I2NSF L. Xia
Internet Draft J. Strassner
Intended status: Standard Track D.Zhang
Huawei
K. Li
Alibaba
C. Basile
A. Lioy
PoliTO
D. Lopez
TID
E. Lopez
Fortinet
N. BOUTHORS
Qosmos
Luyuan Fang
Microsoft
Expires: December 2017 November 1, 2016
Information Model of NSFs Capabilities
draft-xibassnez-i2nsf-capability-00.txt
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Abstract
This draft aims at defining the concept of capability. Capabilities
are data that unambiguously characterize NSFs (Network Security
Functions). Their correct definition will ease all the management
and automation that can be. Moreover, it allows the definition of
Interfaces to manage NSFs.
This draft is the first trial to merge two previous existing drafts
on NSFs capabilities [I-D.draft-baspez-i2nsf-capabilities-00] and on
the capability interface [I-D.draft-xia-i2nsf-capability-interface-
im-06]. Further work will be needed to homogenize all the concepts
and incorporate the feedback that will result after its publication.
Table of Contents
1. Introduction ................................................ 4
2. Conventions used in this document ........................... 6
2.1. Terminology ............................................ 6
3. Management of NSFs: Design Principles towards a model of
Capabilities ................................................... 7
4. Information Model .......................................... 10
5. Capabilities for security policy enforcement ............... 12
5.1. The CA Policy Model ................................... 13
5.2. Geometric Model of CA Policies ........................ 14
5.3. Condition Types ....................................... 17
5.4. Model of Capabilities for Policy Specification and Enforcement
Purposes ................................................... 19
5.5. Algebra of capabilities ............................... 20
5.6. Examples of NSFs Categories ........................... 21
5.6.1. Network Security ................................. 22
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5.6.2. Content Security .................................. 22
5.6.3. Attack Mitigation ................................. 22
6. Information Sub-Model for Network Security Capabilities ..... 23
6.1. Information Sub-Model for Network Security ............. 23
6.1.1. Network Security Policy Rule Extensions ........... 24
6.1.2. Network Security Policy Rule Operation ............ 26
6.1.3. Network Security Event Sub-Model .................. 27
6.1.3.1. UserSecurityEvent Class Description .......... 29
6.1.3.1.1. The usrSecEventContent Attribute ........ 29
6.1.3.1.2. The usrSecEventFormat Attribute.......... 29
6.1.3.1.3. The usrSecEventType Attribute ........... 30
6.1.3.2. DeviceSecurityEvent Class Description ........ 30
6.1.3.2.1. The devSecEventContent Attribute ........ 30
6.1.3.2.2. The devSecEventFormat Attribute.......... 31
6.1.3.2.3. The devSecEventType Attribute ........... 31
6.1.3.2.4. The devSecEventTypeInfo[0..n] Attribute . 31
6.1.3.2.5. The devSecEventTypeSeverity Attribute ... 32
6.1.3.3. SystemSecurityEvent Class Description ........ 32
6.1.3.3.1. The sysSecEventContent Attribute ........ 32
6.1.3.3.2. The sysSecEventFormat Attribute.......... 33
6.1.3.3.3. The sysSecEventType Attribute ........... 33
6.1.3.4. TimeSecurityEvent Class Description .......... 33
6.1.3.4.1. The timeSecEventPeriodBegin Attribute ... 34
6.1.3.4.2. The timeSecEventPeriodEnd Attribute ..... 34
6.1.3.4.3. The timeSecEventTimeZone Attribute ...... 34
6.1.4. Network Security Condition Sub-Model .............. 34
6.1.4.1. PacketSecurityCondition ...................... 36
6.1.4.1.1. PacketSecurityMACCondition .............. 36
6.1.4.1.1.1. The pktSecCondMACDest Attribute .... 37
6.1.4.1.1.2. The pktSecCondMACSrc Attribute ..... 37
6.1.4.1.1.3. The pktSecCondMAC8021Q Attribute ... 37
6.1.4.1.1.4. The pktSecCondMACEtherType Attribute 37
6.1.4.1.1.5. The pktSecCondMACTCI Attribute ..... 37
6.1.4.1.2. PacketSecurityIPv4Condition ............. 37
6.1.4.1.2.1. The pktSecCondIPv4SrcAddr Attribute 37
6.1.4.1.2.2. The pktSecCondIPv4DestAddr Attribute 37
6.1.4.1.2.3. The pktSecCondIPv4ProtocolUsed Attribute
................................................ 38
6.1.4.1.2.4. The pktSecCondIPv4DSCP Attribute ... 38
6.1.4.1.2.5. The pktSecCondIPv4ECN Attribute .... 38
6.1.4.1.2.6. The pktSecCondIPv4TotalLength Attribute
................................................ 38
6.1.4.1.2.7. The pktSecCondIPv4TTL Attribute .... 38
6.1.4.1.3. PacketSecurityIPv6Condition ............. 38
6.1.4.1.3.1. The pktSecCondIPv6SrcAddr Attribute 38
6.1.4.1.3.2. The pktSecCondIPv6DestAddr Attribute 38
6.1.4.1.3.3. The pktSecCondIPv6DSCP Attribute ... 38
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6.1.4.1.3.4. The pktSecCondIPv6ECN Attribute .... 39
6.1.4.1.3.5. The pktSecCondIPv6FlowLabel Attribute39
6.1.4.1.3.6. The pktSecCondIPv6PayloadLength
Attribute ....................................... 39
6.1.4.1.3.7. The pktSecCondIPv6NextHeader Attribute39
6.1.4.1.3.8. The pktSecCondIPv6HopLimit Attribute 39
6.1.4.1.4. PacketSecurityTCPCondition .............. 39
6.1.4.1.4.1. The pktSecCondTPCSrcPort Attribute . 39
6.1.4.1.4.2. The pktSecCondTPCDestPort Attribute 39
6.1.4.1.4.3. The pktSecCondTPCSeqNum Attribute .. 40
6.1.4.1.4.4. The pktSecCondTPCFlags Attribute ... 40
6.1.4.1.5. PacketSecurityUDPCondition .............. 40
6.1.4.1.5.1. The pktSecCondUDPSrcPort Attribute . 40
6.1.4.1.5.2. The pktSecCondUDPDestPort Attribute 40
6.1.4.1.5.3. The pktSecCondUDPLength Attribute .. 40
6.1.4.2. PacketPayloadSecurityCondition ............... 40
6.1.4.3. TargetSecurityCondition ...................... 40
6.1.4.4. UserSecurityCondition ........................ 41
6.1.4.5. SecurityContextCondition ..................... 41
6.1.4.6. GenericContextSecurityCondition .............. 41
6.1.5. Network Security Action Sub-Model ................. 42
6.1.5.1. IngressAction ................................ 43
6.1.5.2. EgressAction ................................. 43
6.1.5.3. ApplyProfileAction ........................... 43
6.1.5.4. ApplySignatureAction ......................... 43
6.2. Information Model for Content Security Control ......... 43
6.3. Information Model for Attack Mitigation Control ........ 44
7. Security Considerations ..................................... 45
8. IANA Considerations ......................................... 46
9. References .................................................. 46
9.1. Normative References ................................... 46
9.2. Informative References ................................. 46
10. Acknowledgments ............................................ 47
Appendix A. .................................................... 48
A.1. AuthenticationECAPolicyRule Class Definition ........... 48
A.2. AuthorizationECAPolicyRuleClass Definition ............. 50
A.3. AccountingECAPolicyRuleClass Definition ................ 52
A.4. TrafficInspectionECAPolicyRuleClass Definition.......... 54
A.5. ApplyProfileECAPolicyRuleClass Definition .............. 56
A.6. ApplySignatureECAPolicyRuleClass Definition ............ 58
1. Introduction
The rapid development of virtualized systems, along with the demand
of security services in virtualized systems, requires advanced
security protection in various scenarios. Examples include network
devices in an enterprise network, User Equipment (UE) in a mobile
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network, devices in the Internet of Things (IoT), or residential
access users [I-D.draft-ietf-i2nsf-problem-and-use-cases].
Capabilities are precise information that characterize in an
unambiguous way (in a given virtualized system) what a NSF can do in
terms of security policy enforcement and how a Controller can
interact with it in order to enforce a security policy. Even if the
aim is a general of capabilities, the unambiguity of capabilities is
only assured in a given virtualized system.
According to [I-D.draft-ietf-i2nsf-framework], there are two types
of I2NSF interfaces available for security rules provisioning:
o Interface between I2NSF clients and a security controller (Client
Facing Interface): This is a service-oriented interface, whose
main objective is to define a communication channel over which
information defining security services controlling client's
specific flow can be requested. This enables security information
to be exchanged between various applications (e.g., OpenStack, or
various BSS/OSS components) and other components (e.g., security
controllers). The design goal of the service interface is to
decouple the security service in the application layer from
various kinds of security devices and their device-specific
security functions.
Interface between NSFs (e.g., firewall, intrusion prevention, or
anti-virus) and a security controller (NSFs Facing Interface):
This interface is independent of how the NSFs are implemented
(e.g., run in Virtual Machines (VMs) or physical appliances). The
NSFs Facing Interface is used to decouple the security management
scheme from the set of NSFs and their various implementations for
this scheme, so as to specify and monitor a number of flow based
security policies to individual NSFs. According to the definition
in [I-D.draft-ietf-i2nsf-framework], NSFs Facing Interface
includes sub-interfaces of Capability Interface, Registration
Interface and Monitoring Interface. This document proposes the
information model design for the first two interfaces (Capability
and Registration), the Monitoring Interface information model is
discussed in [I-D.draft-zhang-i2nsf-info-model-monitoring].
This document is organized as follows: Section 3 discusses the
design principles for NSF capabilities and related ECA model.
Section 4 further describes design principles for I2NSF capability
information model. Section 5 provides more details about the design
of network security capability. Section 6 presents further
information on specific aspects of the information model.
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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 references to [I-D.draft-ietf-i2nsf-terminology] for
more specific security related and I2NSF scoped terminology
definitions.
2.1. Terminology
AAA -Access control, Authorization, Authentication
ACL - Access Control List
AD - Active Directory
ANSI - American National Standards Institute
DDoS - Distributed Deny of Services
FW - Firewall
I2NSF - Interface to Network Security Functions
INCITS - International Committee for Information Technology
Standards
IoT - Internet of Things
IPS - Intrusion Prevention System
LDAP - Lightweight Directory Access Protocol
NAT - Network Address Translation
NBI - North-bound Interface
NIST - National Institute of Standard Technology
NSF - Network Security Function
RBAC - Role Based Access Control
UE - User Equipment
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URL - Uniform/Universal Resource Locator
VM - Virtual Machine
WAF - Web Application Firewall
3. Management of NSFs: Design Principles towards a model of
Capabilities
Some basic principles for security capabilities and the systems that
have to manage them need to be considered:
o Flexibility: each security capability should be an independent
function, with minimum overlap or dependency to other
capabilities. This enables each security capability to be
utilized and assembled together freely. More importantly, changes
to one capability will not affect other capabilities;
o High level of abstraction: each capability should be associated
to a unified interface to make it programmable; this in turn
provides a standardized ability to describe and report its
processing results and corresponding statistics information.
Furthermore, it facilitates the multi-vendor interoperability;
o Automation: The system must have the ability to auto-discover,
auto-negotiate, and auto-update security capabilities. These
features are especially useful for the management of a large
number of NSFs. They are essential to add smart services
(refinement, analysis, capability reasoning, optimization) on top
of the virtual layer;
o Scalability: the management system must have the 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, the security capability must
support reporting statistics to the security controller to assist
its decision on whether it needs to invoke scaling or not.
Based on the above principles, a set of abstract and vendor-neutral
capabilities with standard interfaces is needed together with a
model of capabilities that allows to unambiguously determine what
NSFs can do in terms of security policy enforcement. The security
controller can compare the requirements of clients to the set of
capabilities that are currently available in order to choose which
NSFs are needed to meet those requirements. Note that this choice is
independent of vendor, and instead relies specifically on the
capabilities (i.e., the description) of the functions provided. This
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also facilitates the customization of the functionality of the
selected NSFs by setting the parameters of their interfaces.
Furthermore, when an unknown threat (e.g., zero-day exploits,
unknown malware, and APTs) is reported by a network security device,
new capabilities may be created, and/or existing capabilities may be
updated (e.g., signature and algorithm), to correspond to the new
functionality provided by the NSF to handle the threat. The new
capabilities are provided from different vendors after their
analysis of the new threats and subsequent installation of the
functions required to report on (and possibly mitigate) the threat.
New capabilities may be sent to and stored in a centralized
repository, or stored separately in a local repository. In either
cases, a standard interface is needed during this automated update
process.
In defining the capabilities of a NSF, the "Event-Condition-Action"
(ECA) policy rule set model in [I-D.draft-ietf-i2nsf-framework]
should be here as the basis for the design:
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 policy
rules for I2NSF, it is used to determine whether the Condition
clause of the 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 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 make a decision. When used in the context of
policy rules for I2NSF, it is used to determine whether or not
the set of Actions in that Policy Rule can be executed or not.
The following are exemplary types of conditions:
? Packet content values: Refer to the kind of information or
attributes acquired directly from the packet headers or
payloads that can be used in the security policy. It can be
any fields or attributes in the packet L2/L3/L4 header, or
special segment of bytes in the packet payload;
? Context values: Refer to the context information for the
received packets. It can be (and not limited to):
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* User: The user (or user group) information to which a
network flow is associated. A user has many attributes,
such as name, id, password, authentication mode, and so
on. The combination of name and id (where id could be a
password, a certificate, or other means of identifying
the user) is often used in the security policy to
identify the user. For example, if an NSF is aware of
the IP (or MAC) address associated with the user, the
NSF can use a pre-defined or dynamically learned name-
address association to enforce the security functions
for this given user (or user group);
* Schedule: Time or time range when packet or flow is
received;
* Region: The geographic location where network traffic is
received;
* Target: The target indicates the entity to which the
security services are applied. This can be a service,
application, or device. A service is identified by the
protocol type and/or port number. An application is a
computer program for a specific task or purpose. It
provides additional semantics (e.g., dependencies
between services) for matching traffic. A device is a
managed entity that is connected to the network. The
attributes that can identify a device include type (e.g.,
router, switch, pc) and operating system (e.g., Windows,
Linux, or Android), as well as the device's owner;
* State: It refers to various states to which the network
flow is associated. It can be either the TCP session
state (e.g., new, established, related, invalid, or
untracked), the session AAA state (e.g., authenticated
but not authorized), or the access mode of the device
(e.g., wireline, wireless, or cellular; these could be
augmented with additional attributes, such as the type
of VPN that is being used);
* Direction: the direction of the network flow.
o Action: NSFs provide security functions by executing various
Actions, which at least includes:
? Ingress actions, such as pass, drop, mirroring, etc;
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? Egress actions, such as invoke signaling, tunnel
encapsulation, packet forwarding and/or transformation;
? Applying a specific Functional Profile or signature - e.g.,
an IPS Profile, a signature file, an anti-virus file, or a
URL filtering file. It is one of the key properties that
determine the effectiveness of the NSF, and is mostly vendor-
specific today. One goal of I2NSF is to standardize the form
and functional interface of those security capabilities while
supporting vendor-specific implementations of each. However,
it is important to properly model the parts that are related
to the action (what is enforced) and the conditions (on what
it is enforced).
The above ECA ruleset is very general and easily extensible, thus
can avoid any potential constraints which could limit the
implementation of the network security control capability.
4. Information Model
An information model will be developed in order to describe in an
abstract and vendor independent manner all the aspects related to
the capabilities of NSFs. A detailed information model will be
designed in the next versions of this draft as a consequence of the
discussions, feedback, and extensions that will originate after the
publication of this draft. In this version of the draft, we present
a simplified view that only highlights the most important concepts.
The I2NSF capability interface is in charge of controlling and
managing the NSFs by means of the information about the capabilities
each NSF owns. This is done using the following approach:
1) User of the capability interface selects the set of capabilities
required to meet the needs of the application;
2) A management entity uses the information model to match chosen
capabilities to NSFs, independent of vendor;
3) A management entity takes the above information and creates or
uses vendor-specific data models to install the NSFs identified by
the chosen capabilities;
4) Control and monitoring can then begin.
This assumes that an external model, or set of models, is used to
define the concept of an ECA Policy Rule and its components (e.g.,
Event, Condition, and Action objects).
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Since Capabilities are unambiguous only within the same management
system, and are not inherent characteristics that differentiate
objects, it is also assumed that an external model (or set of models)
will define a generic metadata concept.
The Capability is a general abstract concept. Currently, the most
promising approach for defining the information model of the
Capabilities uses the sub-classing to define non-overlapping and
independent concepts. For instance, the Capability model that will
be presented in the next sections that abstractly determines the
security policies that a NSF can enforce does not overlap with an
independent model that specifies how a NSF can be contacted by the
controller (i.e., the protocols and secure channels) and when (i.e.,
the events to which it reacts). Capabilities are sub-classed from an
appropriate class in the external metadata model.
The capability interface is used for advertising, creating,
selecting and managing a set of specific security capabilities
independent of the type and vendor of device that contains the NSF.
That is, the user of the capability interface does not care whether
the NSF is virtualized or hosted in a physical device, the vendor of
the NSF, and which set of entities the NSF is communicating with
(e.g., a firewall or an IPS). Instead, the user only cares about the
set of capabilities that the NSF has, such as packet filtering or
deep packet inspection. The overall structure is illustrated in the
figure below:
+-------------------------+ 0..n 0..n +---------------+
| |/ \ \| External |
| External ECA Info Model + A ----------------+ Metadata |
| |\ / Aggregates /| Info Model |
+-------------------------+ Metadata +------+--------+
/ \
|
|
|
+----+-------+
| Capability |
| Sub-Model |
+------------+
Figure 1. The Overall I2NSF Information Model Design
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This draft defines the Capability sub-Model shown in Figure 1. This
model assumes that another, generic, information model for defining
ECA policy rules (which includes a specific one for the CA part of
ECA policy rules) exists outside of I2NSF.
It also assumes that Capabilities are modeled as metadata, since a
Capability is something that describes and/or prescribes
functionality about an object, but is not an inherent part of that
object. Hence, the Security Capability Sub-Model extends the generic
external metadata model.
Both of these external models could, but do not have to, draw from
the SUPA model [I-D.draft-ietf-supa-generic-policy-info-model].
The external ECA Information Model supplies at least a set of
objects that represent a generic ECA Policy Rule, and a set of
objects 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.
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.
5. Capabilities for security policy enforcement
At present, a variety of NSFs produced by multiple security vendors
provide various security 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 are intended to describe the potentiality that
Network Security Functions (NSFs) have for security policy
enforcement purposes. Security Capabilities are abstract concepts
that are independent of the actual security control that will
implement them. However, every NSF will be associated to the
capabilities it owns. Security Capabilities are required to allow
differentiating among network functions. It would be a market
enabler having a way to substitute a NSF with an equivalent one
(i.e., having the same functionality). Moreover, Security
Capabilities are very useful to reason about generic functions,
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which may be needed at design time. That is, it is not needed to
refer to a specific product when designing the network; rather the
functions characterized by their capabilities are considered.
Therefore, we have developed another model where Security
Capabilities determine what a security control can do in terms of
conditions, actions, resolution strategies, external data, if it
supports default action, etc. That is, Security Capabilities define
without any ambiguity the actions a function can do in term of
security policy enforcement. The Security Capability model is built
on a predefined general policy model. The type of policies that a
NSF can enforce is obtained by customizing the general policy model
with the Security Capability information.
The Capability Model has been preliminarily validated by verifying
that is allows the correct description of several existing security
controls.
5.1. The CA Policy Model
The starting point of the design of our capability model is a simple
observation. As human beings, we all understand immediately each
other when we refer to security controls by just naming their
category. For instance, experts agree on what is a NAT, a filtering
control, or a VPN concentrator. Network security experts
unequivocally refer to "packet filters" as stateless devices able to
allow or deny packets forwarding based on conditions on source and
destination IP addresses, source and destination ports, and IP
protocol type fields [Alshaer]. Moreover, it is known that packet
filter rules are prioritized and it is possible to specify a default
action. More precisely, packet filters implement the First Matching
Rule (FMR) or Last Matching Rule (LMR) resolution strategies.
However, we feel the need for more information in case of other
devices, like stateful firewalls or application layer filters.
These devices filter packets or communications, but there are
differences among products in the packets and communications that
they can categorize and the states they maintain. 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, apply
anti-reply protections, and authenticate peers.
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The purpose is to build a model of security capabilities that allow
automatic management of virtualized systems, where intelligent
components are able to properly identify and manage NSFs, and allow
NSFs to properly declare their functionality so that they can be
used in the correct way.
5.2. Geometric Model of CA Policies
We refer in this draft to the policy model defined in [Bas12] as
geometric model, which is summarized here. Policies are specified by
means of a set of rules in the "if condition then action" format
[RFC3198]. Rules are formed by a condition clause and an action
clause. This model can be further extended to support events, that
is, in the Event-Condition-Action paradigms. However, for our
purpose, the geometric model will only be used to define the CA part
of the ECA model that we have selected as reference.
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 and
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 instance AH-transport mode
and ESP-transport mode (and combinations thereof) are a more precise
and univocal definition of channel protection actions.
Conditions are typed predicates concerning a given selector. A
selector describes the values that a protocol field may take, e.g.,
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 2
the conditions are s1 <= S1 (read as s1 subset of or equal to S1)
and s2 <= S2 (s1 of or equal to S2), both s1 and s2 match the packet
x1, while only s2 matches x2.
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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 2: Geometric representation of a rule r=(c,a) that matches x1
but does not match 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
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.
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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 union of hyper-
rectangles (as they are Cartesian product of conditions) are valid.
This is an intrinsic constraint of the policy languages as they
specify 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 1 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 matche a packet (rules
matche a packet), if all the conditions forming the clauses match
the packet: in Figure 1, 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
of the function e(.) to:
e(ri) = (ri,f1(ri),f2(ri),...)
where E={fj:R -> Xj} (j=1,2,...) is the set that includes all the
functions that map rules to external attributes in Xj. However, E, e,
and all the Xj are determined by the resolution strategy used.
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A policy is thus a function p: S -> A that connects each point of
the selection space to an action taken from the action set A
according to the rules in R. By also assuming RS(0)=d (where 0 is
the empty-set) and RS(ri)=ai, the policy p can be described with
this formula
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, and the default
action d.
Note that, the geometric model also supports ECA paradigms by simply
modeling events like an additional selector.
5.3. Condition Types
After having analyzed the literature and the existing security
controls, we have categorized the types of selectors in 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 of the IP header is a 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 is only meaningful to specify conditions
proto = tcp, udp (protocol type field equals to TCP or UDP)
proto != tcp (protocol type field different from TCP)
No other operators are allowed on exact-match selectors, for
instance
proto < 62 (invalid condition)
is not a valid condition, even if protocol types map to integers.
Range-based selectors are ordered sets where it is possible to
naturally specify ranges as they can be easily mapped to integers.
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As an example, the ports in the TCP protocol are well represented
using a range-based selector (e.g., 1024-65535). As an example
source_port = 80
source_port < 1024
source_port < 30000 && source_port >= 1024
are valid conditions.
We include in the range-based selectors all the category of
selectors that have 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
the IP address selector (e.g., 10.10.1.*). There is no need to
distinguish between prefix match and 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 regex-based
selectors, where the matching is performed by using regular
expressions. This selector type is frequent at the application layer,
where data are often represented as strings of text. The regex-based
selector type also includes as sub-case the string-based selectors,
where matching is evaluated using string matching algorithms (SMA)
[Cormen] Indeed, for our purposes, string matching 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 that offers various access control capabilities, allows the
definition of conditions on URLs that can be evaluated with SMA
(e.g., dstdomain) or regex matching (e.g., dstdom_regex).
As an example,
URL = *.website.*
matches all the URLs that contain a domain, subdomain named website
and the ones whose path contain the string .website.
MIME_type = video/*
matches all the MIME objects whose type is video.
Finally, we introduce the idea of custom check selectors. For
instance the malware analysis looks for specific patterns and
returns a Boolean value is an example of custom check selector, if
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the logic of checking is not seen (nor really interesting) from the
outside.
In order to be properly used by high-level policy based processed
(like reasoning systems, refinement systems) these custom check
selector need at least to be described as black-boxes, that is, the
list of fields that they process (inputs) in order to return the
Boolean verdict (output).
More examples of custom check selectors will be presented in the
next versions of the draft. Some example is already present in
Section 6.
5.4. Model of Capabilities for Policy Specification and Enforcement
Purposes
Our model of capabilities is based on actions and traffic
classification features. Indeed, the need for enforcing one of the
actions that a security control can apply to packets/flows is the
main reason to use a security control. Moreover, security controls
have classification features that permit the identification of the
target packets/flows of the actions enforced, i.e., the selectors
presented in Section 5.2. A security manager decides for a specific
security control depending on the actions and classification
features. If the security control can enforce the needed actions and
has the classification features needed to identify the packets flows
required by a policy, then the security control is capable of
enforcing the policy. Our refinement model needs to know NSFs
capabilities to perform its operations.
However, security controls may have specific characteristics that
automatic processes or administrators need to know when they have to
generate configurations, like the available resolution strategies
and the possibility to set default actions. We have ignored, to
simplify this presentation, options to generate configurations that
may have better performance, like the use of chains or ad hoc
structures [Taylor]. Adding support to these forms of optimization
is certainly feasible with a limited effort but it was outside the
scope of this paper, that is, to show that adding security awareness
to NFV management and orchestration features is possible. It is one
of the task for future work.
Capabilities can be used for two purposes: describing generic
security functions, and describing specific products. With the term
generic security function (GNSF) we denote known classes of security
functions. The idea is to have generic components whose behavior is
as well understood as for the network components (i.e., a switch is
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a switch and we know to use it even if it may have some vendor-
specific functions). These generic functions can be substituted by
any product that owns the required capability at instantiation time.
We have analyzed several classes of NSFs to prove the validity of
our approach. We found the common features and defined a set of
generic NSFs, including packet filter, URL filter, HTTP filter, VPN
gateway, anti-virus, anti-malware, content filter, monitoring,
anonymity proxy that will be described in a data model TBD.
Moreover, we have also categorized common extensions of the generic
NSFs, packet filters that may decide based on time information.
Moreover, some other packet filters add stateful features at ISO/OSI
layer 4.
The next section will introduce our algebra to compose capabilities,
defined to associate NSFs to capabilities and to check whether a NSF
has the capabilities needed to enforce policies.
5.5. Algebra of capabilities
Our capabilities are defined by a 4-tuple, that is every NSF N will
be associated to a 4-tuple (Ac; Cc; RSc; Dc) such that:
(Ac; Cc; RSc; Dc) <= (XAC; XCC; XRSC; XDC)= K
where
o XAC is the set of all the supported actions, that is, the set of
all the actions supported by at least one of the existing NSFs;
o Ac <= XAC is a set of actions that determine the actions actually
available at the NSF N;
o XCC is set of all the supported conditions types, that is, the
set of all the conditions that can be to specify rules in at
least one of the existing NSFs;
o Cc <= XCC is the sef of conditions actually available at the NSF
N;
o XRSC is the set of all the existing resolutions strategies,
o RSc <= XCC is the set of resolution strategies that can be used
to specify solve conflicts of multiple matching rules at the NSF
N;
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o XDC={F} U XAC, is the set of all the existing actions plus a
dummy symbol F, a placeholder value that can be used to indicate
that the default action can be freely selected by the policy
editor; and
o Dc <= XDC, Dc may be {F}, to indicate that the default action can
be freely selected by the policy editor, thus it can vary in
every policy, or an explicit action {a<=XAC} to indicate that the
default action is fixed and the policy editor will not have the
possibility to choice it.
Given cap1=(Ac1,Cc1,RSc1,def1) and cap2=(Ac2,Cc2,RSc2,def2), we
define two operations that are useful to manipulate capabilities:
o capability addition: cap1+cap2 = (Ac1 U Ac2, Cc1 U Cc2, RSc1,def1)
o capability subtraction: cap_1-cap_2 = (Ac1\Ac2,Cc1\Cc2,RSc1,def1)
Note that addition and subtraction do not alter the resolution
strategy and the default action method, as our main intent was to
model addition of modules.
As an example, a generic packet filter that supports the first
matching rule resolution strategies, allows the explicit
specification of default actions and also supports time-based
conditions. The description of its capabilities is the following:
Apf = {Allow, Deny}
Cpf= {IPsrc,IPdst,Psrc,Pdst,protType}
Ctime = {timestart,days,datestart,datestop}
cap_pf=(Apf; Cpf; {FMR}; F)
cap_pf+time=cap_pf + Ctime
By abuse of notation, we have written cap_pf+time=cap_pf + Ctime to
shorten the more correct expression cap_pf+time=cap_pf +(;Ctime;;).
5.6. Examples of NSFs Categories
As an example of the application of the general capability model, we
present in the next sections three examples of common categories:
network security, content security, and attack mitigation.
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5.6.1. Network Security
Network security is a category that describes the inspecting and
processing of network traffic based on 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 context to 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.
5.6.2. Content Security
Content security is another category of security capabilities
applied to application layer. Through detecting the contents carried
over the traffic in application layer, these capabilities can
realize various security functions, such as defending against
intrusion, inspecting virus, filtering malicious URL or junk email,
blocking illegal web access or malicious data retrieval.
Generally, each type of threat in the application layer has a set of
unique characteristics, and requires handling with a set of specific
methods. Thus, these NSFs will be characterized by their own
security capabilities.
5.6.3. Attack Mitigation
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, and each set
further consists of a number of specific attacks:
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, ssl DDoS.
o Single-packet attack:
?Scanning and sniffing attacks: IP sweep, port scanning, etc
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?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 capability, for
detection and mitigation.
Overall, the implementation and management of this category of
security capabilities of attack mitigation control is very similar
to content security control. A standard interface, through which the
security controller can choose and customize the given security
capabilities according to specific requirements, is essential.
6. Information Sub-Model for Network Security Capabilities
The purpose of the Capability Framework Information Sub-Model is to
define the concept of a Capability from an external metadata model,
and enable Capabilities to be aggregated to appropriate objects. In
the following sections we will present the cases of Network Security,
Content Security, and Attack Mitigation sub-models.
6.1. 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:
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+---------------------+
+---------------+ | |
| |/ \ \| A Common Superclass |
| ECAPolicyRule + A -------------+ for ECA Objects |
| |\ / /| |
+-------+-------+ +---------+-----------+
/ \ / \
| |
| |
(subclasses to define Network (subclasses of Event,
Security ECA Policy Rules, Condition, and Action Objects
such as InspectTraffic) for Network Security Control)
Figure 3. 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 Info
Model. The Network Security Sub-Model extends both to define
security-specific ECA policy rules, as well as Events, Conditions,
and Actions.
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, and actions),
and optionally, metadata. It can be applied to both uni-directional
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, enable a set of actions to be executed.
An example of an I2NSF Policy Rule is, in pseudo-code:
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**.
6.1.1. 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
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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 4. 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
to define Security 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 basic, but necessary, information.
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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.
The SecurityECAPolicyRule defines network security policy as a
container that aggregates Event, Condition, and Action objects,
which are described in Section 6.1.3, 6.1.4, and 6.1.5, respectively.
Events, Conditions, and Actions can be generic or security-specific.
Section 4.6 defines the concept of default security Actions.
Brief class descriptions of these six ECA Policy Rules are provided
in the Appendix A.
6.1.2. Network Security Policy Rule Operation
Network security policy consists of a number of more granular ECA
Policy Rules formed from the information model described above. In
simpler cases, where the Event and Condition clauses remain
unchanged, then network security control may be performed by calling
additional network security actions. Network security policy
examines and performs basic processing of the traffic as follows:
1. For a given SecurityECAPolicyRule (which can be generic or
specific to security, such as those in Figure 3), the NSF
evaluates the Event clause. It may use security Event objects to
do all or part of this evaluation, which are defined in section
4.3.3. If the Event clause evaluates to TRUE, then the Condition
clause of this SecurityECAPolicyRule is evaluated; otherwise,
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 4.3.4. If the Condition clause evaluates to
TRUE, then the set of Actions in this SecurityECAPolicyRule MUST
be executed. This is defined as "matching" the
SecurityECAPolicyRule; otherwise, execution of this
SecurityECAPolicyRule is stopped, and the next
SecurityECAPolicyRule (if one exists) is evaluated;
3. If none of the SecurityECAPolicyRules are matched, then the NSF
denies the traffic by default;
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4. If the traffic matches a rule, the NSF performs the defined
Actions on the traffic. It may use security Action objects to do
all or part of this execution, which are defined in section 4.3.5.
If the action is "deny", the NSF blocks the traffic. 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;
5. If other security capabilities (e.g., Anti-virus or IPS) are
referenced in the SecurityECAPolicyRule, and the Action defined
in the rule is permit or mirror, the NSF performs the referenced
security capabilities.
Metadata attached to the SecurityECAPolicyRule MAY be used to
control how the SecurityECAPolicyRule is evaluated. This is called a
Policy Rule Evaluation Strategy. For example, one strategy is to
match and execute the first SecurityECAPolicyRule, and then exit
without executing any other SecurityECAPolicyRules (even if they
matched). In contrast, a second strategy is to first collect all
SecurityECAPolicyRules that matched, and then execute them according
to a pre-defined order (e.g., the priority of each
SecurityECAPolicyRule).
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.
6.1.3. Network Security Event Sub-Model
Figure 10 shows a more detailed design of the Event subclasses that
are contained in the Network Security Information Sub-Model.
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+---------------------+
+---------------+ 1..n 1..n| |
| |/ \ \| A Common Superclass |
| ECAPolicyRule + A ---------+ for ECA Objects |
| |\ / /| |
+---------------+ +-----------+---------+
/ \
|
|
+--------------+--------+------+
| | |
| | |
+-----+----+ +------+------+ +-----+-----+
| An Event | | A Condition | | An Action |
| Class | | Class | | Class |
+-----+----+ +-------------+ +-----------+
/ \
|
|
|
+-----------+---+----------------+--------------+-- ...
| | | |
| | | |
+-------+----+ +--------+-----+ +--------+-----+ +------+-----+
|UserSecurity| | Device | | System | |TimeSecurity|
| Event | | SecurityEvent| | SecurityEvent| | Event |
+------------+ +--------------+ +--------------+ +------------+
Figure 5. Network Security Info Sub-Model Event Class Extensions
The four Event classes shown in Figure 5 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.
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 10). However, this makes it harder to use any
generic Event model with the I2NSF events. Assumptions are:
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- The generic Event class is abstract
- 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 10 would be
subclasses of the Atomic Event)
- 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
Brief class descriptions are provided in the following sub-sections.
6.1.3.1. 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:
6.1.3.1.1. 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).
6.1.3.1.2. 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:
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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)
6.1.3.1.3. 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
6.1.3.2. 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:
6.1.3.2.1. 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
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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).
6.1.3.2.2. 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)
6.1.3.2.3. 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.
6.1.3.2.4. 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.
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6.1.3.2.5. 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 include:
0: unknown
1: cleared
2: indeterminate
3: critical
4: major
5: minor
6: warning
Values 1-6 are from X.733.
6.1.3.3. 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:
6.1.3.3.1. 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).
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6.1.3.3.2. 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)
6.1.3.3.3. 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
6.1.3.4. 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:
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6.1.3.4.1. 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).
6.1.3.4.2. 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.
6.1.3.4.3. 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.
6.1.4. Network Security Condition Sub-Model
Figure 6 shows a more detailed design of the Condition subclasses
that are contained in the Network Security Information Sub-Model.
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+---------------------+
+---------------+ 1..n 1..n | |
| |/ \ \| A Common Superclass |
| ECAPolicyRule+ A ----------+ for ECA Objects |
| |\ / /| |
+-------+-------+ +-----------+---------+
/ \
|
|
+--------------+----------+----+
| | |
| | |
+-----+----+ +------+------+ +-----+-----+
| An Event | | A Condition | | An Action |
| Class | | Class | | Class |
+----------+ +------+------+ +-----------+
/ \
|
|
+--------+----------+------+---+---------+--------+--- ...
| | | | | |
| | | | | |
+-----+-----+ | +-------+-------+ | +------+-----+ |
| Packet | | | PacketPayload | | | Target | |
| Security | | | Security | | | Security | |
| Condition | | | Condition | | | Condition | |
+-----------+ | +---------------+ | +------------+ |
| | |
+------+-------+ +----------+------+ +--------+-------+
| UserSecurity | | SecurityContext | | GenericContext |
| Condition | | Condition | | Condition |
+--------------+ +-----------------+ +----------------+
Figure 6. Network Security Info Sub-Model Condition Class
Extensions
The six Condition classes shown in Figure 6 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
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of the generic Condition class, and a superclass of the six
Condition classes shown in Figure 11), this makes it harder to use
any generic Condition model with the I2NSF conditions.
Brief class descriptions are provided in the following sub-sections.
6.1.4.1. 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 involve different types of packet formats. Its
subclasses are shown in Figure 7, and are defined in the following
sections.
+-------------------------+
| PacketSecurityCondition |
+------------+------------+
/ \
|
|
+---------+----------+---+-----+----------+
| | | | |
| | | | |
+--------+-------+ | +--------+-------+ | +--------+-------+
| PacketSecurity | | | PacketSecurity | | | PacketSecurity |
| MACCondition | | | IPv4Condition | | | IPv6Condition |
+----------------+ | +----------------+ | +----------------+
| |
+--------+-------+ +--------+-------+
| TCPCondition | | UDPCondition |
+----------------+ +----------------+
Figure 7. Network Security Info Sub-Model PacketSecurityCondition
Class Extensions
6.1.4.1.1. 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:
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6.1.4.1.1.1. The pktSecCondMACDest Attribute
This is a mandatory string attribute, and defines the MAC
destination address (6 octets long).
6.1.4.1.1.2. The pktSecCondMACSrc Attribute
This is a mandatory string attribute, and defines the MAC source
address (6 octets long).
6.1.4.1.1.3. 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.
6.1.4.1.1.4. 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.
6.1.4.1.1.5. 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).
6.1.4.1.2. 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:
6.1.4.1.2.1. The pktSecCondIPv4SrcAddr Attribute
This is a mandatory string attribute, and defines the IPv4 Source
Address (32 bits).
6.1.4.1.2.2. The pktSecCondIPv4DestAddr Attribute
This is a mandatory string attribute, and defines the IPv4
Destination Address (32 bits).
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6.1.4.1.2.3. The pktSecCondIPv4ProtocolUsed Attribute
This is a mandatory string attribute, and defines the protocol used
in the data portion of the IP datagram (8 bits).
6.1.4.1.2.4. The pktSecCondIPv4DSCP Attribute
This is a mandatory string attribute, and defines the Differentiated
Services Code Point field (6 bits).
6.1.4.1.2.5. The pktSecCondIPv4ECN Attribute
This is an optional string attribute, and defines the Explicit
Congestion Notification field (2 bits).
6.1.4.1.2.6. 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).
6.1.4.1.2.7. The pktSecCondIPv4TTL Attribute
This is a mandatory string attribute, and defines the Time To Live
in seconds (8 bits).
6.1.4.1.3. 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:
6.1.4.1.3.1. The pktSecCondIPv6SrcAddr Attribute
This is a mandatory string attribute, and defines the IPv6 Source
Address (128 bits).
6.1.4.1.3.2. The pktSecCondIPv6DestAddr Attribute
This is a mandatory string attribute, and defines the IPv6
Destination Address (128 bits).
6.1.4.1.3.3. 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.
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6.1.4.1.3.4. 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.
6.1.4.1.3.5. 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).
6.1.4.1.3.6. 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).
6.1.4.1.3.7. 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).
6.1.4.1.3.8. The pktSecCondIPv6HopLimit Attribute
This is a mandatory string attribute, and defines the maximum number
of hops that this packet can traverse (8 bits).
6.1.4.1.4. 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:
6.1.4.1.4.1. The pktSecCondTPCSrcPort Attribute
This is a mandatory string attribute, and defines the Source Port
(16 bits).
6.1.4.1.4.2. The pktSecCondTPCDestPort Attribute
This is a mandatory string attribute, and defines the Destination
Port (16 bits).
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6.1.4.1.4.3. The pktSecCondTPCSeqNum Attribute
This is a mandatory string attribute, and defines the sequence
number (32 bits).
6.1.4.1.4.4. The pktSecCondTPCFlags Attribute
This is a mandatory string attribute, and defines the nine Control
bit flags (9 bits).
6.1.4.1.5. 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:
6.1.4.1.5.1. The pktSecCondUDPSrcPort Attribute
This is a mandatory string attribute, and defines the UDP Source
Port (16 bits).
6.1.4.1.5.2. The pktSecCondUDPDestPort Attribute
This is a mandatory string attribute, and defines the UDP
Destination Port (16 bits).
6.1.4.1.5.3. The pktSecCondUDPLength Attribute
This is a mandatory string attribute, and defines the length in
bytes of the UDP header and data (16 bits).
6.1.4.2. 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.
6.1.4.3. 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
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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
6.1.4.4. 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.
6.1.4.5. 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.
6.1.4.6. 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.
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6.1.5. Network Security Action Sub-Model
Figure 7 shows a more detailed design of the Action subclasses that
are contained in the Network Security Information Sub-Model.
+---------------------+
+---------------+ 1..n 1..n | |
| |/ \ \| A Common Superclass |
| ECAPolicyRule+ A ----------+ for ECA Objects |
| |\ / /| |
+---------------+ +-----------+---------+
/ \
|
|
+--------------+--------+------+
| | |
| | |
+-----+----+ +------+------+ +-----+-----+
| An Event | | A Condition | | An Action |
| Class | | Class | | Class |
+----------+ +-------------+ +-----+-----+
/ \
|
|
+------------+-------------+------------------+-------- ...
| | | |
| | | |
+----+----+ +----+---+ +------+-------+ +-------+--------+
| Ingress | | Egress | | ApplyProfile | | ApplySignature |
| Action | | Action | | Action | | Action |
+---------+ +--------+ +--------------+ +----------------+
Figure 7. Network Security Info Sub-Model Action Extensions
The four Action classes shown in Figure 7 extend the (external)
generic Action class to represent Actions that perform a Network
Security Control function. Brief class descriptions are provided in
the following sub-sections.
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6.1.5.1. IngressAction
The purpose of this Class is to represent actions performed on
packets that enter an NSF. Examples include pass, drop, mirror
traffic.
6.1.5.2. EgressAction
The purpose of this Class is to represent actions performed on
packets that exit an NSF. Examples include pass, drop, mirror
traffic, signal, encapsulate.
6.1.5.3. ApplyProfileAction
The purpose of this Class is to represent applying a profile to
packets to perform content security and/or attack mitigation control.
6.1.5.4. ApplySignatureAction
The purpose of this Class is to represent applying a signature file
to packets to perform content security and/or attack mitigation
control.
6.2. Information Model for Content Security Control
The block for content security control is composed of a number of
security capabilities, while each one aims for protecting against a
specific type of threat in the application layer.
Following figure shows a basic structure of the information model:
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+----------------------------------+
| |
| |
| Anti-Virus |
| Intrusion Prevention |
| URL Filtering |
| File Blocking |
| Data Filtering |
| Application Behavior Control |
| Mail Filtering |
| Packet Capturing |
| File Isolation |
| ... |
| |
| |
| |
| |
| Information model |
| for content security|
| control |
+----------------------------------+
Figure 8. The basic structure of information model for content
security control
The detailed description about the standard interface and the
parameters for all the security capabilities of this category are
TBD.
6.3. Information Model for Attack Mitigation Control
The block for attack mitigation control is composed of a number of
security capabilities, while each one aims for mitigating a specific
type of network attack.
Following figure shows a basic structure of the information model:
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Please view in a fixed-width font such as Courier.
+-------------------------------------------------+
| |
| +---------------------+ +---------------+ |
| |Attack mitigation | | General Shared| |
| |capabilites: | | Parameters: | |
| | SYN flood, | | | |
| | UDP flood, | | | |
| | ICMP flood, | | | |
| | IP fragment flood, | | | |
| | IPv6 related attacks| | | |
| | HTTP flood, | | | |
| | HTTPS flood, | | | |
| | DNS flood, | | | |
| | DNS amplification, | | | |
| | SSL DDoS, | | | |
| | IP sweep, | | | |
| | Port scanning, | | | |
| | Ping of Death, | | | |
| | Oversized ICMP | | | |
| | | | | |
| | ... | | | |
| | | | | |
| +---------------------+ +---------------+ |
| |
| Information model |
| for attack mitigation|
| control |
+-------------------------------------------------+
Figure 9. The basic structure of information model for attack
mitigation control
The detailed description about the standard interface and the
general shared parameters for all the security capabilities of this
category are TBD.
7. Security Considerations
The security capability policy information sent to NSFs should be
protected by the secure communication channel, to ensure the
confidentiality and integrity. In another side, the NSFs and
security controller can all be faked, which lead to undesirable
results, i.e., security policy leakage from security controller,
faked security controller sending false information to mislead the
NSFs. The mutual authentication is essential to protected against
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this kind of attack. The current mainstream security technologies
(i.e., TLS, DTLS, IPSEC, X.509 PKI) can be employed appropriately to
provide the above security functionalities.
In addition, to defend against the DDoS attack caused by the
security controller sending too much configuration messages to the
NSFs, the rate limiting or similar mechanisms should be considered
in NSF, whether in advance or just in the process of DDoS attack.
8. IANA Considerations
This document requires no IANA actions. RFC Editor: Please remove
this section before publication.
9. References
9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to 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 the
Network Configuration Protocol (NETCONF)", RFC 6020,
October 2010.
[RFC5511] Farrel, A., "Routing Backus-Naur Form (RBNF): A Syntax
Used to Form Encoding Rules in 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 Policy-Based
Management", RFC 3198, DOI 10.17487/RFC3198,
November 2001, <http://www.rfc-editor.org/info/rfc3198>.
9.2. Informative References
[INCITS359 RBAC] NIST/INCITS, "American National Standard for
Information Technology - Role Based Access Control",
INCITS 359, April, 2003
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[I-D.draft-ietf-i2nsf-problem-and-use-cases] Hares, S., et.al.,
"I2NSF Problem Statement and Use cases", Work in Progress,
February, 2016.
[I-D.draft-ietf-i2nsf-framework] Lopez, E., et.al., "Framework for
Interface to Network Security Functions", Work in Progress,
October, 2016.
[I-D.draft-ietf-i2nsf-terminology] Hares, S., et.al., "Interface to
Network Security Functions (I2NSF) Terminology", Work in
Progress, April, 2016
[I-D.draft-ietf-supa-generic-policy-info-model] Strassner, J.,
Halpern, J., Coleman, J., "Generic Policy Information
Model for Simplified Use of Policy Abstractions (SUPA)",
Work in Progress, June, 2016.
[I-D.draft-baspez-i2nsf-capabilities-00] Basile C., Lopez D. R., "A
Model of Security Capabilities for Network Security
Functions", July 2016
[I-D.draft-xia-i2nsf-capability-interface-im-06] Xia L., et al.,
"Information Model of Interface to Network Security
Functions Capability Interface", June 2016
[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 A. Lioy, "Analysis of application-layer
filtering policies with application to HTTP", 2015.
[Cormen] Cormen, T., "Introduction to Algorithms", 2009.
[Lunt] van Lunteren, J. and T. Engbersen, "Fast and scalable
packet classification", 2003.
[Taylor] Taylor, D. and J. Turner, "Scalable packet classification
using distributed crossproducting of field labels", 2004.
10. Acknowledgments
This document was prepared using 2-Word-v2.0.template.dot.
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Appendix A.
Six exemplary policy rules of Network Security Capability are
introduced in this Appendix to clarify how to create different kinds
of specific ECA policy rules.
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 ECA
Policy Rule that can verify whether an entity has an attribute of a
specific value.
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. Hence, this document recommends the
following design:
+----------------+
+----------------+ 1..n 1...n | |
| |/ \ HasAuthenticationMethod \| Authentication |
| Authentication + A ----------+-----------------+ Method |
| ECAPolicyRule |\ / ^ /| |
| | | +----------------+
+----------------+ |
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|
+------------+-------------+
| AuthenticationRuleDetail |
+------------+-------------+
/ \ 0..n
|
| PolicyControlsAuthentication
|
/ \
A
\ / 0..n
+----------+--------------+
| ManagementECAPolicyRule |
+-------------------------+
Figure 10. Modeling Authentication Mechanisms
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 below.
Figure 10 defines an aggregation between the
AuthenticationECAPolicyRule and an externalAuthenticationMethod
class (which is likely a superclass for different types of
authentication mechanisms). This decouples the implementation of
authentication mechanisms from how authentication mechanisms are
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
policies to control the configuration of the
AuthenticationRuleDetail association class. This enables the entire
authentication process to be managed by ECAPolicyRules.
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, called (for
example) authenticationMethodCurrent and
authenticationMethodSupported, to represent the
HasAuthenticationMethod aggregation and its association class. The
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former is a string attribute that defines the current authentication
method used by this AuthenticationECAPolicyRule, while the latter
defines 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 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:
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+---------------+
+----------------+ 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
below.
Figure 11 defines an aggregation between the
AuthorizationECAPolicyRule and an external AuthorizationMethod class
(which is likely a superclass for different types of authorization
mechanisms). This decouples the implementation of authorization
mechanisms from how authorization mechanisms are 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
policies to control the configuration of the AuthorizationRuleDetail
association class. This enables the entire authorization process to
be managed by ECAPolicyRules.
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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 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:
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+-------------+
+----------------+ 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
below.
Figure 12 defines an aggregation between the AccountingECAPolicyRule
and an external AccountingMethod class (which is likely a superclass
for different types of accounting mechanisms). This decouples the
implementation of accounting mechanisms from how accounting
mechanisms are 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 policies
to control the configuration of the AccountingRuleDetail association
class. This enables the entire accounting process to be managed by
ECAPolicyRules.
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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
authorization capability, which this AccountingECAPolicyRule can
advertise.
A.4. TrafficInspectionECAPolicyRuleClass Definition
The purpose of a TrafficInspectionECAPolicyRule is to define an 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:
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+------------------+
+-------------------+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 below.
Figure 13 defines an aggregation between the
TrafficInspectionECAPolicyRule and an external TrafficInspection
class (which is likely a superclass for different types of traffic
inspection mechanisms). This decouples the implementation of traffic
inspection mechanisms from how traffic inspection mechanisms are
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
policies to control the configuration of the TrafficInspectionDetail
association class. This enables the entire traffic inspection
process to be managed by ECAPolicyRules.
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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 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:
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+-------------+
+-------------------+ 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
below.
Figure 14 defines an aggregation between the
ApplyProfileECAPolicyRule and an external Profile class (which is
likely a superclass for different types of Profiles). 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 Profileis 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 by ECAPolicyRules.
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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 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:
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+-------------+
+---------------+ 1..n 1..n | |
| |/ \ SignatureApplied \| |
| ApplySignature+ A ----------+--------------+ Signature |
| ECAPolicyRule |\ / ^ /| |
| | | +-------------+
+---------------+ |
|
+------------+-----------+
| SignatureAppliedDetail |
+------------+-----------+
/ \ 0..n
|
| PolicyControlsSignatureApplication
|
/ \
A
\ / 0..n
+----------+--------------+
| ManagementECAPolicyRule |
+-------------------------+
Figure 15. Modeling Sginature Application Mechanisms
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 below.
Figure 15 defines an aggregation between the
ApplySignatureECAPolicyRule and an external Signature object class
(which is likely a superclass for different types of Signature
objects). 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.
Similarly, the PolicyControlsSignatureApplication aggregation
defines policies to control the configuration of the
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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.
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Authors' Addresses
Liang Xia (Frank)
Huawei
101 Software Avenue, Yuhuatai District
Nanjing, Jiangsu 210012
China
Email: Frank.xialiang@huawei.com
John Strassner
Huawei
Email: John.sc.Strassner@huawei.com
DaCheng Zhang
Huawei
Email: dacheng.zhang@huawei.com
Kepeng Li
Alibaba
Email: kepeng.lkp@alibaba-inc.com
Cataldo Basile, Antonio Lioy
Politecnico di Torino
Corso Duca degli Abruzzi, 34
Torino, 10129
Italy
Email: cataldo.basile@polito.it
Antonio Lioy
Politecnico di Torino
Corso Duca degli Abruzzi, 34
Torino, 10129
Italy
Email: lioy@polito.it
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Diego R. Lopez
Telefonica I+D
Zurbaran, 12
Madrid, 28010
Spain
Phone: +34 913 129 041
Email: diego.r.lopez@telefonica.com
Edward Lopez
Fortinet
899 Kifer Road
Sunnyvale, CA 94086
Phone: +1 703 220 0988
EMail: elopez@fortinet.com
Nicolas BOUTHORS
Qosmos
Email: Nicolas.BOUTHORS@qosmos.com
Luyuan Fang
Microsoft
15590 NE 31st St
Redmond, WA 98052
Email: lufang@microsoft.com
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