I2NSF Consumer-Facing Interface YANG Data Model
Department of Computer Science and Engineering
Sungkyunkwan University2066 Seobu-Ro, Jangan-GuSuwonGyeonggi-Do16419Republic of Korea+82 31 299 4957+82 31 290 7996pauljeong@skku.eduhttp://iotlab.skku.edu/people-jaehoon-jeong.php
Department of Electronic, Electrical and Computer Engineering
Sungkyunkwan University2066 Seobu-Ro, Jangan-GuSuwonGyeonggi-Do16419Republic of Korea+82 31 299 4957darkhong@skku.edu
Korea Telecom
70 Yuseong-Ro, Yuseong-GuDaejeon305-811Republic of Korea+82 42 870 8409taejin.ahn@kt.com
Juniper Networks
1133 Innovation WaySunnyvaleCA94089USArkkumar@juniper.net
Huawei
7453 Hickory HillSalineMI48176USA+1-734-604-0332shares@ndzh.com
Security
I2NSF Working GroupInternet-Draft
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.
In a framework of Interface to Network Security Functions (I2NSF)
, 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 ) 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
as the basic model for both the NSF-Facing interface and Consumer-Facing Interface
security policy model of this document.
explains differences between an information and data model.
This document uses the guidelines in to define both the
information and data model for Consumer-Facing Interface.
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 leads to a rapid
advance in the network industry. 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
when, and only
when, they appear in all capitals, as shown here.
This document uses the terminology described in .
This document follows the guidelines of ,
uses the common YANG types defined in , and
adopts the Network Management Datastore Architecture (NMDA) . The meaning of
the symbols in tree diagrams is defined in .
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.
shows the YANG tree of the
Policy object. The Policy object SHALL have the following information:
This field identifies the name of this object.
The language field indicates the language tag that is used
for the natural language text that is included in all of the 'description' attributes.
The language field is encoded following the rules in Section 2.1 of .
The default language tag is "en-US".
This field represents how to resolve conflicts that occur between
actions of the same or different policy rules that
are matched and contained in this particular NSF. The resolution
strategy is described in in detail.
This field contains a list of rules. These rules are defined
for 1) communication between two Endpoint Groups, 2) for
preventing communication with externally or internally
identified threats, and 3) for implementing business requirement
such as controlling access to internal or external resources
for meeting regulatory compliance or business objectives.
An organization may restrict certain communication between a
set of user and applications for example. The threats may be
from threat feeds obtained from external sources or dynamically
identified by using specialty devices in the network. Rule
conflict analysis should be triggered by the monitoring service
to perform an exhaustive detection of anomalies among the
configuration rules installed into the security functions.
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.
shows the YANG data tree of the Rule object.
The rule object SHALL have the following information:
This field identifies the name of this object.This field identifies the priority of the rule.This field includes the information to determine whether the Rule Condition can be evaluated or not. See details in .This field contains all the checking conditions to apply to the objective traffic. See details .This field identifies the action taken when a rule is matched. There is always an implicit action to drop traffic if no rule is matched for a traffic type. See details in .
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).
shows the YANG tree
of the Event object. Event object SHALL have following information:
is defined as a warning about any changes of
configuration, any access violation, the information of
sessions and traffic flows.
is defined as a warning related to service degradation
in system hardware.
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.
shows the YANG tree of
the Condition object. The Condition Sub-model SHALL have following information:
This field represents the general firewall case, where a
security admin can set up firewall conditions using the
information present in this field. The firewall attributes
are represented by source, destination, transport layer protocol,
port numbers, and ICMP parameters. Note that the YANG
module only provide high-level ICMP messages that is shared between
ICMPv4 and ICMPv6 (e.g., Destination Unreachable: Port
Unreachable which is ICMPv4 type 3 code 3 or ICMPv6 type 1
code 4). Also note that QUIC protocol
is excluded in the data model as
it is not considered in the initial I2NSF documents .
The QUIC traffic should not be treated as UDP traffic and
will be considered in the future I2NSF documents.
This field represents the condition for DDoS mitigation, where
a security admin can set up DDoS mitigation conditions using
the information present in this field. The rate of packet,
byte, or flow threshold can be configured to mitigate the
DDoS.
This field represents the condition for Antivirus, where
a security admin can set up Antivirus conditions using
the information present in this field. The file names or types
can be configured to be allowed without the Antivirus
interuption.
This field contains the payload string information. This
information is useful when security rule condition is based
on the string contents of incoming or outgoing packets. The
name referring to the payload-groups defined and registered
in the endpoint-groups.
This field represents the URL to be filtered. This information
can be used to block or allow a certain URL or website. The
url-name is a group of URL or websites to be matched.
This field contains the call source-id, call destination-id,
and user-agent. This information can be used to filter
a caller id or receiver id to prevent any VoIP or VoCN
exploits or attack.
This field provide extra information for the condition for
filtering the network traffic.
The given context conditions are application filter, device type,
user condition, and geographic location.
This field contains the information obtained from threat-feeds
(e.g., Palo-Alto, or RSA-netwitness). This information is
useful when security rule condition is based on the existing
threat reports gathered by other sources.
This object represents actions that Security Admin wants to perform
based on certain traffic class.
shows the YANG tree of the Action object. The Action object SHALL
have following information:
This field identifies the action when a rule is matched by an NSF. The action could be one of "pass", "drop", "reject", "rate-limit", "mirror", "invoke-signaling", "tunnel-encapsulation", "forwarding", and "transformation".This field identifies the action when a rule is matched by an NSF. The action could be one of "rule-log" and "session-log".
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 .
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. shows the YANG tree of the User-Group object.
The User-Group object SHALL have the following information:
This field identifies the name of this object. This represents the MAC address of a user in the user group. This represents the IPv4 address range of a user in the user group. This represents the IPv6 address range of a user in the user group.
This object represents a Device-Group. shows the YANG tree of the Device-group object. The Device-Group object SHALL have the following information:
This field identifies the name of this object. This represents the IPv4 address of a device in the device group. This represents the IPv6 address of a device in the device group. This represents the IPv4 address range of a device in the device group. This represents the IPv6 address range of a device in the device group. This represents the application layer protocols of devices. If this is not set, it cannot support the appropriate protocol
This object represents a location group based on either tag or other information.
shows the YANG tree of
the Location-Group object.
The Location-Group object SHALL have the following information:
This field identifies the name of this object. This field represents the IPv4 Geo-ip address of a location . This field represents the IPv6 Geo-ip address of a location . This field represents the continent where the location group member is located.
This object represents a URL group based on a Uniform Resource Locator (URL) or web address.
shows the YANG tree of
the URL-Group object.
The URLn-Group object SHALL have the following information:
This field identifies the name of this object. This field represents the new URL added by a user to the URL database.
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. shows the YANG tree of a Threat-Prevention object.
This object represents a threat feed which provides the signatures
of malicious activities. shows
the YANG tree of a Threat-feed-list.
The Threat-Feed object SHALL have the following information:
This field identifies the name of
this object. This is the description of
the threat feed. The description should have the clear
indication of the security attack such as attack type (e.g.,
APT) and file types used (e.g., executable malware). This field contains the threat
signatures of malicious programs or activities provided by
the threat-feed. The examples of signature types are "YARA",
"SURICATA", and "SNORT"
.
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.
This object represents a custom list created for the purpose of
defining an exception to threat feeds. shows the YANG tree of a Payload-content list.
The Payload-Content object SHALL have the following information:
This field identifies the name of this object. For example, the name "backdoor" indicates the payload content is related to a backdoor attack.This represents the description of how the payload content is related to a security attack. This contains the payload contents, which are involed in a security attack, such as strings.
Network Configuration Access Control Model (NACM) provides a user group
with an access control with the following features :
Independent control of action, data, and notification access is
provided. A simple and familiar set of datastore permissions is used. Support for YANG security tagging allows default security modes
to automatically exclude sensitive data. Separate default access modes for read, write, and execute
permissions are provided. Access control rules are applied to configurable groups of users.
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.
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
or a RESTCONF server
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 a user group for the
I2NSF Consumer-Facing Interface can be seen in
.
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 .
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 .
It makes references to
.
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.
shows an example XML representation of the registered information for the user-group and device-group with IPv4 addresses .
Also, shows an example XML representation of the registered information for the user-group and device-group with IPv6 addresses .
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 policy name is "security_policy_for_blocking_sns".
The rule name is "block_access_to_sns_during_office_hours".
The Source is "employees".
The destination target is "sns-websites". "sns-websites" is the key which represents the list containing the information, such as URL, about sns-websites.
The action required is to "drop" any attempt to connect to websites related to Social networking.
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. 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 policy name is "security_policy_for_blocking_malicious_voip_packets".
The rule name is "Block_malicious_voip_and_vocn_packets".
The Source is "malicious-id". This can be a single ID or a list of IDs, depending on how the ID are stored in the database. The "malicious-id" is the key so that the security admin can read every stored malicious VOIP IDs that are named as "malicious-id".
The destination target is "employees". "employees" is the key which represents the list containing information about employees, such as IP addresses.
The action required is "drop" when any incoming packets are from "malicious-id".
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
The policy name is "security_policy_for_ddos_attacks".
The rule name is "1000_packets_per_second".
The rate limit exists to limit the incoming amount of packets per second. In this case the rate limit is "1000" packets per second. This amount depends on the packet receiving capacity of the server devices.
The Source is all sources which send abnormal amount of packets.
The action required is to "drop" packet reception is more than 1000 packets per second.
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.
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.
The NACM is enabled.
As a group name, Example-Group is specified.
As members of the group, Alice, Bob, and Eve are specified.
As a rule list name, Example-Group-Rules is specified for
managing privileges of Example-Group's members.
As the first rule name, Example-Group-Rule1 is specified.
This rule is used to give read privilege to Example-Group's members
for the module of the I2NSF Consumer-Facing Interface.
As the second rule name, Example-Group-Rule2 is specified.
This rule is used to deny create, update, and delete privileges
against Example-Group's members for the module of the I2NSF
Consumer-Facing Interface.
This document requests IANA to register the following URI in the
"IETF XML Registry" :
This document requests IANA to register the following YANG
module in the "YANG Module Names" registry :
The YANG module specified in this document defines a data
schema designed to be accessed through network management
protocols such as NETCONF or
RESTCONF . The lowest NETCONF layer
is the secure transport layer, and the required secure
transport is Secure Shell (SSH) .
The lowest RESTCONF layer is HTTPS, and the required secure
transport is TLS .
The Network Configuration Access Control Model (NACM)
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:
list i2nsf-cfi-policy: Writing to almost any element of
this YANG module would directly impact on the configuration
of NSFs, e.g., completely turning off security monitoring
and mitigation capabilities; altering the scope of this
monitoring and mitigation; creating an overwhelming logging
volume to overwhelm downstream analytics or storage
capacity; creating logging patterns which are confusing;
or rendering useless trained statistics or artificial
intelligence models.
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:
list i2nsf-cfi-policy: The leak of this node to an attacker
could reveal the specific configuration of security
controls to an attacker. An attacker can craft an attack
path that avoids observation or mitigations; one may reveal
topology information to inform additional targets or enable
lateral movement; one enables the construction of an attack
path that avoids observation or mitigations; one provides
an indication that the operator has discovered the attack.
This node also holds a list of endpoint data that is
considered private to the users.
Assigned Internet Protocol NumbersInternet Assigned Numbers Authority (IANA)Internet Control Message Procotol version 6 (ICMPv6) ParametersInternet Assigned Numbers Authority (IANA)ContinentBritannicaYARASURICATASNORTStructured Threat Information Expression (STIX)
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), 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).
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-20:
This version updated a 'leaf language' pattern by adding extra
parentheses around
"[A-Za-z]{2,3}(-[A-Za-z]{3}(-[A-Za-z]{3}){0,2})?" and removing
a range character '-' between characters 'Y' and 'Z' in
"|([0-9][A-Za-z0-9]{3})))*(-[0-9A-WY-Za-wy-z]" as 'Y' is
alphabetically adjacent to 'Z'.