Internet-Draft | Consumer-Facing Interface YANG Data Mode | August 2022 |
Jeong, et al. | Expires 9 February 2023 | [Page] |
This document describes an information model and the corresponding YANG data model for the Consumer-Facing Interface of the Security Controller in an Interface to Network Security Functions (I2NSF) system in a Network Functions Virtualization (NFV) environment. The information model defines various types of managed objects and the relationship among them needed to build the flow policies from users' perspective. This information model is based on the "Event-Condition-Action" (ECA) policy model defined by a capability information model for I2NSF, and the YANG data model is defined for enabling 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 NSFs using a Developer's Management System (DMS). Assuming that vendors also provide the front-end web applications to an I2NSF User, the Consumer-Facing Interface is required because the web applications developed by each vendor need to have a standard interface specifying the data types used when the I2NSF User and Security Controller communicate with each other using this interface. Therefore, this document specifies the required information, 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. These policies can easily be translated by the Security Controller into low-level security policies. The Security Controller delivers the translated policies to Network Security Functions (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 Security Administrator (i.e., 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. An information model captures the managed objects and relationship among these objects. The information model proposed in this document is structured in accordance with the "Event-Condition-Action" (ECA) policy model.¶
An NSF Capability model is proposed 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.¶
[RFC3444] explains differences between an information and data model. This document uses the guidelines in [RFC3444] to define both the information and data model for Consumer-Facing Interface. Figure 1 shows a high-level abstraction of Consumer-Facing Interface. A data model, which represents an implementation of the information model in a specific data representation language, is also defined in 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. Since conceptual models can be implemented in different ways, multiple data models can be derived from a single information model.¶
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 represents a mechanism to express a Security Policy by Security Administrator (i.e., I2NSF User) using Consumer-Facing Interface toward Security Controller; the policy would be enforced on an NSF. Figure 2 shows the YANG tree of the Policy object. The Policy object SHALL have the following information:¶
A policy is 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 may be related segmentation, threat mitigation or telemetry data collection from an NSF in the network, which will be specified as the sub-model of the policy model in the subsequent sections. 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 Rule could be activated based on a security event (i.e., system event and system alarm). Figure 4 shows the YANG tree of the Event object. Event object SHALL have following information:¶
This object represents Conditions that Security Administrator wants to apply the checking on the traffic in order to determine whether the set of actions in the Rule can be executed or not. The Condition Sub-model consists of three different types of containers each representing different cases, such as general firewall and DDoS-mitigation cases, and a case when the condition is based on the payload strings of packets. Each containers have source and destination-target to represent the source and destination for each case. Figure 5 shows the YANG tree of the Condition object. The Condition Sub-model SHALL have following information:¶
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 mapping 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 following information:¶
The Policy Endpoint Group is a very important part of building User-Construct based policies. A Security Administrator would create and use these objects to represent a logical entity in their business environment, where a Security Policy is to be applied. There are multiple managed objects that constitute a Policy's Endpoint Group, as shown in Figure 7. Figure 8 shows the YANG tree of the Endpoint-Groups object. This section lists these objects and relationship among them.¶
It is assumed that the information of Endpoint Groups (e.g., User-group, Device-group, and Location-group) such as the IP address(es) of each member in a group are stored in the I2NSF database available to the Security Controller, and that the IP address information of each group in the I2NSF database is synchronized with other systems in the networks under the same administration.¶
This object represents a User-Group. Figure 9 shows the YANG tree of the User-Group object. The User-Group object SHALL have the following information:¶
This object represents a Device-Group. Figure 10 shows the YANG tree of the Device-group object. The Device-Group object SHALL have the following information:¶
This object represents a location group based on either tag or other information. Figure 11 shows the YANG tree of the Location-Group object. The Location-Group object SHALL have the following information:¶
This object represents a URL group based on a Uniform Resource Locator (URL) or web address. Figure 12 shows the YANG tree of the URL-Group object. The URL-Group object SHALL have the following information:¶
The threat prevention plays an important part in the overall security posture by reducing the attack surfaces. This information could come from various threat feeds (i.e., sources for obtaining the threat information). There are multiple managed objects that constitute this category. This section lists these objects and relationship among them. Figure 14 shows the YANG tree of a Threat-Prevention object.¶
This object represents a threat feed which provides the signatures of malicious activities. Figure 15 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. The retrieval of the threat signatures by the I2NSF User is out of scope in this document.¶
Note that signature-set in I2NSF Capability [I-D.ietf-i2nsf-capability-data-model] is the setting of signatures, which means the configuration of signatures for Intrusion Prevention System (IPS). On the other hand, signature-type in Consumer-Facing Interface is the type of signatures (e.g., YARA signatures, SNORT signatures, and Suricata signatures).¶
This object represents a custom list created for the purpose of defining an exception to threat feeds. Figure 16 shows the YANG tree of a Payload-content list. The Payload-Content object SHALL have the following information:¶
Network Configuration Access Control Model (NACM) provides a user group with an access control with the following features [RFC8341]:¶
The data model of the I2NSF Consumer-Facing Interface utilizes the NACM's mechanisms to manage the access control on the I2NSF Consumer-Facing Interface. The NACM with the above features can be used to set up the access control rules of a user group in the I2NSF Consumer-Facing Interface.¶
Figure 17 shows part of the NACM module to enable the access control of a user group for the I2NSF Consumer-Facing Interface. To use the NACM, a user needs to configure either a NETCONF server [RFC6241] or a RESTCONF server [RFC8040] to enable the NACM module. Then, the user can simply use an account of root or admin user for the access control for the module of the I2NSF Consumer-Facing Interface (i.e., ietf-i2nsf-cons-facing-interface). An XML example to configure the access control of a user group for the I2NSF Consumer-Facing Interface can be seen in Section 9.¶
The main objective of this document is to provide the YANG data model of 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 must be aligned with the information model of the Consumer-Facing Interface. The transformation of the information model is performed so that this YANG data model can facilitate the efficient delivery of the control or management messages.¶
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 suggests use cases for security policy rules such as time-based firewall, VoIP/VoCN security service, and DDoS-attack mitigation in Section 8.¶
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] [RFC0793] [RFC0854] [RFC0959] [RFC1939] [RFC2595] [RFC3022] [RFC3261] [RFC3986] [RFC4250] [RFC4340] [RFC4443] [RFC5321] [RFC5646] [RFC8075] [RFC8335] [RFC8805] [RFC9051] [RFC9110] [RFC9112] [RFC9113] [RFC9260] [IANA-ICMP-Parameters] [IANA-ICMPv6-Parameters] [I-D.ietf-i2nsf-capability-data-model] [I-D.ietf-i2nsf-nsf-monitoring-data-model] [I-D.ietf-tcpm-rfc793bis] [SNORT] [STIX] [SURICATA] [YARA].¶
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 use cases are: Database registration, time-based firewall for web filtering, VoIP/VoCN security service, and DDoS-attack mitigation.¶
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 either of three different groups (i.e., user-group, device-group, and url-group), each of them should be registered with information such as ip-addresses or protocols used by devices.¶
Figure 19 shows an example XML representation of the registered information for the user-group and device-group with IPv4 addresses [RFC5737].¶
Also, Figure 20 shows an example XML representation of the registered information for the user-group and device-group with 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 comming from 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 seucurity 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 are more than the set threshold, then the admin can set the percentage of the packets to be dropped to safely maintain the service. In this scenario, the source is set as "any" to block any sources which send abnormal amount of packets. The destination is set as "web_server01". Once the rule is set and delivered and enforced to the nsfs by the securiy controller, the NSFs will monitor the incoming packet amounts and the destination to act according to the rule set. The XML instance is described below:¶
DDoS-condition Firewall¶
This is an example for creating privileges for a group of users (i.e., a user group) to access and use the I2NSF Consumer-Facing Interface to create security policies via the interface. For the access control of the Consumer-Facing Interface, the NACM module can be used. Figure 24 shows an XML example the access control of a user group (named Example-Group) for I2NSF Consumer-Facing Interface A group called Example-Group can be created and configured with NACM for the Consumer-Facing Interface. For Example-Group, a rule list can created with the name of Example-Group-Rules. Example-Group-Rules has two rules of Example-Group-Rule1 and Example-Group-Rule2 as follows. For Example-Group-Rule1, the privilege of "Read" is allowed to Example-Group for the Consumer-Facing Interface. On the other hand, for Example-Group-Rule2, the privileges of "Create", "Update", and "Delete" are denied against Example-Group for the Consumer-Facing Interface.¶
The access control for the I2NSF Consumer-Facing Interface is as follows.¶
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 are collected into a single list node with the following sensitivity/vulnerability:¶
Some of the readable data nodes in this YANG module may be considered sensitive or vulnerable in some network environments. It is thus important to control read access (e.g., via get, get-config, or notification) to these data nodes. These are the subtrees and data nodes with their sensitivity/vulnerability:¶
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-22:¶