I2NSF D. Lopez
Internet-Draft Telefonica I+D
Intended status: Informational E. Lopez
Expires: April 25, 2018 Curveball Networks
L. Dunbar
J. Strassner
Huawei
R. Kumar
Juniper Networks
October 10, 2017
Framework for Interface to Network Security Functions
draft-ietf-i2nsf-framework-08
Abstract
This document describes the framework for the Interface to Network
Security Functions (I2NSF), and defines a reference model (including
major functional components) for I2NSF. Network security functions
(NSFs) are packet-processing engines that inspect and optionally
modify packets traversing networks, either directly or in the context
of sessions to which the packet is associated.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on February 25, 2018.
Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
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(http://trustee.ietf.org/license-info) in effect on the date of
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions used in this document . . . . . . . . . . . . . . 3
2.1. Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Definitions . . . . . . . . . . . . . . . . . . . . . . . 4
3. I2NSF Reference Model . . . . . . . . . . . . . . . . . . . . 4
3.1. I2NSF Consumer-Facing Interface . . . . . . . . . . . . . 6
3.2. I2NSF NSF-Facing Interface . . . . . . . . . . . . . . . . 6
3.3. I2NSF Registration Interface . . . . . . . . . . . . . . . 7
4. Threats Associated with Externally Provided NSFs . . . . . . . 7
5. Avoiding NSF Ossification . . . . . . . . . . . . . . . . . . 8
6. The Network Connecting I2NSF Components . . . . . . . . . . . 9
6.1. Network Connecting I2NSF Users and I2NSF Controller . . . 9
6.2. Network Connecting the Controller and NSFs . . . . . . . 9
6.3. Interface to vNSFs . . . . . . . . . . . . . . . . . . . . 10
7. I2NSF Flow Security Policy Structure . . . . . . . . . . . . . 12
7.1. Customer-Facing Flow Security Policy Structure . . . . . . 12
7.2. NSF-Facing Flow Security Policy Structure . . . . . . . . 13
7.3. Differences from ACL Data Models . . . . . . . . . . . . . 14
8. Capability Negotiation . . . . . . . . . . . . . . . . . . . . 15
9. Registration Considerations . . . . . . . . . . . . . . . . . 16
9.1. Flow-Based NSF Capability Characterization . . . . . . . . 16
9.2. Registration Categories . . . . . . . . . . . . . . . . . 17
10. Manageability Considerations . . . . . . . . . . . . . . . . . 19
11. Security Considerations . . . . . . . . . . . . . . . . . . . 20
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20
13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 20
14. References . . . . . . . . . . . . . . . . . . . . . . . . . . 20
14.1. Normative References . . . . . . . . . . . . . . . . . . . 20
14.2. Informative References . . . . . . . . . . . . . . . . . . 21
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 22
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1. Introduction
This document describes the framework for the Interface to Network
Security Functions (I2NSF), and defines a reference model (including
major functional components) for I2NSF. This includes an analysis of
the threats implied by the deployment of Network Security Functions
(NSFs) that are externally provided. It also describes how I2NSF
facilitates implementing security functions in a technology- and
vendor-independent manner in Software-Defined Networking (SDN) and
Network Function Virtualization (NFV) environments, while avoiding
potential constraints that could limit the capabilities of NSFs.
The I2NSF use cases [RFC8192] call for standard interfaces for users
of an I2NSF system (e.g., applications, overlay or cloud network
management system, or enterprise network administrator or management
system), to inform the I2NSF system which I2NSF functions should be
applied to which traffic (or traffic patterns). The I2NSF system
realizes this as a set of security rules for monitoring and
controlling the behavior of different traffic. It also provides
standard interfaces for users to monitor flow-based security
functions hosted and managed by different administrative domains.
[RFC8192] also describes the motivation and the problem space for
an Interface to Network Security Functions system.
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 [RFC2119].
In this document, these words will appear with that interpretation
only when in ALL CAPS. Lower case uses of these words are not to be
interpreted as carrying RFC-2119 significance.
Note: as this is an informational document, no RFC-2119 key words
are used.
2.1. Acronyms
The following acronyms are used in this document:
DOTS Distributed Denial-of-Service Open Threat Signaling
IDS Intrusion Detection System
IoT Internet of Things
IPS Intrusion Protection System
NSF Network Security Function
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2.2. Definitions
The following terms, which are used in this document, are defined in
the I2NSF terminology document [I-D.ietf-i2nsf-terminology]:
Capability
Controller
Firewall
I2NSF Consumer
I2NSF NSF-Facing Interface
I2NSF Policy Rule
I2NSF Producer
I2NSF Registration Interface
I2NSF Registry
Interface
Interface Group
Intrusion Detection System
Intrusion Protection System
Network Security Function
Role
3. I2NSF Reference Model
Figure 1 shows a reference model (including major functional
components and interfaces) for an I2NSF system. This figure is drawn
from the point-of-view of the Network Operator Management System;
hence, this view does not assume any particular management
architecture for either the NSFs or for how NSFs are managed (on the
developer's side). In particular, the Network Operator Management
System does not participate in NSF data plane activities.
Note that the term "Controller" is defined in
[I-D.ietf-i2nsf-terminology].
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+-------------------------------------------------------+
| I2NSF User (e.g., Overlay Network Mgmt, Enterprise |
| Network Mgmt, another network domain's mgmt, etc.) |
+--------------------+----------------------------------+
|
| I2NSF Consumer-Facing Interface
|
| I2NSF
+------------+---------+ Registration +-------------+
| Network Operator Mgmt| Interface | Developer's |
| System | < --------- > | Mgmt System |
+----------------+-----+ +-------------+
|
| I2NSF NSF-Facing Interface
|
+---------------+----+------------+---------------+
| | | |
+---+---+ +---+---+ +---+---+ +---+---+
| NSF-1 | ... | NSF-m | | NSF-1 | ... | NSF-m | ...
+-------+ +-------+ +-------+ +-------+
Developer Mgmt System A Developer Mgmt System B
Figure 1: I2NSF Reference Model
When defining I2NSF interfaces, this framework adheres to the
following principles:
o Agnostic of network topology and NSF location in the network
o Agnostic of provider of the NSF (i.e., independent of the way that
the provider makes an NSF available, as well as how the provider
allows the NSF to be managed)
o Agnostic of any vendor-specific operational, administrative, and
management implementation, hosting environment, and form-factor
(physical or virtual)
o Agnostic to NSF control plane implementation (e.g., signaling
capabilities)
o Agnostic to NSF data plane implementation (e.g., encapsulation
capabilities)
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3.1. I2NSF Consumer-Facing Interface
The I2NSF Consumer-Facing Interface is used to enable different users
of a given I2NSF system to define, manage, and monitor security
policies for specific flows within an administrative domain. The
location and implementation of I2NSF policies are irrelevant to the
consumer of I2NSF policies.
Some examples of I2NSF Consumers include:
o A videoconference network manager that needs to dynamically inform
the underlay network to allow, rate-limit, or deny flows (some of
which are encrypted) based on specific fields in the packets for a
certain time span.
o Enterprise network administrators and management systems that need
to request their provider network to enforce specific I2NSF
policies for particular flows.
o An IoT management system sending requests to the underlay network
to block flows that match a set of specific conditions.
3.2. I2NSF NSF-Facing Interface
The I2NSF NSF-Facing Interface (NSF-Facing Interface for short) is
used to specify and monitor flow-based security policies enforced by
one or more NSFs. Note that the I2NSF Management System does not
need to use all features of a given NSF, nor does it need to use all
available NSFs. Hence, this abstraction enables NSF features to be
treated as building blocks by an NSF system; thus, developers are
free to use the security functions defined by NSFs independent of
vendor and technology.
Flow-based NSFs [RFC8192] inspect packets in the order that they
are received. Note that all Interface Groups require the NSF to be
registered using the Registration Interface. The Interface to
flow-based NSFs can be categorized as follows:
1. NSF Operational and Administrative Interface: an Interface Group
used by the I2NSF Management System to program the operational
state of the NSF; this also includes administrative control
functions. I2NSF Policy Rules represent one way to change this
Interface Group in a consistent manner. Since applications and
I2NSF Components need to dynamically control the behavior of
traffic that they send and receive, much of the I2NSF effort is
focused on this Interface Group.
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2. Monitoring Interface: an Interface Group used by the the I2NSF
Management System to obtain monitoring information from one or
more selected NSFs. Each interface in this Interface Group could
be a query- or a report-based interface. The difference is that
a query-based interface is used by the the I2NSF Management
System to obatin information, whereas a report-based interface
is used by the NSF to provide information. The functionality of
this Interface Group may also be defined by other protocols,
such as SYSLOG and DOTS (Distributed Denial-of-Service Open
Threat Signaling). The I2NSF Management System may take one or
more actions based on the receipt of information; this should be
specified by an I2NSF Policy Rule. This Interface Group does
NOT change the operational state of the NSF.
This document uses the flow-based paradigm to develop the NSF-Facing
Interface. A common trait of flow-based NSFs is in the processing
of packets based on the content (e.g., header/payload) and/or
context (e.g., session state, authentication state) of the
received packets. This feature is one of the requirements for
defining the behavior of I2NSF.
3.3. I2NSF Registration Interface
NSFs provided by different vendors may have different capabilities.
In order to automate the process of utilizing multiple types of
security functions provided by different vendors, it is necessary to
have a dedicated interface for vendors to define the capabilities of
(i.e., register) their NSFs. This Interface is called the
I2NSF Registration Interface.
An NSF's capabilities can either be pre-configured or retrieved
dynamically through the I2NSF Registration Interface. If a new
function that is exposed to the consumer is added to an NSF, then
the capabilities of that new function should be registered in the
I2NSF Registry via the I2NSF Registration Interface, so that
interested management and control entities may be made aware of them.
4. Threats Associated with Externally Provided NSFs
While associated with a much higher flexibility, and in many cases a
necessary approach given the deployment conditions, the usage of
externally provided NSFs implies several additional concerns in
security. The most relevant threats associated with a security
platform of this nature are:
o An unknown/unauthorized user can try to impersonate another user
that can legitimately access external NSF services. This attack
may lead to accessing the I2NSF Policy Rules and applications of
the attacked user, and/or to generate network traffic outside the
security functions with a falsified identity.
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o An authorized user may misuse assigned privileges to alter the
network traffic processing of other users in the NSF underlay or
platform.
o A user may try to install malformed elements (e.g., I2NSF Policy
Rules, or configuration files), trying to directly take the
control of a NSF or the whole provider platform. For example,
a user may exploit a vulnerability on one of the functions, or
may try to intercept or modify the traffic of other users in the
same provider platform.
o A malicious provider can modify the software (e.g., the operating
system or the specific NSF implementation) to alter the behavior
of one or more NSFs. This event has a high impact on all users
accessing NSFs, since the provider has the highest level of
privileges controlling the operation of the software.
o A user that has physical access to the provider platform can
modify the behavior of the hardware/software components, or the
components themselves. For example, the user can access a serial
console (most devices offer this interface for maintenance
reasons) to access the NSF software with the same level of
privilege of the provider.
The above threats may be mitigated by requiring the use of an AAA
framework for all users to access the I2NSF environment. This could
be further enhanced by requiring attestation to be used to detect
changes to the I2NSF environment by authorized parties.
5. Avoiding NSF Ossification
A basic tenet in the introduction of I2NSF standards is that the
standards should not make it easier for attackers to compromise the
network. Therefore, in constructing standards for I2NSF Interfaces
as well as I2NSF Policy Rules, it is equally important to allow
support for specific functions, as this enables the introduction of
NSFs that evolve to meet new threats. Proposed standards for I2NSF
Interfaces to communicate with NSFs, as well as I2NSF Policy Rules
to control NSF functionality, should not:
o Narrowly define NSF categories, or their roles, when implemented
within a network
o Attempt to impose functional requirements or constraints, either
directly or indirectly, upon NSF developers
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o Be a limited lowest common denominator approach, where interfaces
can only support a limited set of standardized functions, without
allowing for developer-specific functions
o Be seen as endorsing a best common practice for the implementation
of NSFs; rather, this document describes the conceptual structure
and reference model of I2NSF
To prevent constraints on NSF developers' creativity and innovation,
this document recommends the Flow-based NSF interfaces to be designed
from the paradigm of processing packets in the network. Flow-based
NSFs ultimately are packet-processing engines that inspect packets
traversing networks, either directly or in the context of sessions in
which the packet is associated. The goal is to create a workable
interface to NSFs that aids in their integration within legacy, SDN,
and/or NFV environments, while avoiding potential constraints which
could limit their functional capabilities.
6. The Network Connecting I2NSF Components
6.1. Network Connecting I2NSF Users and the I2NSF Controller
As a general principle, in the I2NSF environment, users directly
interact with the I2NSF Controller. Given the role of the I2NSF
Controller, a mutual authentication of users and the I2NSF
Controller may be required. I2NSF does not mandate a specific
authentication scheme; it is up to the users to choose available
authentication schemes based on their needs.
Upon successful authentication, a trusted connection between the
user and the I2NSF Controller (or an endpoint designated by it) will
be established. All traffic to and from the NSF environment will
flow through this connection. The connection is intended not only to
be secure, but trusted in the sense that it should be bound to the
mutual authentication between the user and the I2NSF Controller, as
described in [I-D.pastor-i2nsf-remote-attestation]. The only
possible exception is when the required level of assurance is lower,
(see Section 4.1 of [I-D.pastor-i2nsf-remote-attestation]), in which
case the user must be made aware of this circumstance.
6.2. Network Connecting the I2NSF Controller and NSFs
Most likely the NSFs are not directly attached to the I2NSF
Controller; for example, NSFs can be distributed across the network.
The network that connects the I2NSF Controller with the NSFs can be
the same network that carries the data traffic, or can be a dedicated
network for management purposes only. In either case, packet loss
could happen due to failure, congestion, or other reasons.
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Therefore, the transport mechanism used to carry the control messages
and monitoring information should provide reliable message delivery.
Transport redundancy mechanisms such as Multipath TCP (MPTCP) and the
Stream Control Transmission Protocol (SCTP) will need to be evaluated
for applicability. Latency requirements for control message delivery
must also be evaluated.
The network connection between the I2NSF Controller and NSFs can
rely either on:
o Closed environments, where there is only one administrative
domain. Less restrictive access control and simpler validation
can be used inside the domain because of the protected nature of
a closed environment.
o Open environments, where one or more NSFs can be hosted in one or
more external administrative domains that are reached via secure
external network connections. This requires more restrictive
security control to be placed over the I2NSF interface. The
information over the I2NSF interfaces shall be exchanged by
using the trusted connection described in section 6.1.
When running in an open environment, I2NSF needs to rely on the use
of standard I2NSF interfaces to properly verify peer identities
(e.g., through an AAA framework). The implementations of identity
management functions, as well as the AAA framework, are out of scope
for I2NSF.
6.3. Interface to vNSFs
There are some unique characteristics in interfacing to virtual NSFs:
o There could be multiple instantiations of one single NSF that has
been distributed across a network. When different instantiations
are visible to the I2NSF Controller, different policies may be
applied to different instantiations of an individual NSF (e.g.,
to reflect the different roles that each vNSF is designated for).
Therefore, it is recommended that Roles, in addition to the use
of robust identities, be used to distinguish between different
instantiations of the same vNSF. Note that this also applies to
physical NSFs.
o When multiple instantiations of one single NSF appear as one
single entity to the I2NSF Controller, the I2NSF Controller may
need to either get assistance from other entities in the I2NSF
Management System, and/or delegate the provisioning of the
multiple instantiations of the (single) NSF to other entities in
the I2NSF Management System. This is shown in Figure 2 below.
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o Policies enforced by one vNSF instance may need to be retrieved
and moved to another vNSF of the same type when user flows are
moved from one vNSF to another.
o Multiple vNSFs may share the same physical platform.
o There may be scenarios where multiple vNSFs collectively perform
the security policies needed.
+------------------------+
| I2NSF Controller |
+------------------------+
^ ^
| |
+-----------+ +------------+
| |
v v
+ - - - - - - - - - - - - - - - + + - - - - - - - - - - - - - - - +
| NSF-A +--------------+ | | NSF-B +--------------+ |
| | NSF Manager | | | | NSF Manager | |
| +--------------+ | | +--------------+ |
| + - - - - - - - - - - - - - + | | + - - - - - - - - - - - - - + |
| |+---------+ +---------+| | | |+---------+ +---------+| |
| || NSF-A#1 | ... | NSF-A#n || | | || NSF-B#1 | ... | NSF-B#m || |
| |+---------+ +---------+| | | |+---------+ +---------+| |
| | NSF-A cluster | | | | NSF-B cluster | |
| + - - - - - - - - - - - - - + | | + - - - - - - - - - - - - - + |
+ - - - - - - - - - - - - - - - + + - - - - - - - - - - - - - - - +
Figure 2: Cluster of NSF Instantiations Management
6.4. Consistency
There are three basic models of consistency:
o centralized, which uses a single manager to impose behavior
o decentralized, in which managers make decisions without being
aware of each other (i.e., managers do not exchange information)
o distributed, in which managers make explicit use of information
exchange to arrive at a decision
This document does NOT make a recommendation on which of the above
three models to use. I2NSF Policy Rules, coupled with an appropriate
management strategy, is applicable to the design and integration of
any of the above three consistency models.
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7. I2NSF Flow Security Policy Structure
Even though security functions come in a variety of form factors and
have different features, provisioning to flow-based NSFs can be
standardized by using policy rules.
In this version of I2NSF, policy rules are limited to imperative
paradigms. I2NSF is using an Event - Condition - Action (ECA) policy,
where:
o An Event clause is used to trigger the evaluation of the
Condition clause of the Policy Rule.
o A Condition clause is used to determine whether or not the set of
Actions in the I2NSF Policy Rule can be executed or not.
o An Action clause defines the type of operations that may be
performed on this packet or flow.
Each of the above three clauses are defined to be Boolean clauses.
This means that each is a logical statement that evaluates to either
TRUE or FALSE.
The above concepts are described in detail in
[I-D.draft-xibassnez-i2nsf-capability].
7.1. Customer-Facing Flow Security Policy Structure
This layer is for the user's network management system to express and
monitor the needed flow security policies for their specific flows.
Some customers may not have the requisite security skills to express
security requirements or policies that are precise enough to
implement in an NSF. These customers may instead express
expectations (e.g., goals, or intent) of the functionality desired
by their security policies. Customers may also express guidelines,
such as which types of destinations are (or are not) allowed for
certain users. As a result, there could be different levels of
content and abstractions used in Service Layer policies. Here
are some examples of more abstract security Policies that can be
developed based on the I2NSF defined customer-facing interface:
Enable Internet access for authenticated users
Any operation on a HighValueAsset must use the corporate network
The use of FTP from any user except the CxOGroup must be audited
Streaming media applications are prohibited on the corporate
network during business hours
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Scan email for malware detection protect traffic to corporate
network with integrity and confidentiality
Remove tracking data from Facebook [website = *.facebook.com]
One flow policy over the Customer-Facing Interface may need multiple
NSFs at various locations to achieve the desired enforcement. Some
flow security policies from users may not be granted because of
resource constraints. [I-D.xie-i2nsf-demo-outline-design] describes
an implementation of translating a set of user policies to the flow
policies to individual NSFs.
I2NSF will first focus on user policies that can be modeled as
closely as possible to the flow security policies used by individual
NSFs. An I2NSF user flow policy should be similar in structure to
the structure of an I2NSF Policy Rule, but with more of a user-
oriented expression for the packet content, context, and other parts
of an ECA policy rule. This enables the user to construct an I2NSF
Policy Rule without having to know the exact syntax of the desired
content (e.g., actual tags or addresses) to match in the packets. For
example, when used in the context of policy rules over the Client
Facing Interface:
An Event can be "the client has passed the AAA process"
A Condition can be matching user identifier, or from specific
ingress or egress points
An action can be establishing a IPsec tunnel
7.2. NSF-Facing Flow Security Policy Structure
The NSF-Facing Interface is to pass explicit rules to individual NSFs
to treat packets, as well as methods to monitor the execution status
of those functions.
Here are some examples of events over the NSF facing interface:
time == 08:00
notification that a NSF state changes from standby to active
user logon or logoff
Here are some examples of conditions over the NSF facing interface
o Packet content values that look for one or more packet headers,
data from the packet payload, bits in the packet, or data that
are derived from the packet.
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o Context values that are based on measured and/or inferred
knowledge, which can be used to define the state and environment
in which a managed entity exists or has existed. In addition to
state data, this includes data from sessions, direction of the
traffic, time, and geo-location information. State refers to the
behavior of a managed entity at a particular point in time.
Hence, it may refer to situations in which multiple pieces of
information that are not available at the same time must be
analyzed. For example, tracking established TCP connections
(connections that have gone through the initial three-way
handshake).
Actions to individual flow-based NSFs include:
o Actions performed on ingress packets, such as pass, drop,
rate limiting, and mirroring.
o Actions performed on egress packets, such as invoke signaling,
tunnel encapsulation, packet forwarding and/or transformation.
o Applying a specific functional profile or signature - e.g., an IPS
Profile, a signature file, an anti-virus file, or a URL filtering
file. Many flow-based NSFs utilize profile and/or signature files
to achieve more effective threat detection and prevention. It is
not uncommon for a NSF to apply different profiles and/or
signatures for different flows. Some profiles/signatures do not
require any knowledge of past or future activities, while others
are stateful, and may need to maintain state for a specific length
of time.
The functional profile or signature file is one of the key properties
that determine the effectiveness of the NSF, and is mostly NSF-
specific today. The rulesets and software interfaces of I2NSF aim to
specify the format to pass profile and signature files while
supporting specific functionalities of each.
Policy consistency among multiple security function instances is very
critical because security policies are no longer maintained by one
central security device, but instead are enforced by multiple
security functions instantiated at various locations.
7.3. Differences from ACL Data Models
Policy rules are very different from ACLs. An ACL is NOT a policy.
Rather, policies are used to manage the construction and lifecycle
of an ACL.
[I-D.ietf-netmod-acl-model] has defined rules for the Access
Control List supported by most routers/switches that forward packets
based on packets' L2, L3, or sometimes L4 headers. The actions for
Access Control Lists include Pass, Drop, or Redirect.
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The functional profiles (or signatures) for NSFs are not present in
[I-D.ietf-netmod-acl-model] because the functional profiles are
unique to specific NSFs. For example, most IPS/IDS implementations
have their proprietary functions/profiles. One of the goals of I2NSF
is to define a common envelop format for exchanging or sharing
profiles among different organizations to achieve more effective
protection against threats.
The "packet content matching" of the I2NSF policies should not only
include the matching criteria specified by
[I-D.ietf-netmod-acl-model], but also the L4-L7 fields depending
on the NSFs selected.
Some Flow-based NSFs need matching criteria that include the context
associated with the packets. This may also include metadata.
The I2NSF "actions" should extend the actions specified by
[I-D.ietf-netmod-acl-model] to include applying statistics
functions, threat profiles, or signature files that clients provide.
8. Capability Negotiation
It is very possible that the underlay network (or provider network)
does not have the capability or resource to enforce the flow security
policies requested by the overlay network (or enterprise network).
Therefore, it is required that the I2NSF system support dynamic
discovery capabilities, as well as a query mechanism, so that the
I2NSF system can expose appropriate security services using
I2NSF capabilities. This may also be used to support negotiation
between a user and the I2NSF system. Such dynamic negotiation
facilitates the delivery of the required security service(s). The
outcome of the negotiation would feed the I2NSF Management System,
which would then dynamically allocate appropriate NSFs (along with
any resources needed by the allocated NSFs) and configure the set of
security services that meet the requirements of the user.
When an NSF cannot perform the desired provisioning (e.g., due to
resource constraints), it must inform the I2NSF Management System.
The protocol needed for this security function/capability negotiation
may be somewhat correlated to the dynamic service parameter
negotiation procedure described in [RFC7297]. The Connectivity
Provisioning Profile (CPP) template, even though currently covering
only Connectivity requirements, includes security clauses such as
isolation requirements and non-via nodes. Hence, it could be extended
as a basis for the negotiation procedure. Likewise, the companion
Connectivity Provisioning Negotiation Protocol (CPNP) could be a
candidate for the negotiation procedure.
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"Security-as-a-Service" would be a typical example of the kind of
(CPP-based) negotiation procedures that could take place between a
corporate customer and a service provider. However, more security
specific parameters have to be considered.
[I.D.-draft-xibassnez-i2nsf-capability] describes the concepts of
capabilities in detail.
9. Registration Considerations
9.1. Flow-Based NSF Capability Characterization
There are many types of flow-based NSFs. Firewall, IPS, and IDS are
the commonly deployed flow-based NSFs. However, the differences
among them are definitely blurring, due to more powerful technology,
integration of platforms, and new threats. Basic types of
flow-based NSFs include:
o Firewall - A device or a function that analyzes packet headers and
enforces policy based on protocol type, source address,
destination address, source port, destination port, and/or other
attributes of the packet header. Packets that do not match policy
are rejected. Note that additional functions, such as logging and
notification of a system administrator, could optionally be
enforced as well.
o IDS (Intrusion Detection System) - A device or function that
analyzes packets, both header and payload, looking for known
events. When a known event is detected, a log message is
generated detailing the event. Note that additional functions,
such as notification of a system administrator, could optionally
be enforced as well.
o IPS (Intrusion Prevention System) - A device or function that
analyzes packets, both header and payload, looking for known
events. When a known event is detected, the packet is rejected.
Note that additional functions, such as logging and notification
of a system administrator, could optionally be enforced as well.
Flow-based NSFs differ in the depth of packet header or payload they
can inspect, the various session/context states they can maintain,
and the specific profiles and the actions they can apply. An example
of a session is "allowing outbound connection requests and only
allowing return traffic from the external network".
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9.2. Registration Categories
Developers can register their NSFs using Packet Content Match
categories. The IDR (Inter-Domain Routing) Flow Specification
[RFC5575] has specified 12 different packet header matching types.
More packet content matching types have been proposed in the IDR WG.
I2NSF should re-use the packet matching types being specified as much
as possible. More matching types might be added for Flow-based NSFS.
Tables 1-4 below list the applicable packet content categories that
can be potentially used as packet matching types by Flow-based NSFs:
+-----------------------------------------------------------+
| Packet Content Matching Capability Index |
+---------------+-------------------------------------------+
| Layer 2 | Layer 2 header fields: |
| Header | Source/Destination/s-VID/c-VID/EtherType/.|
| | |
|---------------+-------------------------------------------+
| Layer 3 | Layer header fields: |
| | protocol |
| IPv4 Header | dest port |
| | src port |
| | src address |
| | dest address |
| | dscp |
| | length |
| | flags |
| | ttl |
| | |
| IPv6 Header | |
| | addr |
| | protocol/nh |
| | src port |
| | dest port |
| | src address |
| | dest address |
| | length |
| | traffic class |
| | hop limit |
| | flow label |
| | dscp |
| TCP | Port |
| SCTP | syn |
| DCCP | ack |
| | fin |
| | rst |
| | ? psh |
| | ? urg |
| | ? window |
| | sockstress |
| | Note: bitmap could be used to |
| | represent all the fields |
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| UDP | |
| | flood abuse |
| | fragment abuse |
| | Port |
| HTTP layer | |
| | | hash collision |
| | | http - get flood |
| | | http - post flood |
| | | http - random/invalid url |
| | | http - slowloris |
| | | http - slow read |
| | | http - r-u-dead-yet (rudy) |
| | | http - malformed request |
| | | http - xss |
| | | https - ssl session exhaustion |
+---------------+----------+--------------------------------+
| IETF PCP | Configurable |
| | Ports |
| | |
+---------------+-------------------------------------------+
| IETF TRAM | profile |
| | |
| | |
|---------------+-------------------------------------------+
Table 1: Packet Content Matching Capability Index
Notes: DCCP: Datagram Congestion Control Protocol
PCP: Port Control Protocol
TRAM: TURN Revised and Modernized, where TURN stands for
Traversal Using Relays around NAT
+-----------------------------------------------------------+
| Context Matching Capability Index |
+---------------+-------------------------------------------+
| Session | Session state, |
| | bidirectional state |
| | |
+---------------+-------------------------------------------+
| Time | time span |
| | time occurrence |
+---------------+-------------------------------------------+
| Events | Event URL, variables |
+---------------+-------------------------------------------+
| Location | Text string, GPS coords, URL |
+---------------+-------------------------------------------+
| Connection | Internet (unsecured), Internet |
| Type | (secured by VPN, etc.), Intranet, ... |
+---------------+-------------------------------------------+
| Direction | Inbound, Outbound |
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+---------------+-------------------------------------------+
| State | Authentication State |
| | Authorization State |
| | Accounting State |
| | Session State |
+---------------+-------------------------------------------+
Table 2: Context Matching Capability Index
+-----------------------------------------------------------+
| Action Capability Index |
+---------------+-------------------------------------------+
| Ingress port | SFC header termination, |
| | VxLAN header termination |
+---------------+-------------------------------------------+
| | Pass |
| Actions | Deny |
| | Mirror |
| | Simple Statistics: Count (X min; Day;..)|
| | Client specified Functions: URL |
+---------------+-------------------------------------------+
| Egress | Encap SFC, VxLAN, or other header |
+---------------+-------------------------------------------+
Table 3: Action Capability Index
+-----------------------------------------------------------+
| Functional Profile Index |
+---------------+-------------------------------------------+
| Profile types | Name, type, or Flexible |
| Signature | Profile/signature URL Command for |
| | I2NSF Controller to enable/disable |
+---------------+-------------------------------------------+
Table 4: Function Profile Index
10. Manageability Considerations
Management of NSFs includes:
o Lifecycle management and resource management of NSFs
o Configuration of devices, such as address configuration, device
internal attributes configuration, etc.
o Signaling
o Policy rules provisioning
Currently, I2NSF only focuses on the policy rule provisioning part.
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11. Security Considerations
NSF control and monitoring demand trustworthy, robust, and fully
secured access. Therefore, proper secure communication channels
have to be carefully specified for carrying the controlling and
monitoring information between the NSFs and their management
entity or entities. This has been discussed in Section 4.
This framework is intended for enterprise users, with or without
cloud service offerings. Privacy of users should be provided by
using existing standard mechanisms, such as encryption;
anonymization of data should also be done (if possible depending
on the transport used). Such mechanisms require confidentiality
and integrity.
12. IANA Considerations
This document requires no IANA actions. RFC Editor: Please remove
this section before publication.
13. Acknowledgements
This document includes significant contributions from Christian
Jacquenet (Orange), Seetharama Rao Durbha (Cablelabs), Mohamed
Boucadair (Orange), Ramki Krishnan (Dell), Anil Lohiya (Juniper
Networks), Joe Parrott (BT), Frank Xialing (Huawei), and
XiaoJun Zhuang (China Mobile).
Some of the results leading to this work have received funding from
the European Union Seventh Framework Programme (FP7/2007-2013) under
grant agreement no. 611458.
14. References
14.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC5575] Marques, P., Sheth, N., Raszuk, R., Greene, B., Mauch, J.,
and D. McPherson, "Dissemination of Flow Specification
Rules", RFC 5575, August 2009,
<http://www.rfc-editor.org/info/rfc5575>.
[RFC7297] Boucadair, M., Jacquenet, C., and N. Wang, "IP
Connectivity Provisioning Profile (CPP)", RFC 7297,
July 2014,
<http://www.rfc-editor.org/info/rfc7297>.
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14.2. Informative References
[RFC8192]
Hares, S., Dunbar, L., Lopez, D., Zarny, M., and C.
Jacquenet, "I2NSF Problem Statement and Use cases",
RFC 8192, July 2017
https://datatracker.ietf.org/doc/rfc8192/.
[I-D.ietf-netmod-acl-model]
Bogdanovic, D., Sreenivasa, K., Huang, L., and D. Blair,
"Network Access Control List (ACL) YANG Data Model",
draft-ietf-netmod-acl-model-13 (work in progress),
October, 2017.
[I-D.ietf-i2nsf-terminology]
Hares, S., Strassner, J., Lopez, D., Xia, L., and H.
Birkholz, "Interface to Network Security Functions (I2NSF)
Terminology", draft-ietf-i2nsf-terminology-04 (work in
progress), July 2017.
[I-D.draft-xibassnez-i2nsf-capability]
Xia, L., Strassner, J., Basile, C., and Lopez, D.,
"Information Model of NSFs Capabilities",
draft-xibassnez-i2nsf-capability-02.txt (work in
progress), July, 2017.
[I-D.pastor-i2nsf-remote-attestation]
Pastor, A., Lopez, D., and A. Shaw, "Remote Attestation
Procedures for Network Security Functions (NSFs) through
the I2NSF Security Controller",
draft-pastor-i2nsf-nsf-remote-attestation-02 (work in
progress), September 2017.
[I-D.xie-i2nsf-demo-outline-design]
Xie, Y., Xia, L., and J. Wu, "Interface to Network
Security Functions Demo Outline Design",
draft-xie-i2nsf-demo-outline-design-00 (work in progress),
April 2015.
[gs_NFV] "ETSI NFV Group Specification; Network Functions
Virtualization (NFV) Use Cases. ETSI GS NFV 001v1.1.1",
2013.
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Authors' Addresses
Diego R. Lopez
Telefonica I+D
Editor Jose Manuel Lara, 9
Seville, 41013
Spain
Phone: +34 682 051 091
Email: diego.r.lopez@telefonica.com
Edward Lopez
Curveball Networks
Chantilly, Virgina
USA
Phone: +1 703 220 0988
Email: elopez@fortinet.com
Linda Dunbar
Huawei
Email: Linda.Dunbar@huawei.com
John Strassner
Huawei
Email: John.sc.Strassner@huawei.com
Rakesh Kumar
Juniper Networks
Email: rkkumar@juniper.net
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