wdiff draft-ietf-i2nsf-capability-01.txt draft-ietf-i2nsf-capability-02.txt

I2NSF L. Xia
Internet-Draft
Internet Draft J. Strassner
Intended status: Standard Track Huawei
Expires: October 3, 2018 January 02, 2019 C. Basile
PoliTO
D. Lopez
TID
April 3,
July 02, 2018

Information Model of NSFs Capabilities
draft-ietf-i2nsf-capability-01.txt

Abstract

This document defines the concept of an NSF (Network Security
Function) Capability, as well as its information model. Capabilities
are a set of features that are available from a managed entity, and
are represented as data that unambiguously characterizes an NSF.
Capabilities enable management entities to determine the set offer
features from available NSFs that will be used, and simplify the
management of NSFs.
draft-ietf-i2nsf-capability-02.txt

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Abstract

This draft defines the concept of an NSF (Network Security Function)
capability, as well as its information model. Capabilities are a set
of features that are available from a managed entity, and are
represented as data that unambiguously characterizes an NSF.
Capabilities enable management entities to determine the set of
features from available NSFs that will be used, and simplify the
management of NSFs.

Table of Contents

1. Introduction ................................................... 4 ................................................. 2
2. Conventions used in this document .............................. 5 ............................ 3
2.1. Acronyms .................................................. 5 ................................................ 3
3. Capability Information Model Design ............................ 6 .......................... 4
3.1. Design Principles and ECA Policy Model Overview ........... 6 ......... 5
3.2. Relation with the External Information Model .............. ............ 8
3.3. I2NSF Capability Information Model Theory of Operation ... 10 .. 9
3.3.1. I2NSF Capability Information Model ................ 11
3.3.2. The SecurityCapability class ...................... 13
3.3.3. I2NSF Condition Clause Operator Types ............... 11
3.3.2 ............. 14
3.3.4. Capability Selection and Usage ...................... 12
3.3.3. .................... 16
3.3.5. Capability Algebra ................................. 13
3.4. Initial NSFs Capability Categories ....................... 16
3.4.1. Network Security Capabilities ....................... 16
3.4.2. Content Security Capabilities ....................... 17
3.4.3. Attack Mitigation Capabilities ...................... ............................... 17
4. Information Sub-Model for Network Security Capabilities ....... 18
4.1. Information Sub-Model for Network Security ............... 18
4.1.1. Network Security Policy Rule Extensions ............. IANA Considerations ......................................... 19
4.1.2. Network Security Policy Rule Operation ..............
5. References .................................................. 19
5.1. Normative References ................................... 19
5.2. Informative References ................................. 20
4.1.3. Network Security Event Sub-Model ....................
6. Acknowledgments ............................................. 22
4.1.4. Network Security Condition Sub-Model ................ 23
4.1.5. Network Security Action Sub-Model ................... 25
4.2. Information Model for I2NSF Capabilities ................. 26
4.3. Information Model for Content Security Capabilities ...... 27
4.4. Information Model for Attack Mitigation Capabilities ..... 28
5. Security Considerations ....................................... 29
6. IANA Considerations ........................................... 29
7. Contributors .................................................. 29
8. References .................................................... 29
8.1. Normative References ..................................... 29
8.2. Informative References ................................... 30
Appendix A. Network Security Capability Policy Rule Definitions .. 32
A.1. AuthenticationECAPolicyRule Class Definition ............. 32
A.2. AuthorizationECAPolicyRuleClass Definition ............... 34
A.3. AccountingECAPolicyRuleClass Definition .................. 35
A.4. TrafficInspectionECAPolicyRuleClass Definition ........... 37
A.5. ApplyProfileECAPolicyRuleClass Definition ................ 38
A.6. ApplySignatureECAPolicyRuleClass Definition .............. 40
Appendix B. Network Security Event Class Definitions ............. 42
B.1. UserSecurityEvent Class Description ...................... 42
B.1.1. The usrSecEventContent Attribute .................... 42
B.1.2. The usrSecEventFormat Attribute ..................... 42
B.1.3. The usrSecEventType Attribute ....................... 42
B.2. DeviceSecurityEvent Class Description .................... 43
B.2.1. The devSecEventContent Attribute .................... 43
B.2.2. The devSecEventFormat Attribute ..................... 43
B.2.3. The devSecEventType Attribute ....................... 44
B.2.4. The devSecEventTypeInfo[0..n] Attribute ............. 44
B.2.5. The devSecEventTypeSeverity Attribute ............... 44

Table of Contents (continued)

B.3. SystemSecurityEvent Class Description .................... 44
B.3.1. The sysSecEventContent Attribute .................... 45
B.3.2. The sysSecEventFormat Attribute ..................... 45
B.3.3. The sysSecEventType Attribute ....................... 45
B.4. TimeSecurityEvent Class Description ...................... 45
B.4.1. The timeSecEventPeriodBegin Attribute ............... 46
B.4.2. The timeSecEventPeriodEnd Attribute ................. 46
B.4.3. The timeSecEventTimeZone Attribute .................. 46
Appendix C. Network Security Condition Class Definitions ......... 47
C.1. PacketSecurityCondition .................................. 47
C.1.1. PacketSecurityMACCondition .......................... 47
C.1.1.1. The pktSecCondMACDest Attribute ................ 47
C.1.1.2. The pktSecCondMACSrc Attribute ................. 47
C.1.1.3. The pktSecCondMAC8021Q Attribute ............... 48
C.1.1.4. The pktSecCondMACEtherType Attribute ........... 48
C.1.1.5. The pktSecCondMACTCI Attribute ................. 48
C.1.2. PacketSecurityIPv4Condition ......................... 48
C.1.2.1. The pktSecCondIPv4SrcAddr Attribute ............ 48
C.1.2.2. The pktSecCondIPv4DestAddr Attribute ........... 48
C.1.2.3. The pktSecCondIPv4ProtocolUsed Attribute ....... 48
C.1.2.4. The pktSecCondIPv4DSCP Attribute ............... 48
C.1.2.5. The pktSecCondIPv4ECN Attribute ................ 48
C.1.2.6. The pktSecCondIPv4TotalLength Attribute ........ 49
C.1.2.7. The pktSecCondIPv4TTL Attribute ................ 49
C.1.3. PacketSecurityIPv6Condition ......................... 49
C.1.3.1. The pktSecCondIPv6SrcAddr Attribute ............ 49
C.1.3.2. The pktSecCondIPv6DestAddr Attribute ........... 49
C.1.3.3. The pktSecCondIPv6DSCP Attribute ............... 49
C.1.3.4. The pktSecCondIPv6ECN Attribute ................ 49
C.1.3.5. The pktSecCondIPv6FlowLabel Attribute .......... 49
C.1.3.6. The pktSecCondIPv6PayloadLength Attribute ...... 49
C.1.3.7. The pktSecCondIPv6NextHeader Attribute ......... 50
C.1.3.8. The pktSecCondIPv6HopLimit Attribute ........... 50
C.1.4. PacketSecurityTCPCondition .......................... 50
C.1.4.1. The pktSecCondTCPSrcPort Attribute ............. 50
C.1.4.2. The pktSecCondTCPDestPort Attribute ............ 50
C.1.4.3. The pktSecCondTCPSeqNum Attribute .............. 50
C.1.4.4. The pktSecCondTCPFlags Attribute ............... 50
C.1.5. PacketSecurityUDPCondition ....................... 50
C.1.5.1.1. The pktSecCondUDPSrcPort Attribute ........ 50
C.1.5.1.2. The pktSecCondUDPDestPort Attribute ....... 51
C.1.5.1.3. The pktSecCondUDPLength Attribute ......... 51
C.2. PacketPayloadSecurityCondition ........................... 51
C.3. TargetSecurityCondition .................................. 51
C.4. UserSecurityCondition .................................... 51
C.5. SecurityContextCondition ................................. 52
C.6. GenericContextSecurityCondition .......................... 52

Table of Contents (continued)

Appendix D. Network Security Action Class Definitions ............. 53
D.1. IngressAction ............................................ 53
D.2. EgressAction ............................................. 53
D.3. ApplyProfileAction ....................................... 53
Appendix E. Geometric Model ...................................... 54
Authors' Addresses ............................................... 57

1. Introduction

The rapid development of virtualized systems requires advanced
security protection in various scenarios. Examples include network
devices in an enterprise network, user equipments User Equipment in a mobile
network, devices in the Internet of Things, or residential access
users [RFC8192].

NSFs produced by multiple security vendors provide various security
Capabilities
capabilities to customers. Multiple NSFs can be combined together to
provide security services over the given network traffic, regardless
of whether the NSFs are implemented as physical or virtual
functions.

Security Capabilities describe the set of network security-related
features functions that Network Security
Functions (NSFs) are available to use provide for security policy
enforcement purposes. Security Capabilities are independent of the
actual security control mechanisms that will implement them.

Every NSF
registers SHOULD be described with the set of Capabilities capabilities it
offers. Security Capabilities
are a market enabler, providing a way to define customized security
protection by unambiguously describing the security features offered
by a given NSF. Moreover, Security Capabilities enable security functionality to be
described in a vendor-neutral manner. That is, it is not required needed to
refer to a specific product or technology when designing the
network; rather, the functionality functions characterized by their
Capabilities capabilities
are considered.

According to [RFC8329], there Security Capabilities are two types of I2NSF interfaces
available for security policy provisioning:

o Interface between I2NSF users and applications, and a security
controller (Consumer-Facing Interface): this is a service-
oriented interface that provides market enabler,
providing a communication channel
between consumers of NSF data and services and the network
operator's security controller. This enables security
information way to be exchanged between various applications (e.g.,
OpenStack, or various BSS/OSS components) and the define customized security
controller. The design goal of the Consumer-Facing Interface
is to decouple protection by
unambiguously describing the specification of security services from
their implementations.

o Interface between NSFs (e.g., firewall, intrusion prevention,
or anti-virus) and the security controller (NSF-Facing
Interface): The NSF-Facing Interface is used to decouple the
security management scheme from the set of NSFs and their
various implementations for this scheme, and is independent
of how the NSFs are implemented (e.g., run in Virtual
Machines or physical appliances). This document defines an
object-oriented information model for network security, content
security, and attack mitigation Capabilities, along with
associated I2NSF Policy objects. features offered by a given
NSF.

This document is organized as follows. Section 2 defines conventions
and acronyms used. Section 3 discusses the design principles for the
I2NSF Capability information model and related policy model objects.
Section 4 defines the structure of the capability information model, which
describes the policy related ECA model, and capability objects design; details of the
provides detailed information model elements are contained in the appendices. design of I2NSF network security
capability.

2. Conventions used in this document

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC-2119 [RFC2119].

This document uses terminology defined in
[I-D.draft-ietf-i2nsf-terminology] [I-D.draft-ietf-i2nsf-
terminology] for security related and I2NSF scoped terminology.

2.1. Acronyms

AAA: Access control, Authorization, Authentication
ACL: Access Control List
(D)DoD: (Distributed) Denial of Service (attack)
ECA: Event-Condition-Action
FMR: First Matching Rule (resolution strategy)
FW: Firewall
GNSF: Generic Network Security Function
HTTP: HyperText Transfer Protocol
I2NSF:

I2NSF - Interface to Network Security Functions
IPS: Intrusion Prevention System
LMR: Last Matching Rule (resolution strategy)
MIME: Multipurpose Internet Mail Extensions
NAT: Network Address Translation
NSF:

NSF - Network Security Function
RPC: Remote Procedure Call
SMA: String Matching Algorithm
URL: Uniform Resource Locator
VPN: Virtual Private Network

DNF - Disjunctive Normal Form
3. Capability Information Model Design

The starting point of the design of the

A Capability information model Information Model (CapIM) is a formalization of the
functionality that an NSF advertises. This enables the categorization precise
specification of types what an NSF can do in terms of security functions. policy
enforcement, so that computer-based tasks can unambiguously refer
to, use, configure, and manage NSFs. Capabilities MUST be defined in
a vendor- and technology-independent manner (e.g., regardless of the
differences among vendors and individual products).

Humans are able to refer to categories of security controls and
understand each other. For instance, security experts agree on what
is meant by the terms "IPS", "Anti-Virus", "NAT", "filtering", and "VPN concentrator". Network
As a further example, network security experts unequivocally refer
to "packet filters" as stateless devices able to allow or deny
packet forwarding based on various conditions (e.g., source and
destination IP addresses, source and destination ports, and IP
protocol type fields) [Alshaer].

However, more information is required in case of other devices, like
stateful firewalls or application layer filters. These devices
filter packets or communications, but there are differences in the
packets and communications that they can categorize and the states
they maintain. Humans deal with these differences by asking more
questions to determine the specific category and functionality of
the device. Machines can follow a similar approach, which is
commonly referred to as question-answering [Hirschman] [Galitsky].
In this context, the CapIM and the derived Data Models provide
important and rich information sources.

Analogous considerations can be applied for channel protection
protocols, where we all understand that they will protect packets by
means of symmetric algorithms whose keys could have been negotiated
with asymmetric cryptography, but they may work at different layers
and support different algorithms and protocols. To ensure
protection, these protocols apply integrity, optionally
confidentiality, anti-reply protections, and authenticate peers.

3.1. Capability Information Model Overview

This document defines

The CapIM is intended to clarify these ambiguities by providing a model
formal description of security Capabilities NSF functionality. The set of functions that provides
are advertised MAY be restricted according to the foundation for privileges of the
user or application that is viewing those functions. I2NSF
Capabilities enable unambiguous specification of the security
capabilities available in a (virtualized) networking environment,
and their automatic management processing by means of NSFs. computer-based
techniques.

This includes enabling the security controller to properly identify
and manage NSFs, and allow NSFs to properly declare their functionalities,
functionality, so that they can be used in the correct way.

3.1. Design Principles and ECA Policy Model Overview

This document defines an information model for representing NSF
capabilities. Some basic design principles for security Capabilities capabilities
and the systems that have to manage them are:

o Independence: each security Capability should capability SHOULD be an independent
function, with minimum overlap or dependency on other
Capabilities.
capabilities. This enables each security Capability capability to be
utilized and assembled together freely. More importantly, changes
to a Capability will not one capability SHOULD NOT affect other Capabilities. capabilities. This
follows the Single Responsibility Principle [Martin] [OODSRP].

o Abstraction: each Capability should capability MUST be defined in a vendor-
independent manner, manner.

o Advertisement: A dedicated, well-known interface MUST be used to
advertise and associated register the capabilities of each NSF. This same
interface MUST be used by other I2NSF Components to determine
what Capabilities are currently available to them.

o Execution: a dedicated, well-known interface MUST be used to provide
configure and monitor the use of a capability. This provides a
standardized ability to describe its functionality, and report
its processing results. This facilitates multi-vendor
interoperability.

o Automation: the system has MUST have the ability to discover, negotiate, auto-discover,
auto-negotiate, and update auto-update its security Capabilities automatically capabilities (i.e.,
without human intervention). These features are useful especially useful
for the management of a large number of NSFs. They are essential to add
for adding smart services (e.g., analysis, refinement, Capability analysis, capability
reasoning, and optimization) for to the security scheme employed.
These features are supported by many design patterns, including
the Observer Pattern [OODOP], the Mediator Pattern [OODMP], and a
set of Message Exchange Patterns [Hohpe].

o Scalability: the management system must SHOULD have the Capability capability to
scale up/down or scale in/out. Thus, it can meet various
performance requirements derived from changeable network traffic
or service requests. In addition, security Capabilities capabilities that are
affected by scalability changes must SHOULD support reporting
statistics to the security controller to assist its decision on
whether it needs to invoke scaling or not. However, this requirement is for
information only, and is beyond the scope of this document.

Based on the above principles, this document defines a set of abstract and vendor-neutral
Capabilities with standard interfaces is defined. This provides a
Capability capability
model that enables a an NSF to register (and hence advertise) its set
of NSFs capabilities that are required at other I2NSF Components can use. These
capabilities MAY have their access control restricted by policy;
this is out of scope for this document. The set of capabilities
provided by a given time to be selected, as well as the unambiguous definition set of NSFs unambiguously define the security
offered by the set of NSFs used. The security controller can compare
the requirements of users and applications to the set of Capabilities
capabilities that are currently available in order to choose which
capabilities of which NSFs are needed to meet those requirements.
Note that this choice is independent of vendor, and instead relies
specifically on the Capabilities capabilities (i.e., the description) of the
functions provided. The security controller may also be able to customize the
functionality of selected NSFs.

Furthermore, when an unknown threat (e.g., zero-day exploits and
unknown malware) is reported by an NSF, new Capabilities capabilities may be
created, and/or existing Capabilities capabilities may be updated (e.g., by
updating its signature and algorithm). This results in enhancing the
existing NSFs (and/or creating new NSFs) to address the new threats.
New Capabilities capabilities may be sent to and stored in a centralized
repository, or stored separately in a vendor's local repository. In
either case, a standard interface facilitates the update process.

Note
This document specifies a metadata model that MAY be used to further
describe and/or prescribe the characteristics and behavior of the
I2NSF capability model. For example, in this case, metadata could be
used to describe the updating of the capability, and prescribe the
particular version that an implementation should use. This initial
version of the model covers and has been validated to describe NSFs
that are designed with a set of capabilities (which covers most of
the existing NSFs). Checking the behavior of the model with systems cannot
that change capabilities dynamically create a new Capability
without human interaction. This is an area for further study.

3.2. ECA Policy Model Overview at runtime has been extensively
explored (e.g., impact on automatic registration).

The "Event-Condition-Action" (ECA) policy model in [RFC8329] is used
as the basis for the design of I2NSF Policy Rules; the capability model; definitions of the following
all I2NSF policy-related terms are also specified defined in
[I-D.draft-ietf-i2nsf-terminology]: [I-D.draft-ietf-
i2nsf-terminology]. The following three terms define the structure
and behavior of an I2NSF imperative policy rule:

o Event: An Event is defined as any important occurrence in time of
a change in the system being managed, and/or in the environment
of the system being managed. When used in the context of I2NSF
Policy Rules, it is used to determine whether the Condition
clause of the I2NSF Policy Rule can be evaluated or not. Examples
of an I2NSF Event include time and user actions (e.g., logon,
logoff, and actions that violate an ACL).

o Condition: A condition is defined as a set of attributes,
features, and/or values that are to be compared with a set of
known attributes, features, and/or values in order to determine
whether or not the set of Actions in that (imperative) I2NSF
Policy Rule can be executed or not. Examples of I2NSF Conditions
include matching attributes of a packet or flow, and comparing
the internal state of an NSF to a desired state.

o Action: An action is used to control and monitor aspects of
flow-based flow-
based NSFs when the event and condition clauses are satisfied.
NSFs provide security functions by executing various Actions.
Examples of I2NSF Actions include providing intrusion detection
and/or protection, web and flow filtering, and deep packet
inspection for packets and flows.

An I2NSF Policy Rule is made up of three Boolean clauses: an Event
clause, a Condition clause, and an Action clause. This structure is
also called an ECA (Event-Condition-Action) Policy Rule. A Boolean
clause is a logical statement that evaluates to either TRUE or
FALSE. It may be made up of one or more terms; if more than one term, term
is present, then a each term in the Boolean clause connects the terms is combined using
logical connectives (i.e., AND, OR, and NOT). It

An I2NSF ECA Policy Rule has the following semantics:

IF <event-clause> is TRUE

IF <condition-clause> is TRUE

THEN execute <action-clause> [constrained by metadata]

END-IF

Technically, the "Policy Rule" is really a container that aggregates
the above three clauses, as well as metadata. Aggregating metadata
enables business logic to be used to prescribe behavior. For
example, suppose a particular ECA Policy Rule contains three actions
(A1, A2, and A3, in that order). Action A2 has a priority of 10;
actions A1 and A3 have no priority specified. Then, metadata may be
used to restrict the set of actions that can be executed when the
event and condition clauses of this ECA Policy Rule are evaluated to
be TRUE; two examples are: (1) only the first action (A1) is
executed, and then the policy rule returns to its caller, or (2) all
actions are executed, starting with the highest priority.

The above ECA policy model is very general and easily extensible,
and can avoid potential constraints that could limit the
implementation of generic security Capabilities.

3.3. extensible.

3.2. Relation with the External Information Model

Note: the symbology used from this point forward is taken from
section 3.3 of [I-D.draft-ietf-supa-generic-policy-info-model].

The I2NSF NSF-Facing Interface is in charge of selecting used to select and
managing manage the NSFs
using their Capabilities. capabilities. This is done by using the following approaches: approach:

1) Each NSF registers its Capabilities capabilities with the management system
when it "joins",
through a dedicated interface, and hence hence, makes its Capabilities capabilities
available to the management system;

2) The security controller selects the set of Capabilities
required to meet compares the needs of the security service
with the set of capabilities from all available NSFs that it manages;
manages using the CapIM;

3) The security controller uses the Capability information model
to match chosen Capabilities CapIM to NSFs, independent select the final set of vendor;
NSFs to be used;

4) The security controller takes the above information and creates or
uses one or more data models from the Capability
information model CapIM to manage the NSFs;

5) Control and monitoring can then begin.

This assumes that an external information model is used to define
the concept of an ECA Policy Rule and its components (e.g., Event,
Condition, and Action objects). This enables I2NSF Policy Rules
[I-D.draft-ietf-i2nsf-terminology] [I-
D.draft-ietf-i2nsf-terminology] to be subclassed from an external
information model.

Capabilities are defined as classes (e.g.,

The external ECA Information Model supplies at least a set of objects)
objects that
exhibit represent a generic ECA Policy Rule, and a common set of characteristics
objects that represent Events, Conditions, and behavior
[I-D.draft-ietf-supa-generic-policy-info-model].

Each Capability is made up of at least one model element (e.g.,
attribute, method, or relationship) Actions that differentiates it from all
other objects in can be
aggregated by the system. Capabilities are, generically, a type
of metadata generic ECA Policy Rule. This enables appropriate
I2NSF Components to reuse this generic model for different purposes,
as well as specialize it (i.e., information create new model objects) to
represent concepts that describes, are specific to I2NSF and/or prescribes,
the behavior of objects); hence, it an application
that is using I2NSF.

It is also assumed that an the external
information model is used ECA Information Model also has the
ability to define aggregate metadata. This enables metadata (preferably, in the
form to be used to
prescribe and/or describe characteristics and behavior of a class hierarchy). Therefore, it is assumed that the ECA
Policy Rule. Specifically, Capabilities are subclassed from an this
external metadata model.

The Capability sub-model is used for advertising, creating,
selecting, and managing a set of specific security If the desired Capabilities
independent of are already
defined in the type and vendor of device CapIM, then no further action is necessary.
Otherwise, new Capabilities SHOULD be defined either by defining new
classes that contains can wrap existing classes using the NSF.
That is, decorator pattern
[Gamma] or by another mechanism (e.g., through subclassing); the user
parent class of the NSF-Facing Interface does not care whether
the NSF is virtualized new Capability SHOULD be either an existing
CapIM metadata class or hosted in a physical device, who the
vendor of class defined in the NSF is, and which set of entities external metadata
information model. In either case, the NSF is
communicating with (e.g., a firewall or an IPS). Instead, ECA objects can use the user
only cares about
existing aggregation between them and the set Metadata class to add
metadata to appropriate ECA objects.

Detailed descriptions of each portion of Capabilities that the NSF has, such as
packet filtering or deep packet inspection. The overall structure
is illustrated information model are
given in the figure below:

3.3. I2NSF +-----+------+
Security Policies | Capability |
| Sub-Model |
+------------+

Figure 1. The Overall I2NSF Information Model Design

This draft defines a set Theory of extensions to a generic, external, ECA
Policy Model Operation

Capabilities are typically used to represent various NSF ECA Security Policy Rules. It
also defines the Capability Sub-Model; this enables ECA Policy
Rules to control which functions that can
be invoked. Capabilities are seen by which actors, objects, and hence, can be used by in the I2NSF system. Finally, it places requirements on what
type
event, condition, and/or action clauses of extensions are required to the generic, external, an I2NSF ECA
information model and Policy Rule.

The I2NSF CapIM refines a predefined (and external) metadata models, in order to manage model;
the
lifecycle application of I2NSF Capabilities.

Both of the external models shown in Figure 1 could, but do not have
to, be based on the SUPA information model
[I-D.draft-ietf-supa-generic-policy-info-model]. Note that classes in
the Capability Sub-Model will inherit the AggregatesMetadata
aggregation from the External Metadata Information Model.

The external ECA Information Model supplies at least one set of classes
that represent a generic ECA Policy Rule, and a set of classes that
represent Events, Conditions, and Actions that can be aggregated by
the generic ECA Policy Rule. This enables I2NSF to reuse this
generic model for different purposes, as well as refine it (i.e.,
create new subclasses, or add attributes and relationships) to
represent I2NSF-specific concepts.

It is assumed that the external ECA Information Model has the
ability to aggregate metadata. Capabilities are then sub-classed
from an appropriate class in the external Metadata Information Model;
this enables the ECA objects to use the existing aggregation between
them and Metadata to add Metadata to appropriate ECA objects.

Detailed descriptions of each portion of the information model are
given in the following sections.

3.4. I2NSF Capability Information Model: Theory of Operation

Capabilities are typically used to represent NSF functions that can
be invoked. Capabilities are objects, and hence, can be used in the
event, condition, and/or action clauses of an I2NSF ECA Policy Rule.
The I2NSF Capability information model refines a predefined metadata
model; the application of I2NSF Capabilities is done by refining a
predefined ECA Policy Rule Capabilities is done by refining a
predefined (and external) ECA Policy Rule information model that
defines how to use, manage, or otherwise manipulate a set of Capabilities.
capabilities. In this approach, an I2NSF Policy Rule is a container
that is made up of three clauses: an event clause, a condition
clause, and an action clause. When the I2NSF policy engine receives
a set of events, it matches those events to events in active ECA
Policy Rules. If the event matches, then this triggers the
evaluation of the condition clause of the matched I2NSF Policy Rule.
The condition clause is then evaluated; if it matches, then the set
of actions in the matched I2NSF Policy Rule MAY be executed.

This document defines additional important extensions to both The
operation of each of these clauses MAY be affected by metadata that
is aggregated by either the
external ECA Policy Rule model and the external Metadata model that
are used and/or by each clause,
as well as the I2NSF Information Model; examples include selected resolution strategy, external data, and default action. All these
extensions come from the geometric strategy.

Condition clauses are logical formulas that combine one or more
conditions that evaluate to a Boolean (i.e., true or false) result.
The values in a condition clause are built on values received or
owned by the NSF. For instance, the condition clause 'ip source ==
1.2.3.4' is true when the IP address is equal to 1.2.3.4. Two or
more conditions require a formal mechanism to represent how to
operate on each condition to produce a result. For the purposes of
this document, every condition clause MUST be expressed in either
conjunctive or disjunctive normal form. Informally, conjunctive
normal form expresses a clause as a set of sub-clauses that are
logically ANDed together, where each sub-clause contains only terms
that use OR and/or NOT operators). Similarly, disjunctive normal
form is a set of sub-clauses that are logically ORed together, where
each sub-clause contains only terms that use AND and/or NOT
operators.

This document defines additional important extensions to both the
external ECA Policy Rule model and the external Metadata model that
are used by the I2NSF CapIM; examples include resolution strategy,
external data, and default actions. All these extensions come from
the geometric model defined in [Bas12]. A more detailed description
is provided in Appendix E; a summary of the important points of this
geometric model follows.

Formally, given a set of actions in an I2NSF Policy Rule, the
resolution strategy maps all the possible subsets of actions to an
outcome. In other words, the resolution strategy is included in the an
I2NSF Policy Rule to decide how to evaluate all the actions in a
particular I2NSF Policy Rule. This is then extended to include all
possible I2NSF Policy Rules that can be applied in a particular
scenario. Hence, the final action set from all the
matching I2NSF Policy Rules
is deduced. Rule.

Some concrete examples of resolution strategy are the are:

o First Matching Rule (FMR) or

o Last Matching Rule (LMR) resolution strategies. When
no rule matches a packet,

o Prioritized Matching Rule (PMR) with Errors (PMRE)

o Prioritized Matching Rule with No Errors (PMRN)

In the NSFs may select above, a default action, if
they support one.

Resolution strategies PMR strategy is defined as follows:

1. Order all actions by their Priority (highest is first, no
priority is last); actions that have the same priority may be
appear in any order in their relative location.

2. For PMRE: if any action fails to execute properly, temporarily
stop execution of all actions. Invoke the error handler of the
failed action. If the error handler is able to recover from the
error, then continue execution of any remaining actions; else,
terminate execution of the ECA Policy Rule.

3. For PMRN: if any action fails to execute properly, stop
execution of all actions. Invoke the error handler of the failed
action, but regardless of the result, execution of the ECA
Policy Rule MUST be terminated.

Regardless of the resolution strategy, when no rule matches a
packet, a default action MAY be executed.

Resolution strategies may use, besides intrinsic rule data (i.e.,
event, condition, and action clauses), "external data" associated to
each rule, such as priority, identity of the creator, and creation
time. Two examples of this are attaching metadata to the policy
action and/or policy rule, and associating the policy rule with
another class to convey such information.

3.4.1.

3.3.1. I2NSF Condition Clause Operator Types

After having analyzed the literature and some existing NSFs, the
types Capability Information Model

Figure 1 below shows one example of selectors are categorized as exact-match, range-based,
regex-based, and custom-match [Bas15][Lunt].

Exact-match selectors are (unstructured) sets: elements can only be
checked for equality, as no order is defined on them. As an example,
the protocol type field external model. This is a
simplified version of the IP header MEF Policy model [PDO]. For our purposes:

o MCMPolicyObject is an unordered set of
integer values associated to protocols. The assigned protocol
numbers are maintained by the IANA (http://www.iana.org/assignments/
protocol-numbers/protocol-numbers.xhtml).

In this selector, it abstract class, and is only meaningful to specify condition clauses
that use either the "equals" or "not equals" operators:

proto = tcp, udp (protocol type field equals to TCP or UDP)
proto != tcp (protocol type field different derived from TCP)

No other operators are allowed on exact-match selectors. For example,
the following
MCMManagedEntity [MCM]

o MCMPolicyStructure is an invalid condition clause, even if protocol abstract superclass for building
different types
map to integers:

proto < 62 (invalid condition)

Range-based selectors are ordered sets where it is possible to
naturally specify ranges as they can of Policy Rules (currently, for I2NSF, only
imperative (i.e., ECA) Policy Rules are considered)

o An I2NSFECAPolicyRule could be easily mapped to integers.
As an example, the ports in the TCP protocol may subclassed from MCMECAPolicyRule

o I2NSF Events, Conditions, and Actions could be represented with
a range-based selector (e.g., 1024-65535). As another example, subclasses from
MCMPolicyEvent, MCMPolicyCondition, and MCMPolicyAction

o MCMMetaData is aggregated by MCMEntity, which is the
following are examples superclass
of valid condition clauses:

source_port = 80
source_port < 1024
source_port < 30000 && source_port >= 1024

We include, in range-based selectors, MCMManagedEntity. So all Policy objects may aggregate
MCMMetaData
+------------------------+
+---------------+ |HasPolicyStructure |
|MCMPolicyObject| |ComponentDecoratorDetail|
+-------A-------+ +---------------------*--+
| *
| *
+---------------+----------------+ *
| | *
+-------+----------+ +----------+----------------+1..* *
|MCMPolicyStructure| |MCMPolicyStructureComponent|<------*+
+--------A---------+ +-----------A---------------+ |
| | |
| +------------+--------+ |
| | | 0..1 ^
+-------+--------+ +-------+-------+ +-----------+---------------V+
|MCMECAPolicyRule| |MCMPolicyClause| |MCMPolicyClauseComponent |
+----------------+ +---------------+ |Decorator |
+---------------A------------+
|
|
+--------+---------+
|MCMPolicyComponent|
+--------A---------+
|
|
+--------------------+---------------+----+
+-------+------+ +---------+--------+ +--------+------+
|MCMPolicyEvent| |MCMPolicyCondition| |MCMPolicyAction|
+--------------+ +------------------+ +---------------+

Figure 1 Exemplary External Information Model (from the category of selectors that
have been defined MEF)

The CapIM model uses the Decorator Pattern [Gamma]. The decorator
pattern enables a base object to be "wrapped" by Al-Shaer et al. as "prefix-match" [Alshaer].
These selectors allow zero or more
decorator objects. The Decorator MAY attach additional
characteristics and behavior, in the specification of ranges form of values attributes at runtime
in a transparent manner without requiring recompilation and/or
redeployment. This is done by means using composition instead of simple regular expressions. The typical case is
inheritance. Objects can "wrap" (more formally, extend the IP address
selector (e.g., 10.10.1.*).

There interface
of) an object. In essence, a new object can be built out of pre-
existing objects.

The Decorator Pattern is no need applied to distinguish between prefix match and range-based
selectors; for example, the address range "10.10.1.*" maps allow NSF instances to
"[10.10.1.0,10.10.1.255]".

Another category aggregate
I2NSFSecurityCapability instances. By means of selector types includes those based on regular
expressions. this aggregation, an
NSF can be associated to the functions it provides in terms of
security policy enforcement, both at specification time (i.e., when
a vendor provides a new NSF), statically, when a NSF is added to a
(virtualized) networking environment, and dynamically, during
network operations. Figure 2 shows an NSF aggregating zero or more
SecurityCapabilities. This selector type may be thought of as an NSF possessing
(or defining) zero or more Security Capabilities. This "possession"
(or "definition") is used frequently at the application
layer, where data are often represented in UML as strings of text. an aggregated, called
HasSecurityCapability. The
regex-based selector type also includes string-based selectors, where
matching hasSecurityCapabilityDetail is evaluated using string matching algorithms (SMA)
[Cormen]. Indeed, for our purposes, string matching an
association class that allows NSF instances to aggregate
I2NSFSecurityCapability instances. An NSF MAY be described by 0 or
more SecurityCapabilities.

Since there can be mapped to
regular expressions, even if in practice SMA are much faster. For
instance, Squid (http://www.squid-cache.org/), a popular Web caching
proxy many types of NSF that offers various access control Capabilities, allows have many different types
of I2NSFSecurityCapabilities, the definition of conditions on URLs that can a SecurityCapability
must be evaluated with SMA
(e.g., dstdomain) or regex matching (e.g., dstdom_regex).

As done using the context of an example, NSF. This is realized by an
association class in UML. HasSecurityCapabilityDetail is an
association class. This yields the condition clause:

"URL = *.website.*"

matches all following design:

+-----+0..n 0..n+--------------------+
| |/ \ HasSecurityCapability | |
| NSF | A ----------+----------------+ SecurityCapability |
| |\ / ^ | |
+-----+ | +--------------------+
|
+-------------+---------------+
| HasSecurityCapabilityDetail |
+ ----------------------------+

Figure 2 Defining SecurityCapabilities of an NSF

This enables the URLs that contain a subdomain named website and HasSecurityCapabilityDetail association class to be
the
ones whose path contain target of a Policy Rule. That is, the string ".website.". As another example,
the condition clause:

"MIME_type = video/*"

matches all MIME objects whose type is video.

Finally, the idea of a custom check selector is introduced. For
instance, malware analysis can look for specific patterns,
HasSecurityCapabilityDetail class has attributes and
returns a Boolean value if the pattern is found or not.

In order to be properly used by high-level policy-based processing
systems (such as reasoning systems methods that
define which I2NSFSecurityCapabilities of this NSF are visible and policy translation systems),
these custom check selectors
can be modeled as black-boxes (i.e., a
function used [MCM].

3.3.2. The SecurityCapability class

The SecurityCapability class defines the concept of metadata that has a defined set
define security-related capabilities. It is subclassed from an
appropriate class of inputs and outputs for a
particular state), which provide an associated Boolean output.

More examples external metadata information
model.Subclasses of custom check selectors will be presented in the
next versions of SecurityCapability class can be used to
answer the draft. Some examples are already present in
Section 6.

3.4.2. Capability Selection and Usage

Capability selection and usage following questions:

o What are based on the set of security
traffic classification and action features events that an NSF provides;
these are defined caught by the Capability model. If the NSF has the
classification features needed to identify trigger the packets/flows
required by a policy, and
condition clause evaluation (Event subclass)?

o What kind of condition clauses can enforce be specified on the needed actions, then
that particular NSF is capable of enforcing the policy.

NSFs may also have specific characteristics that automatic processes
or administrators need to know when they have to generate
configurations, like
define valid rules? This question splits into two questions:
(1) what are the available resolution strategies conditions that can be specified (Condition
subclass), and the
possibility (2) how to set default actions.

The Capability information model can be used for two purposes:
describing the features provided by generic security functions, and
describing the features provided by specific products. The term
Generic Network Security Function (GNSF) refers to the classes build a valid condition clause from a
set of
security functions that individual conditions (ClauseEvaluation class).

o What are known by a particular system. The idea
is to have generic components whose behavior is well understood, so the actions that the generic component NSF can be used even if it has some vendor-
specific functions. These generic functions represent enforce (Action class)?

o How to define a point of
interoperability, and can be provided by any product that offers correct policy on the
required Capabilities. GNSF examples include packet filter, URL
filter, HTTP filter, VPN gateway, anti-virus, anti-malware, content
filter, monitoring, NSF?

3.3.3. I2NSF Condition Clause Operator Types

After having analyzed the literature and anonymity proxy; these will be described
later in a revision some existing NSFs, the
types of this draft selectors are categorized as well exact-match, range-based,
regex-based, and custom-match [Bas15][Lunt].

Exact-match selectors are (unstructured) sets: elements can only be
checked for equality, as in no order is defined on them. As an upcoming data
model contribution.

The next section will introduce
example, the algebra to define protocol type field of the
information model IP header is an unordered
set of Capability registration. This associates
NSFs integer values associated to Capabilities, and checks whether an NSF has protocols. The assigned protocol
numbers are maintained by the
Capabilities needed to enforce policies.

3.4.3. Capability Algebra

We introduce a Capability Algebra IANA
(http://www.iana.org/assignments/protocol-numbers/protocol-
numbers.xhtml).

In this selector, it is only meaningful to ensure specify condition clauses
that use either the actions of
different policy rules do not conflict with each other.

Formally, two I2NSF Policy Actions conflict with each other if:

o the event clauses of each evaluate "equals" or "not equals operators":

proto = tcp, udp (protocol type field equals to TRUE
o TCP or UDP)

proto != tcp (protocol type field different from TCP)

No other operators are allowed on exact-match selectors. For
example, the following is an invalid condition clauses of each evaluate clause, even if
protocol types map to TRUE
o the action clauses affect integers:

proto < 62 (invalid condition)

Range-based selectors are ordered sets where it is possible to
naturally specify ranges as they can be easily mapped to integers.
As an example, the same object ports in different ways the TCP protocol may be represented
using a range-based selector (e.g., 1024-65535). For example, if we the
following are examples of valid condition clauses:

source_port = 80

source_port < 1024

source_port < 30000 && source_port >= 1024

We include, in range-based selectors, the category of selectors that
have two Policies:

P1: During 8am-6pm, if traffic been defined by Al-Shaer et al. as "prefix-match" [Alshaer].
These selectors allow the specification of ranges of values by means
of simple regular expressions. The typical case is external, then run through FW
P2: During 7am-8pm, conduct anti-malware investigation the IP address
selector (e.g., 10.10.1.*). There is no conflict need to distinguish between P1
prefix match and P2, since range-based selectors as 10.10.1.* easily maps to
[10.10.1.0, 10.10.1.255].

Another category of selector types includes the actions are
different. However, consider these two policies:

P3: During 8am-6pm, John gets GoldService
P4: During 10am-4pm, FTP from all users gets BronzeService

P3 and P4 are now in conflict, because between regex-based
selectors, where the hours of 10am and
4pm, matching is performed by using regular
expressions. This selector type is used frequently at the actions of P3 and P4
application layer, where data are different and apply to the same
user (i.e., John).

Let us define the concept of a "matched" policy rule often represented as one in which
its event and condition clauses are both evaluate strings of
text. The regex-based selector type also includes string-based
selectors, where matching is evaluated using string matching
algorithms (SMA) [Cormen]. Indeed, for our purposes, string matching
can be mapped to true. This enables
the actions regular expressions, even if in this policy rule to be evaluated. Then, the
conflict matrix is defined by practice SMA are
much faster. For instance, Squid (http://www.squid-cache.org/), a 5-tuple {Ac, Cc, Ec, RSc, Dc},
where:

o Ac is
popular Web caching proxy that offers various access control
capabilities, allows the set definition of Actions currently available from conditions on URLs that can
be evaluated with SMA (e.g., dstdomain) or regex matching (e.g.,
dstdom_regex).

As an example, the NSF;
o Cc is condition clause:

URL = *.website.*

matches all the set of Conditions currently available from URLs that contain a subdomain named website and the NSF;
o Ec is
ones whose path contain the set of Events string ".website.". As another example,
the NSF condition clause:

MIME_type = video/*

matches all MIME objects whose type is able to respond to.
Therefore, video.

Finally, the event clause idea of an I2NSF ECA Policy Rule that a custom check selector is
written introduced. For
instance, malware analysis can look for an NSF will only allow specific patterns, and
returns a set of designated events
in Ec. For compatibility purposes, we will assume that Boolean value if Ec={}
(that is, Ec is empty), the NSF only accepts CA policies.
o RSc pattern is the set of Resolution Strategies that can found or not.

In order to be properly used to
specify how to resolve conflicts by high-level policy-based processing
systems (such as reasoning systems and policy translation systems),
these custom check selectors can be modeled as black-boxes (i.e., a
function that occur between has a defined set of inputs and outputs for a
particular state), which provide an associated Boolean output.

More examples of custom check selectors will be presented in the actions
next versions of the same or different policy rules that draft. Some examples are matched and
contained already present in this particular NSF;
o Dc defines
Section 6.

3.3.4. Capability Selection and Usage

Capability selection and usage are based on the notion set of a Default security
traffic classification and action features that can be used to
specify a predefined action when no other alternative action
was matched an NSF provides;
these are defined by the currently executing I2NSF Policy Rule. An
analogy is capability model. If the use of a default statement in a C switch
statement. This field of NSF has the Capability algebra
classification features needed to identify the packets/flows
required by a policy, and can take enforce the
following values:
- An explicit action (that has been predefined; typically,
this means needed actions, then that it
particular NSF is fixed and not configurable), denoted
as Dc ={a}. In this case, capable of enforcing the NSF will always use policy.

NSFs may also have specific characteristics that automatic processes
or administrators need to know when they have to generate
configurations, like the
action as as available resolution strategies and the default action.
- A
possibility to set of explicit actions, denoted Dc={a1,a2, ...};
typically, this means that any **one** action default actions.

The capability information model can be used
as for two purposes:
describing the default action. This enables features provided by generic security functions, and
describing the policy writer features provided by specific products. The term
Generic Network Security Function (GNSF) refers to
choose one the classes of
security functions that are known by a predefined set of actions {a1, a2, ...} particular system. The idea
is to
serve as the default action.

- A fully configurable default action, denoted as Dc={F}.
Here, F have generic components whose behavior is a dummy symbol (i.e., a placeholder value) well understood, so
that the generic component can be used to indicate that the default action even if it has some vendor-
specific functions. These generic functions represent a point of
interoperability, and can be
freely selected provided by any product that offers the policy editor from the actions Ac
available at the NSF. In other words, one of the actions
Ac may
required capabilities. GNSF examples include packet filter, URL
filter, HTTP filter, VPN gateway, anti-virus, anti-malware, content
filter, monitoring, and anonymity proxy; these will be selected by the policy writer to act described
later in a revision of this draft as the
default action.
- No default action, denoted well as Dc={}, for cases where in an upcoming data
model contribution.

The next section will introduce the
NSF does not allow algebra to compose the explicit selection
information model of a default
action.

*** Note capability registration, defined to WG: please review associate
NSFs to capabilities and to check whether a NSF has the following paragraphs
*
* Interesting capabilities
needed to enforce policies.

3.3.5. Capability concepts that could be considered for Algebra

We introduce a next
* version of the Capability model and algebra include:
*
* o Event clause representation (e.g., conjunctive vs. disjunctive
* normal form for Boolean clauses)
* o Event clause evaluation function, which would enable more
* complex expressions than simple Boolean expressions Algebra to be used
*
*
* ensure that the actions of
different policy rules do not conflict with each.

Formally, two I2NSF Policy Rules conflict with each other if:

o Condition clause representation (e.g., conjunctive vs.
* disjunctive normal form for Boolean clauses)
* the event clauses of each evaluate to TRUE

o Condition clause evaluation function, which would enable more
* complex expressions than simple Boolean expressions the condition clauses of each evaluate to be used
* TRUE

o Action clause evaluation strategies (e.g., execute first
* action only, execute last the action only, execute all actions,
* execute clauses affect the same object in different ways

For example, if we have two Policy Rules in the same Policy:

R1: During 8am-6pm, if traffic is external, then run through FW
R2: During 7am-8pm, conduct anti-malware investigation

There is no conflict between R1 and R2, since the actions are
different. However, consider these two rules:

R3: During 8am-6pm, John gets GoldService
R4: During 10am-4pm, FTP from all users gets BronzeService

R3 and R4 are now in conflict, between the hours of 10am and 4pm,
because the actions until an action fails)
* o The use of metadata, which can be associated R3 and R4 are different and apply to both an I2NSF
* Policy Rule as well the same
user (i.e., John).

Let us define the concept of a "matched" policy rule as objects contained one in which
its event and condition clauses both evaluate to true. Then, the
behavior of the I2NSF Policy
* Rule (e.g., an action), that describe Rule, as specified by the object and/or
* prescribe behavior. Descriptive examples include adding
* authorship information and defining CapIM, is defined
by a time period when an NSF
* can be used to be defined; prescriptive examples include
* defining rule priorities and/or ordering.
*
* Given two sets of Capabilities, denoted as
*
* cap1=(Ac1,Cc1,Ec1,RSc1,Dc1) and
* cap2=(Ac2,Cc2,Ec2,RSc2,Dc2),
*
* two set operations are defined for manipulating Capabilities:
*
* o Capability addition:
* cap1+cap2 = {Ac1 U Ac2, Cc1 U Cc2, Ec1 U Ec2, RSc1, Dc1}
* 6-tuple {Ac, Cc, Ec, RSc, Dc, EVc}, where:

o Capability subtraction:
* cap1-cap2 = {Ac1 \ Ac2, Cc1 \ Cc2, Ec1 \ Ec2, RSc1, Dc1}
*
* In the above formulae, "U" Ac is the set union operator and "\" of Actions currently available from the NSF;

o Cc is the
* set difference operator.

* The addition and subtraction of Capabilities are defined as currently available from the
* addition (set union) and subtraction (set difference) of both NSF;

o Ec is the
* Capabilities and their associated actions. set of Events that an NSF can catch. Note that **only** the
* leftmost (in this case, the first matched policy rule) Resolution
* Strategy and Default Action are used.
*
* Note: actions, events, and conditions are **symmetric**. This means
* for NSF
(e.g., a packet filter) that when two matched policy rules are merged, the resultant actions
* and Capabilities are defined as not able to react to events,
this set will be empty;

o RSc is the union set of each individual matched
* policy rule. However, both resolution strategies and default actions
* are **asymmetric** (meaning Resolution Strategies that in general, they can **not** be
* combined, as one has used to be chosen). In order
specify how to simplify this, we
* have chosen resolve conflicts that occur between the **leftmost** resolution strategy and actions
of the
* **leftmost** default action same or different policy rules that are chosen. This enables the developer
* to view the leftmost matched rule as the "base" to which other
* and
contained in this particular NSF;

o Dc defines the notion of a Default action. This action can be
either an explicit action that has been chosen {a}, or a set of
actions {F}, where F is a dummy symbol (i.e., a placeholder
value) that can be used to indicate that the default action can
be freely selected by the policy editor. This is denoted as {F} U
{a}.

EVc defines the set of Condition Clause Evaluation Rules that can be
used at the NSF to decide when the condition clause is true given
the result of the evaluation of the individual conditions. Before
introducing the rest of the capability model, we will introduce the
symbols that we will use to represent set operations:

o "U" is the union operation, A U B returns a new set that includes
all the elements in A and all the elements in B

o "\" is the set minus operation, A \ B returns all the elements
that are added.
*
* in A but not in B.

Given two sets of capabilities, denoted as cap1=(Ac1,Cc1,
Ec1,RSc1,Dc1,EVc1) and cap2=(Ac2,Cc2,Ec2,RSc2,Dc2,EVc2)
two set operations are defined for manipulating capabilities:

o capability addition: cap1+cap2 = {Ac1 U Ac2, Cc1 U Cc2, Ec1 U
Ec2, RSc1 U RSc2, Dc1 U DC2, EVc1 U EVc2}

o capability subtraction: cap_1-cap_2 = {Ac1 \ Ac2, Cc1 \ Cc2, Ec1
\ Ec2, RSc1 U RSc2, Dc1 U DC2, EVc1 U EVc2}

In the above formulae, "U" is the set union operator and "\" is the
set difference operator.

The addition and subtraction of capabilities are defined as the
addition (set union) and subtraction (set difference) of both the
capabilities and their associated actions. Note that the Resolution
Strategies and Default Actions are added in both cases.

As an example, assume that a packet filter Capability, capability, Cpf, is
*
defined. Further, assume that a second Capability, capability, called Ctime,
*
exists, and that it defines time-based conditions. Suppose we need
*
to construct a new generic packet filter, Cpfgen, that adds
* time-based time-
based conditions to Cpf.
*
*
* Conceptually, this is simply the addition
of the Cpf and Ctime
* Capabilities, capabilities, as follows:
*

Apf = {Allow, Deny}
*
Cpf = {IPsrc,IPdst,Psrc,Pdst,protType}
*
Epf = {}
*
RSpf = {FMR}
*
Dpf = {A1}
*
*
EVpf = {DNF}

Atime = {Allow, Deny, Log}
*
Ctime = {timestart, timeend, datestart, datestop}
*
Etime = {}
*
RStime = {LMR}
*
Dtime = {A2}
*
*
EVtime = {}

Then, Cpfgen is defined as:
*

Cpfgen = {Apf U Atime, Cpf U Ctime, Epf U Etime, RSpf, Dpf}
* RSpf U RStime,
Dpf U Time, EVpf U EVtime}
= {Allow, Deny, Log},
* {{IPsrc, IPdst, Psrc, Pdst, protType}
{{IPsrc,IPdst,Psrc,Pdst,protType} U
* {timestart, timeend,
datestart, datestop}},
* {},
* {FMR},
* {A1}
*
* datestop}}
{}
{FMR, LMR}
{A1, A2}
{DNF}

In other words, Cpfgen provides three actions (Allow, Deny, Log),
*
filters traffic based on a 5-tuple that is logically ANDed with a
*
time period, can use either FMR or LMR (but obviously not both), and uses FMR; it provides
can provide either A1 or A2 (but again, not both) as a default action, and
* it does not react
action. In any case, multiple conditions will be processed with DNF
when evaluating the condition clause.

4. IANA Considerations

TBD

5. References

5.1. Normative References

[RFC2119] Bradner, S., "Key words for use in RFCs to events.

* Note: We are investigating, Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.

[RFC2234] Crocker, D. and Overell, P.(Editors), "Augmented BNF for
Syntax Specifications: ABNF", RFC 2234, Internet Mail
Consortium and Demon Internet Ltd., November 1997.

[RFC6020] Bjorklund, M., "YANG - A Data Modeling Language for a next revision of this draft, the
* possibility
Network Configuration Protocol (NETCONF)", RFC 6020,
October 2010.

[RFC5511] Farrel, A., "Routing Backus-Naur Form (RBNF): A Syntax
Used to add further operations that do not follow the
* symmetric vs. asymmetric properties presented Form Encoding Rules in the previous note.
* We are looking Various Routing Protocol
Specifications", RFC 5511, April 2009.

[RFC3198] Westerinen, A., Schnizlein, J., Strassner, J., Scherling,
M., Quinn, B., Herzog, S., Huynh, A., Carlson, M., Perry,
J., and S. Waldbusser, "Terminology for use cases that may justify the complexity added
* by the availability of more Capability manipulation operations.
*
*** End Note Policy-Based
Management", RFC 3198, DOI 10.17487/RFC3198,
November 2001, <http://www.rfc-editor.org/info/rfc3198>.

[RFC8192] Hares, S., Lopez, D., Zarny, M., Jacquenet, C., Kumar,
R., and J. Jeong, "Interface to WG

3.5. Initial NSFs Capability Categories

The following subsections define three common categories of
Capabilities: network security, content security, Network Security Functions
(I2NSF): Problem Statement and attack
mitigation. Future versions of this document may expand both the
number of categories as well as the types of Capabilities within a
given category.

3.5.1. Use Cases", RFC 8192,
DOI 10.17487/RFC8192, July 2017,
<https://www.rfc-editor.org/info/rfc8192>.

[RFC8329] Lopez, D., Lopez, E., Dunbar, L., Strassner, J. and R.
Kumar, "Framework for Interface to Network Security Capabilities
Functions", RFC 8329, February 2018.

5.2. Informative References

[INCITS359 RBAC] NIST/INCITS, "American National Standard for
Information Technology - Role Based Access Control",
INCITS 359, April, 2003

[I-D.draft-ietf-i2nsf-terminology] Hares, S., et.al., "Interface to
Network security is a category that describes the inspecting and
processing of network traffic based on the use of pre-defined
security policies.

The inspecting portion may be thought of as a packet-processing
engine that inspects packets traversing networks, either directly or
in the context of flows with which the packet is associated. From
the perspective of packet-processing, implementations differ in the
depths of packet headers and/or payloads they can inspect, the
various flow and context states they can maintain, and the actions
that can be applied to the packets or flows.

3.5.2. Content Security Capabilities

Content security is another category of security Capabilities
applied to the application layer. Through analyzing traffic contents
carried in, for example, the application layer, content security
Capabilities can be used to identify various security functions that
are required. These include defending against intrusion, inspecting
for viruses, filtering malicious URL or junk email, blocking illegal
web access, or preventing malicious data retrieval.

Generally, each type of threat Functions (I2NSF) Terminology", Work in the content security category has
a set of unique characteristics, and requires handling using a set
of methods that are specific to that type of content. Thus, these
Capabilities will be characterized by their own content-specific
security functions.

3.5.3. Attack Mitigation Capabilities

This category of security Capabilities is used to detect and mitigate
various types of network attacks. Today's common network attacks can
be classified into the following sets:

o DDoS attacks:
- Network layer DDoS attacks: Examples include SYN flood, UDP
flood, ICMP flood, IP fragment flood, IPv6 Routing header
attack, and IPv6 duplicate address detection attack;
- Application layer DDoS attacks: Examples include HTTP flood,
https flood, cache-bypass HTTP floods, WordPress XML RPC
floods, and ssl DDoS.
o Single-packet attacks:
- Scanning and sniffing attacks: IP sweep, port scanning, etc.
- malformed packet attacks: Ping of Death, Teardrop, etc.
- special packet attacks: Oversized ICMP, Tracert, IP timestamp
option packets, etc.

Each type of network attack has its own network behaviors and
packet/flow characteristics. Therefore, each type of attack needs a
special security function, which is advertised as a set of
Capabilities, for detection and mitigation. The implementation and
management of this category of security Capabilities of attack
mitigation control is very similar to the content security control
category. A standard interface, through which the security controller
can choose and customize the given security Capabilities according to
specific requirements, is essential.

4. Information Sub-Model for Network Security Capabilities

The purpose of the Capability Information Sub-Model is to define the
concept of a Capability, and enable Capabilities to be aggregated to
appropriate objects. The following sections present the Network
Security, Content Security, and Attack Mitigation Capability
sub-models.

4.1. Information Sub-Model for Network Security

The purpose of the Network Security Information Sub-Model is to
define how network traffic is defined, and determine if one or more
network security features need to be applied to the traffic or not.
Its basic structure is shown in the following figure:

+---------------------+
+---------------+ 1..n 1..n | |
| |/ \ \| A Common Superclass |
| ECAPolicyRule + A -------------+ for ECA Objects |
| |\ / /| |
+-------+-------+ +---------+-----------+
/ \ / \
| |
| |
(subclasses to define Network (subclasses of Event,
Security ECA Policy Rules Condition, and Action Objects
extensibly, so that other for Network Security
Policy Rules can be added)
Progress, January, 2018

[I-D.draft-ietf-supa-generic-policy-info-model] Strassner, J.,
Halpern, J., Coleman, J., "Generic Policy Rules)

Figure 2. Network Security Information Sub-Model Overview

In the above figure, the ECAPolicyRule, along with the Event,
Condition, and Action Objects, are defined in the external ECA Information Model. The Network Security Sub-Model extends all of
these objects in order to define security-specific ECA Policy Rules,
as well as extensions to the (generic) Event, Condition, and
Action objects.

An I2NSF Policy Rule is a special type of Policy Rule that is in
event-condition-action (ECA) form. It consists of the Policy Rule,
components of a Policy Rule (e.g., events, conditions, actions, and
some extensions like resolution policy, default action and external
data), and optionally, metadata. It can be applied to both uni- and
bi-directional traffic across the NSF.

Each rule is triggered by one or more events. If the set of events
evaluates to true, then a set of conditions are evaluated and, if
true, then enable a set of actions to be executed. This takes the
following conceptual form:

IF <event-clause> is TRUE
IF <condition-clause> is TRUE
THEN execute <action-clause>
END-IF
END-IF

In the above example, the Event, Condition, and Action portions of a
Policy Rule are all **Boolean Clauses**. Hence, they can contain
combinations of terms connected by the three logical connectives
operators (i.e., AND, OR, NOT). An example is:

((SLA==GOLD) AND ((numPackets>burstRate) OR NOT(bwAvail<minBW)))

Note that Metadata, such as Capabilities, can be aggregated by I2NSF
ECA Policy Rules.

4.1.1. Network Security Policy Rule Extensions

Figure 3 shows an example of more detailed design of the ECA Policy
Rule subclasses that are contained in the Network Security
Information Sub-Model, which just illustrates how more specific
Network Security Policies are inherited and extended from the
SecurityECAPolicyRule class. Any new kinds of specific Network
Security Policy can be created by following the same pattern of
class design as below.

+---------------+
| External |
| ECAPolicyRule |
+-------+-------+
/ \
|
|
+------------+----------+
| SecurityECAPolicyRule |
+------------+----------+
|
|
+----+-----+--------+-----+----+---------+---------+--- ...
| | | | | |
| | | | | |
+------+-------+ | +-----+-------+ | +------+------+ |
|Authentication| | | Accounting | | |ApplyProfile | |
|ECAPolicyRule | | |ECAPolicyRule| | |ECAPolicyRule| |
+--------------+ | +-------------+ | +-------------+ |
| | |
+------+------+ +------+------+ +--------------+
|Authorization| | Traffic | |ApplySignature|
|ECAPolicyRule| | Inspection | |ECAPolicyRule |
+-------------+ |ECAPolicyRule| +--------------+
+-------------+

Figure 3. Network Security Info Sub-Model ECAPolicyRule Extensions

The SecurityECAPolicyRule is the top of the I2NSF ECA Policy Rule
hierarchy. It inherits from the (external) generic ECA Policy Rule,
and represents the specialization of this generic ECA Policy Rule to
add security-specific ECA Policy Rules. The SecurityECAPolicyRule
contains all of the attributes, methods, and relationships defined in
its superclass, and adds additional concepts that are required for
Network Security (these will be defined in the next version of this
draft). The six SecurityECAPolicyRule subclasses extend the
SecurityECAPolicyRule class to represent six different types of
Network Security ECA Policy Rules. It is assumed that the (external)
generic ECAPolicyRule class defines basic information in the form of
attributes, such as an unique object ID, as well as a description
and other necessary information.

*** Note to WG
*
* The design in Figure 3 represents the simplest conceptual design
* for network security. An alternative model would be to use a
* software pattern (e.g., the Decorator pattern); this would result
* in the SecurityECAPolicyRule class being "wrapped" by one or more
* of the six subclasses shown in Figure 3. The advantage of such a
* pattern is to reduce the number of active objects at runtime, as
* well as offer the ability to combine multiple actions of different
* policy rules (e.g., inspect traffic and then apply a filter) into
* one. The disadvantage is that it is a more complex software design.
* The design team is requesting feedback from the WG regarding this.
*
*** End of Note to WG

It is assumed that the (external) generic ECA Policy Rule is
abstract; the SecurityECAPolicyRule is also abstract. This enables
data model optimizations to be made while making this information
model detailed but flexible and extensible. For example, abstract
classes may be collapsed into concrete classes.

The SecurityECAPolicyRule defines network security policy as a
container that aggregates Event, Condition, and Action objects,
which are described in Section 4.1.3, 4.1.4, and 4.1.5,
respectively. Events, Conditions, and Actions can be generic or
security-specific.

Brief class descriptions of these six ECA Policy Rules are provided
in Appendix A.

4.1.2. Network Security Policy Rule Operation

A Network Security Policy consists of one or more ECA Policy Rules
formed from the information model described above. In simpler cases,
where the Event and Condition clauses remain unchanged, then the
action of one Policy Rule may invoke additional network security
actions from other Policy Rules. Network security policy examines
and performs basic processing of the traffic as follows:

1. The NSF evaluates the Event clause of a given
SecurityECAPolicyRule (which can be generic or specific to
security, such as those in Figure 3). It may use security
Event objects to do all or part of this evaluation, which are
defined in section 4.1.3. If the Event clause evaluates to
be TRUE, then the Condition clause of this SecurityECAPolicyRule
is evaluated; otherwise, the execution of this
SecurityECAPolicyRule is stopped, and the next
SecurityECAPolicyRule (if one exists) is evaluated.

2. The Condition clause is then evaluated. It may use security
Condition objects to do all or part of this evaluation, which
are defined in section 4.1.4. If the Condition clause
evaluates to TRUE, it is defined as "matching" the
SecurityECAPolicyRule; otherwise, execution of this
SecurityECAPolicyRule is stopped, and the next
SecurityECAPolicyRule (if one exists) is evaluated.
3. The set of actions to be executed are retrieved, and then the
resolution strategy is used to define their execution order.
This process includes using any optional external data
associated with the SecurityECAPolicyRule.
4. Execution then takes one of the following three forms:
a. If one or more actions is selected, then the NSF may
perform those actions as defined by the resolution
strategy. For example, the resolution strategy may only
allow a single action to be executed (e.g., FMR or LMR),
or it may allow all actions to be executed (optionally,
in a particular order). In these and other cases, the NSF
Capability MUST clearly define how execution will be done.
It may use security Action objects to do all or part of
this execution, which are defined in section 4.1.5. If the
basic Action is permit or mirror, the NSF firstly performs
that function, and then checks whether certain other
security Capabilities are referenced in the rule. If yes,
go to step 5. If no, the traffic is permitted.
b. If no actions are selected, and if a default action exists,
then the default action is performed. Otherwise, no actions
are performed.
c. Otherwise, the traffic is denied.
5. If other security Capabilities (e.g., the conditions and/or
actions implied by Anti-virus or IPS profile NSFs) are
referenced in the action set of the SecurityECAPolicyRule, the
NSF can be configured to use the referenced security
Capabilities (e.g., check conditions or enforce actions).
Execution then terminates.

One policy or rule can be applied multiple times to different
managed objects (e.g., links, devices, networks, VPNS). This not
only guarantees consistent policy enforcement, but also decreases
the configuration workload.

4.1.3. Network Security Event Sub-Model

Figure 4 shows a more detailed design of the Event subclasses that
are contained in the Network Security Information Sub-Model.

The four Event classes shown in Figure 4 extend the (external)
generic Event class to represent Events that are of interest to
Network Security. It is assumed that the (external) generic Event
class defines basic Event information in the form of attributes,
such as a unique event ID, a description, as well as the date and
time that the event occurred.

Figure 4. Network Security Info Sub-Model Event Class Extensions

The following are assumptions that define the functionality of the
generic Event class. If desired, these could be defined as
attributes in a SecurityEvent class (which would be a subclass of
the generic Event class, and a superclass of the four Event classes
shown in Figure 4). However, this makes it harder to use any
generic Event model with the I2NSF events. Assumptions are:

- All four SecurityEvent subclasses are concrete
- The generic Event class uses the composite pattern, so
individual Events as well as hierarchies of Events are
available (the four subclasses in Figure 4 would be
subclasses of the Atomic Event class); otherwise, a mechanism
is needed to be able to group Events into a collection
- The generic Event class has a mechanism to uniquely identify
the source of the Event
- The generic Event class has a mechanism to separate header
information from its payload
- The generic Event class has a mechanism to attach zero or more
metadata objects to it

*** Note to WG:
*
* The design in Figure 4 represents the simplest conceptual design
* design for describing Security Events. An alternative model would
* be to use a software pattern (e.g., the Decorator pattern); this
* would result in the SecurityEvent class being "wrapped" by one or
* more of the four subclasses shown in Figure 4. The advantage of
* such a pattern is to reduce the number of active objects at runtime,
* as well as offer the ability to combine multiple events of different
* types into one. The disadvantage is that it is a more complex
* software design.
*
*** End of Note to WG

Brief class descriptions are provided in Appendix B.

4.1.4. Network Security Condition Sub-Model

Figure 5 shows a more detailed design of the Condition subclasses
that are contained in the Network Security Information Sub-Model.
The six Condition classes shown in Figure 5 extend the (external)
generic Condition class to represent Conditions that are of interest
to Network Security. It is assumed that the (external) generic
Condition class is abstract, so that data model optimizations may be
defined. It is also assumed that the generic Condition class defines
basic Condition information in the form of attributes, such as a
unique object ID, a description, as well as a mechanism to attach
zero or more metadata objects to it. While this could be defined as
attributes in a SecurityCondition class (which would be a subclass
of the generic Condition class, and a superclass of the six
Condition classes shown in Figure 5), this makes it harder to use
any generic Condition model with the I2NSF conditions.

Figure 5. Network Security Info Sub-Model Condition Class Extensions

Brief class descriptions are provided in Appendix C.

4.1.5. Network Security Action Sub-Model

Figure 6 shows a more detailed design of the Action subclasses that
are contained in the Network Security Information Sub-Model.

The four Action classes shown in Figure 6 extend the (external)
generic Action class to represent Actions that perform a Network
Security Control function.

The three Action classes shown in Figure 6 extend the (external)
generic Action class to represent Actions that are of interest to
Network Security. It is assumed that the (external) generic Action
class is abstract, so that data model optimizations may be defined.

+---------------------+
+---------------+ 1..n 1..n | |
| |/ \ \| A Common Superclass |
| ECAPolicyRule+ A -------------+ for ECA Objects |
| |\ / /| |
+---------------+ +-----------+---------+
/ \
|
|
+--------------+--------+------+
| | |
| | |
+-----+----+ +------+------+ +-----+-----+
| An Event | | A Condition | | An Action |
| Class | | Class | | Class |
+----------+ +-------------+ +-----+-----+
/ \
|
|
+-----------------+---------------+------- ...
| | |
| | |
+---+-----+ +----+---+ +------+-------+
| Ingress | | Egress | | ApplyProfile |
| Action | | Action | | Action |
+---------+ +--------+ +--------------+

Figure 6. Network Security Info Sub-Model Action Extensions

It is also assumed that the generic Action class defines basic
Action information in the form of attributes, such as a unique
object ID, a description, as well as a mechanism to attach zero or
more metadata objects to it. While this could be defined as
attributes in a SecurityAction class (which would be a subclass of
the generic Action class, and a superclass of the six Action classes
shown in Figure 6), this makes it harder to use any generic Action
model with the I2NSF actions.

*** Note to WG
* The design in Figure 6 represents the simplest conceptual design
* for describing Security Actions. An alternative model would be to
* use a software pattern (e.g., the Decorator pattern); this would
* result in the SecurityAction class being "wrapped" by one or more
* of the three subclasses shown in Figure 6. The advantage of such a
* pattern is to reduce the number of active objects at runtime, as
* well as offer the ability to combine multiple actions of different
* types into one. The disadvantage is that it is a more complex
* software design.
* The design team is requesting feedback from the WG regarding this.
*** End of Note to WG

Brief class descriptions are provided in Appendix D.

4.2. Information Model for I2NSF Capabilities

The I2NSF Capability Model is made up of a number of Capabilities
that represent various content security and attack mitigation
functions. Each Capability protects against a specific type of
threat in the application layer. This is shown in Figure 7.

Figure 7. I2NSF Security Capability High-Level Model

Figure 7 shows a common I2NSF Security Capability class, called
SecurityCapability. This enables us to add common attributes,
relationships, and behavior to this class without affecting the
design of the external metadata information model. All I2NSF
Security Capabilities are then subclassed from the
SecuritCapability class.

Note: the SecurityCapability class will be defined in the next
version of this draft, after feedback from the WG is obtained.

4.3. Information Model for Content Security Capabilities

Content security is composed of a number of distinct security
Capabilities; each such Capability protects against a specific type
of threat in the application layer. Content security is a type of
Generic Network Security Function (GNSF), which summarizes a
well-defined set of security Capabilities, and was shown in Figure 7.

Figure 8 shows exemplary types of the content security GNSF.

Figure 8. Network Security Capability Information Model

The detailed description about a standard interface, and the
parameters for all the security Capabilities of this category, will
be defined in a future version of this document.

4.4. Information Model for Attack Mitigation Capabilities

Attack mitigation is composed of a number of GNSFs; each one
protects against a specific type of network attack. Attack
Mitigation security is a type of GNSF, which summarizes a
well-defined set of security Capabilities, and was shown in
Figure 7. Figure 9 shows exemplary types of Attack Mitigation GNSFs.

Figure 9. Attack Mitigation Capability Information Model

The detailed description about a standard interface, and the
parameters for all the security Capabilities of this category, will
be defined in a future version of this document.

5. Security Considerations

The security Capability policy information sent to NSFs should be
protected by a secure communication channel, to ensure its
confidentiality and integrity. Note that the NSFs and security
controller can all be spoofed, which leads to undesirable results
(e.g., security policy leakage from security controller, or a spoofed
security controller sending false information to mislead the NSFs).
Hence, mutual authentication MUST be supported to protected against
this kind of threat. The current mainstream security technologies
(i.e., TLS, DTLS, and IPSEC) can be employed to protect against the
above threats.

In addition, to defend against DDoS attacks caused by a hostile
security controller sending too many configuration messages to the
NSFs, rate limiting or similar mechanisms should be considered.

6. IANA Considerations

TBD

7. Contributors

The following people contributed to creating this document, and are
listed below in alphabetical order:

Antonio Lioy (Politecnico di Torino)
Dacheng Zhang (Huawei)
Edward Lopez (Fortinet)
Fulvio Valenza (Politecnico di Torino)
Kepeng Li (Alibaba)
Luyuan Fang (Microsoft)
Nicolas Bouthors (QoSmos)

8. References

8.1. Normative References

[RFC2119]
Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[RFC3539]
Aboba, B., and Wood, J., "Authentication, Authorization, and
Accounting (AAA) Transport Profile", RFC 3539, June 2003.

8.2. Informative References

[RFC2975]
Aboba, B., et al., "Introduction to Accounting Management",
RFC 2975, October 2000.
[RFC8192]
Hares, S., et.al., "I2NSF Problem Statement and Use cases",
RFC8192, July 2017.
[RFC8329]
Lopez, E., et.al., "Framework for Interface to Network Security
Functions", RFC 8329, February 2018.
[I-D.draft-ietf-i2nsf-terminology]
Hares, S., et.al., "Interface to Network Security Functions
(I2NSF) Terminology", draft-ietf-i2nsf-terminology-03,
March, 2017
[I-D.draft-ietf-supa-generic-policy-info-model]
Strassner, J., Halpern, J., van der Meer, S., "Generic Policy
Information Model for Simplified Use of Policy Abstractions
(SUPA)", draft-ietf-supa-generic-policy-info-model-03,
May, 2017.
[Alshaer]
Al Shaer, E. and H. Hamed, "Modeling and management of firewall
policies", 2004.
[Bas12]
Basile, C., Cappadonia, A., and A. Lioy, "Network-Level Access
Control Policy Analysis and Transformation", 2012.
[Bas15]
Basile, C. and Lioy, A., "Analysis of application-layer filtering
policies with application to HTTP", IEEE/ACM Transactions on
Networking, Vol 23, Issue 1, February 2015.
[Cormen]
Cormen, T., "Introduction to Algorithms", 2009.
[Hohpe]
Hohpe, G. and Woolf, B., "Enterprise Integration Patterns",
Addison-Wesley, 2003, ISBN 0-32-120068-3
[Lunt]
van Lunteren, J. and T. Engbersen, "Fast and scalable packet
classification", IEEE Journal on Selected Areas in Communication,
vol 21, Issue 4, September 2003.
[Martin]
Martin, R.C., "Agile Software Development, Principles, Patterns,
and Practices", Prentice-Hall, 2002, ISBN: 0-13-597444-5
[OODMP]
http://www.oodesign.com/mediator-pattern.html
[OODOP]
http://www.oodesign.com/observer-pattern.html
[OODSRP]
http://www.oodesign.com/single-responsibility-principle.html

Appendix A. Network Security Capability Policy Rule Definitions

Six exemplary Network Security Capability Policy Rules are
introduced in this Appendix to clarify how to create different kinds
of specific ECA policy rules to manage Network Security Capabilities.

Note that there is a common pattern that defines how these
ECAPolicyRules operate; this simplifies their implementation. All of
these six ECA Policy Rules are concrete classes.

In addition, none of these six subclasses define attributes. This
enables them to be viewed as simple object containers, and hence,
applicable to a wide variety of content. It also means that the
content of the function (e.g., how an entity is authenticated, what
specific traffic is inspected, or which particular signature is
applied) is defined solely by the set of events, conditions, and
actions that are contained by the particular subclass. This enables
the policy rule, with its aggregated set of events, conditions, and
actions, to be treated as a reusable object.

A.1. AuthenticationECAPolicyRule Class Definition

The purpose of an AuthenticationECAPolicyRule is to define an I2NSF
ECA Policy Rule that can verify whether an entity has an attribute
of a specific value. A high-level conceputal figure is shown below.

+----------------+
+----------------+ 1..n 1...n | |
| |/ \ HasAuthenticationMethod \| Authentication |
| Authentication + A ----------+-----------------+ Method |
| ECAPolicyRule |\ / ^ /| |
| | | +----------------+
+----------------+ |
|
+------------+-------------+
| AuthenticationRuleDetail |
+------------+-------------+
/ \ 0..n
|
| PolicyControlsAuthentication
|
/ \
A
\ / 0..n
+----------+--------------+
| ManagementECAPolicyRule |
+-------------------------+

Figure 10. Modeling Authentication Mechanisms

This class does NOT define the authentication method used. This is
because this would effectively "enclose" this information within the
AuthenticationECAPolicyRule. This has two drawbacks. First, other
entities that need to use information from the Authentication
class(es) could not; they would have to associate with the
AuthenticationECAPolicyRule class, and those other classes would not
likely be interested in the AuthenticationECAPolicyRule. Second, the
evolution of new authentication methods should be independent of the
AuthenticationECAPolicyRule; this cannot happen if the
Authentication class(es) are embedded in the
AuthenticationECAPolicyRule.

This document only defines the AuthenticationECAPolicyRule; all other
classes, and the aggregations, are defined in an external model. For
completeness, descriptions of how the two aggregations are used are
described below.

Figure 10 defines an aggregation between an external class, which
defines one or more authentication methods, and an
AuthenticationECAPolicyRule. This decouples the implementation of
authentication mechanisms from how authentication mechanisms are
managed and used.

Since different AuthenticationECAPolicyRules can use different
authentication mechanisms in different ways, the aggregation is
realized as an association class. This enables the attributes and
methods of the association class (i.e., AuthenticationRuleDetail) to
be used to define how a given AuthenticationMethod is used by a
particular AuthenticationECAPolicyRule.

Similarly, the PolicyControlsAuthentication aggregation defines
Policy Rules to control the configuration of the
AuthenticationRuleDetail association class. This enables the entire
authentication process to be managed by ECA PolicyRules.

Note: a data model MAY choose to collapse this design into a more
efficient implementation. For example, a data model could define two
attributes for the AuthenticationECAPolicyRule class (e.g., called
authenticationMethodCurrent and authenticationMethodSupported), to
represent the HasAuthenticationMethod aggregation and its
association class. The former would be a string attribute that
defines the current authentication method used by this
AuthenticationECAPolicyRule, while the latter would define a set of
authentication methods, in the form of an authentication Capability,
which this AuthenticationECAPolicyRule can advertise.

A.2. AuthorizationECAPolicyRuleClass Definition

The purpose of an AuthorizationECAPolicyRule is to define an I2NSF
ECA Policy Rule that can determine whether access to a resource
should be given and, if so, what permissions should be granted to
the entity that is accessing the resource.

This class does NOT define the authorization method(s) used. This
is because this would effectively "enclose" this information within
the AuthorizationECAPolicyRule. This has two drawbacks. First, other
entities that need to use information from the Authorization
class(es) could not; they would have to associate with the
AuthorizationECAPolicyRule class, and those other classes would not
likely be interested in the AuthorizationECAPolicyRule. Second, the
evolution of new authorization methods should be independent of the
AuthorizationECAPolicyRule; this cannot happen if the Authorization
class(es) are embedded in the AuthorizationECAPolicyRule. Hence,
this document recommends the following design:

+---------------+
+----------------+ 1..n 1...n | |
| |/ \ HasAuthorizationMethod \| Authorization |
| Authorization + A ----------+----------------+ Method |
| ECAPolicyRule |\ / ^ /| |
| | | +---------------+
+----------------+ |
|
+------------+------------+
| AuthorizationRuleDetail |
+------------+------------+
/ \ 0..n
|
| PolicyControlsAuthorization
|
/ \
A
\ / 0..n
+----------+--------------+
| ManagementECAPolicyRule |
+-------------------------+

Figure 11. Modeling Authorization Mechanisms

This document only defines the AuthorizationECAPolicyRule; all other
classes, and the aggregations, are defined in an external model. For
completeness, descriptions of how the two aggregations are used are
described below.

Figure 11 defines an aggregation between the
AuthorizationECAPolicyRule and an external class that defines one or
more authorization methods. This decouples the implementation of
authorization mechanisms from how authorization mechanisms are
managed and used.

Since different AuthorizationECAPolicyRules can use different
authorization mechanisms in different ways, the aggregation is
realized as an association class. This enables the attributes and
methods of the association class (i.e., AuthorizationRuleDetail)
to be used to define how a given AuthorizationMethod is used by a
particular AuthorizationECAPolicyRule.

Similarly, the PolicyControlsAuthorization aggregation defines
Policy Rules to control the configuration of the
AuthorizationRuleDetail association class. This enables the entire
authorization process to be managed by ECA PolicyRules.

Note: a data model MAY choose to collapse this design into a more
efficient implementation. For example, a data model could define
two attributes for the AuthorizationECAPolicyRule class, called
(for example) authorizationMethodCurrent and
authorizationMethodSupported, to represent the
HasAuthorizationMethod aggregation and its association class. The
former is a string attribute that defines the current authorization
method used by this AuthorizationECAPolicyRule, while the latter
defines a set of authorization methods, in the form of an
authorization Capability, which this AuthorizationECAPolicyRule
can advertise.

A.3. AccountingECAPolicyRuleClass Definition

The purpose of an AccountingECAPolicyRule is to define an I2NSF
ECA Policy Rule that can determine which information to collect,
and how to collect that information, from which set of resources
for the purpose of trend analysis, auditing, billing, or cost
allocation [RFC2975] [RFC3539].

This class does NOT define the accounting method(s) used. This is
because this would effectively "enclose" this information within
the AccountingECAPolicyRule. This has two drawbacks. First, other
entities that need to use information from the Accounting class(es)
could not; they would have to associate with the
AccountingECAPolicyRule class, and those other classes would not
likely be interested in the AccountingECAPolicyRule. Second, the
evolution of new accounting methods should be independent of the
AccountingECAPolicyRule; this cannot happen if the Accounting
class(es) are embedded in the AccountingECAPolicyRule. Hence, this
document recommends the following design:

+-------------+
+----------------+ 1..n 1...n | |
| |/ \ HasAccountingMethod \| Accounting |
| Accounting + A ----------+--------------+ Method |
| ECAPolicyRule |\ / ^ /| |
| | | +-------------+
+----------------+ |
|
+----------+-----------+
| AccountingRuleDetail |
+----------+-----------+
/ \ 0..n
|
| PolicyControlsAccounting
|
/ \
A
\ / 0..n
+----------+--------------+
| ManagementECAPolicyRule |
+-------------------------+

Figure 12. Modeling Accounting Mechanisms

This document only defines the AccountingECAPolicyRule; all other
classes, and the aggregations, are defined in an external model.
For completeness, descriptions of how the two aggregations are used
are described below.

Figure 12 defines an aggregation between the AccountingECAPolicyRule
and an external class that defines one or more accounting methods.
This decouples the implementation of accounting mechanisms from how
accounting mechanisms are managed and used.

Since different AccountingECAPolicyRules can use different
accounting mechanisms in different ways, the aggregation is realized
as an association class. This enables the attributes and methods of
the association class (i.e., AccountingRuleDetail) to be used to
define how a given AccountingMethod is used by a particular
AccountingECAPolicyRule.

Similarly, the PolicyControlsAccounting aggregation defines Policy
Rules to control the configuration of the AccountingRuleDetail
association class. This enables the entire accounting process to be
managed by ECA PolicyRules.

Note: a data model MAY choose to collapse this design into a more
efficient implementation. For example, a data model could define
two attributes for the AccountingECAPolicyRule class, called
(for example) accountingMethodCurrent and accountingMethodSupported,
to represent the HasAccountingMethod aggregation and its association
class.

The former is a string attribute that defines the current accounting
method used by this AccountingECAPolicyRule, while the latter
defines a set of accounting methods, in the form of an accounting
Capability, which this AccountingECAPolicyRule can advertise.

A.4. TrafficInspectionECAPolicyRuleClass Definition

The purpose of a TrafficInspectionECAPolicyRule is to define an I2NSF
ECA Policy Rule that, based on a given context, can determine which
traffic to examine on which devices, which information to collect
from those devices, and how to collect that information.

This class does NOT define the traffic inspection method(s) used.
This is because this would effectively "enclose" this information
within the TrafficInspectionECAPolicyRule. This has two drawbacks.
First, other entities that need to use information from the
TrafficInspection class(es) could not; they would have to associate
with the TrafficInspectionECAPolicyRule class, and those other
classes would not likely be interested in the
TrafficInspectionECAPolicyRule. Second, the evolution of new traffic
inspection methods should be independent of the
TrafficInspectionECAPolicyRule; this cannot happen if the
TrafficInspection class(es) are embedded in the
TrafficInspectionECAPolicyRule. Hence, this document recommends the
following design:

+------------------+
+-------------------+1..n 1..n| |
| |/ \ HasTrafficInspection \| Traffic |
| TrafficInspection + A ----------+-------------+ InspectionMethod |
| ECAPolicyRule |\ / ^ / | |
| | | +------------------+
+-------------------+ |
|
+------------+------------+
| TrafficInspectionDetail |
+------------+------------+
/ \ 0..n
|
| PolicyControlsTrafficInspection
|
/ \
A
\ / 0..n
+----------+--------------+
| ManagementECAPolicyRule |
+-------------------------+

Figure 13. Modeling Traffic Inspection Mechanisms

This document only defines the TrafficInspectionECAPolicyRule; all
other classes, and the aggregations, are defined in an external
model. For completeness, descriptions of how the two aggregations
are used are described below.

Figure 13 defines an aggregation between the
TrafficInspectionECAPolicyRule and an external class that defines
one or more traffic inspection mechanisms. This decouples the
implementation of traffic inspection mechanisms from how traffic
inspection mechanisms are managed and used.

Since different TrafficInspectionECAPolicyRules can use different
traffic inspection mechanisms in different ways, the aggregation is
realized as an association class. This enables the attributes and
methods of the association class (i.e., TrafficInspectionDetail) to
be used to define how a given TrafficInspectionMethod is used by a
particular TrafficInspectionECAPolicyRule.

Similarly, the PolicyControlsTrafficInspection aggregation defines
Policy Rules to control the configuration of the
TrafficInspectionDetail association class. This enables the entire
traffic inspection process to be managed by ECA PolicyRules.

Note: a data model MAY choose to collapse this design into a more
efficient implementation. For example, a data model could define
two attributes for the TrafficInspectionECAPolicyRule class, called
(for example) trafficInspectionMethodCurrent and
trafficInspectionMethodSupported, to represent the
HasTrafficInspectionMethod aggregation and its association class.
The former is a string attribute that defines the current traffic
inspection method used by this TrafficInspectionECAPolicyRule,
while the latter defines a set of traffic inspection methods, in
the form of a traffic inspection Capability, which this
TrafficInspectionECAPolicyRule can advertise.

A.5. ApplyProfileECAPolicyRuleClass Definition

The purpose of an ApplyProfileECAPolicyRule is to define an I2NSF
ECA Policy Rule that, based on a given context, can apply a
particular profile to specific traffic. The profile defines the
security Capabilities for content security control and/or attack
mitigation control; these will be described in sections 4.4 and
4.5, respectively.

This class does NOT define the set of Profiles used. This is
because this would effectively "enclose" this information within
the ApplyProfileECAPolicyRule. This has two drawbacks. First, other
entities that need to use information from the Profile class(es)
could not; they would have to associate with the
ApplyProfileECAPolicyRule class, and those other classes would not
likely be interested in the ApplyProfileECAPolicyRule. Second, the
evolution of new Profile classes should be independent of the
ApplyProfileECAPolicyRule; this cannot happen if the Profile
class(es) are embedded in the ApplyProfileECAPolicyRule. Hence,
this document recommends the following design:

+-------------+
+-------------------+ 1..n 1..n | |
| |/ \ ProfileApplied \| |
| ApplyProfile + A -----------+-------------+ Profile |
| ECAPolicyRule |\ / ^ /| |
| | | +-------------+
+-------------------+ |
|
+------------+---------+
| ProfileAppliedDetail |
+------------+---------+
/ \ 0..n
|
|
PolicyControlsProfileApplication |
|
/ \
A
\ / 0..n
+----------+--------------+
| ManagementECAPolicyRule |
+-------------------------+

Figure 14. Modeling Profile ApplicationMechanisms

This document only defines the ApplyProfileECAPolicyRule; all other
classes, and the aggregations, are defined in an external model.
For completeness, descriptions of how the two aggregations are used
are described below.

Figure 14 defines an aggregation between the
ApplyProfileECAPolicyRule and an external Profile class. This
decouples the implementation of Profiles from how Profiles are used.

Since different ApplyProfileECAPolicyRules can use different
Profiles in different ways, the aggregation is realized as an
association class. This enables the attributes and methods of the
association class (i.e., ProfileAppliedDetail) to be used to define
how a given Profile is used by a particular
ApplyProfileECAPolicyRule.

Similarly, the PolicyControlsProfileApplication aggregation defines
policies to control the configuration of the ProfileAppliedDetail
association class. This enables the application of Profiles to be
managed and used by ECA PolicyRules.

Note: a data model MAY choose to collapse this design into a more
efficient implementation. For example, a data model could define two
attributes for the ApplyProfileECAPolicyRuleclass, called (for
example) profileAppliedCurrent and profileAppliedSupported, to
represent the ProfileApplied aggregation and its association class.
The former is a string attribute that defines the current Profile
used by this ApplyProfileECAPolicyRule, while the latter defines a
set of Profiles, in the form of a Profile Capability, which this
ApplyProfileECAPolicyRule can advertise.

A.6. ApplySignatureECAPolicyRuleClass Definition

The purpose of an ApplySignatureECAPolicyRule is to define an I2NSF
ECA Policy Rule that, based on a given context, can determine which
Signature object (e.g., an anti-virus file, or aURL filtering file,
or a script) to apply to which traffic. The Signature object defines
the security Capabilities for content security control and/or attack
mitigation control; these will be described in sections 4.4 and 4.5,
respectively.

This class does NOT define the set of Signature objects used. This
is because this would effectively "enclose" this information within
the ApplySignatureECAPolicyRule. This has two drawbacks. First,
other entities that need to use information from the Signature
object class(es) could not; they would have to associate with the
ApplySignatureECAPolicyRule class, and those other classes would not
likely be interested in the ApplySignatureECAPolicyRule. Second, the
evolution of new Signature object classes should be independent of
the ApplySignatureECAPolicyRule; this cannot happen if the Signature
object class(es) are embedded in the ApplySignatureECAPolicyRule.
Hence, this document recommends the following design:

This document only defines the ApplySignatureECAPolicyRule; all
other classes, and the aggregations, are defined in an external
model. For completeness, descriptions of how the two aggregations
are used are described below.

Figure 15 defines an aggregation between the
ApplySignatureECAPolicyRule and an external Signature object class.
This decouples the implementation of signature objects from how
Signature objects are used.

Since different ApplySignatureECAPolicyRules can use different
Signature objects in different ways, the aggregation is realized as
an association class. This enables the attributes and methods of the
association class (i.e., SignatureAppliedDetail) to be used to
define how a given Signature object is used by a particular
ApplySignatureECAPolicyRule.

+-------------+
+---------------+ 1..n 1..n | |
| |/ \ SignatureApplied \| |
| ApplySignature+ A ----------+--------------+ Signature |
| ECAPolicyRule |\ / ^ /| |
| | | +-------------+
+---------------+ |
|
+------------+-----------+
| SignatureAppliedDetail |
+------------+-----------+
/ \ 0..n
|
| PolicyControlsSignatureApplication
|
/ \
A
\ / 0..n
+----------+--------------+
| ManagementECAPolicyRule |
+-------------------------+

Figure 15. Modeling Sginature Application Mechanisms

Similarly, the PolicyControlsSignatureApplication aggregation
defines policies to control the configuration of the
SignatureAppliedDetail association class. This enables the
application of the Signature object to be managed by policy.

Note: a data model MAY choose to collapse this design into a more
efficient implementation. For example, a data model could define
two attributes for the ApplySignatureECAPolicyRule class, called
(for example) signature signatureAppliedCurrent and
signatureAppliedSupported, to represent the SignatureApplied
aggregation and its association class. The former is a string
attribute that defines the current Signature object used by this
ApplySignatureECAPolicyRule, while the latter defines a set of
Signature objects, in the form of a Signature Capability, which
this ApplySignatureECAPolicyRule can advertise.

Appendix B. Network Security Event Class Definitions

This Appendix defines a preliminary set of Network Security Event
classes, along with their attributes.

B.1. UserSecurityEvent Class Description

The purpose of this class is to represent Events that are initiated
by a user, such as logon and logoff Events. Information in this
Event may be used as part of a test to determine if the Condition
clause in this ECA Policy Rule should be evaluated or not. Examples
include user identification data and the type of connection used by
the user.

The UserSecurityEvent class defines the following attributes.

B.1.1. The usrSecEventContent Attribute

This is a mandatory string that contains the content of the
UserSecurityEvent. The format of the content is specified in the
usrSecEventFormat class attribute, and the type of Event is defined
in the usrSecEventType class attribute. An example of the
usrSecEventContent attribute is the string "hrAdmin", with the
usrSecEventFormat set to 1 (GUID) and the usrSecEventType attribute
set to 5 (new logon).

B.1.2. The usrSecEventFormat Attribute

This is a mandatory non-negative enumerated integer, which is used
to specify the data type of the usrSecEventContent attribute. The
content is specified in the usrSecEventContent class attribute, and
the type of Event is defined in the usrSecEventType class attribute.
An example of the usrSecEventContent attribute is the string
"hrAdmin", with the usrSecEventFormat attribute set to 1 (GUID) and
the usrSecEventType attribute set to 5 (new logon). Values include:

0: unknown
1: GUID (Generic Unique IDentifier)
2: UUID (Universal Unique IDentifier)
3: URI (Uniform Resource Identifier)
4: FQDN (Fully Qualified Domain Name)
5: FQPN (Fully Qualified Path Name)

B.1.3. The usrSecEventType Attribute

This is a mandatory non-negative enumerated integer, which is used
to specify the type of Event that involves this user. The content
and format are specified in the usrSecEventContent and
usrSecEventFormat class attributes, respectively.

An example of the usrSecEventContent attribute is the string
"hrAdmin", with the usrSecEventFormat attribute set to 1 (GUID), and
the usrSecEventType attribute set to 5 (new logon). Values include:

0: unknown
1: new user created
2: new user group created
3: user deleted
4: user group deleted
5: user logon
6: user logoff
7: user access request
8: user access granted
9: user access violation

B.2. DeviceSecurityEvent Class Description

The purpose of a DeviceSecurityEvent is to represent Events that
provide information from the Device that are important to I2NSF
Security. Information in this Event may be used as part of a test
to determine if the Condition clause in this ECA Policy Rule should
be evaluated or not. Examples include alarms and various device
statistics (e.g., a type of threshold that was exceeded), which may
signal the need for further action.

The DeviceSecurityEvent class defines the following attributes.

B.2.1. The devSecEventContent Attribute

This is a mandatory string that contains the content of the
DeviceSecurityEvent. The format of the content is specified in the
devSecEventFormat class attribute, and the type of Event is defined
in the devSecEventType class attribute. An example of the
devSecEventContent attribute is "alarm", with the devSecEventFormat
attribute set to 1 (GUID), the devSecEventType attribute set to
5 (new logon).

B.2.2. The devSecEventFormat Attribute

This is a mandatory non-negative enumerated integer, which is used
to specify the data type of the devSecEventContent attribute.
Values include:

0: unknown
1: GUID (Generic Unique IDentifier)
2: UUID (Universal Unique IDentifier)
3: URI (Uniform Resource Identifier)
4: FQDN (Fully Qualified Domain Name)
5: FQPN (Fully Qualified Path Name)

B.2.3. The devSecEventType Attribute

This is a mandatory non-negative enumerated integer, which is used
to specify the type of Event that was generated by this device.
Values include:

0: unknown
1: communications alarm
2: quality of service alarm
3: processing error alarm
4: equipment error alarm
5: environmental error alarm

Values 1-5 are defined in X.733. Additional types of errors may also
be defined.

B.2.4. The devSecEventTypeInfo[0..n] Attribute

This is an optional array of strings, which is used to provide
additional information describing the specifics of the Event
generated by this Device. For example, this attribute could contain
probable cause information in the first array, trend information in
the second array, proposed repair actions in the third array, and
additional information in the fourth array.

B.2.5. The devSecEventTypeSeverity Attribute

This is a mandatory non-negative enumerated integer, which is used
to specify the perceived severity of the Event generated by this
Device. Values (which are defined in X.733) include:

0: unknown
1: cleared
2: indeterminate
3: critical
4: major
5: minor
6: warning

B.3. SystemSecurityEvent Class Description

The purpose of a SystemSecurityEvent is to represent Events that
are detected by the management system, instead of Events that are
generated by a user or a device. Information in this Event may be
used as part of a test to determine if the Condition clause in
this ECA Policy Rule should be evaluated or not. Examples include
an event issued by an analytics system that warns against a
particular pattern of unknown user accesses, or an Event issued by
a management system that represents a set of correlated and/or
filtered Events.

The SystemSecurityEvent class defines the following attributes.

B.3.1. The sysSecEventContent Attribute

This is a mandatory string that contains the content of the
SystemSecurityEvent. The format of the content is specified in the
sysSecEventFormat class attribute, and the type of Event is defined
in the sysSecEventType class attribute. An example of the
sysSecEventContent attribute is the string "sysadmin3", with the
sysSecEventFormat attribute set to 1 (GUID), and the sysSecEventType
attribute set to 2 (audit log cleared).

B.3.2. The sysSecEventFormat Attribute

This is a mandatory non-negative enumerated integer, which is used
to specify the data type of the sysSecEventContent attribute.
Values include:

0: unknown
1: GUID (Generic Unique IDentifier)
2: UUID (Universal Unique IDentifier)
3: URI (Uniform Resource Identifier)
4: FQDN (Fully Qualified Domain Name)
5: FQPN (Fully Qualified Path Name)

B.3.3. The sysSecEventType Attribute

This is a mandatory non-negative enumerated integer, which is used
to specify the type of Event that involves this device.
Values include:

0: unknown
1: audit log written to
2: audit log cleared
3: policy created
4: policy edited
5: policy deleted
6: policy executed

B.4. TimeSecurityEvent Class Description

The purpose of a TimeSecurityEvent is to represent Events that are
temporal in nature (e.g., the start or end of a period of time).
Time events signify an individual occurrence, or a time period, in
which a significant event happened. Information in this Event may be
used as part of a test to determine if the Condition clause in this
ECA Policy Rule should be evaluated or not. Examples include issuing
an Event at a specific time to indicate that a particular resource
should not be accessed, or that different authentication and
authorization mechanisms should now be used (e.g., because it is now
past regular business hours).

The TimeSecurityEvent class defines the following attributes.

B.4.1. The timeSecEventPeriodBegin Attribute

This is a mandatory DateTime attribute, and represents the beginning
of a time period. It has a value that has a date and/or a time
component (as in the Java or Python libraries).

B.4.2. The timeSecEventPeriodEnd Attribute

This is a mandatory DateTime attribute, and represents the end of a
time period. It has a value that has a date and/or a time component
(as in the Java or Python libraries). If this is a single Event
occurence, and not a time period when the Event can occur, then the
timeSecEventPeriodEnd attribute may be ignored.

B.4.3. The timeSecEventTimeZone Attribute

This is a mandatory string attribute, and defines the time zone that
this Event occurred in using the format specified in ISO8601.

Appendix C. Network Security Condition Class Definitions

This Appendix defines a preliminary set of Network Security Condition
classes, along with their attributes.

C.1. PacketSecurityCondition

The purpose of this Class is to represent packet header information
that can be used as part of a test to determine if the set of Policy
Actions in this ECA Policy Rule should be executed or not. This class
is abstract, and serves as the superclass of more detailed conditions
that act on different types of packet formats. Its subclasses are
shown in Figure 16, and are defined in the following sections.

+-------------------------+
| PacketSecurityCondition |
+------------+------------+
/ \
|
|
+---------+----------+---+-----+----------+
| | | | |
| | | | |
+--------+-------+ | +--------+-------+ | +--------+-------+
| PacketSecurity | | | PacketSecurity | | | PacketSecurity |
| MACCondition | | | IPv4Condition | | | IPv6Condition |
+----------------+ | +----------------+ | +----------------+
| |
+--------+-------+ +--------+-------+
| TCPCondition | | UDPCondition |
+----------------+ +----------------+

Figure 16. Network Security Info Sub-Model PacketSecurityCondition
Class Extensions

C.1.1. PacketSecurityMACCondition

The purpose of this Class is to represent packet MAC packet header
information that can be used as part of a test to determine if the
set of Policy Actions in this ECA Policy Rule should be executed or
not. This class is concrete, and defines the following attributes.

C.1.1.1. The pktSecCondMACDest Attribute

This is a mandatory string attribute, and defines the MAC
destination address (6 octets long).

C.1.1.2. The pktSecCondMACSrc Attribute

This is a mandatory string attribute, and defines the MAC source
address (6 octets long).

C.1.1.3. The pktSecCondMAC8021Q Attribute

This is an optional string attribute, and defines the 802.1Q tag
value (2 octets long). This defines VLAN membership and 802.1p
priority values.

C.1.1.4. The pktSecCondMACEtherType Attribute

This is a mandatory string attribute, and defines the EtherType
field (2 octets long). Values up to and including 1500 indicate the
size of the payload in octets; values of 1536 and above define
which protocol is encapsulated in the payload of the frame.

C.1.1.5. The pktSecCondMACTCI Attribute

This is an optional string attribute, and defines the Tag Control
Information. This consists of a 3 bit user priority field, a drop
eligible indicator (1 bit), and a VLAN identifier (12 bits).

C.1.2. PacketSecurityIPv4Condition

The purpose of this Class is to represent packet IPv4 packet header
information that can be used as part of a test to determine if the
set of Policy Actions in this ECA Policy Rule should be executed or
not. This class is concrete, and defines the following attributes.

C.1.2.1. The pktSecCondIPv4SrcAddr Attribute

This is a mandatory string attribute, and defines the IPv4 Source
Address (32 bits).

C.1.2.2. The pktSecCondIPv4DestAddr Attribute

This is a mandatory string attribute, and defines the IPv4
Destination Address (32 bits).

C.1.2.3. The pktSecCondIPv4ProtocolUsed Attribute

This is a mandatory string attribute, and defines the protocol used
in the data portion of the IP datagram (8 bits).

C.1.2.4. The pktSecCondIPv4DSCP Attribute

This is a mandatory string attribute, and defines the Differentiated
Services Code Point field (6 bits).

C.1.2.5. The pktSecCondIPv4ECN Attribute

This is an optional string attribute, and defines the Explicit
Congestion Notification field (2 bits).

C.1.2.6. The pktSecCondIPv4TotalLength Attribute

This is a mandatory string attribute, and defines the total length
of the packet (including header and data) in bytes (16 bits).

C.1.2.7. The pktSecCondIPv4TTL Attribute

This is a mandatory string attribute, and defines the Time To Live
in seconds (8 bits).

C.1.3. PacketSecurityIPv6Condition

The purpose of this Class is to represent packet IPv6 packet header
information that can be used as part of a test to determine if the
set of Policy Actions in this ECA Policy Rule should be executed or
not. This class is concrete, and defines the following attributes.

C.1.3.1. The pktSecCondIPv6SrcAddr Attribute

This is a mandatory string attribute, and defines the IPv6 Source
Address (128 bits).

C.1.3.2. The pktSecCondIPv6DestAddr Attribute

This is a mandatory string attribute, and defines the IPv6
Destination Address (128 bits).

C.1.3.3. The pktSecCondIPv6DSCP Attribute

This is a mandatory string attribute, and defines the Differentiated
Services Code Point field (6 bits). It consists of the six most
significant bits of the Traffic Class field in the IPv6 header.

C.1.3.4. The pktSecCondIPv6ECN Attribute

This is a mandatory string attribute, and defines the Explicit
Congestion Notification field (2 bits). It consists of the two least
significant bits of the Traffic Class field in the IPv6 header.

C.1.3.5. The pktSecCondIPv6FlowLabel Attribute

This is a mandatory string attribute, and defines an IPv6 flow
label. This, in combination with the Source and Destination Address
fields, enables efficient IPv6 flow classification by using only the
IPv6 main header fields (20 bits).

C.1.3.6. The pktSecCondIPv6PayloadLength Attribute

This is a mandatory string attribute, and defines the total length
of the packet (including the fixed and any extension headers, and
data) in bytes (16 bits).

C.1.3.7. The pktSecCondIPv6NextHeader Attribute

This is a mandatory string attribute, and defines the type of the
next header (e.g., which extension header to use) (8 bits).

C.1.3.8. The pktSecCondIPv6HopLimit Attribute

This is a mandatory string attribute, and defines the maximum
number of hops that this packet can traverse (8 bits).

C.1.4. PacketSecurityTCPCondition

The purpose of this Class is to represent packet TCP packet header
information that can be used as part of a test to determine if the
set of Policy Actions in this ECA Policy Rule should be executed or
not. This class is concrete, and defines the following attributes.

C.1.4.1. The pktSecCondTPCSrcPort Attribute

This is a mandatory string attribute, and defines the Source Port
number (16 bits).

C.1.4.2. The pktSecCondTPCDestPort Attribute

This is a mandatory string attribute, and defines the Destination
Port number (16 bits).

C.1.4.3. The pktSecCondTCPSeqNum Attribute

This is a mandatory string attribute, and defines the sequence
number (32 bits).

C.1.4.4. The pktSecCondTCPFlags Attribute

This is a mandatory string attribute, and defines the nine Control
bit flags (9 bits).

C.1.5. PacketSecurityUDPCondition

The purpose of this Class is to represent packet UDP packet header
information that can be used as part of a test to determine if the
set of Policy Actions in this ECA Policy Rule should be executed or
not. This class is concrete, and defines the following attributes.

C.1.5.1.1. The pktSecCondUDPSrcPort Attribute

This is a mandatory string attribute, and defines the UDP Source
Port number (16 bits).

C.1.5.1.2. The pktSecCondUDPDestPort Attribute

This is a mandatory string attribute, and defines the UDP
Destination Port number (16 bits).

C.1.5.1.3. The pktSecCondUDPLength Attribute

This is a mandatory string attribute, and defines the length in
bytes of the UDP header and data (16 bits).

C.2. PacketPayloadSecurityCondition

The purpose of this Class is to represent packet payload data that
can be used as part of a test to determine if the set of Policy
Actions in this ECA Policy Rule should be executed or not. Examples
include a specific set of bytes in the packet payload.

C.3. TargetSecurityCondition

The purpose of this Class is to represent information about
different targets of this policy (i.e., entities to which this
Policy Rule should be applied), which can be used as part of a
test to determine if the set of Policy Actions in this ECA Policy
Rule should be executed or not. Examples include whether the
targeted entities are playing the same role, or whether each
device is administered by the same set of users, groups, or roles.
This Class has several important subclasses, including:

a. ServiceSecurityContextCondition is the superclass for all
information that can be used in an ECA Policy Rule that
specifies data about the type of service to be analyzed
(e.g., the protocol type and port number)
b. ApplicationSecurityContextCondition is the superclass for all
information that can be used in a ECA Policy Rule that
specifies data that identifies a particular application
(including metadata, such as risk level)
c. DeviceSecurityContextCondition is the superclass for all
information that can be used in a ECA Policy Rule that
specifies data about a device type and/or device OS that is
being used

C.4. UserSecurityCondition

The purpose of this Class is to represent data about the user or
group referenced in this ECA Policy Rule that can be used as part of
a test to determine if the set of Policy Actions in this ECA Policy
Rule should be evaluated or not. Examples include the user or group
id used, the type of connection used, whether a given user or group
is playing a particular role, or whether a given user or group has
failed to login a particular number of times.

C.5. SecurityContextCondition

The purpose of this Class is to represent security conditions that
are part of a specific context, which can be used as part of a test
to determine if the set of Policy Actions in this ECA Policy Rule
should be evaluated or not. Examples include testing to determine
if a particular pattern of security-related data have occurred, or
if the current session state matches the expected session state.

C.6. GenericContextSecurityCondition

The purpose of this Class is to represent generic contextual
information in which this ECA Policy Rule is being executed, which
can be used as part of a test to determine if the set of Policy
Actions in this ECA Policy Rule should be evaluated or not.
Examples include geographic location and temporal information.

Appendix D. Network Security Action Class Definitions

This Appendix defines a preliminary set of Network Security Action
classes, along with their attributes.

D.1. IngressAction

The purpose of this Class is to represent actions performed on
packets that enter an NSF. Examples include pass, dropp, or
mirror traffic.

D.2. EgressAction

The purpose of this Class is to represent actions performed on
packets that exit an NSF. Examples include pass, drop, or mirror
traffic, signal, and encapsulate.

D.3. ApplyProfileAction

The purpose of this Class is to define the application of a profile
to packets to perform content security and/or attack mitigation
control.

Appendix E. Geometric Model

The geometric model defined in [Bas12] is summarized here. Note that
our work has extended the work of [Bas12] to model ECA Policy Rules,
instead of just condition-action Policy Rules. However, the
geometric model in this Appendix is simplified in this version of
this I-D, and is used to define just the CA part of the ECA model.

All the actions available to the security function are well known
and organized in an action set A.

For filtering controls, the enforceable actions are either Allow or
Deny, thus A={Allow,Deny}. For channel protection controls, they may
be informally written as "enforce confidentiality", "enforce data
authentication and integrity", and "enforce confidentiality and data
authentication and integrity". However, these actions need to be
instantiated to the technology used. For example, AH-transport mode
and ESP-transport mode (and combinations thereof) are a more precise
definition of channel protection actions.

Conditions are typed predicates concerning a given selector. A
selector describes the values that a protocol field may take. For
example, the IP source selector is the set of all possible IP
addresses, and it may also refer to the part of the packet where the
values come from (e.g., the IP source selector refers to the IP
source field in the IP header). Geometrically, a condition is the
subset of its selector for which it evaluates to true. A condition
on a given selector matches a packet if the value of the field
referred to by the selector belongs to the condition. For instance,
in Figure 17 the conditions are s1 <= S1 (read as s1 subset of or
equal to S1) and s2 <= S2 (s2 subset of or equal to S2), both s1 and
s2 match the packet x1, while only s2 matches x2.

To consider conditions in different selectors, the decision space is
extended using the Cartesian product because distinct selectors
refer to different fields, possibly from different protocol headers.
Hence, given a policy-enabled element that allows the definition of
conditions on the selectors S1, S2,..., Sm (where m is the number
of Selectors available at the security control we want to model),
its selection space is:

S=S1 X S2 X ... X Sm

S2 ^ Destination port
|
| x2
+......o
| .
| .
--+.............+------------------------------------+
| | . | |
s | . | |
e | . | (rectangle) |
g | . | condition clause (c) |
m | . | here the action a is applied |
e | . | |
n | . | x1=point=packet |
t +.............|.............o |
| | . | . |
--+.............+------------------------------------+
| . . . .
| . . . .
+------------+------+-------------+----------------------+------>
| |---- segment = condition in S1 -----| S1
+ IP source

Figure 17: Geometric representation of a rule r=(c,a) that
matches x1, but does not match x2.

Accordingly, the condition clause c is a subset of S:

c = s1 X s2 X ... X sm <= S1 X S2 X ... X Sm = S

S represents the totality of the packets that are individually
selectable by the security control to model when we use it to
enforce a policy. Unfortunately, not all its subsets are valid
condition clauses: only hyper-rectangles, or the union of
hyper-rectangles (as they are Cartesian product of conditions),
are valid. This is an intrinsic constraint of the policy
language, as it specifies rules by defining a condition for each
selector. Languages that allow specification of conditions as
relations over more fields are modeled by the geometric model as
more complex geometric shapes determined by the equations. However,
the algorithms to compute intersections are much more sophisticated
than intersection hyper-rectangles. Figure 17 graphically represents
a condition clause c in a two-dimensional selection space.

In the geometric model, a rule is expressed as r=(c,a), where c <= S
(the condition clause is a subset of the selection space), and the
action a belongs to A. Rule condition clauses match a packet (rules
match a packet), if all the conditions forming the clauses match the
packet. In Figure 17, the rule with condition clause c matches the
packet x1 but not x2.

The rule set R is composed of n rules ri=(ci,ai).

The decision criteria for the action to apply when a packet matches
two or more rules is abstracted by means of the resolution strategy

RS: Pow(R) -> A

where Pow(R) is the power set of rules in R.

Formally, given a set of rules, the resolution strategy maps all the
possible subsets of rules to an action a in A. When no rule matches a
packet, the security controls may select the default action d in A,
if they support one.

Resolution strategies may use, besides intrinsic rule data (i.e.,
condition clause and action clause), also external data associated to
each rule, such as priority, identity of the creator, and creation
time. Formally, every rule ri is associated by means
Model for Simplified Use of the
function e(.):

e(ri) = (ri,f1(ri),f2(ri),...)

where E={fj:R -> Xj} (j=1,2,...) is the set that includes all
functions that map rules to external attributes Policy Abstractions (SUPA)",
Work in Xj. However,
E, e, Progress, May, 2017.

[Alshaer] Al Shaer, E. and all the Xj are determined by the resolution strategy used.

A policy is thus a function p: S -> A that connects each point H. Hamed, "Modeling and management of
the selection space
firewall policies", 2004.

[Bas12] Basile, C., Cappadonia, A., and A. Lioy, "Network-Level
Access Control Policy Analysis and Transformation", 2012.

[Bas15] Basile, C. and A. Lioy, "Analysis of application-layer
filtering policies with application to an action taken from the action set A
according HTTP", 2015.

[Cormen] Cormen, T., "Introduction to the rules in Algorithms", 2009.

[Galitsky] Galitsky, B. and Pampapathi, R., "Can many agents answer
questions better than one", First Monday, 2005;
http://dx.doi.org/10.5210/fm.v10i1.1204

[Gamma] Gamma, E., Helm, R. By also assuming RS(0)=d (where 0 is
the empty-set) Johnson, R., Vlissides, J., "Design
Patterns: Elements of Reusable Object-Oriented
Software", Addison-Wesley, Nov, 1994.
ISBN 978-0201633610

[Hirschman]Hirschman, L., and Gaizauskas, R., "Natural Language
Question Answering: The View from Here", Natural Language
Engineering 7:4, pgs 275-300, Cambridge University Press,
2001

[Hohpe] Hohpe, G. and RS(ri)=ai, the policy p can be described as:

p(x)=RS(match{R(x)}).

Therefore, in the geometric model, a policy is completely defined by
the 4-tuple (R,RS,E,d): the rule set R, the resolution function RS,
the set E of mappings to the external attributes, Woolf, B., "Enterprise Integration
Patterns", Addison-Wesley, 2003, ISBN 0-32-120068-3

[Lunt] van Lunteren, J. and the default
action d.

Note that, the geometric model also supports ECA paradigms by simply
modeling events like an additional selector. T. Engbersen, "Fast and scalable
packet classification", 2003.

[Martin] Martin, R.C., "Agile Software Development, Principles,
Patterns, and Practices", Prentice-Hall, 2002,
ISBN: 0-13-597444-5

[MCM] MEF, "MEF Core Model", Technical Specification MEF X,
April 2018

[OODMP] http://www.oodesign.com/mediator-pattern.html

[OODSOP] http://www.oodesign.com/observer-pattern.html

[OODSRP] http://www.oodesign.com/single-responsibility-
principle.html

[PDO] MEF, "Policy Driven Orchestration", Technical
Specification MEF Y, January 2018

[Taylor] Taylor, D. and J. Turner, "Scalable packet classification
using distributed crossproducting of field labels", 2004.

6. Acknowledgments

This document was prepared using 2-Word-v2.0.template.dot.

Authors' Addresses

Cataldo Basile
Politecnico di Torino
Corso Duca degli Abruzzi, 34
Torino, 10129
Italy
Email: cataldo.basile@polito.it

Liang Xia (Frank)
Huawei
101 Software Avenue, Yuhuatai District
Nanjing, Jiangsu 210012
China
Email: Frank.xialiang@huawei.com

John Strassner
Huawei
2330 Central Expressway
Santa Clara, CA 95050 USA
Email: John.sc.Strassner@huawei.com

Cataldo Basile
Politecnico di Torino
Corso Duca degli Abruzzi, 34
Torino, 10129
Italy
Email: cataldo.basile@polito.it

Diego R. Lopez
Telefonica I+D
Zurbaran, 12
Madrid, 28010
Spain
Phone: +34 913 129 041
Email: diego.r.lopez@telefonica.com