        leaf-list application-filter-capabilities{
          type identityref {
            base application-protocol;
          }
          description
            "Context capabilities based on the application protocol";
        }

        leaf-list device-type-capabilities {
          type identityref {
            base device-type;
          }
          description
            "Context capabilities based on the device attribute that
             can identify a device type
             (i.e., router, switch, pc, ios, or android).";
        }

        leaf-list user-condition-capabilities {
          type identityref {
            base user-condition;
          }
          description
            "Context capabilities based on user condition, such as
             user-id or user-name. The users can collected into a
             user-group and identified with group-id or group-name.
             An NSF is aware of the IP address of the user provided
             by a unified user management system via network. Based
             on name-address association, an NSF is able to enforce
             the security functions over the given user (or user
             group)";
        }

        leaf-list geographic-capabilities {
          type identityref {
            base geographic-location;
          }
          description
            "Context condition capabilities based on the geographical
             location of the source or destination";
        }
      }
    }

    container action-capabilities {
      description
        "Action capabilities.
         If a network security function has the action capabilities,
         the network security function supports the attendant
         actions for policy rules.";

      leaf-list ingress-action-capability {
        type identityref {
          base ingress-action;
        }
        description
          "Ingress-action capabilities";
      }

      leaf-list egress-action-capability {
        type identityref {
          base egress-action;
        }
        description
          "Egress-action capabilities";
      }

      leaf-list log-action-capability {
        type identityref {
          base log-action;
        }
        description
          "Log-action capabilities";
      }
    }

    leaf-list resolution-strategy-capabilities {
      type identityref {
        base resolution-strategy;
      }
      description
        "Resolution strategy capabilities.
         The resolution strategies can be used to specify how
         to resolve conflicts that occur between the actions
         of the same or different policy rules that are matched
         for the same packet and by particular NSF.";
    }

    leaf-list default-action-capabilities {
      type identityref {
        base default-action;
      }
      description
        "Default action capabilities.
         A default action is used to execute I2NSF policy rules
         when no rule matches a packet. The default action is
         defined as pass, drop, rate-limit, or mirror.";
    }
  }

  /*
   * Data nodes
   */

  list nsf {
    key "nsf-name";
    description
      "The list of Network Security Functions (NSFs)";
    leaf nsf-name {
      type string;
      mandatory true;
      description
        "The name of Network Security Function (NSF)";
    }
    uses nsf-capabilities;
  }
}

<CODE ENDS>
Figure 3: YANG Data Module of I2NSF Capability

7. IANA Considerations

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

ID: yang:ietf-i2nsf-capability
URI: urn:ietf:params:xml:ns:yang:ietf-i2nsf-capability
Registrant Contact: The IESG.
XML: N/A; the requested URI is an XML namespace.
Filename: [ TBD-at-Registration ]
Reference: [ RFC-to-be ]

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

Name: ietf-i2nsf-capability
Maintained by IANA? N
Namespace: urn:ietf:params:xml:ns:yang:ietf-i2nsf-capability
Prefix: nsfcap
Module:
Reference: [ RFC-to-be ]

8. Privacy Considerations

This YANG module specifies the capabilities of NSFs. These capabilities are consistent with the diverse set of network security functions in common use in enterprise security operations. The configuration of the capabilities may entail privacy sensitive information as explicitly outlined in Section 9. The NSFs implementing these capabilities may inspect, alter or drop user traffic; and be capable of attributing user traffic to individual users.

Due to the sensitivity of these capabilities, notice must be provided to and consent must be received from the users of the network. Additionally, the collected data and associated infrastructure must be secured to prevent the leakage or unauthorized disclosure of this private data.

9. 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 layer of NETCONF protocol layers MUST use Secure Shell (SSH) [RFC4254][RFC6242] as a secure transport layer. The lowest layer of RESTCONF protocol layers MUST use HTTP over Transport Layer Security (TLS), that is, HTTPS [RFC7230][RFC8446] as a secure transport layer.

The Network Configuration Access Control Model (NACM) [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 contents. Thus, NACM SHOULD be used to restrict the NSF registration from unauthorized users.

There are a number of data nodes defined in this YANG module that are writable, creatable, and deletable (i.e., config true, which is the default). These data nodes may be considered sensitive or vulnerable in some network environments. Write operations to these data nodes could have a negative effect on network and security operations. These data nodes are collected into a single list node. This list node is defined by list nsf with the following sensitivity/vulnerability:

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

Some of the capability indicators (i.e., identities) defined in this document are highly sensitive and/or privileged operations that inherently require access to individuals' private data. These are subtrees and data nodes that are considered privacy sensitive:

It is noted that some private information is made accessible in this manner. Thus, the nodes/entities given access to this data MUST be tightly secured, monitored, and audited to prevent leakage or other unauthorized disclosure of private data. Refer to [RFC6973] for the description of privacy aspects that protocol designers (including YANG data model designers) should consider along with regular security and privacy analysis.

10. References

10.1. Normative References

[RFC0768]
Postel, J., "User Datagram Protocol", STD 6, RFC 768, DOI 10.17487/RFC0768, , <https://www.rfc-editor.org/info/rfc768>.
[RFC0791]
Postel, J., "Internet Protocol", STD 5, RFC 791, DOI 10.17487/RFC0791, , <https://www.rfc-editor.org/info/rfc791>.
[RFC0792]
Postel, J., "Internet Control Message Protocol", STD 5, RFC 792, DOI 10.17487/RFC0792, , <https://www.rfc-editor.org/info/rfc792>.
[RFC0854]
Postel, J. and J. Reynolds, "Telnet Protocol Specification", STD 8, RFC 854, DOI 10.17487/RFC0854, , <https://www.rfc-editor.org/info/rfc854>.
[RFC0959]
Postel, J. and J. Reynolds, "File Transfer Protocol", STD 9, RFC 959, DOI 10.17487/RFC0959, , <https://www.rfc-editor.org/info/rfc959>.
[RFC1939]
Myers, J. and M. Rose, "Post Office Protocol - Version 3", STD 53, RFC 1939, DOI 10.17487/RFC1939, , <https://www.rfc-editor.org/info/rfc1939>.
[RFC2119]
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <https://www.rfc-editor.org/info/rfc2119>.
[RFC2474]
Nichols, K., Blake, S., Baker, F., and D. Black, "Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 Headers", RFC 2474, DOI 10.17487/RFC2474, , <https://www.rfc-editor.org/info/rfc2474>.
[RFC3168]
Ramakrishnan, K., Floyd, S., and D. Black, "The Addition of Explicit Congestion Notification (ECN) to IP", RFC 3168, DOI 10.17487/RFC3168, , <https://www.rfc-editor.org/info/rfc3168>.
[RFC3261]
Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP: Session Initiation Protocol", RFC 3261, DOI 10.17487/RFC3261, , <https://www.rfc-editor.org/info/rfc3261>.
[RFC3688]
Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, , <https://www.rfc-editor.org/info/rfc3688>.
[RFC4250]
Lehtinen, S. and C. Lonvick, Ed., "The Secure Shell (SSH) Protocol Assigned Numbers", RFC 4250, DOI 10.17487/RFC4250, , <https://www.rfc-editor.org/info/rfc4250>.
[RFC4254]
Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH) Connection Protocol", RFC 4254, DOI 10.17487/RFC4254, , <https://www.rfc-editor.org/info/rfc4254>.
[RFC4340]
Kohler, E., Handley, M., and S. Floyd, "Datagram Congestion Control Protocol (DCCP)", RFC 4340, DOI 10.17487/RFC4340, , <https://www.rfc-editor.org/info/rfc4340>.
[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, , <https://www.rfc-editor.org/info/rfc4443>.
[RFC4766]
Wood, M. and M. Erlinger, "Intrusion Detection Message Exchange Requirements", RFC 4766, DOI 10.17487/RFC4766, , <https://www.rfc-editor.org/info/rfc4766>.
[RFC4960]
Stewart, R., Ed., "Stream Control Transmission Protocol", RFC 4960, DOI 10.17487/RFC4960, , <https://www.rfc-editor.org/info/rfc4960>.
[RFC5103]
Trammell, B. and E. Boschi, "Bidirectional Flow Export Using IP Flow Information Export (IPFIX)", RFC 5103, DOI 10.17487/RFC5103, , <https://www.rfc-editor.org/info/rfc5103>.
[RFC5321]
Klensin, J., "Simple Mail Transfer Protocol", RFC 5321, DOI 10.17487/RFC5321, , <https://www.rfc-editor.org/info/rfc5321>.
[RFC5595]
Fairhurst, G., "The Datagram Congestion Control Protocol (DCCP) Service Codes", RFC 5595, DOI 10.17487/RFC5595, , <https://www.rfc-editor.org/info/rfc5595>.
[RFC6020]
Bjorklund, M., Ed., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, , <https://www.rfc-editor.org/info/rfc6020>.
[RFC6241]
Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., and A. Bierman, Ed., "Network Configuration Protocol (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, , <https://www.rfc-editor.org/info/rfc6241>.
[RFC6242]
Wasserman, M., "Using the NETCONF Protocol over Secure Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, , <https://www.rfc-editor.org/info/rfc6242>.
[RFC6335]
Cotton, M., Eggert, L., Touch, J., Westerlund, M., and S. Cheshire, "Internet Assigned Numbers Authority (IANA) Procedures for the Management of the Service Name and Transport Protocol Port Number Registry", BCP 165, RFC 6335, DOI 10.17487/RFC6335, , <https://www.rfc-editor.org/info/rfc6335>.
[RFC6437]
Amante, S., Carpenter, B., Jiang, S., and J. Rajahalme, "IPv6 Flow Label Specification", RFC 6437, DOI 10.17487/RFC6437, , <https://www.rfc-editor.org/info/rfc6437>.
[RFC6864]
Touch, J., "Updated Specification of the IPv4 ID Field", RFC 6864, DOI 10.17487/RFC6864, , <https://www.rfc-editor.org/info/rfc6864>.
[RFC6991]
Schoenwaelder, J., Ed., "Common YANG Data Types", RFC 6991, DOI 10.17487/RFC6991, , <https://www.rfc-editor.org/info/rfc6991>.
[RFC7230]
Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing", RFC 7230, DOI 10.17487/RFC7230, , <https://www.rfc-editor.org/info/rfc7230>.
[RFC7231]
Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content", RFC 7231, DOI 10.17487/RFC7231, , <https://www.rfc-editor.org/info/rfc7231>.
[RFC7323]
Borman, D., Braden, B., Jacobson, V., and R. Scheffenegger, Ed., "TCP Extensions for High Performance", RFC 7323, DOI 10.17487/RFC7323, , <https://www.rfc-editor.org/info/rfc7323>.
[RFC7950]
Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, , <https://www.rfc-editor.org/info/rfc7950>.
[RFC8040]
Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, , <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, , <https://www.rfc-editor.org/info/rfc8174>.
[RFC8200]
Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6) Specification", STD 86, RFC 8200, DOI 10.17487/RFC8200, , <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, , <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, , <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, , <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, , <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, , <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, , <https://www.rfc-editor.org/info/rfc8525>.
[RFC8805]
Kline, E., Duleba, K., Szamonek, Z., Moser, S., and W. Kumari, "A Format for Self-Published IP Geolocation Feeds", RFC 8805, DOI 10.17487/RFC8805, , <https://www.rfc-editor.org/info/rfc8805>.
[RFC9051]
Melnikov, A., Ed. and B. Leiba, Ed., "Internet Message Access Protocol (IMAP) - Version 4rev2", RFC 9051, DOI 10.17487/RFC9051, , <https://www.rfc-editor.org/info/rfc9051>.
[I-D.ietf-tcpm-rfc793bis]
Eddy, W. M., "Transmission Control Protocol (TCP) Specification", Work in Progress, Internet-Draft, draft-ietf-tcpm-rfc793bis-25, , <https://www.ietf.org/archive/id/draft-ietf-tcpm-rfc793bis-25.txt>.
[I-D.ietf-tcpm-accurate-ecn]
Briscoe, B., Kühlewind, M., and R. Scheffenegger, "More Accurate ECN Feedback in TCP", Work in Progress, Internet-Draft, draft-ietf-tcpm-accurate-ecn-15, , <https://www.ietf.org/archive/id/draft-ietf-tcpm-accurate-ecn-15.txt>.
[I-D.ietf-tsvwg-udp-options]
Touch, J., "Transport Options for UDP", Work in Progress, Internet-Draft, draft-ietf-tsvwg-udp-options-13, , <https://www.ietf.org/archive/id/draft-ietf-tsvwg-udp-options-13.txt>.
[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-12, , <https://www.ietf.org/archive/id/draft-ietf-i2nsf-nsf-monitoring-data-model-12.txt>.

10.2. Informative References

[RFC2818]
Rescorla, E., "HTTP Over TLS", RFC 2818, DOI 10.17487/RFC2818, , <https://www.rfc-editor.org/info/rfc2818>.
[RFC6691]
Borman, D., "TCP Options and Maximum Segment Size (MSS)", RFC 6691, DOI 10.17487/RFC6691, , <https://www.rfc-editor.org/info/rfc6691>.
[RFC6973]
Cooper, A., Tschofenig, H., Aboba, B., Peterson, J., Morris, J., Hansen, M., and R. Smith, "Privacy Considerations for Internet Protocols", RFC 6973, DOI 10.17487/RFC6973, , <https://www.rfc-editor.org/info/rfc6973>.
[RFC8192]
Hares, S., Lopez, D., Zarny, M., Jacquenet, C., Kumar, R., and J. Jeong, "Interface to Network Security Functions (I2NSF): Problem Statement and Use Cases", RFC 8192, DOI 10.17487/RFC8192, , <https://www.rfc-editor.org/info/rfc8192>.
[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-16, , <https://www.ietf.org/archive/id/draft-ietf-i2nsf-nsf-facing-interface-dm-16.txt>.
[I-D.ietf-i2nsf-registration-interface-dm]
Hyun, S., Jeong, J. P., Roh, T., Wi, S., and J. Park, "I2NSF Registration Interface YANG Data Model", Work in Progress, Internet-Draft, draft-ietf-i2nsf-registration-interface-dm-13, , <https://www.ietf.org/archive/id/draft-ietf-i2nsf-registration-interface-dm-13.txt>.
[IANA-Protocol-Numbers]
"Assigned Internet Protocol Numbers", Available: https://www.iana.org/assignments/protocol-numbers/protocol-numbers.xhtml, .
[IEEE802.3-2018]
Committee, I. S., "IEEE 802.3-2018 - IEEE Standard for Ethernet", , <https://ieeexplore.ieee.org/document/8457469>.
[Alshaer]
Shaer, Al., Hamed, E., and H. Hamed, "Modeling and management of firewall policies", .
[Hirschman]
Hirschman, L. and R. Gaizauskas, "Natural Language Question Answering: The View from Here", Natural Language Engineering 7:4, pgs 275-300, Cambridge University Press , .
[Hohpe]
Hohpe, G. and B. Woolf, "Enterprise Integration Patterns", ISBN 0-32-120068-3 , .
[Martin]
Martin, R.C., "Agile Software Development, Principles, Patterns, and Practices", Prentice-Hall , ISBN: 0-13-597444-5 , .
[OODMP]
"https://www.oodesign.com/mediator-pattern.html".
[OODOP]
"https://www.oodesign.com/mediator-pattern.html".
[OODSRP]
"https://www.oodesign.com/mediator-pattern.html".

Appendix A. Configuration Examples

This section shows configuration examples of "ietf-i2nsf-capability" module for capabilities registration of general firewall.

A.1. Example 1: Registration for the Capabilities of a General Firewall

This section shows a configuration example for the capabilities registration of a general firewall in either an IPv4 network or an IPv6 network.

<nsf xmlns="urn:ietf:params:xml:ns:yang:ietf-i2nsf-capability">
 <nsf-name>general_firewall</nsf-name>
 <condition-capabilities>
  <generic-nsf-capabilities>
   <ipv4-capability>next-header</ipv4-capability>
   <ipv4-capability>flow-direction</ipv4-capability>
   <ipv4-capability>source-address</ipv4-capability>
   <ipv4-capability>destination-address</ipv4-capability>
   <tcp-capability>source-port-number</tcp-capability>
   <tcp-capability>destination-port-number</tcp-capability>
   <udp-capability>source-port-number</udp-capability>
   <udp-capability>destination-port-number</udp-capability>
  </generic-nsf-capabilities>
 </condition-capabilities>
 <action-capabilities>
  <ingress-action-capability>pass</ingress-action-capability>
  <ingress-action-capability>drop</ingress-action-capability>
  <ingress-action-capability>mirror</ingress-action-capability>
  <egress-action-capability>pass</egress-action-capability>
  <egress-action-capability>drop</egress-action-capability>
  <egress-action-capability>mirror</egress-action-capability>
 </action-capabilities>
</nsf>
Figure 4: Configuration XML for the Capabilities Registration of a General Firewall in an IPv4 Network

Figure 4 shows the configuration XML for the capabilities registration of a general firewall as an NSF in an IPv4 network. Its capabilities are as follows.

  1. The name of the NSF is general_firewall.
  2. The NSF can inspect the IPv4 protocol header field, flow direction, source address(es), and destination address(es)
  3. The NSF can inspect the port number(s) and flow direction for the transport layer protocol, i.e., TCP and UDP.
  4. The NSF can control whether the packets are allowed to pass, drop, or mirror. 
<nsf xmlns="urn:ietf:params:xml:ns:yang:ietf-i2nsf-capability">
 <nsf-name>general_firewall</nsf-name>
 <condition-capabilities>
  <generic-nsf-capabilities>
   <ipv6-capability>next-header</ipv6-capability>
   <ipv6-capability>flow-direction</ipv6-capability>
   <ipv6-capability>source-address</ipv6-capability>
   <ipv6-capability>destination-address</ipv6-capability>
   <tcp-capability>source-port-number</tcp-capability>
   <tcp-capability>destination-port-number</tcp-capability>
   <udp-capability>source-port-number</udp-capability>
   <udp-capability>destination-port-number</udp-capability>
  </generic-nsf-capabilities>
 </condition-capabilities>
 <action-capabilities>
  <ingress-action-capability>pass</ingress-action-capability>
  <ingress-action-capability>drop</ingress-action-capability>
  <ingress-action-capability>mirror</ingress-action-capability>
  <egress-action-capability>pass</egress-action-capability>
  <egress-action-capability>drop</egress-action-capability>
  <egress-action-capability>mirror</egress-action-capability>
 </action-capabilities>
</nsf>
Figure 5: Configuration XML for the Capabilities Registration of a General Firewall in an IPv6 Network

In addition, Figure 5 shows the configuration XML for the capabilities registration of a general firewall as an NSF in an IPv6 network. Its capabilities are as follows.

  1. The name of the NSF is general_firewall.
  2. The NSF can inspect IPv6 next header, flow direction, source address(es), and destination address(es)
  3. The NSF can inspect the port number(s) and flow direction for the transport layer protocol, i.e., TCP and UDP.
  4. The NSF can control whether the packets are allowed to pass, drop, or mirror.

A.2. Example 2: Registration for the Capabilities of a Time-based Firewall

This section shows a configuration example for the capabilities registration of a time-based firewall in either an IPv4 network or an IPv6 network.

<nsf xmlns="urn:ietf:params:xml:ns:yang:ietf-i2nsf-capability">
 <nsf-name>time_based_firewall</nsf-name>
 <event-capabilities>
   <time-capabilities>absolute-time</time-capabilities>
   <time-capabilities>periodic-time</time-capabilities>
 </event-capabilities>
 <condition-capabilities>
  <generic-nsf-capabilities>
   <ipv4-capability>next-header</ipv4-capability>
   <ipv4-capability>flow-direction</ipv4-capability>
   <ipv4-capability>source-address</ipv4-capability>
   <ipv4-capability>destination-address</ipv4-capability>
  </generic-nsf-capabilities>
 </condition-capabilities>
 <action-capabilities>
  <ingress-action-capability>pass</ingress-action-capability>
  <ingress-action-capability>drop</ingress-action-capability>
  <ingress-action-capability>mirror</ingress-action-capability>
  <egress-action-capability>pass</egress-action-capability>
  <egress-action-capability>drop</egress-action-capability>
  <egress-action-capability>mirror</egress-action-capability>
 </action-capabilities>
</nsf>
Figure 6: Configuration XML for the Capabilities Registration of a Time-based Firewall in an IPv4 Network

Figure 6 shows the configuration XML for the capabilities registration of a time-based firewall as an NSF in an IPv4 network. Its capabilities are as follows.

  1. The name of the NSF is time_based_firewall.
  2. The NSF can execute the security policy rule according to absolute time and periodic time.
  3. The NSF can inspect the IPv4 protocol header field, flow direction, source address(es), and destination address(es).
  4. The NSF can control whether the packets are allowed to pass, drop, or mirror. 
<nsf xmlns="urn:ietf:params:xml:ns:yang:ietf-i2nsf-capability">
 <nsf-name>time_based_firewall</nsf-name>
 <event-capabilities>
   <time-capabilities>absolute-time</time-capabilities>
   <time-capabilities>periodic-time</time-capabilities>
 </event-capabilities>
 <condition-capabilities>
  <generic-nsf-capabilities>
   <ipv6-capability>next-header</ipv6-capability>
   <ipv6-capability>flow-direction</ipv6-capability>
   <ipv6-capability>source-address</ipv6-capability>
   <ipv6-capability>destination-address</ipv6-capability>
  </generic-nsf-capabilities>
 </condition-capabilities>
 <action-capabilities>
  <ingress-action-capability>pass</ingress-action-capability>
  <ingress-action-capability>drop</ingress-action-capability>
  <ingress-action-capability>mirror</ingress-action-capability>
  <egress-action-capability>pass</egress-action-capability>
  <egress-action-capability>drop</egress-action-capability>
  <egress-action-capability>mirror</egress-action-capability>
 </action-capabilities>
</nsf>
Figure 7: Configuration XML for the Capabilities Registration of a Time-based Firewall in an IPv6 Network

In addition, Figure 7 shows the configuration XML for the capabilities registration of a time-based firewall as an NSF in an IPv6 network. Its capabilities are as follows.

  1. The name of the NSF is time_based_firewall.
  2. The NSF can execute the security policy rule according to absolute time and periodic time.
  3. The NSF can inspect the IPv6 protocol header field, flow direction, source address(es), and destination address(es).
  4. The NSF can control whether the packets are allowed to pass, drop, or mirror.

A.3. Example 3: Registration for the Capabilities of a Web Filter

This section shows a configuration example for the capabilities registration of a web filter.

<nsf xmlns="urn:ietf:params:xml:ns:yang:ietf-i2nsf-capability">
 <nsf-name>web_filter</nsf-name>
 <condition-capabilities>
  <advanced-nsf-capabilities>
   <url-filtering-capability>user-defined</url-filtering-capability>
  </advanced-nsf-capabilities>
 </condition-capabilities>
 <action-capabilities>
  <ingress-action-capability>pass</ingress-action-capability>
  <ingress-action-capability>drop</ingress-action-capability>
  <ingress-action-capability>mirror</ingress-action-capability>
  <egress-action-capability>pass</egress-action-capability>
  <egress-action-capability>drop</egress-action-capability>
  <egress-action-capability>mirror</egress-action-capability>
 </action-capabilities>
</nsf>
Figure 8: Configuration XML for the Capabilities Registration of a Web Filter

Figure 8 shows the configuration XML for the capabilities registration of a web filter as an NSF. Its capabilities are as follows.

  1. The name of the NSF is web_filter.
  2. The NSF can inspect a URL matched from a user-defined URL. User can specify their own URL.
  3. The NSF can control whether the packets are allowed to pass, drop, or mirror.
  4. Overall, the NSF can compare the URL of a packet to a user-defined database. The matched packet can be passed, dropped, or mirrored.

A.4. Example 4: Registration for the Capabilities of a VoIP/VoLTE Filter

This section shows a configuration example for the capabilities registration of a VoIP/VoLTE filter.

<nsf xmlns="urn:ietf:params:xml:ns:yang:ietf-i2nsf-capability">
 <nsf-name>voip_volte_filter</nsf-name>
 <condition-capabilities>
  <advanced-nsf-capabilities>
   <voip-volte-filtering-capability>
    call-id
   </voip-volte-filtering-capability>
  </advanced-nsf-capabilities>
 </condition-capabilities>
 <action-capabilities>
  <ingress-action-capability>pass</ingress-action-capability>
  <ingress-action-capability>drop</ingress-action-capability>
  <ingress-action-capability>mirror</ingress-action-capability>
  <egress-action-capability>pass</egress-action-capability>
  <egress-action-capability>drop</egress-action-capability>
  <egress-action-capability>mirror</egress-action-capability>
 </action-capabilities>
</nsf>
Figure 9: Configuration XML for the Capabilities Registration of a VoIP/VoLTE Filter

Figure 9 shows the configuration XML for the capabilities registration of a VoIP/VoLTE filter as an NSF. Its capabilities are as follows.

  1. The name of the NSF is voip_volte_filter.
  2. The NSF can inspect a voice call id for VoIP/VoLTE packets.
  3. The NSF can control whether the packets are allowed to pass, drop, or mirror.

A.5. Example 5: Registration for the Capabilities of a HTTP and HTTPS Flood Mitigator

This section shows a configuration example for the capabilities registration of a HTTP and HTTPS flood mitigator.

<nsf xmlns="urn:ietf:params:xml:ns:yang:ietf-i2nsf-capability">
 <nsf-name>DDoS_mitigator</nsf-name>
 <condition-capabilities>
  <advanced-nsf-capabilities>
   <anti-ddos-capability>packet-rate</anti-ddos-capability>
   <anti-ddos-capability>byte-rate</anti-ddos-capability>
   <anti-ddos-capability>flow-rate</anti-ddos-capability>
  </advanced-nsf-capabilities>
 </condition-capabilities>
 <action-capabilities>
  <ingress-action-capability>pass</ingress-action-capability>
  <ingress-action-capability>drop</ingress-action-capability>
  <ingress-action-capability>mirror</ingress-action-capability>
  <egress-action-capability>pass</egress-action-capability>
  <egress-action-capability>drop</egress-action-capability>
  <egress-action-capability>mirror</egress-action-capability>
 </action-capabilities>
</nsf>
Figure 10: Configuration XML for the Capabilities Registration of a HTTP and HTTPS Flood Mitigator

Figure 10 shows the configuration XML for the capabilities registration of a HTTP and HTTPS flood mitigator as an NSF. Its capabilities are as follows.

  1. The name of the NSF is DDoS_mitigator.
  2. The NSF can detect the amount of packet, flow, and byte rate in the network for potential DDoS Attack.
  3. The NSF can control whether the packets are allowed to pass, drop, or mirror.

Appendix B. Acknowledgments

This document is a product by the I2NSF Working Group (WG) including WG Chairs (i.e., Linda Dunbar and Yoav Nir) and Diego Lopez. This document took advantage of the review and comments from the following experts: Roman Danyliw, Acee Lindem, Paul Wouters (SecDir), Michael Scharf (TSVART), Dan Romascanu (GenART), and Tom Petch. We authors sincerely appreciate their sincere efforts and kind help.

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 grant funded by the MSIT (2020-0-00395, Standard Development of Blockchain based Network Management Automation Technology).

Appendix C. Contributors

The following are co-authors of this document:

Patrick Lingga - Department of Electrical and Computer Engineering, Sungkyunkwan University, 2066 Seobu-ro Jangan-gu, Suwon, Gyeonggi-do 16419, Republic of Korea, EMail: patricklink@skku.edu

Liang Xia - Huawei, 101 Software Avenue, Nanjing, Jiangsu 210012, China, EMail: Frank.Xialiang@huawei.com

Cataldo Basile - Politecnico di Torino, Corso Duca degli Abruzzi, 34, Torino, 10129, Italy, EMail: cataldo.basile@polito.it

John Strassner - Huawei, 2330 Central Expressway, Santa Clara, CA 95050, USA, EMail: John.sc.Strassner@huawei.com

Diego R. Lopez - Telefonica I+D, Zurbaran, 12, Madrid, 28010, Spain, Email: diego.r.lopez@telefonica.com

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

Daeyoung Hyun - Department of Computer Science and Engineering, Sungkyunkwan University, 2066 Seobu-ro Jangan-gu, Suwon, Gyeonggi-do 16419, Republic of Korea, EMail: dyhyun@skku.edu

Dongjin Hong - Department of Electronic, Electrical and Computer Engineering, Sungkyunkwan University, 2066 Seobu-ro Jangan-gu, Suwon, Gyeonggi-do 16419, Republic of Korea, EMail: dong.jin@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

Tae-Jin Ahn Korea Telecom 70 Yuseong-Ro, Yuseong-Gu Daejeon, 305-811 Republic of Korea EMail: taejin.ahn@kt.com

Se-Hui Lee Korea Telecom 70 Yuseong-Ro, Yuseong-Gu Daejeon, 305-811 Republic of Korea EMail: sehuilee@kt.com

Authors' Addresses

Susan Hares (editor)
Huawei
7453 Hickory Hill
Saline, MI 48176
United States of America
Phone: +1-734-604-0332
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
URI: http://iotlab.skku.edu/people-jaehoon-jeong.php
Jinyong (Tim) Kim
Department of Electronic, Electrical and Computer Engineering
Sungkyunkwan University
2066 Seobu-Ro, Jangan-Gu
Suwon
Gyeonggi-Do
16419
Republic of Korea
Phone: +82 10 8273 0930
Robert Moskowitz
HTT Consulting
Oak Park, MI
United States of America
Phone: +1-248-968-9809
Qiushi Lin
Huawei
Huawei Industrial Base
Shenzhen
Guangdong 518129,
China