Internet-Draft | NSF Monitoring Interface YANG Data Model | April 2022 |
Jeong, et al. | Expires 21 October 2022 | [Page] |
- Workgroup:
- Network Working Group
- Internet-Draft:
- draft-ietf-i2nsf-nsf-monitoring-data-model-18
- Published:
- Intended Status:
- Standards Track
- Expires:
I2NSF NSF Monitoring Interface YANG Data Model
Abstract
This document proposes an information model and the corresponding YANG data model of an interface for monitoring Network Security Functions (NSFs) in the Interface to Network Security Functions (I2NSF) framework. If the monitoring of NSFs is performed with the NSF monitoring interface in a standard way, it is possible to detect the indication of malicious activity, anomalous behavior, the potential sign of denial-of-service attacks, or system overload in a timely manner. This monitoring functionality is based on the monitoring information that is generated by NSFs. Thus, this document describes not only an information model for the NSF monitoring interface along with a YANG tree diagram, but also the corresponding YANG data model.¶
Status of This Memo
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This Internet-Draft will expire on 21 October 2022.¶
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Copyright (c) 2022 IETF Trust and the persons identified as the document authors. All rights reserved.¶
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1. Introduction
According to [RFC8329], the interface provided by a Network Security Function (NSF) (e.g., Firewall, IPS, or Anti-DDoS function) to enable the collection of monitoring information is referred to as an I2NSF Monitoring Interface. This interface enables the sharing of vital data from the NSFs (e.g., events, records, and counters) to an NSF data collector (e.g., Security Controller) through a variety of mechanisms (e.g., queries and notifications). The monitoring of NSF plays an important role in an overall security framework, if it is done in a timely 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 (DoS) attacks.¶
This document defines an information model of an NSF monitoring interface that provides visibility into an NSF for the NSF data collector (note that an NSF data collector is defined as an entity to collect NSF monitoring data from an NSF, such as 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 Monitoring Interface. The information model for the NSF monitoring interface presented in this document is complementary for the security policy provisioning functionality of the NSF-Facing Interface specified in [I-D.ietf-i2nsf-nsf-facing-interface-dm].¶
This document also defines a YANG [RFC7950] data model for the NSF monitoring interface, which is derived from the information model for the NSF monitoring interface.¶
Note that this document covers a subset of monitoring data for systems and NSFs, which are related to security.¶
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]. In addition, the following terms are defined in this document:¶
- I2NSF User: An entity that delivers a high-level security policy to the Security Controller and may request monitoring information via the NSF data collector.¶
- Monitoring Information: Relevant data that can be processed to know the status and performance of the network and the NSF. The monitoring information in an I2NSF environment consists of I2NSF Events, I2NSF Records, and I2NSF Counters (see Section 4.1 for the detailed definition). This information is to be delivered to the NSF data collector.¶
- Notification: Unsolicited transmission of monitoring information.¶
- NSF Data Collector: An entity that collects NSF monitoring information from NSFs, such as Security Controller.¶
- Subscription: An agreement initialized by the NSF data collector to receive monitoring information from an NSF. The method to subscribe follows the method by either NETCONF or RESTCONF, explained in [RFC5277] and [RFC8650], respectively.¶
This document follows the guidelines of [RFC8407], uses the common YANG types defined in [RFC6991], and adopts the Network Management Datastore Architecture (NMDA) [RFC8342]. The meaning of the symbols in tree diagrams is defined in [RFC8340].¶
3. Use Cases for NSF Monitoring Data
As mentioned earlier, monitoring plays a critical role in an overall security framework. The monitoring of the NSF provides very valuable information to an NSF data collector (e.g., Security Controller) in maintaining the provisioned security posture. Besides this, there are various other reasons to monitor the NSF as listed below:¶
- The I2NSF User that is the security administrator can configure a policy that is triggered on a specific event occurring in the NSF or the network [RFC8329] [I-D.ietf-i2nsf-consumer-facing-interface-dm]. If an NSF data collector (e.g., Security Controller) detects the specified event, it can configure additional security functions as defined by policies.¶
- The events triggered by an NSF as a result of security policy violation can be used by Security Information and Event Management (SIEM) to detect any suspicious activity in a larger correlation context.¶
- The information (i.e., events, records, and counters) from an NSF can be used to build advanced analytics, such as behavior and predictive models to improve security posture in large deployments.¶
- The NSF data collector can use events from the NSF for achieving high availability. It can take corrective actions such as restarting a failed NSF and horizontally scaling up the NSF.¶
- The information (i.e., events, records, and counters) from the NSF can aid in the root cause analysis of an operational issue, so it can improve debugging.¶
- The records from the NSF can be used to build historical data for operation and business reasons.¶
4. Classification of NSF Monitoring Data
In order to maintain a strong security posture, it is not only necessary to configure an NSF's security policies but also to continuously monitor the NSF by checking acquirable and observable data. This enables security administrators to assess the state of the networks 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 monitoring elements and their scopes that can be acquired from an NSF and can be used as NSF monitoring data. In essence, this monitoring data can be leveraged to support constant visibility on multiple levels of granularity and can be consumed by the corresponding functions.¶
Three basic domains of monitoring data originating from a system entity [RFC4949], i.e., an NSF, are discussed in this document.¶
- Retention and Emission from NSFs¶
- Notifications for Events and Records¶
- Push and Pull for the retrieval of monitoring data from NSFs¶
Every system entity creates information about some context with defined I2NSF monitoring data, and so every system entity that provides such information can be an I2NSF component. This information is intended to be consumed by other I2NSF components, which deals with NSF monitoring data in an automated fashion.¶
4.1. Retention and Emission from NSFs
A system entity (e.g., NSF) first retains I2NSF monitoring data inside its own system before emitting the information to another I2NSF component (e.g., NSF Data Collector). The I2NSF monitoring information consist of I2NSF Events, I2NSF Records, and I2NSF Counters as follows:¶
- I2NSF Event:
- I2NSF Event is defined as an important occurrence at a particular time, that is, a change in the system being managed or a change in the environment of the system being managed. An I2NSF Event requires immediate attention and should be notified as soon as possible. When used in the context of an (imperative) I2NSF Policy Rule, an I2NSF Event is used to determine whether the Condition clause of that Policy Rule can be evaluated or not. The Alarm Management Framework in [RFC3877] defines an event as something that happens which may be of interest. Examples of an event are a fault, a change in status, crossing a threshold, or an external input to the system. In the I2NSF domain, I2NSF events are created following the definition of an event in the Alarm Management Framework.¶
- I2NSF Record:
- A record is defined as an item of information that is kept to be looked at and used in the future. Typically, records are the information, which is based on operational and informational data (i.e., various changes in system characteristics). They are generated by a system entity (e.g., NSF) at particular instants to be kept without any changes afterward. A set of records has an ordering in time based on when they are generated. Unlike I2NSF Events, records do not require immediate attention but may be useful for visibility and retroactive cyber forensics. Records are typically stored in log-files or databases on a system entity or NSF. The examples of records include user activities, device performance, and network status. They are important for debugging, auditing, and security forensic of a system entity or the network having the system entity.¶
- I2NSF Counter:
- An I2NSF Counter is defined as a specific representation of an information element whose value changes very frequently. Prominent examples are network interface counters for protocol data unit (PDU) amount, byte amount, drop counters, and error counters. Counters are useful in debugging and visibility into operational behavior of a system entity (e.g., NSF). When an NSF data collector asks for the value of a counter, a system entity MUST update the counter information and emit the latest information to the NSF data collector.¶
Retention is defined as the storing of monitoring data in NSFs. The retention of I2NSF monitoring information may be affected by the importance of the data. The importance of the data could be context-dependent, where it may not just be based on the type of data, but may also depend on where it is deployed, e.g., a test lab and testbed. The local policy and configuration will dictate the policies and procedures to review, archive, or purge the collected monitoring data.¶
Emission is defined as the delivery of monitoring data in NSFs to an NSF data collector. The I2NSF monitoring information retained on a system entity (e.g., NSF) may be delivered to a corresponding I2NSF User via an NSF data collector. The information consists of the aggregated records, typically in the form of log-files or databases. For the NSF Monitoring Interface to deliver the information to the NSF data collector, the NSF needs to accommodate standardized delivery protocols, such as NETCONF [RFC6241] and RESTCONF [RFC8040]. The NSF data collector can forward the information to the I2NSF User through standardized delivery protocols (e.g., RESTCONF and NETCONF). The interface for the delivery of Monitoring Data from the NSF data collector to the I2NSF User is out of the scope of this document.¶
4.2. Notifications for Events and Records
A specific task of an I2NSF User is to provide I2NSF Policy Rules. The rules of a policy are composed of three clauses: Event, Condition, and Action clauses. In consequence, an I2NSF Event is specified to trigger the evaluation of the Condition clause of the I2NSF Policy Rule. Such an I2NSF Event is defined as an important occurrence at a particular time in the system being managed, and/or in the environment of the system being managed whose concept aligns well with the generic definition of Event from [RFC3877].¶
Another role of the I2NSF Event is to trigger a notification for monitoring the status of an NSF. A notification is defined in [RFC3877] as an unsolicited transmission of management information. System alarm (called alarm) is defined as a warning related to service degradation in system hardware in Section 6.1. System event (called alert) is defined as a warning about any changes of configuration, any access violation, information about sessions and traffic flows in Section 6.2. Both an alarm and an alert are I2NSF Events that can be delivered as a notification. The model illustrated in this document introduces a complementary type of information that can be a conveyed notification.¶
In I2NSF monitoring, a notification is used to deliver either an event or a record via the I2NSF Monitoring Interface. The difference between the event and record is the timing by which the notifications are emitted. An event is emitted as soon as it happens in order to notify an NSF Data Collector of the problem that needs immediate attention. A record is not emitted immediately to the NSF Data Collector, and it can be emitted periodically to the NSF Data Collector.¶
It is important to note that an NSF Data Collector as a consumer (i.e., observer) of a notification assesses the importance of the notification rather than an NSF as a producer. The producer can include metadata in a notification that supports the observer in assessing its importance (e.g., severity).¶
4.3. Push and Pull for the retrieval of monitoring data from NSFs
An important aspect of monitoring information is the freshness of the information. From the perspective of security, it is important to notice changes in the current status of the network. The I2NSF Monitoring Interface provides the means of sending monitored information from the NSFs to an NSF data collector in a timely manner. Monitoring information can be acquired by a client (i.e., NSF data collector) from a server (i.e., NSF) using push [RFC5277] [RFC8641] or pull methods [RFC6241] [RFC8040].¶
The pull is a query-based method to obtain information from the NSF. In this method, the NSF will remain passive until the information is requested from the NSF data collector. Once a request is accepted (with proper authentication), the NSF MUST update the information before sending it to the NSF data collector.¶
The push is a report-based method to obtain information from the NSF. The report-based method ensures the information can be delivered immediately without any requests. This method is used by the NSF to actively provide information to the NSF data collector. To receive the information, the NSF data collector subscribes to the NSF for the information.¶
These acquisition methods are used for different types of monitoring information. The information that has a high level of urgency (i.e., I2NSF Event) should be provided with the push method, while information that has a lower level of urgency (i.e., I2NSF Record and I2NSF Counter) can be provided with either the pull method or push method.¶
5. Basic Information Model for Monitoring Data
As explained in the above section, there is a wealth of data available from NSFs 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 metadata with that message, which are listed as below:¶
- message: The extra detailed description of NSF monitoring data to give an NSF data collector the context information as metadata.¶
- vendor-name: The vendor's name of the NSF that generates the message.¶
- device-model: The model of the device, can be represented by the device model name or serial number. This field is used to identify the model of the device that provides the security service.¶
- software-version: The version of the software used to provide the security service.¶
- nsf-name: The name or IP address of the NSF generating the message. If the given nsf-name is not an IP address, the name can be an arbitrary string including a FQDN (Fully Qualified Domain Name). The name MUST be unique in the scope of management domain for a different NSF to identify the NSF that generates the message.¶
- timestamp: The time when the message was generated. For the notification operations (i.e., System Alarms, System Events, NSF Events, System Logs, and NSF Logs), this is represented by the eventTime of NETCONF event notification [RFC5277] For other operations (i.e., System Counter and NSF Counter), the timestamp MUST be provided separately. The time format used is following the rules in Section 5.6 of [RFC3339].¶
- language: describes the human language intended for the user, so that it allows a user to verify the language that is used in the notification (i.e., '../message', '/i2nsf-log/i2nsf-nsf-system-access-log/output', and '/i2nsf-log/i2nsf-system-user-activity-log/additional-info/cause'). The attribute is encoded following the rules in Section 2.1 of [RFC5646]. The default language tag is "en-US".¶
6. Extended Information Model for Monitoring Data
The extended information model is the specific monitoring data that covers the additional information associated with the detailed information of status and performance of the network and the NSF over the basic information model. The extended information combined with the basic information creates the monitoring information (i.e., I2NSF Event, Record, and Counter).¶
The extended monitoring information has settable characteristics for data collection as follows:¶
- Acquisition method: The method to obtain the message. It can be a "query" or a "subscription". A "query" is a request-based method to acquire the solicited information. A "subscription" is a report-based method that pushes information to the subscriber.¶
- Emission type: The cause type for the message to be emitted. This attribute is used only when the acquisition method is a "subscription" method. The emission type can be either "on-change" or "periodic". An "on-change" message is emitted when an important event happens in the NSF. A "periodic" message is emitted at a certain time interval. The time to periodically emit the message is configurable.¶
- Dampening type: The type of message dampening to stop the rapid transmission of messages. The dampening types are "on-repetition" and "no-dampening". The "on-repetition" type limits the transmitted "on-change" message to one message at a certain interval (e.g., 100 centiseconds). This interval is defined as dampening-period in [RFC8641]. The dampening-period is configurable in the unit of centiseconds. The "no-dampening" type does not limit the transmission for the messages of the same type. In short, "on-repetition" means that the dampening is active and "no-dampening" is inactive. Activating the dampening for an "on-change" type of message is RECOMMENDED to reduce the number of messages generated.¶
Note that the characteristic information is not mandatory to be included in a monitoring message. The information is expected to be stored and may or may not be useful in some ways in the future. In any case, the inclusion of the characteristic information is up to the implementation.¶
6.1. System Alarms
System alarms have the following characteristics:¶
- acquisition-method: subscription¶
- emission-type: on-change¶
- dampening-type: on-repetition or no-dampening¶
6.1.1. Memory Alarm
The memory is the hardware to store information temporarily or for a short period, i.e., Random Access Memory (RAM). The memory-alarm is emitted when the memory usage exceeds the threshold. The following information should be included in a Memory Alarm:¶
- event-name: memory-alarm.¶
- usage: specifies the amount of memory used in percentage.¶
- threshold: The threshold triggering the alarm in percentage.¶
- severity: The severity level of the message. There are four levels, i.e., critical, high, middle, and low.¶
- message: Simple information as a human readable text string such as "The memory usage exceeded the threshold" or with extra information.¶
6.1.2. CPU Alarm
CPU is the Central Processing Unit that executes basic operations of the system. The cpu-alarm is emitted when the CPU usage exceeds the threshold. The following information should be included in a CPU Alarm:¶
- event-name: cpu-alarm.¶
- usage: Specifies the CPU utilization in percentage.¶
- threshold: The threshold triggering the event in percentage.¶
- severity: The severity level of the message. There are four levels, i.e., critical, high, middle, and low.¶
- message: Simple information as a human readable text string such as "The CPU usage exceeded the threshold" or with extra information.¶
6.1.3. Disk (Storage) Alarm
Disk or storage is the hardware to store information for a long time, i.e., Hard Disk or Solid-State Drive. The disk-alarm is emitted when the Disk usage exceeds the threshold. The following information should be included in a Disk Alarm:¶
- event-name: disk-alarm.¶
- usage: Specifies the ratio of the used disk space to the whole disk space in terms of percentage.¶
- threshold: The threshold triggering the event in percentage.¶
- severity: The severity level of the message. There are four levels, i.e., critical, high, middle, and low.¶
- message: Simple information as a human readable text string such as "The disk usage exceeded the threshold" or with extra information.¶
6.1.4. Hardware Alarm
The hardware-alarm is emitted when a hardware, e.g., CPU, memory, disk, or interface, problem is detected. The following information should be included in a Hardware Alarm:¶
- event-name: hardware-alarm.¶
- component-name: It indicates the hardware component responsible for generating this alarm.¶
- severity: The severity level of the message. There are four levels, i.e., critical, high, middle, and low.¶
- message: Simple information as a human readable text string such as "The hardware component has failed or degraded" or with extra information.¶
6.1.5. Interface Alarm
Interface is the network interface for connecting a device with the network. The interface-alarm is emitted when the state of the interface is changed. The following information should be included in an Interface Alarm:¶
- event-name: interface-alarm.¶
- interface-name: The name of the interface.¶
- interface-state: The status of the interface, i.e., down, up (not congested), congested (up but congested), testing, unknown, dormant, not-present, and lower-layer-down.¶
- severity: The severity level of the message. There are four levels, i.e., critical, high, middle, and low.¶
- message: Simple information as a human readable text string such as "The interface is 'interface-state'" or with extra information.¶
6.2. System Events
System events (as alerts) have the following characteristics:¶
- acquisition-method: subscription¶
- emission-type: on-change¶
- dampening-type: on-repetition or no-dampening¶
6.2.1. Access Violation
The access-violation system event is an event when a user tries to access (read, write, create, or delete) any information or execute commands above their privilege. The following information should be included in this event:¶
- event-name: access-violation.¶
-
identity: The information to identify the attempted access violation. The minimum information (extensible) that should be included:¶
- authentication: The method to verify the valid user, i.e., pre-configured-key and certificate-authority.¶
- message: The message as a human readable text string to give the context of the event, such as "Access is denied".¶
6.2.2. Configuration Change
A configuration change is a system event when a new configuration is added or an existing configuration is modified. The following information should be included in this event:¶
- event-name: configuration-change.¶
-
identity: The information to identify the user that updated the configuration. The minimum information (extensible) that should be included:¶
- authentication: The method to verify the valid user, i.e., pre-configured-key and certificate-authority.¶
- message: The message as a human readable text string to give the context of the event, such as "Configuration is modified", "New configuration is added", or "A configuration has been removed".¶
- changes: Describes the modification that was made to the configuration. The minimum information that must be provided is the name of the policy that has been altered (added, modified, or removed). Other detailed information about the configuration changes is up to the implementation.¶
6.2.3. Session Table Event
A session is defined as a connection (i.e., traffic flow) of a data plane (e.g., TCP, UDP, and SCTP). Session Table Event is the event triggered by the session table of an NSF. A session table holds the information of the currently active sessions. The following information should be included in a Session Table Event:¶
- event-name: detection-session-table.¶
- current-session: The number of concurrent sessions.¶
- maximum-session: The maximum number of sessions that the session table can support.¶
- threshold: The threshold (in terms of an allowed number of sessions) triggering the event.¶
- message: The message as a human readable text string to give the context of the event, such as "The number of sessions exceeded the table threshold".¶
6.2.4. Traffic Flows
Traffic flows need to be monitored because they might be used for security attacks to the network. The following information should be included in this event:¶
- event-name: traffic-flows.¶
- interface-name: The mnemonic name of the network interface¶
- interface-type: The type of a network interface such as an ingress or egress interface.¶
- src-mac: The source MAC address of the traffic flow. This information may or may not be included depending on the type of traffic flow. For example, the information will be useful and should be included if the traffic flows are traffic flows of Link Layer Discovery Protocol (LLDP) [IEEE-802.1AB], Address Resolution Protocol (ARP) for IPv4 [RFC0826], and Neighbor Discovery Protocol (ND) for IPv6 [RFC4861].¶
- dst-mac: The destination MAC address of the traffic flow. This information may or may not be included depending on the type of traffic flow. For example, the information will be useful and should be included if the traffic flows are LLDP, ARP for IPv4, or ND for IPv6 traffic flows.¶
- src-ip: The source IPv4 or IPv6 address of the traffic flow.¶
- dst-ip: The destination IPv4 or IPv6 address of the traffic flow.¶
- src-port: The transport layer source port number of the traffic flow.¶
- dst-port: The transport layer destination port number of the traffic flow.¶
- protocol: The protocol of the traffic flow.¶
- measurement-time: The duration of the measurement in seconds for the arrival rate and arrival throughput of packets of a traffic flow. These two metrics (i.e., arrival rate and arrival throughput) are measured over the past measurement duration before now.¶
- arrival-rate: Arrival rate of packets of the traffic flow in packets per second measured over the past "measurement-time".¶
- arrival-throughput: Arrival rate of packets of the traffic flow in bytes per second measured over the past "measurement-time".¶
Note that the NSF Monitoring Interface data model is focused on a generic method to collect the monitoring information of systems and NSFs including traffic flows related to security attacks and system resource usages. On the other hand, IPFIX [RFC7011] is a standard method to collect general information on traffic flows rather than security.¶
6.3. NSF Events
The NSF events provide the event that is detected by a specific NSF that supported a certain capability. This section only discusses the monitoring data for the advanced NSFs discussed in [I-D.ietf-i2nsf-capability-data-model]. The NSF events information can be extended to support other types of NSF. NSF events have the following characteristics:¶
- acquisition-method: subscription¶
- emission-type: on-change¶
- dampening-type: on-repetition or no-dampening¶
6.3.1. DDoS Detection
The following information should be included in a Denial-of-Service (DoS) or Distributed Denial-of-Service (DDoS) Event:¶
- event-name: detection-ddos.¶
- attack-type: The type of DoS or DDoS Attack, i.e., 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, TLS flood, and NTP amplification flood. This can be extended with additional types of DoS or DDoS attack.¶
- attack-src-ip: The IP addresses of the source of the DDoS attack. Note that not all IP addresses should be included but only limited IP addresses are included to conserve the server resources. The listed attacking IP addresses can be an arbitrary sampling of the "top talkers", i.e., the attackers that send the highest amount of traffic.¶
- attack-dst-ip: The destination IPv4 or IPv6 addresses of attack traffic. It can hold multiple IPv4 or IPv6 addresses.¶
- attack-src-port: The transport layer source port numbers of the attack traffic. Note that not all ports will have been seen on all the corresponding source IP addresses.¶
- attack-dst-port: The transport layer destination port numbers that the attack traffic aims at. Note that not all ports will have been seen on all the corresponding destination IP addresses.¶
- start-time: The time stamp indicating when the attack started. The time format used is following the rules in Section 5.6 of [RFC3339].¶
- end-time: The time stamp indicating when the attack ended. If the attack is still ongoing when sending out the notification, this field can be empty. The time format used is following the rules in Section 5.6 of [RFC3339].¶
- attack-rate: The packets per second of attack traffic.¶
- attack-throughput: The bytes per second of attack traffic.¶
- rule-name: The name of the I2NSF Policy Rule being triggered. Note that rule-name is used to match a detected NSF event with a policy rule in [I-D.ietf-i2nsf-nsf-facing-interface-dm].¶
6.3.2. Virus Event
This information is used when a virus is detected within a traffic flow or inside a host. Note that "malware" is a more generic word for malicious software, including virus and worm. In the document, "virus" is used to represent "malware" such that they are interchangeable. The following information should be included in a Virus Event:¶
- event-name: detection-virus.¶
- virus-name: Name of the virus.¶
- virus-type: Type of the virus. e.g., trojan, worm, and macro virus.¶
-
The following information is used only when the virus is detected within the traffic flow and not yet attacking the host:¶
-
The following information is used only when the virus is detected within a host system:¶
- host: The name or IP address of the host/device that is infected by the virus. If the given name is not an IP address, the name can be an arbitrary string including a FQDN (Fully Qualified Domain Name). The name MUST be unique in the scope of management domain for identifying the device that has been infected with a virus.¶
- os: The operating system of the host that has the virus.¶
- file-type: The type of file (indicated by the file's suffix, e.g., .exe) virus code is found in (if applicable).¶
- file-name: The name of the file where the virus is hidden.¶
- rule-name: The name of the rule being triggered.¶
Note "host" is used only when the virus is detected within a host itself. Thus, the traffic flow information such as the source and destination IP addresses is not important, so the elements of the traffic flow (i.e., dst-ip, src-ip, src-port, and dst-port) are not specified above. On the other hand, when the virus is detected within a traffic flow and not yet attacking a host, the element of "host" is not specified above.¶
6.3.3. Intrusion Event
The following information should be included in an Intrusion Event:¶
- event-name: detection-intrusion.¶
- attack-type: Attack type, e.g., brutal force or buffer overflow.¶
- src-ip: The source IP address of the flow.¶
- dst-ip: The destination IP address of the flow.¶
- src-port: The source port number of the flow.¶
- dst-port: The destination port number of the flow¶
- protocol: The employed transport layer protocol. e.g., TCP or UDP. Note that QUIC protocol [RFC9000] is excluded in the data model as it is not considered in the initial I2NSF documents [RFC8329]. The QUIC traffic should not be treated as generic UDP traffic and will be considered in the future I2NSF documents.¶
- app: The employed application layer protocol. e.g., HTTP or FTP.¶
- rule-name: The name of the I2NSF Policy Rule being triggered.¶
6.3.4. Web Attack Event
The following information should be included in a Web Attack Alarm:¶
- event-name: detection-web-attack.¶
- attack-type: Concrete web attack type. e.g., SQL injection, command injection, XSS, or CSRF.¶
- src-ip: The source IP address of the packet.¶
- dst-ip: The destination IP address of the packet.¶
- src-port: The source port number of the packet.¶
- dst-port: The destination port number of the packet.¶
- req-method: The HTTP method of the request. For instance, "PUT" and "GET" in HTTP.¶
- req-target: The HTTP Request Target.¶
- response-code: The HTTP Response status code.¶
- cookies: The HTTP Cookie header field of the request from the user agent. Note that though cookies have many historical infelicities that degrade security and privacy, the Cookie and Set-Cookie header fields are widely used on the Internet [RFC6265]. Thus, the cookies information needs to be kept confidential and is NOT RECOMMENDED to be included in the monitoring data unless the information is absolutely necessary to help to enhance the security of the network.¶
- req-host: The HTTP Host header field of the request.¶
- filtering-type: URL filtering type. e.g., deny-list, allow-list, and unknown.¶
- rule-name: The name of the I2NSF Policy Rule being triggered.¶
6.3.5. VoIP/VoCN Event
The following information should be included in a VoIP (Voice over Internet Protocol) and VoCN (Voice over Cellular Network, such as Voice over LTE or 5G) Event:¶
- event-name: detection-voip-vocn¶
- source-voice-id: The detected source voice Call ID for VoIP and VoCN that violates the policy.¶
- destination-voice-id: The destination voice Call ID for VoIP and VoCN that violates the policy.¶
- user-agent: The user agent for VoIP and VoCN that violates the policy.¶
- src-ip: The source IP address of the VoIP/VoCN.¶
- dst-ip: The destination IP address of the VoIP/VoCN.¶
- src-port: The source port number of the VoIP/VoCN.¶
- dst-port: The destination port number of VoIP/VoCN.¶
- rule-name: The name of the I2NSF Policy Rule being triggered.¶
6.4. System Logs
System log is a record that is used to monitor the activity of the user on the NSF and the status of the NSF. System logs have the following characteristics:¶
- acquisition-method: subscription or query¶
- emission-type: on-change or periodic¶
- dampening-type: on-repetition or no-dampening¶
6.4.1. Access Log
Access logs record administrators' login, logout, and operations on a device. By analyzing them, some security vulnerabilities can be identified. The following information should be included in an operation report:¶
-
identity: The information to identify the user. The minimum information (extensible) that should be included:¶
- authentication: The method to verify the valid user, i.e., pre-configured-key and certificate-authority.¶
- operation-type: The operation type that the administrator executed, e.g., login, logout, configuration, and other.¶
- input: The operation performed by a user after login. The operation is a command given by a user.¶
- output: The result after executing the input.¶
6.4.2. Resource Utilization Log
Running reports record the device system's running status, which is useful for device monitoring. The following information should be included in running report:¶
- system-status: The current system's running status.¶
- cpu-usage: Specifies the aggregated CPU usage in percentage.¶
- memory-usage: Specifies the memory usage in percentage.¶
- disk-id: Specifies the disk ID to identify the storage disk.¶
- disk-usage: Specifies the disk usage of disk-id in percentage.¶
- disk-space-left: Specifies the available disk space left of disk-id in percentage.¶
- session-number: Specifies total concurrent sessions.¶
- process-number: Specifies total number of systems processes.¶
- interface-id: Specifies the interface ID to identify the network interface.¶
- in-traffic-rate: The total inbound data plane traffic rate in packets per second.¶
- out-traffic-rate: The total outbound data plane traffic rate in packets per second.¶
- in-traffic-throughput: The total inbound data plane traffic throughput in bytes per second.¶
- out-traffic-throughput: The total outbound data plane traffic throughput in bytes per second.¶
Note that "traffic" includes only the data plane since the monitoring interface focuses on the monitoring of traffic flows for applications, rather than the control plane. In the document, "packet" includes a layer-2 frame, so "packet" and "frame" are interchangeable. Also, note that system resources (e.g., CPU, memory, disk, and interface) are monitored for the sake of security in NSFs even though they are common ones to be monitored by a generic Operations, Administration and Maintenance (OAM) protocol (or module).¶
6.4.3. User Activity Log
User activity logs provide visibility into users' online records (such as login time, online/lockout duration, and login IP addresses) and the actions that users perform. User activity reports are helpful to identify exceptions during a user's login and network access activities. This information should be included in a user's activity report:¶
-
identity: The information to identify the user. The minimum information (extensible) that should be included is as follows:¶
- authentication: The method to verify the valid user, i.e., pre-configured-key and certificate-authority.¶
- online-duration: The duration of a user's activeness (stays in login) during a session.¶
- logout-duration: The duration of a user's inactiveness (not in login) from the last session.¶
-
additional-info: Additional Information for login:¶
6.5. NSF Logs
NSF logs have the folowing characteristics:¶
- acquisition-method: subscription or query¶
- emission-type: on-change¶
- dampening-type: on-repetition or no-dampening¶
6.5.1. Deep Packet Inspection Log
Deep Packet Inspection (DPI) Logs provide statistics of transit traffic at an NSF such that the traffic includes uploaded and downloaded files/data, sent/received emails, and blocking/alert 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.¶
- attack-type: DPI action types. e.g., File Blocking, Data Filtering, and Application Behavior Control.¶
- src-ip: The source IP address of the flow.¶
- dst-ip: The destination IP address of the flow.¶
- src-port: The source port number of the flow.¶
- dst-port: The destination port number of the flow¶
- rule-name: The name of the I2NSF Policy Rule being triggered.¶
- action: Action defined in the file blocking rule, data filtering rule, or application behavior control rule that traffic matches.¶
6.6. System Counter
System counter has the following characteristics:¶
6.6.1. Interface Counter
Interface counters provide visibility into traffic into and out of an NSF, and bandwidth usage.¶
- interface-name: Network interface name configured in NSF.¶
- protocol: The type of network protocol (e.g., IPv4, IPv6, TCP, and UDP). If this field is empty, then the counter is used for all protocols.¶
- measurement-time: The duration of the measurement in seconds for the calculation of statistics such as traffic rate and throughput. The statistic attributes are measured over the past measurement duration before now.¶
- in-total-traffic-pkts: Total inbound packets.¶
- out-total-traffic-pkts: Total outbound packets.¶
- in-total-traffic-bytes: Total inbound bytes.¶
- out-total-traffic-bytes: Total outbound bytes.¶
- in-drop-traffic-pkts: Total inbound drop packets caused by a policy or hardware/resource error.¶
- out-drop-traffic-pkts: Total outbound drop packets caused by a policy or hardware/resource error.¶
- in-drop-traffic-bytes: Total inbound drop bytes caused by a policy or hardware/resource error.¶
- out-drop-traffic-bytes: Total outbound drop bytes caused by a policy or hardware/resource error.¶
- total-traffic: The total number of traffic packets (in and out) in the NSF.¶
- in-traffic-average-rate: Inbound traffic average rate in packets per second.¶
- in-traffic-peak-rate: Inbound traffic peak rate in packets per second.¶
- in-traffic-average-throughput: Inbound traffic average throughput in bytes per second.¶
- in-traffic-peak-throughput: Inbound traffic peak throughput in bytes per second.¶
- out-traffic-average-rate: Outbound traffic average rate in packets per second.¶
- out-traffic-peak-rate: Outbound traffic peak rate in packets per second.¶
- out-traffic-average-throughput: Outbound traffic average throughput in bytes per second.¶
- out-traffic-peak-throughput: Outbound traffic peak throughput in bytes per second.¶
- discontinuity-time: The time of the most recent occasion at which any one or more of the counters suffered a discontinuity. If no such discontinuities have occurred since the last re-initialization of the local management subsystem, then this node contains the time the local management subsystem was re-initialized. The time format used is following the rules in Section 5.6 of [RFC3339].¶
6.7. NSF Counters
NSF counters have the following characteristics:¶
6.7.1. Firewall Counter
Firewall counters provide visibility into traffic signatures and bandwidth usage that correspond to the policy that is configured in a firewall.¶
- policy-name: Security policy name that traffic matches.¶
- measurement-time: The duration of the measurement in seconds for the calculation of statistics such as traffic rate and throughput. The statistic attributes are measured over the past measurement duration before now.¶
- in-interface: Inbound interface of traffic.¶
- out-interface: Outbound interface of traffic.¶
- total-traffic: The total number of traffic packets (in and out) in the firewall.¶
- in-traffic-average-rate: Inbound traffic average rate in packets per second.¶
- in-traffic-peak-rate: Inbound traffic peak rate in packets per second.¶
- in-traffic-average-throughput: Inbound traffic average throughput in bytes per second.¶
- in-traffic-peak-throughput: Inbound traffic peak throughput in bytes per second.¶
- out-traffic-average-rate: Outbound traffic average rate in packets per second.¶
- out-traffic-peak-rate: Outbound traffic peak rate in packets per second.¶
- out-traffic-average-throughput: Outbound traffic average throughput in bytes per second.¶
- out-traffic-peak-throughput: Outbound traffic peak throughput in bytes per second.¶
- discontinuity-time: The time on the most recent occasion at which any one or more of the counters suffered a discontinuity. If no such discontinuities have occurred since the last re-initialization of the local management subsystem, then this node contains the time the local management subsystem was re-initialized. The time format used is following the rules in Section 5.6 of [RFC3339].¶
6.7.2. Policy Hit Counter
Policy hit counters record the security policy that traffic matches and its hit count. That is, when a packet actually matches a policy, it should be added to the statistics of a "policy hit counter" of the policy. The "policy hit counter" provides the "policy-name" that matches the policy's name in the NSF-Facing Interface YANG data model [I-D.ietf-i2nsf-nsf-facing-interface-dm]. It can check if policy configurations are correct or not.¶
- policy-name: Security policy name that traffic matches.¶
- hit-times: The number of times that the security policy matches the specified traffic.¶
- discontinuity-time: The time on the most recent occasion at which any one or more of the counters suffered a discontinuity. If no such discontinuities have occurred since the last re-initialization of the local management subsystem, then this node contains the time the local management subsystem was re-initialized. The time format used is following the rules in Section 5.6 of [RFC3339].¶
7. YANG Tree Structure of NSF Monitoring YANG Module
The tree structure of the NSF monitoring YANG module is provided below:¶
8. YANG Data Model of NSF Monitoring YANG Module
This section describes a YANG module of I2NSF NSF Monitoring. The data model provided in this document uses identities to be used to get information of the monitored of an NSF's monitoring data. Every identity used in the document gives information or status about the current situation of an NSF. This YANG module imports from [RFC6991], [RFC8343], and [I-D.ietf-i2nsf-nsf-facing-interface-dm], and makes references to [RFC0768] [RFC0791] [RFC0792] [RFC0826] [RFC0854] [RFC1939] [RFC0959] [RFC2595] [RFC4340] [RFC4443] [RFC4861] [RFC5321] [RFC5646] [RFC6242] [RFC6265] [RFC8200] [RFC8641] [RFC9051] [I-D.ietf-httpbis-http2bis] [I-D.ietf-httpbis-messaging] [I-D.ietf-httpbis-semantics] [I-D.ietf-tcpm-rfc793bis] [I-D.ietf-tsvwg-rfc4960-bis] [IANA-HTTP-Status-Code] [IEEE-802.1AB]¶
9. I2NSF Event Stream
This section discusses the NETCONF event stream for an I2NSF NSF Monitoring subscription. The YANG module in this document supports "ietf-subscribed-notifications" YANG module [RFC8639] for subscription. The reserved event stream name for this document is "I2NSF-Monitoring". The NETCONF Server (e.g., an NSF) MUST support "I2NSF-Monitoring" event stream for an NSF data collector (e.g., Security Controller). The "I2NSF-Monitoring" event stream contains all I2NSF events described in this document.¶
The following XML example shows the capabilities of the event streams generated by an NSF (e.g., "NETCONF" and "I2NSF-Monitoring" event streams) for the subscription of an NSF data collector. Refer to [RFC5277] for more detailed explanation of Event Streams. The XML examples in this document follow the line breaks as per [RFC8792].¶
10. XML Examples for I2NSF NSF Monitoring
This section shows XML examples of I2NSF NSF Monitoring data delivered via Monitoring Interface from an NSF. The XML examples are following the guidelines from [RFC6241] [RFC7950].¶
10.1. I2NSF System Detection Alarm
The following example shows an alarm triggered by Memory Usage on the server; this example XML file is delivered by an NSF to an NSF data collector:¶
The XML data above shows:¶
- The NSF that sends the information is named "time_based_firewall".¶
- The memory usage of the NSF triggered the alarm.¶
- The monitoring information is received by subscription method.¶
- The monitoring information is emitted "on-change".¶
- The monitoring information is dampened "on-repetition".¶
- The memory usage of the NSF is 91 percent.¶
- The memory threshold to trigger the alarm is 90 percent.¶
- The severity level of the notification is high.¶
10.2. I2NSF Interface Counters
To get the I2NSF system interface counters information by query, NETCONF Client (e.g., NSF data collector) needs to initiate GET connection with NETCONF Server (e.g., NSF). The following XML file can be used to get the state data and filter the information.¶
The following XML file shows the reply from the NETCONF Server (e.g., NSF):¶
11. IANA Considerations
This document requests IANA to register the following URI in the "IETF XML Registry" [RFC3688]:¶
URI: urn:ietf:params:xml:ns:yang:ietf-i2nsf-nsf-monitoring Registrant Contact: The IESG. XML: N/A; the requested URI is an XML namespace.¶
This document requests IANA to register the following YANG module in the "YANG Module Names" registry [RFC7950][RFC8525]:¶
name: ietf-i2nsf-nsf-monitoring namespace: urn:ietf:params:xml:ns:yang:ietf-i2nsf-nsf-monitoring prefix: nsfmi reference: RFC XXXX // RFC Ed.: replace XXXX with an actual RFC number and remove // this note.¶
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 required secure transport is Secure Shell (SSH) [RFC6242]. The lowest RESTCONF layer is HTTPS, and the required secure transport is TLS [RFC8446].¶
The NETCONF access control model [RFC8341] provides a means of restricting access by specific 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 as they all could potentially impact security monitoring and mitigation activities. Write operations (e.g., edit-config) applied to these data nodes without proper protection could result in missed alarms or incorrect alarms information being returned to the NSF data collector. The following are threats that need to be considered and mitigated:¶
- Compromised NSF with valid credentials:
- It can send falsified information to the NSF data collector to mislead detection or mitigation activities; and/or to hide activity. Currently, there is no in-framework mechanism to mitigate this and it is an issue for all monitoring infrastructures. It is important to keep confidential information from unauthorized persons to mitigate the possibility of compromising the NSF with this information.¶
- Compromised NSF data collector with valid credentials:
- It has visibility to all collected security alarms; the entire detection and mitigation infrastructure may be suspect. It is important to keep confidential information from unauthorized persons to mitigate the possibility of compromising the NSF with this information.¶
- Impersonating NSF:
- This involves a system trying to send false information while imitating an NSF; client authentication would help the NSF data collector to identify this invalid NSF in the "push" model (NSF-to-collector), while the "pull" model (collector-to-NSF) should already be addressed with the authentication.¶
- Impersonating NSF data collector:
- This is a rogue NSF data collector with which a legitimate NSF is tricked into communicating; for "push" model (NSF-to-collector), it is important to have valid credentials, without which it should not work; for "pull" model (collector-to-NSF), mutual authentication should be used to mitigate the threat.¶
In addition, to defend against the DDoS attack caused by a lot of NSFs sending massive notifications to the NSF data collector, the rate limiting or similar mechanisms should be considered in both an NSF and NSF data collector, whether in advance or just in the process of DDoS attack.¶
All of the readable data nodes in this YANG module may be considered sensitive in some network environments. These data nodes represent information consistent with the logging commonly performed in network and security operations. They may reveal the specific configuration of a network; vulnerabilities in specific systems; and the deployed security controls and their relative efficacy in detecting or mitigating an attack. To an attacker, this information could inform how to (further) compromise the network, evade detection, or confirm whether they have been observed by the network operator.¶
Additionally, many of the data nodes in this YANG module such as containers "i2nsf-system-user-activity-log", "i2nsf-system-detection-event", and "i2nsf-nsf-detection-voip-vocn" are privacy sensitive. They may describe specific or aggregate user activity including associating user names with specific IP addresses; or users with specific network usage. They may also describe the specific commands that were run by users and the resulting output. Any sensitive information in that command input or output will be visible to the NSF data collector and potentially other entities, and care must be taken to protect the confidentiality of such data from unauthorized parties.¶
13. 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 people: Roman Danyliw, Tim Bray (IANA), Kyle Rose (TSV-ART), Dale R. Worley (Gen-ART), Melinda Shore (SecDir), Valery Smyslov (ART-ART), and Tom Petch. The 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 (2020-0-00395, Standard Development of Blockchain based Network Management Automation Technology). This work was supported in part by the MSIT under the Information Technology Research Center (ITRC) support program (IITP-2021-2017-0-01633) supervised by the IITP.¶
14. Contributors
The following are co-authors of this document:¶
Chaehong Chung - Department of Electronic, Electrical and Computer Engineering, Sungkyunkwan University, 2066 Seobu-ro Jangan-gu, Suwon, Gyeonggi-do 16419, Republic of Korea, Email: darkhong@skku.edu¶
Jinyong (Tim) Kim - Department of Electronic, Electrical and Computer Engineering, Sungkyunkwan University, 2066 Seobu-ro Jangan-gu, Suwon, Gyeonggi-do 16419, Republic of Korea, Email: timkim@skku.edu¶
Dongjin Hong - Department of Electronic, Electrical and Computer Engineering, Sungkyunkwan University, 2066 Seobu-ro Jangan-gu, Suwon, Gyeonggi-do 16419, Republic of Korea, Email: dong.jin@skku.edu¶
Dacheng Zhang - Huawei, Email: dacheng.zhang@huawei.com¶
Yi Wu - Aliababa Group, Email: anren.wy@alibaba-inc.com¶
Rakesh Kumar - Juniper Networks, 1133 Innovation Way, Sunnyvale, CA 94089, USA, Email: rkkumar@juniper.net¶
Anil Lohiya - Juniper Networks, Email: alohiya@juniper.net¶
15. References
15.1. 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>.
- [RFC2595]
- Newman, C., "Using TLS with IMAP, POP3 and ACAP", RFC 2595, DOI 10.17487/RFC2595, , <https://www.rfc-editor.org/info/rfc2595>.
- [RFC3339]
- Klyne, G. and C. Newman, "Date and Time on the Internet: Timestamps", RFC 3339, DOI 10.17487/RFC3339, , <https://www.rfc-editor.org/info/rfc3339>.
- [RFC3688]
- Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, , <https://www.rfc-editor.org/info/rfc3688>.
- [RFC3877]
- Chisholm, S. and D. Romascanu, "Alarm Management Information Base (MIB)", RFC 3877, DOI 10.17487/RFC3877, , <https://www.rfc-editor.org/info/rfc3877>.
- [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>.
- [RFC5277]
- Chisholm, S. and H. Trevino, "NETCONF Event Notifications", RFC 5277, DOI 10.17487/RFC5277, , <https://www.rfc-editor.org/info/rfc5277>.
- [RFC5321]
- Klensin, J., "Simple Mail Transfer Protocol", RFC 5321, DOI 10.17487/RFC5321, , <https://www.rfc-editor.org/info/rfc5321>.
- [RFC5646]
- Phillips, A., Ed. and M. Davis, Ed., "Tags for Identifying Languages", BCP 47, RFC 5646, DOI 10.17487/RFC5646, , <https://www.rfc-editor.org/info/rfc5646>.
- [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>.
- [RFC6265]
- Barth, A., "HTTP State Management Mechanism", RFC 6265, DOI 10.17487/RFC6265, , <https://www.rfc-editor.org/info/rfc6265>.
- [RFC6991]
- Schoenwaelder, J., Ed., "Common YANG Data Types", RFC 6991, DOI 10.17487/RFC6991, , <https://www.rfc-editor.org/info/rfc6991>.
- [RFC7011]
- Claise, B., Ed., Trammell, B., Ed., and P. Aitken, "Specification of the IP Flow Information Export (IPFIX) Protocol for the Exchange of Flow Information", STD 77, RFC 7011, DOI 10.17487/RFC7011, , <https://www.rfc-editor.org/info/rfc7011>.
- [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>.
- [RFC8342]
- Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K., and R. Wilton, "Network Management Datastore Architecture (NMDA)", RFC 8342, DOI 10.17487/RFC8342, , <https://www.rfc-editor.org/info/rfc8342>.
- [RFC8343]
- Bjorklund, M., "A YANG Data Model for Interface Management", RFC 8343, DOI 10.17487/RFC8343, , <https://www.rfc-editor.org/info/rfc8343>.
- [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>.
- [RFC8639]
- Voit, E., Clemm, A., Gonzalez Prieto, A., Nilsen-Nygaard, E., and A. Tripathy, "Subscription to YANG Notifications", RFC 8639, DOI 10.17487/RFC8639, , <https://www.rfc-editor.org/info/rfc8639>.
- [RFC8641]
- Clemm, A. and E. Voit, "Subscription to YANG Notifications for Datastore Updates", RFC 8641, DOI 10.17487/RFC8641, , <https://www.rfc-editor.org/info/rfc8641>.
- [RFC8650]
- Voit, E., Rahman, R., Nilsen-Nygaard, E., Clemm, A., and A. Bierman, "Dynamic Subscription to YANG Events and Datastores over RESTCONF", RFC 8650, DOI 10.17487/RFC8650, , <https://www.rfc-editor.org/info/rfc8650>.
- [RFC9000]
- Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based Multiplexed and Secure Transport", RFC 9000, DOI 10.17487/RFC9000, , <https://www.rfc-editor.org/info/rfc9000>.
- [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-httpbis-http2bis]
- Thomson, M. and C. Benfield, "HTTP/2", Work in Progress, Internet-Draft, draft-ietf-httpbis-http2bis-07, , <https://www.ietf.org/archive/id/draft-ietf-httpbis-http2bis-07.txt>.
- [I-D.ietf-httpbis-messaging]
- Fielding, R. T., Nottingham, M., and J. Reschke, "HTTP/1.1", Work in Progress, Internet-Draft, draft-ietf-httpbis-messaging-19, , <https://www.ietf.org/archive/id/draft-ietf-httpbis-messaging-19.txt>.
- [I-D.ietf-httpbis-semantics]
- Fielding, R. T., Nottingham, M., and J. Reschke, "HTTP Semantics", Work in Progress, Internet-Draft, draft-ietf-httpbis-semantics-19, , <https://www.ietf.org/archive/id/draft-ietf-httpbis-semantics-19.txt>.
- [I-D.ietf-i2nsf-capability-data-model]
- Hares, S., Jeong, J. (., Kim, J. (., Moskowitz, R., and Q. Lin, "I2NSF Capability YANG Data Model", Work in Progress, Internet-Draft, draft-ietf-i2nsf-capability-data-model-30, , <https://www.ietf.org/archive/id/draft-ietf-i2nsf-capability-data-model-30.txt>.
- [I-D.ietf-i2nsf-nsf-facing-interface-dm]
- Kim, J. (., Jeong, J. (., Park, J., Hares, S., and Q. Lin, "I2NSF Network Security Function-Facing Interface YANG Data Model", Work in Progress, Internet-Draft, draft-ietf-i2nsf-nsf-facing-interface-dm-25, , <https://www.ietf.org/archive/id/draft-ietf-i2nsf-nsf-facing-interface-dm-25.txt>.
- [I-D.ietf-tcpm-rfc793bis]
- Eddy, W. M., "Transmission Control Protocol (TCP) Specification", Work in Progress, Internet-Draft, draft-ietf-tcpm-rfc793bis-28, , <https://www.ietf.org/archive/id/draft-ietf-tcpm-rfc793bis-28.txt>.
- [I-D.ietf-tsvwg-rfc4960-bis]
- Stewart, R. R., Tüxen, M., and K. E. E. Nielsen, "Stream Control Transmission Protocol", Work in Progress, Internet-Draft, draft-ietf-tsvwg-rfc4960-bis-19, , <https://www.ietf.org/archive/id/draft-ietf-tsvwg-rfc4960-bis-19.txt>.
15.2. Informative References
- [RFC0826]
- Plummer, D., "An Ethernet Address Resolution Protocol: Or Converting Network Protocol Addresses to 48.bit Ethernet Address for Transmission on Ethernet Hardware", STD 37, RFC 826, DOI 10.17487/RFC0826, , <https://www.rfc-editor.org/info/rfc826>.
- [RFC4861]
- Narten, T., Nordmark, E., Simpson, W., and H. Soliman, "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, DOI 10.17487/RFC4861, , <https://www.rfc-editor.org/info/rfc4861>.
- [RFC4949]
- Shirey, R., "Internet Security Glossary, Version 2", FYI 36, RFC 4949, DOI 10.17487/RFC4949, , <https://www.rfc-editor.org/info/rfc4949>.
- [RFC8792]
- Watsen, K., Auerswald, E., Farrel, A., and Q. Wu, "Handling Long Lines in Content of Internet-Drafts and RFCs", RFC 8792, DOI 10.17487/RFC8792, , <https://www.rfc-editor.org/info/rfc8792>.
- [I-D.ietf-i2nsf-consumer-facing-interface-dm]
- Jeong, J. (., Chung, C., Ahn, T., Kumar, R., and S. Hares, "I2NSF Consumer-Facing Interface YANG Data Model", Work in Progress, Internet-Draft, draft-ietf-i2nsf-consumer-facing-interface-dm-18, , <https://www.ietf.org/archive/id/draft-ietf-i2nsf-consumer-facing-interface-dm-18.txt>.
- [IANA-HTTP-Status-Code]
- Internet Assigned Numbers Authority (IANA), "Hypertext Transfer Protocol (HTTP) Status Code Registry", , <https://www.iana.org/assignments/http-status-codes/http-status-codes.xhtml>.
- [IEEE-802.1AB]
- Institute of Electrical and Electronics Engineers, "IEEE Standard for Local and metropolitan area networks - Station and Media Access Control Connectivity Discovery", , <https://ieeexplore.ieee.org/document/7433915>.
Appendix A. Changes from draft-ietf-i2nsf-nsf-monitoring-data-model-16
The following changes are made from draft-ietf-i2nsf-nsf-monitoring-data-model-16:¶