Network Working Group J. Jeong
Internet-Draft C. Chung
Intended status: Standards Track Sungkyunkwan University
Expires: September 12, 2019 S. Hares
L. Xia
Huawei
H. Birkholz
Fraunhofer SIT
March 11, 2019

I2NSF NSF Monitoring YANG Data Model
draft-ietf-i2nsf-nsf-monitoring-data-model-00

Abstract

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

Editorial Note (To be removed by RFC Editor)

Please update these statements within the document with the RFC number to be assigned to this document:

Please update the "revision" date of the YANG module.

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 September 12, 2019.

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

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Table of Contents

1. Introduction

According to [I-D.ietf-i2nsf-terminology], the interface provided by a Network Security Function (NSF) (e.g., Firewall, IPS, Anti-DDoS, or Anti-Virus function) to administrative entities (e.g., Security Controller) to enable remote management (i.e., configuring and monitoring) is referred to as an I2NSF NSF-Facing Interface [I-D.ietf-i2nsf-nsf-facing-interface-dm]. Monitoring procedures intent to acquire vital types of data with respect to NSFs, (e.g., alarms, records, and counters) via data in motion (e.g., queries, notifications, and events). The monitoring of NSF plays an important role in an overall security framework, if it is done in a timely and comprehensive way. The monitoring information generated by an NSF can be a good, early indication of anomalous behavior or malicious activity, such as denial of service attacks (DoS).

This document defines a comprehensive NSF monitoring information model that provides visibility for an NSF for Security Controller. It specifies the information and illustrates the methods that enable an NSF to provide the information required in order to be monitored in a scalable and efficient way via the NSF-Facing Interface. The information model for monitoring presented in this document is a complementary information model to the information model for the security policy provisioning functionality of the NSF-Facing Interface specified in [I-D.ietf-i2nsf-capability].

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

2. Terminology

2.1. Requirements Notation

This document does not propose a protocol standard, and the use of words such as "should" follow their ordinary English meaning and not that for normative languages defined in [RFC2119] [RFC8174].

2.2. Definitions

The terms, which are used in this document, are defined in the I2NSF terminology document [I-D.ietf-i2nsf-terminology].

2.3. YANG

This document follows the guidelines of [RFC6087], 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. Use Cases for NSF Monitoring Data

As mentioned earlier, monitoring plays a critical role in an overall security framework. The monitoring of the NSF provides very valuable information to the security controller in maintaining the provisioned security posture. Besides this, there are various other reasons to monitor the NSF as listed below:

4. Classification of NSF Monitoring Data

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

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

The Alarm Management Framework in [RFC3877] defines an Event as something that happens which may be of interest. It defines a fault as a change in status, crossing a threshold, or an external input to the system. In the I2NSF domain, I2NSF events [I-D.ietf-i2nsf-terminology] are created and the scope of the Alarm Management Framework's Events is still applicable due to its broad definition. The model presented in this document elaborates on the workflow of creating I2NSF events in the context of NSF monitoring and on the way initial I2NSF events are created.

As with I2NSF components, every generic system entity can include a set of capabilities [I-D.ietf-i2nsf-terminology] that creates information about the context, composition, configuration, state or behavior of that system entity. This information is intended to be provided to other consumers of information and in the scope of this document, which deals with NSF information monitoring in an automated fashion.

4.1. Retention and Emission

Typically, a system entity populates standardized interface, such as SNMP, NETCONF, RESTCONF or CoMI to provide and emit created information directly via NSF-Facing Interface [I-D.ietf-i2nsf-terminology]. Alternatively, the created information is retained inside the system entity (or a hierarchy of system entities in a composite device) via records or counters that are not exposed directly via NSF-Facing Interfaces.

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

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

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

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

4.2. Notifications and Events

A specific task of I2NSF User is to process I2NSF Policy Rules [I-D.ietf-i2nsf-terminology]. The rules of a policy are composed of three clauses: Events, Conditions, and Actions. In consequence, an I2NSF Event is specified to trigger an I2NSF Policy Rule. Such an I2NSF Event is defined as any important occurrence over time in the system being managed, and/or in the environment of the system being managed in [I-D.ietf-i2nsf-terminology], which aligns well with the generic definition of Event from [RFC3877].

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

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

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

4.3. Unsolicited Poll and Solicited Push

The freshness of the monitored information depends on the acquisition method. Ideally, an I2NSF User is accessing every relevant information about the I2NSF Component and is emitting I2NSF Events to a monitor entity(e.g., Security Controller and I2NSF User) NSF timely. Publication of events via a pubsub/broker model, peer-2-peer meshes, or static defined channels are only a few examples on how a solicited push of I2NSF Events can be facilitated. The actual mechanic implemented by an I2NSF Component is out of the scope of this document.

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

4.4. I2NSF Monitoring Terminology for Retained Information

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

5. Conveyance of NSF Monitoring Information

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

5.1. Information Types and Acquisition Methods

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

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

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

6. Basic Information Model for All Monitoring Data

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

7. Extended Information Model for Monitoring Data

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

7.1. System Alarm

Characteristics:

7.1.1. Memory Alarm

The following information should be included in a Memory Alarm:

7.1.2. CPU Alarm

The following information should be included in a CPU Alarm:

7.1.3. Disk Alarm

The following information should be included in a Disk Alarm:

7.1.4. Hardware Alarm

The following information should be included in a Hardware Alarm:

7.1.5. Interface Alarm

The following information should be included in a Interface Alarm:

7.2. System Events

Characteristics:

7.2.1. Access Violation

The following information should be included in this event:

7.2.2. Configuration Change

The following information should be included in this event:

7.3. System Log

Characteristics:

7.3.1. Access Logs

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

7.3.2. Resource Utilization Logs

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

7.3.3. User Activity Logs

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

7.4. System Counters

Characteristics:

7.4.1. Interface counters

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

7.5. NSF Events

Characteristics:

7.5.1. DDoS Event

The following information should be included in a DDoS Event:

7.5.2. Session Table Event

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

7.5.3. Virus Event

The following information should be included in a Virus Event:

7.5.4. Intrusion Event

The following information should be included in an Intrustion Event:

7.5.5. Botnet Event

The following information should be included in a Botnet Event:

7.5.6. Web Attack Event

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

7.6. NSF Logs

Characteristics:

7.6.1. DDoS Logs

Besides the fields in a DDoS Alarm, the following information should be included in a DDoS Logs:

7.6.2. Virus Logs

Besides the fields in a Virus Alarm, the following information should be included in a Virus Logs:

7.6.3. Intrusion Logs

Besides the fields in an Intrusion Alarm, the following information should be included in an Intrusion Logs:

7.6.4. Botnet Logs

Besides the fields in a Botnet Alarm, the following information should be included in a Botnet Logs:

7.6.5. DPI Logs

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

7.6.6. Vulnerabillity Scanning Logs

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

7.6.7. Web Attack Logs

Besides the fields in an Web Attack Alarm, the following information should be included in a Web Attack Report:

7.7. NSF Counters

Characteristics:

7.7.1. Firewall counters

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

7.7.2. Policy Hit Counters

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

8. NSF Monitoring Management in I2NSF

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

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

9. Tree Structure

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

module: ietf-i2nsf-monitor
    +--rw counters
       +--rw system-interface
       |  +--rw acquisition-method?        identityref
       |  +--rw emission-type?             identityref
       |  +--rw dampening-type?            identityref
       |  +--rw interface-name?            string
       |  +--rw in-total-traffic-pkts?     uint32
       |  +--rw out-total-traffic-pkts?    uint32
       |  +--rw in-total-traffic-bytes?    uint32
       |  +--rw out-total-traffic-bytes?   uint32
       |  +--rw in-drop-traffic-pkts?      uint32
       |  +--rw out-drop-traffic-pkts?     uint32
       |  +--rw in-drop-traffic-bytes?     uint32
       |  +--rw out-drop-traffic-bytes?    uint32
       |  +--rw total-traffic?             uint32
       |  +--rw in-traffic-ave-rate?       uint32
       |  +--rw in-traffic-peak-rate?      uint32
       |  +--rw in-traffic-ave-speed?      uint32
       |  +--rw in-traffic-peak-speed?     uint32
       |  +--rw out-traffic-ave-rate?      uint32
       |  +--rw out-traffic-peak-rate?     uint32
       |  +--rw out-traffic-ave-speed?     uint32
       |  +--rw out-traffic-peak-speed?    uint32
       |  +--rw message?                   string
       |  +--rw time-stamp?                yang:date-and-time
       |  +--rw vendor-name?               string
       |  +--rw nsf-name?                  string
       |  +--rw module-name?               string
       |  +--rw severity?                  severity
       +--rw nsf-firewall
       |  +--rw acquisition-method?       identityref
       |  +--rw emission-type?            identityref
       |  +--rw dampening-type?           identityref
       |  +--rw src-ip?                   inet:ipv4-address
       |  +--rw dst-ip?                   inet:ipv4-address
       |  +--rw src-port?                 inet:port-number
       |  +--rw dst-port?                 inet:port-number
       |  +--rw src-zone?                 string
       |  +--rw dst-zone?                 string
       |  +--rw src-region?               string
       |  +--rw dst-region?               string
       |  +--rw policy-id?                uint8
       |  +--rw policy-name?              string
       |  +--rw src-user?                 string
       |  +--rw protocol?                 identityref
       |  +--rw app?                      string
       |  +--rw total-traffic?            uint32
       |  +--rw in-traffic-ave-rate?      uint32
       |  +--rw in-traffic-peak-rate?     uint32
       |  +--rw in-traffic-ave-speed?     uint32
       |  +--rw in-traffic-peak-speed?    uint32
       |  +--rw out-traffic-ave-rate?     uint32
       |  +--rw out-traffic-peak-rate?    uint32
       |  +--rw out-traffic-ave-speed?    uint32
       |  +--rw out-traffic-peak-speed?   uint32
       +--rw nsf-policy-hits
          +--rw acquisition-method?   identityref
          +--rw emission-type?        identityref
          +--rw dampening-type?       identityref
          +--rw src-ip?               inet:ipv4-address
          +--rw dst-ip?               inet:ipv4-address
          +--rw src-port?             inet:port-number
          +--rw dst-port?             inet:port-number
          +--rw src-zone?             string
          +--rw dst-zone?             string
          +--rw src-region?           string
          +--rw dst-region?           string
          +--rw policy-id?            uint8
          +--rw policy-name?          string
          +--rw src-user?             string
          +--rw protocol?             identityref
          +--rw app?                  string
          +--rw message?              string
          +--rw time-stamp?           yang:date-and-time
          +--rw vendor-name?          string
          +--rw nsf-name?             string
          +--rw module-name?          string
          +--rw severity?             severity
          +--rw hit-times?            uint32

  notifications:
    +---n system-detection-alarm
    |  +--ro alarm-catagory?       identityref
    |  +--ro acquisition-method?   identityref
    |  +--ro emission-type?        identityref
    |  +--ro dampening-type?       identityref
    |  +--ro usage?                uint8
    |  +--ro threshold?            uint8
    |  +--ro message?              string
    |  +--ro time-stamp?           yang:date-and-time
    |  +--ro vendor-name?          string
    |  +--ro nsf-name?             string
    |  +--ro module-name?          string
    |  +--ro severity?             severity
    +---n system-detection-event
    |  +--ro event-catagory?       identityref
    |  +--ro acquisition-method?   identityref
    |  +--ro emission-type?        identityref
    |  +--ro dampening-type?       identityref
    |  +--ro user                  string
    |  +--ro group                 string
    |  +--ro login-ip-addr         inet:ipv4-address
    |  +--ro authentication?       identityref
    |  +--ro message?              string
    |  +--ro time-stamp?           yang:date-and-time
    |  +--ro vendor-name?          string
    |  +--ro nsf-name?             string
    |  +--ro module-name?          string
    |  +--ro severity?             severity
    +---n nsf-detection-flood
    |  +--ro event-name?        identityref
    |  +--ro dst-ip?            inet:ipv4-address
    |  +--ro dst-port?          inet:port-number
    |  +--ro rule-id            uint8
    |  +--ro rule-name          string
    |  +--ro profile?           string
    |  +--ro raw-info?          string
    |  +--ro sub-attack-type?   identityref
    |  +--ro start-time         yang:date-and-time
    |  +--ro end-time           yang:date-and-time
    |  +--ro attack-rate?       uint32
    |  +--ro attack-speed?      uint32
    |  +--ro message?           string
    |  +--ro time-stamp?        yang:date-and-time
    |  +--ro vendor-name?       string
    |  +--ro nsf-name?          string
    |  +--ro module-name?       string
    |  +--ro severity?          severity
    +---n nsf-detection-session-table
    |  +--ro current-session?   uint8
    |  +--ro maximum-session?   uint8
    |  +--ro threshold?         uint8
    |  +--ro message?           string
    |  +--ro time-stamp?        yang:date-and-time
    |  +--ro vendor-name?       string
    |  +--ro nsf-name?          string
    |  +--ro module-name?       string
    |  +--ro severity?          severity
    +---n nsf-detection-virus
    |  +--ro src-ip?        inet:ipv4-address
    |  +--ro dst-ip?        inet:ipv4-address
    |  +--ro src-port?      inet:port-number
    |  +--ro dst-port?      inet:port-number
    |  +--ro src-zone?      string
    |  +--ro dst-zone?      string
    |  +--ro rule-id        uint8
    |  +--ro rule-name      string
    |  +--ro profile?       string
    |  +--ro raw-info?      string
    |  +--ro virus?         identityref
    |  +--ro virus-name?    string
    |  +--ro file-type?     string
    |  +--ro file-name?     string
    |  +--ro message?       string
    |  +--ro time-stamp?    yang:date-and-time
    |  +--ro vendor-name?   string
    |  +--ro nsf-name?      string
    |  +--ro module-name?   string
    |  +--ro severity?      severity
    +---n nsf-detection-intrusion
    |  +--ro src-ip?            inet:ipv4-address
    |  +--ro dst-ip?            inet:ipv4-address
    |  +--ro src-port?          inet:port-number
    |  +--ro dst-port?          inet:port-number
    |  +--ro src-zone?          string
    |  +--ro dst-zone?          string
    |  +--ro rule-id            uint8
    |  +--ro rule-name          string
    |  +--ro profile?           string
    |  +--ro raw-info?          string
    |  +--ro protocol?          identityref
    |  +--ro app?               string
    |  +--ro sub-attack-type?   identityref
    |  +--ro message?           string
    |  +--ro time-stamp?        yang:date-and-time
    |  +--ro vendor-name?       string
    |  +--ro nsf-name?          string
    |  +--ro module-name?       string
    |  +--ro severity?          severity
    +---n nsf-detection-botnet
    |  +--ro src-ip?        inet:ipv4-address
    |  +--ro dst-ip?        inet:ipv4-address
    |  +--ro src-port?      inet:port-number
    |  +--ro dst-port?      inet:port-number
    |  +--ro src-zone?      string
    |  +--ro dst-zone?      string
    |  +--ro rule-id        uint8
    |  +--ro rule-name      string
    |  +--ro profile?       string
    |  +--ro raw-info?      string
    |  +--ro attack-type?   identityref
    |  +--ro protocol?      identityref
    |  +--ro botnet-name?   string
    |  +--ro role?          string
    |  +--ro message?       string
    |  +--ro time-stamp?    yang:date-and-time
    |  +--ro vendor-name?   string
    |  +--ro nsf-name?      string
    |  +--ro module-name?   string
    |  +--ro severity?      severity
    +---n nsf-detection-web-attack
    |  +--ro src-ip?            inet:ipv4-address
    |  +--ro dst-ip?            inet:ipv4-address
    |  +--ro src-port?          inet:port-number
    |  +--ro dst-port?          inet:port-number
    |  +--ro src-zone?          string
    |  +--ro dst-zone?          string
    |  +--ro rule-id            uint8
    |  +--ro rule-name          string
    |  +--ro profile?           string
    |  +--ro raw-info?          string
    |  +--ro sub-attack-type?   identityref
    |  +--ro request-method?    identityref
    |  +--ro req-uri?           string
    |  +--ro uri-category?      string
    |  +--ro filtering-type*    identityref
    |  +--ro message?           string
    |  +--ro time-stamp?        yang:date-and-time
    |  +--ro vendor-name?       string
    |  +--ro nsf-name?          string
    |  +--ro module-name?       string
    |  +--ro severity?          severity
    +---n system-access-log
    |  +--ro login-ip              inet:ipv4-address
    |  +--ro administrator?        string
    |  +--ro login-mode?           login-mode
    |  +--ro operation-type?       operation-type
    |  +--ro result?               string
    |  +--ro content?              string
    |  +--ro acquisition-method?   identityref
    |  +--ro emission-type?        identityref
    |  +--ro dampening-type?       identityref
    +---n system-res-util-log
    |  +--ro system-status?        string
    |  +--ro cpu-usage?            uint8
    |  +--ro memory-usage?         uint8
    |  +--ro disk-usage?           uint8
    |  +--ro disk-left?            uint8
    |  +--ro session-num?          uint8
    |  +--ro process-num?          uint8
    |  +--ro in-traffic-rate?      uint32
    |  +--ro out-traffic-rate?     uint32
    |  +--ro in-traffic-speed?     uint32
    |  +--ro out-traffic-speed?    uint32
    |  +--ro acquisition-method?   identityref
    |  +--ro emission-type?        identityref
    |  +--ro dampening-type?       identityref
    +---n system-user-activity-log
    |  +--ro acquisition-method?   identityref
    |  +--ro emission-type?        identityref
    |  +--ro dampening-type?       identityref
    |  +--ro user                  string
    |  +--ro group                 string
    |  +--ro login-ip-addr         inet:ipv4-address
    |  +--ro authentication?       identityref
    |  +--ro access?               identityref
    |  +--ro online-duration?      string
    |  +--ro logout-duration?      string
    |  +--ro addtional-info?       string
    +---n nsf-log-ddos
    |  +--ro attack-type?          identityref
    |  +--ro attack-ave-rate?      uint32
    |  +--ro attack-ave-speed?     uint32
    |  +--ro attack-pkt-num?       uint32
    |  +--ro attack-src-ip?        inet:ipv4-address
    |  +--ro action?               log-action
    |  +--ro acquisition-method?   identityref
    |  +--ro emission-type?        identityref
    |  +--ro dampening-type?       identityref
    |  +--ro message?              string
    |  +--ro time-stamp?           yang:date-and-time
    |  +--ro vendor-name?          string
    |  +--ro nsf-name?             string
    |  +--ro module-name?          string
    |  +--ro severity?             severity
    +---n nsf-log-virus
    |  +--ro attack-type?          identityref
    |  +--ro action?               log-action
    |  +--ro os?                   string
    |  +--ro time                  yang:date-and-time
    |  +--ro acquisition-method?   identityref
    |  +--ro emission-type?        identityref
    |  +--ro dampening-type?       identityref
    |  +--ro message?              string
    |  +--ro time-stamp?           yang:date-and-time
    |  +--ro vendor-name?          string
    |  +--ro nsf-name?             string
    |  +--ro module-name?          string
    |  +--ro severity?             severity
    +---n nsf-log-intrusion
    |  +--ro attack-type?          identityref
    |  +--ro action?               log-action
    |  +--ro time                  yang:date-and-time
    |  +--ro attack-rate?          uint32
    |  +--ro attack-speed?         uint32
    |  +--ro acquisition-method?   identityref
    |  +--ro emission-type?        identityref
    |  +--ro dampening-type?       identityref
    |  +--ro message?              string
    |  +--ro time-stamp?           yang:date-and-time
    |  +--ro vendor-name?          string
    |  +--ro nsf-name?             string
    |  +--ro module-name?          string
    |  +--ro severity?             severity
    +---n nsf-log-botnet
    |  +--ro attack-type?          identityref
    |  +--ro action?               log-action
    |  +--ro botnet-pkt-num?       uint8
    |  +--ro os?                   string
    |  +--ro acquisition-method?   identityref
    |  +--ro emission-type?        identityref
    |  +--ro dampening-type?       identityref
    |  +--ro message?              string
    |  +--ro time-stamp?           yang:date-and-time
    |  +--ro vendor-name?          string
    |  +--ro nsf-name?             string
    |  +--ro module-name?          string
    |  +--ro severity?             severity
    +---n nsf-log-dpi
    |  +--ro attack-type?          dpi-type
    |  +--ro acquisition-method?   identityref
    |  +--ro emission-type?        identityref
    |  +--ro dampening-type?       identityref
    |  +--ro src-ip?               inet:ipv4-address
    |  +--ro dst-ip?               inet:ipv4-address
    |  +--ro src-port?             inet:port-number
    |  +--ro dst-port?             inet:port-number
    |  +--ro src-zone?             string
    |  +--ro dst-zone?             string
    |  +--ro src-region?           string
    |  +--ro dst-region?           string
    |  +--ro policy-id?            uint8
    |  +--ro policy-name?          string
    |  +--ro src-user?             string
    |  +--ro protocol?             identityref
    |  +--ro app?                  string
    |  +--ro message?              string
    |  +--ro time-stamp?           yang:date-and-time
    |  +--ro vendor-name?          string
    |  +--ro nsf-name?             string
    |  +--ro module-name?          string
    |  +--ro severity?             severity
    +---n nsf-log-vuln-scan
    |  +--ro vulnerability-id?     uint8
    |  +--ro victim-ip?            inet:ipv4-address
    |  +--ro protocol?             identityref
    |  +--ro port-num?             inet:port-number
    |  +--ro level?                severity
    |  +--ro os?                   string
    |  +--ro vulnerability-info?   string
    |  +--ro fix-suggestion?       string
    |  +--ro service?              string
    |  +--ro acquisition-method?   identityref
    |  +--ro emission-type?        identityref
    |  +--ro dampening-type?       identityref
    |  +--ro message?              string
    |  +--ro time-stamp?           yang:date-and-time
    |  +--ro vendor-name?          string
    |  +--ro nsf-name?             string
    |  +--ro module-name?          string
    |  +--ro severity?             severity
    +---n nsf-log-web-attack
       +--ro attack-type?          identityref
       +--ro rsp-code?             string
       +--ro req-clientapp?        string
       +--ro req-cookies?          string
       +--ro req-host?             string
       +--ro raw-info?             string
       +--ro acquisition-method?   identityref
       +--ro emission-type?        identityref
       +--ro dampening-type?       identityref
       +--ro message?              string
       +--ro time-stamp?           yang:date-and-time
       +--ro vendor-name?          string
       +--ro nsf-name?             string
       +--ro module-name?          string
       +--ro severity?             severity

Figure 1: Information Model for NSF Monitoring

10. YANG Data Model

This section introduces a YANG data model for the information model of the NSF monitoring inforamtion model.

<CODE BEGINS> file "ietf-i2nsf-monitor@2019-03-11.yang"
module ietf-i2nsf-monitor {
    yang-version 1.1;
    namespace
      "urn:ietf:params:xml:ns:yang:ietf-i2nsf-monitor";
    prefix
      iim;
    import ietf-inet-types{
      prefix inet;
      reference
        "Section 4 of RFC 6991";
    }
    import ietf-yang-types {
      prefix yang;
      reference
        "Section 3 of RFC 6991";
    }
    organization
      "IETF I2NSF (Interface to Network Security Functions)
       Working Group";
    contact
      "WG Web: <http://tools.ietf.org/wg/i2nsf>
       WG List: <mailto:i2nsf@ietf.org>

       WG Chair: Linda Dunbar
       <mailto:Linda.duhbar@huawei.com>

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

       Editor: Chaehong Chung
       <mailto:darkhong@skku.edu>";

    description
      "This module is a YANG module for monitoring NSFs.

      Copyright (c) 2018 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
      (http://trustee.ietf.org/license-info).

      This version of this YANG module is part of RFC 6087; see
      the RFC itself for full legal notices.";

    revision "2019-03-11" {
      description "First revision";
      reference
        "RFC XXXX: I2NSF NSF Monitoring YANG Data Model";
    }

    typedef severity {
      type enumeration {
        enum high {
          description
            "high-level";
        }
        enum middle {
          description
            "middle-level";
        }
        enum low {
          description
            "low-level";
        }
      }
      description
        "An indicator representing severity";
    }
    typedef log-action {
      type enumeration {
        enum allow {
          description
            "If action is allow";
        }
        enum alert {
          description
            "If action is alert";
        }
        enum block {
          description
            "If action is block";
        }
        enum discard {
          description
            "If action is discard";
        }
        enum declare {
          description
            "If action is declare";
        }
        enum block-ip {
          description
            "If action is block-ip";
        }
        enum block-service{
          description
            "If action is block-service";
        }
      }
      description
        "This is used for protocol";
    }
    typedef dpi-type{
      type enumeration {
        enum file-blocking{
          description
            "DPI for blocking file";
        }
        enum data-filtering{
          description
            "DPI for filtering data";
        }
        enum application-behavior-control{
          description
            "DPI for controlling application behavior";
        }
      }
      description
        "This is used for dpi type";
    }
    typedef operation-type{
      type enumeration {
        enum login{
          description
            "Login operation";
        }
        enum logout{
          description
            "Logout operation";
        }
        enum configuration{
          description
            "Configuration operation";
        }
      }
      description
        "An indicator representing operation-type";
    }
    typedef login-mode{
      type enumeration {
        enum root{
          description
            "Root login-mode";
        }
        enum user{
          description
            "User login-mode";
        }
        enum guest{
          description
            "Guest login-mode";
        }
      }
      description
        "An indicater representing login-mode";
    }

    identity characteristics {
      description
      "Base identity for monitoring information
      characteristics";
    }
    identity acquisition-method {
      base characteristics;
      description
      "The type of acquisition-method. Can be multiple 
      types at once.";
    }
    identity subscription {
      base acquisition-method;
      description
      "The acquisition-method type is subscription";
    }
    identity query {
      base acquisition-method;
      description
      "The acquisition-method type is query";
    }
    identity emission-type {
      base characteristics;
      description
      "The type of emission-type.";
    }
    identity periodical {
      base emission-type;
      description
      "The emission-type type is periodical.";
    }
    identity on-change {
      base emission-type;
      description
      "The emission-type type is on-change.";
    }
    identity dampening-type {
      base characteristics;
      description
      "The type of dampening-type.";
    }
    identity no-dampening {
      base dampening-type;
      description
      "The dampening-type is no-dampening.";
    }
    identity on-repetition {
      base dampening-type;
      description
      "The dampening-type is on-repetition.";
    }
    identity none {
      base dampening-type;
      description
      "The dampening-type is none.";
    }

    identity authentication-mode {
      description
        "User authentication mode types:
         e.g., Local Authentication,
         Third-Party Server Authentication,
         Authentication Exemption, or Single Sign-On (SSO)
         Authentication.";
    }
    identity local-authentication {
      base authentication-mode;
      description
        "Authentication-mode : local authentication.";
    }
    identity third-party-server-authentication {
      base authentication-mode;
      description
        "If authentication-mode is
        third-part-server-authentication";
    }
    identity exemption-authentication {
      base authentication-mode;
      description
      "If authentication-mode is
      exemption-authentication";
    }
    identity sso-authentication {
      base authentication-mode;
      description
      "If authentication-mode is
      sso-authentication";
    }

    identity alarm-type {
      description
        "Base identity for detectable alarm types";
    }
    identity MEM-USAGE-ALARM {
      base alarm-type;
      description
      "A memory alarm is alerted";
    }
    identity CPU-USAGE-ALARM {
      base alarm-type;
      description
      "A cpu alarm is alerted";
    }
    identity DISK-USAGE-ALARM {
      base alarm-type;
      description
      "A disk alarm is alerted";
    }
    identity HW-FAILURE-ALARM {
      base alarm-type;
      description
      "A hardware alarm is alerted";
    }
    identity IFNET-STATE-ALARM {
      base alarm-type;
      description
      "An interface alarm is alerted";
    }
    identity event-type {
      description
        "Base identity for detectable event types";
    }
    identity ACCESS-DENIED {
      base event-type;
      description
      "The system event is access-denied.";
    }
    identity CONFIG-CHANGE {
      base event-type;
      description
      "The system event is config-change.";
    }

    identity flood-type {
      description
        "Base identity for detectable flood types";
    }
    identity syn-flood {
      base flood-type;
      description
        "A SYN flood is detected";
    }
    identity ack-flood {
      base flood-type;
      description
        "An ACK flood is detected";
    }
    identity syn-ack-flood {
      base flood-type;
      description
        "An SYN-ACK flood is detected";
    }
    identity fin-rst-flood {
      base flood-type;
      description
        "A FIN-RST flood is detected";
    }
    identity tcp-con-flood {
      base flood-type;
      description
        "A TCP connection flood is detected";
    }
    identity udp-flood {
      base flood-type;
      description
        "A UDP flood is detected";
    }
    identity icmp-flood {
      base flood-type;
      description
        "An ICMP flood is detected";
    }
    identity https-flood {
      base flood-type;
      description
        "A HTTPS flood is detected";
    }
    identity http-flood {
      base flood-type;
      description
        "A HTTP flood is detected";
    }
    identity dns-reply-flood {
      base flood-type;
      description
        "A DNS reply flood is detected";
    }
    identity dns-query-flood {
      base flood-type;
      description
        "A DNS query flood is detected";
    }
    identity sip-flood {
      base flood-type;
      description
        "A SIP flood is detected";
    }

    identity nsf-event-name {
      description
      "Base identity for detectable nsf event types";
    }
    identity SEC-EVENT-DDOS {
      base nsf-event-name;
      description
      "The nsf event is sec-event-ddos.";
    }
    identity SESSION-USAGE-HIGH {
      base nsf-event-name;
      description
      "The nsf event is session-usage-high";
    }
    identity SEC-EVENT-VIRUS {
      base nsf-event-name;
      description
      "The nsf event is sec-event-virus";
    }
    identity SEC-EVENT-INTRUSION {
      base nsf-event-name;
      description
      "The nsf event is sec-event-intrusion";
    }
    identity SEC-EVENT-BOTNET {
      base nsf-event-name;
      description
      "The nsf event is sec-event-botnet";
    }
    identity SEC-EVENT-WEBATTACK {
      base nsf-event-name;
      description
      "The nsf event is sec-event-webattack";
    }
    identity attack-type {
      description
        "The root ID of attack based notification
        in the notification taxonomy";
    }
    identity system-attack-type {
      base attack-type;
      description
        "This ID is intended to be used
        in the context of system events";
    }
    identity nsf-attack-type {
      base attack-type;
      description
        "This ID is intended to be used
         in the context of nsf event";
    } 
    identity botnet-attack-type {
      base nsf-attack-type;
      description
        "This is a ID stub limited to indicating
        that this attack type is botnet. 
        The usual semantic and taxonomy is missing 
        and name is used.";
    }
    identity virus-type {
      base nsf-attack-type;
      description
        "The type of virus. Can be multiple types at once.
         This attack type is associated with a detected
         system-log virus-attack";
    }
    identity trojan {
      base virus-type;
      description
        "The detected virus type is trojan";
    }
    identity worm {
      base virus-type;
      description
        "The detected virus type is worm";
    }
    identity macro {
      base virus-type;
      description
        "The detected virus type is macro";
    }
    identity intrusion-attack-type {
      base nsf-attack-type;
      description
        "The attack type is associatied with
        a detectedsystem-log intrusion";
    }
    identity brute-force {
      base intrusion-attack-type; 
      description
        "The intrusion type is brute-force";
    }
    identity buffer-overflow {
      base intrusion-attack-type;
      description
        "The intrusion type is buffer-overflow";
    }
    identity web-attack-type {
      base nsf-attack-type;
      description
        "The attack type associated with
        a detected system-log web-attack";
    }
    identity command-injection {
      base web-attack-type;
      description
        "The detected web attack type is command injection";
    }
    identity xss {
      base web-attack-type;
      description
        "The detected web attack type is XSS";
    }
    identity csrf {
      base web-attack-type;
      description
        "The detected web attack type is CSRF";
    }
    identity ddos-attack-type {
      base nsf-attack-type;
      description
        "The attack type is associated with a detected
        nsf-log event";
    }

    identity req-method {
      description
        "A set of request types (if applicable).
         For instance, PUT or GET in HTTP";
    }
    identity put-req {
      base req-method;
      description
        "The detected request type is PUT";
    }
    identity get-req {
      base req-method;
      description
        "The detected request type is GET";
    }

    identity filter-type {
      description
        "The type of filter used to detect, for example,
         a web-attack. Can be applicable to more than
         web-attacks. Can be more than one type.";
    }
    identity whitelist {
      base filter-type;
      description
        "The applied filter type is whitelist";
    }
    identity blacklist {
      base filter-type;
      description
        "The applied filter type is blacklist";
    }
    identity user-defined {
      base filter-type;
      description
        "The applied filter type is user-defined";
    }
    identity balicious-category {
      base filter-type;
      description
        "The applied filter is balicious category";
    }
    identity unknown-filter {
      base filter-type;
      description
        "The applied filter is unknown";
    }

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

    identity protocol-type {
      description
        "An identity used to enable type choices in leafs
         and leaflists wrt protocol metadata.";
    }
    identity tcp {
      base ipv4;
      base ipv6;
      description
        "TCP protocol type.";
        reference
          "RFC 793: Transmission Control Protocol";
    }
    identity udp {
      base ipv4;
      base ipv6;
      description
      "UDP protocol type.";
      reference
        "RFC 768: User Datagram Protocol";
    }
    identity icmp {
      base ipv4;
      base ipv6;
      description
        "General ICMP protocol type.";
        reference
          "RFC 792: Internet Control Message Protocol";
    }
    identity icmpv4 {
      base ipv4;
      description
        "ICMPv4 protocol type.";
    }
    identity icmpv6 {
      base ipv6;
      description
        "ICMPv6 protocol type.";
    }
    identity ip {
      base protocol-type;
      description
        "General IP protocol type.";
        reference
          "RFC 791: Internet Protocol
          RFC 2460: Internet Protocol, Version 6 (IPv6)";
    }
    identity ipv4 {
      base ip;
      description
        "IPv4 protocol type.";
        reference
          "RFC 791: Internet Protocol";
    }
    identity ipv6 {
      base ip;
      description
        "IPv6 protocol type.";
        reference
          "RFC 2460: Internet Protocol, Version 6 (IPv6)";
    }
    identity http {
      base tcp;
      description
        "HTPP protocol type.";
        reference
          "RFC 2616: Hypertext Transfer Protocol";
    }
    identity ftp {
      base tcp;
      description
       "FTP protocol type.";
       reference
         "RFC 959: File Transfer Protocol";
    }
    grouping common-monitoring-data {
      description
      "The data set of common monitoring";
      leaf message {
        type string;
        description
          "This is a freetext annotation of
          monitoring notification content";
      }
      leaf time-stamp {
        type yang:date-and-time;
        description
          "Indicates the time of message generation";
      }
      leaf vendor-name {
        type string;
        description
          "The name of the NSF vendor";
      }
      leaf nsf-name {
        type string;
        description
          "The name (or IP) of the NSF
          generating the message";
      }
      leaf module-name {
        type string;
        description
          "The module name outputting the message";
      }
      leaf severity {
        type severity;
        description
          "The severity of the alarm such
          asvcritical, high, middle, low.";
      }
    }
    grouping characteristics{
      description
        "A set of monitoring information characteristics";
      leaf acquisition-method {
        type identityref {
          base acquisition-method;
        }
        description
          "The acquisition-method for characteristics";
      }
      leaf emission-type {
        type identityref {
          base emission-type;
        }
        description
          "The emission-type for characteristics";
      }
      leaf dampening-type {
        type identityref {
          base dampening-type;
        }
        description
          "The dampening-type for characteristics";
      }
    }
    grouping i2nsf-system-alarm-type-content {
      description
        "A set of system alarm type contents";
      leaf usage {
        type uint8;
        description
          "specifies the amount of usage";
      }
      leaf threshold {
        type uint8;
        description
          "The threshold triggering the alarm or the event";
      }
    }
    grouping i2nsf-system-event-type-content {
      description
        "System event metadata associated
         with system events caused by user activity.";
      leaf user {
        type string;
        mandatory true;
        description
          "Name of a user";
      }
      leaf group {
        type string;
        mandatory true;
        description
          "Group to which a user belongs.";
      }
      leaf login-ip-addr {
        type inet:ipv4-address;
        mandatory true;
        description
          "Login IP address of a user.";
      }
      leaf authentication {
        type identityref {
          base authentication-mode;
        }
        description
          "The authentication-mode for authentication";
      }
    }
    grouping i2nsf-nsf-event-type-content-extend {
      description
        "A set of common IPv4-related NSF event
        content elements";
      leaf src-ip {
        type inet:ipv4-address;
        description
          "The source IP address of the packet";
      }
      leaf dst-ip {
        type inet:ipv4-address;
        description
          "The destination IP address of the packet";
      }
      leaf src-port {
        type inet:port-number;
        description
          "The source port of the packet";
      }
      leaf dst-port {
        type inet:port-number;
        description
          "The destination port of the packet";
      }
      leaf src-zone {
        type string;
        description
          "The source security zone of the packet";
      }
      leaf dst-zone {
        type string;
        description
          "The destination security zone of the packet";
      }
      leaf rule-id {
        type uint8;
        mandatory true;
        description
          "The ID of the rule being triggered";
      }
      leaf rule-name {
        type string;
        mandatory true;
        description
          "The name of the rule being triggered";
      }
      leaf profile {
        type string;
        description
          "Security profile that traffic matches.";
      }
      leaf raw-info {
        type string;
        description
          "The information describing the packet 
          triggering the event.";
      }
    }
    grouping i2nsf-nsf-event-type-content {
      description
        "A set of common IPv4-related NSF event
        content elements";
      leaf dst-ip {
        type inet:ipv4-address;
        description
          "The destination IP address of the packet";
      }
      leaf dst-port {
        type inet:port-number;
        description
          "The destination port of the packet";
      }
      leaf rule-id {
        type uint8;
        mandatory true;
        description
          "The ID of the rule being triggered";
      }
      leaf rule-name {
        type string;
        mandatory true;
        description
          "The name of the rule being triggered";
      }
      leaf profile {
        type string;
        description
          "Security profile that traffic matches.";
      }
      leaf raw-info {
        type string;
        description
          "The information describing the packet 
          triggering the event.";
      }
    }
    grouping traffic-rates {
      description
        "A set of traffic rates
        for statistics data";
      leaf total-traffic {
        type uint32;
        description
          "Total traffic";
      }
      leaf in-traffic-ave-rate {
        type uint32;
        description
          "Inbound traffic average rate in pps";
      }
      leaf in-traffic-peak-rate {
        type uint32;
        description
          "Inbound traffic peak rate in pps";
      }
      leaf in-traffic-ave-speed {
        type uint32;
        description
          "Inbound traffic average speed in bps";
      }
      leaf in-traffic-peak-speed {
        type uint32;
        description
          "Inbound traffic peak speed in bps";
      }
      leaf out-traffic-ave-rate {
        type uint32;
        description
          "Outbound traffic average rate in pps";
      }
      leaf out-traffic-peak-rate {
        type uint32;
        description
          "Outbound traffic peak rate in pps";
      }
      leaf out-traffic-ave-speed {
        type uint32;
        description
          "Outbound traffic average speed in bps";
      }
      leaf out-traffic-peak-speed {
        type uint32;
        description
          "Outbound traffic peak speed in bps";
      }
    }
    grouping i2nsf-system-counter-type-content{
      description
        "A set of system counter type contents";
      leaf interface-name {
        type string;
        description
          "Network interface name configured in NSF";
      }
      leaf in-total-traffic-pkts {
        type uint32;
        description
          "Total inbound packets";
      }
      leaf out-total-traffic-pkts {
        type uint32;
        description
          "Total outbound packets";
      }
      leaf in-total-traffic-bytes {
        type uint32;
        description
          "Total inbound bytes";
      }
      leaf out-total-traffic-bytes {
        type uint32;
        description
          "Total outbound bytes";
      }
      leaf in-drop-traffic-pkts {
        type uint32;
        description
          "Total inbound drop packets";
      }
      leaf out-drop-traffic-pkts {
        type uint32;
        description
          "Total outbound drop packets";
      }
      leaf in-drop-traffic-bytes {
        type uint32;
        description
          "Total inbound drop bytes";
      }
      leaf out-drop-traffic-bytes {
        type uint32;
        description
          "Total outbound drop bytes";
      }
      uses traffic-rates;
    }
    grouping i2nsf-nsf-counters-type-content{
      description
        "A set of nsf counters type contents";
      leaf src-ip {
        type inet:ipv4-address;
        description
          "The source IP address of the packet";
      }
      leaf dst-ip {
        type inet:ipv4-address;
        description
          "The destination IP address of the packet";
      }
      leaf src-port {
        type inet:port-number;
        description
          "The source port of the packet";
      }
      leaf dst-port {
        type inet:port-number;
        description
          "The destination port of the packet";
      }
      leaf src-zone {
        type string;
        description
          "The source security zone of the packet";
      }
      leaf dst-zone {
        type string;
        description
          "The destination security zone of the packet";
      }
      leaf src-region {
        type string;
        description
          "Source region of the traffic";
      }
      leaf dst-region{
        type string;
        description
          "Destination region of the traffic";
      }
      leaf policy-id {
        type uint8;
        description
          "The ID of the policy being triggered";
      }
      leaf policy-name {
        type string;
        description
          "The name of the policy being triggered";
      }
      leaf src-user{
        type string;
        description
          "User who generates traffic";
      }
      leaf protocol {
        type identityref {
          base protocol-type;
        }
        description
          "Protocol type of traffic";
      }
      leaf app {
        type string;
        description
          "Application type of traffic";
      }
    }

    notification system-detection-alarm {
      description
        "This notification is sent, when a system alarm
        is detected.";
      leaf alarm-catagory {
        type identityref {
          base alarm-type;
        }
        description
          "The alarm catagory for
          system-detection-alarm notification";
      }
      uses characteristics;
      uses i2nsf-system-alarm-type-content;
      uses common-monitoring-data;
    }
    notification system-detection-event {
      description
        "This notification is sent, when a security-sensitive
         authentication action fails.";
      leaf event-catagory {
        type identityref {
          base event-type;
        }
        description
          "The event catagory for system-detection-event";
      }
      uses characteristics;
      uses i2nsf-system-event-type-content;
      uses common-monitoring-data;
    }
    notification nsf-detection-flood {
      description
        "This notification is sent,
        when a specific flood type is detected";
      leaf event-name {
        type identityref {
         base SEC-EVENT-DDOS;
        }
        description
        "The event name for nsf-detection-flood";
      }
      uses i2nsf-nsf-event-type-content;
      leaf sub-attack-type {
        type identityref {
          base flood-type;
        }
        description
          "Any one of Syn flood, ACK flood, SYN-ACK flood,
           FIN/RST flood, TCP Connection flood, UDP flood,
           Icmp flood, HTTPS flood, HTTP flood, DNS query flood,
           DNS reply flood, SIP flood, and etc.";
      }
      leaf start-time {
        type yang:date-and-time;
        mandatory true;
        description
          "The time stamp indicating when the attack started";
      }
      leaf end-time {
        type yang:date-and-time;
        mandatory true;
        description
          "The time stamp indicating when the attack ended";
      }
      leaf attack-rate {
        type uint32;
        description
          "The PPS rate of attack traffic";
      }
      leaf attack-speed {
        type uint32;
        description
          "The BPS speed of attack traffic";
      }
      uses common-monitoring-data;
    }
    notification nsf-detection-session-table {
      description
        "This notification is sent, when an a session table 
        event is deteced";
      leaf current-session {
        type uint8;
        description
          "The number of concurrent sessions";
      }
      leaf maximum-session {
        type uint8;
        description
          "The maximum number of sessions that the session
           table can support";
      }
      leaf threshold {
        type uint8;
        description
          "The threshold triggering the event";
      }
      uses common-monitoring-data;
    }
    notification nsf-detection-virus {
      description
        "This notification is sent, when a virus is detected";
      uses i2nsf-nsf-event-type-content-extend;
      leaf virus {
        type identityref {
          base virus-type;
        }
        description
          "The virus type for nsf-detection-virus notification";
      }
      leaf virus-name {
        type string;
        description
        "The name of the detected virus";
      }

      leaf file-type {
        type string;
        description
          "The type of file virus code 
          is found in (if appicable).";
      }
      leaf file-name {
        type string;
        description
           "The name of file virus code 
           is found in (if appicable).";
      }
      uses common-monitoring-data;
    }
    notification nsf-detection-intrusion {
      description
        "This notification is send, when an intrusion event
         is detected.";
      uses i2nsf-nsf-event-type-content-extend;
      leaf protocol {
        type identityref {
          base protocol-type;
        }
        description
          "The protocol type for 
          nsf-detection-intrusion notification";
      }
      leaf app {
        type string;
        description
          "The employed application layer protocol";
      }
      leaf sub-attack-type {
        type identityref {
          base intrusion-attack-type;
        }
        description
          "The sub attack type for intrusion attack";
      }
      uses common-monitoring-data;
    }
    notification nsf-detection-botnet {
      description
        "This notification is send, when a botnet event is
         detected";
      uses i2nsf-nsf-event-type-content-extend;
      leaf attack-type {
        type identityref {
          base botnet-attack-type;
        }
        description
          "The attack type for botnet attack";
      }
      leaf protocol {
        type identityref {
          base protocol-type;
        }
        description
          "The protocol type for nsf-detection-botnet notification";
      }
      leaf botnet-name {
        type string;
        description
          "The name of the detected botnet";
      }
      leaf role {
        type string;
        description
          "The role of the communicating
           parties within the botnet";
      }
      uses common-monitoring-data;
    }
    notification nsf-detection-web-attack {
      description
        "This notification is send, when an attack event is
         detected";
      uses i2nsf-nsf-event-type-content-extend;
      leaf sub-attack-type {
        type identityref {
          base web-attack-type;
        }
        description
          "Concret web attack type, e.g., sql injection,
           command injection, XSS, CSRF";
      }
      leaf request-method {
        type identityref {
          base req-method;
        }
        description
          "The method of requirement. For instance, PUT or
          GET in HTTP";
      }
      leaf req-uri {
        type string;
        description
        "Requested URI";
      }
      leaf uri-category {
        type string;
        description
        "Matched URI category";
      }
      leaf-list filtering-type {
        type identityref {
          base filter-type;
        }
        description
          "URL filtering type, e.g., Blacklist, Whitelist,
           User-Defined, Predefined, Malicious Category,
           Unknown";
      }
      uses common-monitoring-data;
    }
    notification system-access-log {
      description
        "The notification is send, if there is
        a new system log entry about
         a system access event";
      leaf login-ip {
        type inet:ipv4-address;
        mandatory true;
        description
          "Login IP address of a user";
      }
      leaf administrator {
        type string;
        description
          "Administrator that maintains the device";
      }
      leaf login-mode {
        type login-mode;
        description
          "Specifies the administrator log-in mode";
      }
      leaf operation-type {
        type operation-type;
        description
          "The operation type that the administrator execute";
      }
      leaf result {
        type string;
        description
          "Command execution result";
      }
      leaf content {
        type string;
        description
          "The Operation performed by an administrator 
          after login";
      }
      uses characteristics;
    }
    notification system-res-util-log {
      description
        "This notification is send, if there is
        a new log entry representing ressource
         utiliztation updates.";
      leaf system-status {
         type string;
         description
           "The current systems
           running status";
      }
      leaf cpu-usage {
        type uint8;
        description
          "Specifies the relative amount of
          cpu usage wrt plattform ressources";
      }
      leaf memory-usage {
         type uint8;
         description
           "Specifies the amount of memory usage";
      }
      leaf disk-usage {
        type uint8;
        description
          "Specifies the amount of disk usage";
      }
      leaf disk-left {
         type uint8;
         description
           "Specifies the amount of disk left";
      }
      leaf session-num {
        type uint8;
        description
          "The total number of sessions";
      }
      leaf process-num {
        type uint8;
        description
          "The total number of process";
      }
      leaf in-traffic-rate {
        type uint32;
        description
          "The total inbound traffic rate in pps";
      }
      leaf out-traffic-rate {
        type uint32;
        description
           "The total outbount traffic rate in pps";
      }
      leaf in-traffic-speed {
        type uint32;
        description
          "The total inbound traffic speed in bps";
      }
      leaf out-traffic-speed {
        type uint32;
        description
          "The total outbound traffic speed in bps";
      }
      uses characteristics;
    }
    notification system-user-activity-log {
      description
        "This notification is send, if there is
        a new user activity log entry";
      uses characteristics;
      uses i2nsf-system-event-type-content;
      leaf access {
        type identityref {
          base access-mode;
        }
        description
          "The access type for 
          system-user-activity-log notification";
      }
      leaf online-duration {
        type string;
        description
          "Online duration";
      }
      leaf logout-duration {
        type string;
        description
          "Lockout duration";
      }
      leaf addtional-info {
        type string;
        description
          "User activities. e.g., Successful 
          User Login, Failed Login attempts, 
          User Logout, Successful User 
          Password Change, Failed User 
          Password Change, User Lockout, 
          User Unlocking, Unknown";
      }
    }
    notification nsf-log-ddos {
      description
        "This notification is send, if there is
        a new DDoS event log entry in the nsf log";
      leaf attack-type {
        type identityref {
          base ddos-attack-type;
        }
        description
          "The ddos attack type for
          nsf-log-ddos notification";
      }
      leaf attack-ave-rate {
        type uint32;
        description
          "The ave PPS of attack traffic";
      }
      leaf attack-ave-speed {
        type uint32;
        description
          "the ave bps of attack traffic";
      }
      leaf attack-pkt-num {
        type uint32;
        description
          "the number of attack packets";
      }
      leaf attack-src-ip {
        type inet:ipv4-address;
        description
          "The source IP addresses of attack
           traffics. If there are a large
           amount of IP addresses, then
           pick a certain number of resources
           according to different rules.";
      }
      leaf action {
        type log-action;
        description
          "Action type: allow, alert, 
          block, discard, declare, 
          block-ip, block-service";
      }
      uses characteristics;
      uses common-monitoring-data;
    }
    notification nsf-log-virus {
      description
        "This notification is send, If there is
        a new virus event log enry in the nsf log";
      leaf attack-type {
        type identityref {
          base virus-type;
        }
        description
          "The virus type for nsf-log-virus notification";
      }
      leaf action {
        type log-action;
        description
          "Action type: allow, alert, 
          block, discard, declare, 
          block-ip, block-service";
      }
      leaf os{
        type string;
        description
          "simple os information";
      }
      leaf time {
        type yang:date-and-time;
        mandatory true;
        description
          "Indicate the time when the message 
          is generated";
      }
      uses characteristics;
      uses common-monitoring-data;
    }
    notification nsf-log-intrusion {
      description
        "This notification is send, if there is
        a new intrusion event log entry in the nsf log";
      leaf attack-type {
        type identityref {
          base intrusion-attack-type;
        }
        description
          "The intrusion attack type for
          nsf-log-intrusion notification";
      }
      leaf action {
        type log-action;
        description
          "Action type: allow, alert, 
          block, discard, declare, 
          block-ip, block-service";
      }
      leaf time {
        type yang:date-and-time;
        mandatory true;
        description
          "Indicate the time when the message 
          is generated";
      }
      leaf attack-rate {
        type uint32;
        description
          "The PPS of attack traffic";
      }
      leaf attack-speed {
        type uint32;
        description
          "The bps of attack traffic";
      }
      uses characteristics;
      uses common-monitoring-data;
    }
    notification nsf-log-botnet {
      description
        "This noticiation is send, if there is
        a new botnet event log in the nsf log";
      leaf attack-type {
        type identityref {
          base botnet-attack-type;
        }
        description
          "The botnet attack type for
          nsf-log-botnet notification";
      }
      leaf action {
        type log-action;
        description
          "Action type: allow, alert, 
          block, discard, declare, 
          block-ip, block-service";
      }
      leaf botnet-pkt-num{
        type uint8;
        description
          "The number of the packets sent to
          or from the detected botnet";
      }
      leaf os{
        type string;
        description
          "simple os information";
      }
      uses characteristics;
      uses common-monitoring-data;
    }
    notification nsf-log-dpi {
      description
        "This notification is send, if there is
        a new dpi event in the nsf log";
      leaf attack-type {
        type dpi-type;
        description
          "The type of the dpi";
      }
      uses characteristics;
      uses i2nsf-nsf-counters-type-content;
      uses common-monitoring-data;
    }
    notification nsf-log-vuln-scan {
      description
        "This notification is send, if there is
        a new vulnerability-scan report in the nsf log";
      leaf vulnerability-id {
        type uint8;
        description
          "The vulnerability id";
      }
      leaf victim-ip {
        type inet:ipv4-address;
        description
          "IP address of the victim host
          which has vulnerabilities";
      }
      leaf protocol {
        type identityref {
          base protocol-type;
        }
        description
          "The protocol type for
          nsf-log-vuln-scan notification";
      }
      leaf port-num {
        type inet:port-number;
          description
            "The port number";
      }
      leaf level {
        type severity;
        description
          "The vulnerability severity";
      }
      leaf os {
        type string;
        description
          "simple os information";
      }
      leaf vulnerability-info {
        type string;
        description
          "The information about the vulnerability";
      }
      leaf fix-suggestion {
        type string;
        description
          "The fix suggestion to the vulnerability";
      }
      leaf service {
        type string;
        description
          "The service which has vulnerabillity in the victim host";
      }
      uses characteristics;
      uses common-monitoring-data;
    }
    notification nsf-log-web-attack {
      description
        "This notificatio is send, if there is
        a new web-attack event in the nsf log";
      leaf attack-type {
        type identityref {
          base web-attack-type;
        }
        description
          "The web attack type for
          nsf-log-web-attack notification";
      }
      leaf rsp-code {
        type string;
        description
          "Response code";
      }
      leaf req-clientapp {
        type string;
        description
          "The client application";
      }
      leaf req-cookies {
        type string;
        description
          "Cookies";
      }
      leaf req-host {
        type string;
        description
          "The domain name of the requested host";
      }
      leaf raw-info {
        type string;
        description
          "The information describing
          the packet triggering the event.";
      }
      uses characteristics;
      uses common-monitoring-data;
    }
    container counters {
      description
        "This is probably better covered by an import
        as this will not be notifications.
        Counter are not very suitable as telemetry, maybe
        via periodic subscriptions, which would still
        violate principle of least surprise.";
      container system-interface {
        description
          "The system counter type is interface counter";
        uses characteristics;  
        uses i2nsf-system-counter-type-content;
        uses common-monitoring-data;
      }
      container nsf-firewall {
        description
          "The nsf counter type is firewall counter";
        uses characteristics;  
        uses i2nsf-nsf-counters-type-content;
        uses traffic-rates;
      }
      container nsf-policy-hits {
        description
          "The counters of policy hit";
        uses characteristics;
        uses i2nsf-nsf-counters-type-content;
        uses common-monitoring-data;
        leaf hit-times {
          type uint32;
          description
            "The hit times for policy";
        }
      }
    }
  }
<CODE ENDS>
            

Figure 2: Data Model of Monitoring

11. IANA Considerations

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

  
   name: ietf-i2nsf-monitor
           namespace: urn:ietf:params:xml:ns:yang:ietf-i2nsf-monitor
           prefix: iim
           reference: RFC XXXX
  

This document requests IANA to register the following URI in the "IETF XML Registry" [RFC3688]: [RFC7950].

12. Security Considerations

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

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

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

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

13. References

13.1. Normative References

[I-D.ietf-netconf-subscribed-notifications] Voit, E., Clemm, A., Prieto, A., Nilsen-Nygaard, E. and A. Tripathy, "Subscription to YANG Event Notifications", Internet-Draft draft-ietf-netconf-subscribed-notifications-23, February 2019.
[I-D.ietf-netconf-yang-push] Clemm, A., Voit, E., Prieto, A., Tripathy, A., Nilsen-Nygaard, E., Bierman, A. and B. Lengyel, "Subscription to YANG Datastores", Internet-Draft draft-ietf-netconf-yang-push-22, February 2019.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, January 2004.
[RFC3877] Chisholm, S. and D. Romascanu, "Alarm Management Information Base (MIB)", RFC 3877, DOI 10.17487/RFC3877, September 2004.
[RFC4949] Shirey, R., "Internet Security Glossary, Version 2", FYI 36, RFC 4949, DOI 10.17487/RFC4949, August 2007.
[RFC5424] Gerhards, R., "The Syslog Protocol", RFC 5424, DOI 10.17487/RFC5424, March 2009.
[RFC6241] Enns, R., Bjorklund, M., Schoenwaelder, J. and A. Bierman, "Network Configuration Protocol (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011.
[RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011.
[RFC6587] Gerhards, R. and C. Lonvick, "Transmission of Syslog Messages over TCP", RFC 6587, DOI 10.17487/RFC6587, April 2012.
[RFC6991] Schoenwaelder, J., "Common YANG Data Types", RFC 6991, DOI 10.17487/RFC6991, July 2013.
[RFC7011] Claise, B., Trammell, B. and P. Aitken, "Specification of the IP Flow Information Export (IPFIX) Protocol for the Exchange of Flow Information", STD 77, RFC 7011, DOI 10.17487/RFC7011, September 2013.
[RFC7950] Bjorklund, M., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, August 2016.
[RFC8040] Bierman, A., Bjorklund, M. and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017.
[RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration Access Control Model", STD 91, RFC 8341, DOI 10.17487/RFC8341, March 2018.
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018.

13.2. Informative References

[I-D.ietf-i2nsf-capability] Xia, L., Strassner, J., Basile, C. and D. Lopez, "Information Model of NSFs Capabilities", Internet-Draft draft-ietf-i2nsf-capability-03, October 2018.
[I-D.ietf-i2nsf-consumer-facing-interface-dm] Jeong, J., Kim, E., Ahn, T., Kumar, R. and S. Hares, "I2NSF Consumer-Facing Interface YANG Data Model", Internet-Draft draft-ietf-i2nsf-consumer-facing-interface-dm-03, March 2019.
[I-D.ietf-i2nsf-nsf-facing-interface-dm] Kim, J., Jeong, J., J., J., PARK, P., Hares, S. and Q. Lin, "I2NSF Network Security Function-Facing Interface YANG Data Model", Internet-Draft draft-ietf-i2nsf-nsf-facing-interface-dm-03, March 2019.
[I-D.ietf-i2nsf-registration-interface-dm] Hyun, S., Jeong, J., Roh, T., Wi, S., J., J. and P. PARK, "I2NSF Registration Interface YANG Data Model", Internet-Draft draft-ietf-i2nsf-registration-interface-dm-02, March 2019.
[I-D.ietf-i2nsf-terminology] Hares, S., Strassner, J., Lopez, D., Xia, L. and H. Birkholz, "Interface to Network Security Functions (I2NSF) Terminology", Internet-Draft draft-ietf-i2nsf-terminology-07, January 2019.
[I-D.yang-i2nsf-nfv-architecture] Yang, H., Kim, Y., Jeong, J. and J. Kim, "I2NSF on the NFV Reference Architecture", Internet-Draft draft-yang-i2nsf-nfv-architecture-04, November 2018.
[I-D.yang-i2nsf-security-policy-translation] Yang, J., Jeong, J. and J. Kim, "Security Policy Translation in Interface to Network Security Functions", Internet-Draft draft-yang-i2nsf-security-policy-translation-03, March 2019.
[RFC3954] Claise, B., "Cisco Systems NetFlow Services Export Version 9", RFC 3954, DOI 10.17487/RFC3954, October 2004.
[RFC6087] Bierman, A., "Guidelines for Authors and Reviewers of YANG Data Model Documents", RFC 6087, DOI 10.17487/RFC6087, January 2011.
[RFC8329] Lopez, D., Lopez, E., Dunbar, L., Strassner, J. and R. Kumar, "Framework for Interface to Network Security Functions", RFC 8329, DOI 10.17487/RFC8329, February 2018.
[RFC8340] Bjorklund, M. and L. Berger, "YANG Tree Diagrams", BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018.

Appendix A. Changes from draft-hong-i2nsf-nsf-monitoring-data-model-06

The following changes are made from draft-hong-i2nsf-nsf-monitoring-data-model-06:

Appendix B. Acknowledgments

This work was supported by Institute for Information & communications Technology Promotion (IITP) grant funded by the Korea government (MSIP) (R-20160222-002755, Cloud based Security Intelligence Technology Development for the Customized Security Service Provisioning).

Appendix C. Contributors

This document is made by the group effort of I2NSF working group. Many people actively contributed to this document. The following are considered co-authors:

Authors' Addresses

Jaehoon Paul Jeong Department of Software Sungkyunkwan University 2066 Seobu-Ro, Jangan-Gu Suwon, Gyeonggi-Do 16419 Republic of Korea Phone: +82 31 299 4957 Fax: +82 31 290 7996 EMail: pauljeong@skku.edu URI: http://iotlab.skku.edu/people-jaehoon-jeong.php
Chaehong Chung Department of Computer Engineering Sungkyunkwan University 2066 Seobu-Ro, Jangan-Gu Suwon, Gyeonggi-Do 16419 Republic of Korea Phone: +82 10 8541 7158 EMail: darkhong@skku.edu
Susan Hares Huawei 7453 Hickory Hill Saline, MI 48176 USA Phone: +1-734-604-0332 EMail: shares@ndzh.com
Liang Xia (Frank) Huawei 101 Software Avenue, Yuhuatai District Nanjing, Jiangsu China EMail: Frank.xialiang@huawei.com
Henk Birkholz Fraunhofer Institute for Secure Information Technology Rheinstrasse 75 Darmstadt, 64295 Germany EMail: henk.birkholz@sit.fraunhofer.de