Internet-Draft | Consumer-Facing Interface YANG Data Mode | April 2023 |
Jeong, et al. | Expires 14 October 2023 | [Page] |
This document describes a YANG data model of the Consumer-Facing Interface of the Security Controller in an Interface to Network Security Functions (I2NSF) system in a Network Functions Virtualization (NFV) environment. This document defines various types of managed objects and the relationship among them needed to build the flow policies from users' perspective. The YANG data model is based on the "Event-Condition-Action" (ECA) policy defined by a capability YANG data model for I2NSF. The YANG data model enables different users of a given I2NSF system to define, manage, and monitor flow policies within an administrative domain (e.g., user group).¶
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In a framework of Interface to Network Security Functions (I2NSF) [RFC8329], each vendor can register their Network Security Functions (NSFs) using a Developer's Management System (DMS). Then the I2NSF User (e.g., an application for a security administrator such as a web application) can configure the NSFs by defining high-level security policies. Most vendors provide various proprietary applications or tools to define security policies for their own NSFs. The Consumer-Facing Interface is required because the applications developed by each vendor need to have a standard interface specifying the data types used when the I2NSF User and Security Controller (i.e., Network Operator Management System) communicate with each other using this interface. Therefore, this document specifies the required YANG data model such as their data types and encoding schemes so that high-level security policies (or configuration information for security policies) can be transferred to the Security Controller through the Consumer-Facing Interface. Security Controller will use the given information to translate the high-level security policies into the corresponding low-level security policies. The Security Controller delivers the translated security policies to the NSFs according to their respective security capabilities for the required security enforcement.¶
The Consumer-Facing Interface would be built using a set of objects, with each object capturing a unique set of information from an I2NSF User [RFC8329] needed to express a Security Policy. An object may have relationship with various other objects to express a complete set of requirements. The YANG data model in this document captures the managed objects and relationship among these objects. This model is structured in accordance with the "Event-Condition-Action" (ECA) policy.¶
An NSF Capability YANG data model is defined in [I-D.ietf-i2nsf-capability-data-model] as the basic model for both the NSF-Facing interface and Consumer-Facing Interface security policy model of this document.¶
Data models are defined at a lower level of abstraction and provide many details. They provide details about the implementation of a protocol's specification, e.g., rules that explain how to map managed objects onto lower-level protocol constructs.¶
The efficient and flexible provisioning of network functions by a Network Functions Virtualization (NFV) system supports rapid deployment of newly developed functions. As practical applications, Network Security Functions (NSFs), such as firewall, Intrusion Detection System (IDS)/Intrusion Prevention System (IPS), and attack mitigation, can also be provided as Virtual Network Functions (VNF) in the NFV system. By the efficient virtualization technology, these VNFs might be automatically provisioned and dynamically migrated based on real-time security requirements. This document presents a YANG data model to implement security functions based on NFV.¶
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.¶
This document uses the terminology described in [RFC8329].¶
This document follows the guidelines of [RFC8407], uses the common YANG types defined in [RFC6991], and adopts the Network Management Datastore Architecture (NMDA) [RFC8342]. The meaning of the symbols in tree diagrams is defined in [RFC8340].¶
A Policy object is a means to express a Security Policy set by an I2NSF User with the Consumer-Facing Interface. It is sent to the Security Controller which converts it into an NSF-specific configuration via the NSF-Facing Interface for enforcement of the NSF. Figure 2 shows the YANG tree of the Policy object. The Policy object SHALL have the following information:¶
A policy contains a list of rules. In order to express a Rule, a Rule must have complete information such as where and when a policy needs to be applied. This is done by defining a set of managed objects and relationship among them. A Policy Rule defined in this module is a set of management guidelines that defines a desired behavior based on the Event-Condition-Action policy model (Section 3.1 of [I-D.ietf-i2nsf-capability-data-model]), but that is independent of a specific device and implementation. Figure 3 shows the YANG data tree of the Rule object. The rule object SHALL have the following information:¶
The Event Object contains information related to scheduling a Rule. The Event Object activates the evaluation of the Condition Object based on a security event (i.e., system event or system alarm). Note that an empty Event Object means that the event will always evaluate to true and start the evaluation of the Condition Object. Figure 4 shows the YANG tree of the Event object. Event object SHALL have the following information:¶
The Condition object describes the network traffic pattern or fields that must be matched against the observed network traffic for the rule to trigger. The fields used to express the required conditions to trigger the rule are organized around the class of NSFs expected to be able to observe or compute them. Figure 5 shows the YANG tree of the Condition object. The Condition Sub-model SHALL have the following information:¶
Note that due to the exclusion of QUIC protocol in the I2NSF documents, HTTP/3 is also excluded in the document along with the QUIC protocol. HTTP/3 should neither be interpreted as HTTP/1.1 nor HTTP/2. The data model should be extended or augmented appropriately to support the handling of HTTP/3 traffic according to the needs of the implementer.¶
Note that the identities for ICMP messages provided in the YANG module are combined for ICMPv4 and ICMPv6 such as echo/echo-reply for ICMPv4 and echo-request/echo-reply for ICMPv6. For more information about the comparison between ICMPv4 and ICMPv6 messages, refer to [IANA-ICMP-Parameters] and [IANA-ICMPv6-Parameters].¶
This object represents actions that Security Admin wants to perform based on certain traffic class. Figure 6 shows the YANG tree of the Action object. The Action object SHALL have the following information:¶
The Policy Endpoint Group is the collection of network nodes that are labeled and placed together into a group. As shown in Figure 7, endpoint groups include User-Group (Section 4.1), Device-Group (Section 4.2), Location-Group (Section 4.3), and URL-Group (Section 4.4). An I2NSF User can create and use these objects to represent a logical entity in their business environment, where a security policy is to be applied. Figure 8 shows the YANG tree of the Endpoint-Groups object.¶
The endpoint group information delivered by the I2NSF User should be stored into a secure database available to the Security Controller for the translation from a high-level security policy to the corresponding low-level security policy. The information should be synchronized with other systems in real-time for accurate translation.¶
The User-Group object represents the MAC addresses and IP (IPv4 or IPv6) addresses that are labeled as a group of users (e.g., employees). Figure 9 shows the YANG tree of the User-Group object. The User-Group object SHALL have the following information:¶
The Device-Group object represents the labeled network devices that provide services (e.g., servers) hosted on the IP (IPv4 or IPv6) addresses and application protocol. Figure 10 shows the YANG tree of the Device-group object. The Device-Group object SHALL have the following information:¶
The Location-Group object represents the IP (IPv4 or IPv6) addresses labeled as a geographic location (i.e., country, region, and city). Figure 11 shows the YANG tree of the Location-Group object. The Location-Group object SHALL have the following information:¶
The URL-Group object represents the collection of Uniform Resource Locators (URLs) or hostnames labeled into a group (e.g., sns-websites). Figure 12 shows the YANG tree of the URL-Group object. The URL-Group object SHALL have the following information:¶
The Voice-Group object represents the collection of Session Initiation Protocol (SIP) identities labeled into a group. Figure 13 shows the YANG tree of the Voice-Group object. The Voice-Group object SHALL have the following information:¶
The Threat Prevention model describes information obtained from threat feeds (i.e., sources for obtaining the threat information). The presented information is the features or attributes that identify a well-known threat (e.g., signatures or payload) to prevent malicious activity entering the secured network. There are multiple managed objects that constitute this category. Figure 15 shows the YANG tree of a Threat-Prevention object.¶
This object represents a threat feed which provides the signatures of malicious activities. Figure 16 shows the YANG tree of a Threat-feed-list. The Threat-Feed object SHALL have the following information:¶
It is assumed that the I2NSF User obtains the threat signatures (i.e., threat content patterns) from a threat-feed server (i.e., feed provider), which is a server providing threat signatures. With the obtained threat signatures, the I2NSF User can deliver them to the Security Controller via the Consumer-Facing Interface. The retrieval of the threat signatures by the I2NSF User is out of the scope of this document.¶
Note that the information of a threat feed (i.e., a pair of IOC and Format) is used as information to alert or block traffic that matches IOCs identified in the threat feed. This information is used to update the NSFs that have various content security control capabilities (e.g., IPS, URL-Filtering, Antivirus, and VoIP/VoCN Filter) derived in [I-D.ietf-i2nsf-capability-data-model]. Those capabilities derive specific content security controls such as signature-set, exception-signature, and detect.¶
It is noted that DDoS Open Threat Signaling (dots) can be used to collect threat feeds in the form of signatures [RFC8811].¶
This object represents a list of raw binary patterns of a packet payload content (i.e., data after a transport layer header) to describe a threat. Figure 17 shows the YANG tree of a Payload-content list. The Payload-content object SHALL have the following information:¶
The main objective of this document is to provide the YANG data model of the I2NSF Consumer-Facing Interface. This interface can be used to deliver control and management messages between an I2NSF User and Security Controller for the I2NSF User's high-level security policies.¶
The semantics of the data model is aligned with the information model of the Consumer-Facing Interface. This data model is designed to support the I2NSF framework that can be extended according to the security needs. In other words, the model design is independent of the content and meaning of specific policies as well as the implementation approach.¶
With the YANG data model of I2NSF Consumer-Facing Interface, this document provides examples for security policy rules such as time-based firewall, VoIP/VoCN security service, and DDoS-attack mitigation in Section 7.¶
This section describes a YANG module of Consumer-Facing Interface. This document provides identities in the data model to be used for configuration of an NSF. Each identity is used for a different type of configuration. The details are explained in the description of each identity. This YANG module imports from [RFC6991]. It makes references to [RFC0768] [RFC0792] [RFC0854] [RFC0959] [RFC1939] [RFC2595] [RFC3022] [RFC3261] [RFC3986] [RFC4250] [RFC4340] [RFC4443] [RFC5321] [RFC5646] [RFC8075] [RFC8335] [RFC8727] [RFC9051] [RFC9110] [RFC9112] [RFC9113] [RFC9260] [RFC9293] [GLOB] [IANA-ICMP-Parameters] [IANA-ICMPv6-Parameters] [ISO-3166-1alpha2] [ISO-3166-2] [I-D.ietf-i2nsf-capability-data-model] [I-D.ietf-i2nsf-nsf-monitoring-data-model] [MISPCORE] [OPENIOC] [STIX]¶
This section shows XML configuration examples of high-level security policy rules that are delivered from the I2NSF User to the Security Controller over the Consumer-Facing Interface. The considered examples are: Database registration, time-based firewall for web filtering, VoIP/VoCN security service, and DDoS-attack mitigation.¶
The endpoint-group is used to register known network nodes and label them into a higher-level name (i.e., human recognizable language). If new endpoints are introduced to the network, it is necessary to first register their data to the database. For example, if new members are newly introduced in different groups (i.e., user-group, device-group, url-group, and voice-group), each of them should be registered as separate entities with their corresponding information.¶
Figure 19 shows an example XML representation of the registered information for the user-group, device-group, voice-group in IPv4 address [RFC5737], and url-group.¶
Also, Figure 20 shows an example XML representation of the registered information for the user-group, device-group, and voice-group in IPv6 addresses [RFC3849].¶
The first example scenario is to "block SNS access during office hours" using a time-based firewall policy. In this scenario, all users registered as "employees" in the user-group list are unable to access Social Networking Services (SNS) during the office hours (weekdays). The XML instance is described below:¶
Time-based-condition Firewall¶
The second example scenario is to "block malicious VoIP/VoCN packets coming to a company" using a VoIP policy. In this scenario, the calls coming from VOIP and/or VoCN sources with VoCN IDs that are classified as malicious are dropped. The IP addresses of the employees and malicious VOIP IDs should be blocked are stored in the database or datastore of the enterprise. Here and the rest of the cases assume that the security administrators or someone responsible for the existing and newly generated policies, are not aware of which and/or how many NSFs are needed to meet the security requirements. Figure 22 represents the XML document generated from YANG discussed in previous sections. Once a high-level security policy is created by a security admin, it is delivered by the Consumer-Facing Interface, through RESTCONF server, to the security controller. The XML instance is described below:¶
Custom-condition Firewall¶
The third example scenario is to "Mitigate flood attacks on a company web server" using a DDoS-attack mitigation policy. Here, the time information is not set because the service provided by the network should be maintained at all times. If the packets sent by any sources that target "webservers" are more than the set threshold, then the admin can set the percentage of the packets to be dropped to safely maintain the service. Once the rule is set and delivered and enforced to the NSFs by the security controller, the NSFs will monitor the incoming packet amounts to act according to the rule set. The XML instance is described below:¶
DDoS-condition Firewall¶
This document requests IANA to register the following URI in the "IETF XML Registry" [RFC3688]:¶
URI: urn:ietf:params:xml:ns:yang:ietf-i2nsf-cons-facing-interface 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-cons-facing-interface namespace: urn:ietf:params:xml:ns:yang:ietf-i2nsf-cons-facing-interface prefix: i2nsfcfi reference: RFC XXXX // RFC Ed.: replace XXXX with an actual RFC number and remove // this note.¶
The YANG module specified in this document defines a data schema designed to be accessed through network management protocols such as NETCONF [RFC6241] or RESTCONF [RFC8040]. The lowest NETCONF layer is the secure transport layer, and the required secure transport is Secure Shell (SSH) [RFC6242]. The lowest RESTCONF layer is HTTPS, and the required secure transport is TLS [RFC8446].¶
The Network Configuration Access Control Model (NACM) [RFC8341] provides a means of restricting access to specific NETCONF or RESTCONF users to a preconfigured subset of all available NETCONF or RESTCONF protocol operations and contents. Thus, NACM SHOULD be used to restrict the NSF registration from unauthorized users.¶
There are a number of data nodes defined in this YANG module that are writable, creatable, and deletable (i.e., config true, which is the default). These data nodes may be considered sensitive or vulnerable in some network environments. Write operations to these data nodes could have a negative effect on network and security operations. These data nodes have the following sensitivity/vulnerability:¶
Some of the readable data nodes in this YANG module may be considered sensitive or vulnerable in some network environments. It is thus important to control read access (e.g., via get, get-config, or notification) to these data nodes. These are the subtrees and data nodes with their sensitivity/vulnerability:¶
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, Mahdi F. Dachmehchi, Daeyoung Hyun, Jan Lindblad (YANG doctor), Tom Petch, Charlie Kaufman, Penglin Yang, and Jung-Soo Park. 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 (2020-0-00395-003, Standard Development of Blockchain based Network Management Automation Technology).¶
The following are co-authors of this document:¶
Patrick Lingga - Department of Electrical and Computer Engineering, Sungkyunkwan University, 2066 Seo-ro Jangan-gu, Suwon, Gyeonggi-do 16419, Republic of Korea. EMail: patricklink@skku.edu¶
Jinyong Tim Kim - Department of Electronic, Electrical and Computer Engineering, Sungkyunkwan University, 2066 Seo-ro Jangan-gu, Suwon, Gyeonggi-do 16419, Republic of Korea. EMail: timkim@skku.edu¶
Hyoungshick Kim - Department of Computer Science and Engineering, Sungkyunkwan University, 2066 Seo-ro Jangan-gu, Suwon, Gyeonggi-do 16419, Republic of Korea. EMail: hyoung@skku.edu¶
Eunsoo Kim - Department of Electronic, Electrical and Computer Engineering, Sungkyunkwan University, 2066 Seo-ro Jangan-gu, Suwon, Gyeonggi-do 16419, Republic of Korea. EMail: eskim86@skku.edu¶
Seungjin Lee - Department of Electronic, Electrical and Computer Engineering, Sungkyunkwan University, 2066 Seo-ro Jangan-gu, Suwon, Gyeonggi-do 16419, Republic of Korea. EMail: jine33@skku.edu¶
Anil Lohiya - Juniper Networks, 1133 Innovation Way, Sunnyvale, CA 94089, US. EMail: alohiya@juniper.net¶
Dave Qi - Bloomberg, 731 Lexington Avenue, New York, NY 10022, US. EMail: DQI@bloomberg.net¶
Nabil Bitar - Nokia, 755 Ravendale Drive, Mountain View, CA 94043, US. EMail: nabil.bitar@nokia.com¶
Senad Palislamovic - Nokia, 755 Ravendale Drive, Mountain View, CA 94043, US. EMail: senad.palislamovic@nokia.com¶
Liang Xia - Huawei, 101 Software Avenue, Nanjing, Jiangsu 210012, China. EMail: Frank.Xialiang@huawei.com¶
The following changes are made from draft-ietf-i2nsf-consumer-facing-interface-dm-27:¶