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I2NSF                                                           S. Hares
Internet-Draft                                                 L. Dunbar
Intended status: Standards Track                                  Huawei
Expires: August 5, 2016                                         D. Lopez
                                                          Telefonica I+D
                                                                M. Zarny
                                                           Goldman Sachs
                                                            C. Jacquenet
                                                          France Telecom
                                                        February 2, 2016


                 I2NSF Problem Statement and Use cases
             draft-ietf-i2nsf-problem-and-use-cases-00.txt

Abstract

   This document describes the problem statement for Interface to
   Network Security Functions (I2NSF) and summary of the I2NSF use
   cases.

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-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   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 August 5, 2016.

Copyright Notice

   Copyright (c) 2016 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
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect



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   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Problem Space . . . . . . . . . . . . . . . . . . . . . . . .   4
     3.1.  Facing Security Service Providers . . . . . . . . . . . .   5
       3.1.1.  Diverse Types of Security Functions . . . . . . . . .   5
       3.1.2.  Diverse Interfaces to Control NSFS  . . . . . . . . .   6
       3.1.3.  Diverse Interface to monitor the behavior of NSFs . .   6
       3.1.4.  More Distributed NSFs and vNSFs . . . . . . . . . . .   6
       3.1.5.  More Demand to Control NSFs Dynamically . . . . . . .   7
       3.1.6.  Demand for multi-tenancy to control and monitor NSFs    7
       3.1.7.  Lack of Characterization of NSFs and Capability
               Exchange  . . . . . . . . . . . . . . . . . . . . . .   7
       3.1.8.  Lack of Mechanism for NSFs to utilize external
               profiles  . . . . . . . . . . . . . . . . . . . . . .   8
       3.1.9.  Lack of Mechanisms to accept external alerts to
               trigger automatic configuration changes . . . . . . .   8
       3.1.10. Lack of mechanism for dynamic key distribution to
               NSFs  . . . . . . . . . . . . . . . . . . . . . . . .   8
     3.2.  Challenges Facing Customers . . . . . . . . . . . . . . .  10
       3.2.1.  NSFs from Heterogeneous Administrative Domains  . . .  10
       3.2.2.  Today's Control Requests are Vendor Specific  . . . .  10
       3.2.3.  Difficulty to Monitor the Execution of Desired
               Policies  . . . . . . . . . . . . . . . . . . . . . .  12
     3.3.  Difficulty to Validate Policies across Multiple Domains .  12
     3.4.  Lack of Standard Interface to Inject Feedback to NSF  . .  13
     3.5.  Lack of Standard Interface for Capability Negotiation . .  13
   4.  Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . .  13
     4.1.  General Use Cases . . . . . . . . . . . . . . . . . . . .  14
     4.2.  Access Networks . . . . . . . . . . . . . . . . . . . . .  15
     4.3.  Cloud Datacenter Scenario . . . . . . . . . . . . . . . .  16
       4.3.1.  On-Demand Virtual Firewall Deployment . . . . . . . .  17
       4.3.2.  Firewall Policy Deployment Automation . . . . . . . .  17
       4.3.3.  Client-Specific Security Policy in Cloud VPNs . . . .  18
       4.3.4.  Internal network monitoring . . . . . . . . . . . . .  18
   5.  Management Considerations . . . . . . . . . . . . . . . . . .  18
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  18
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  18
   8.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .  19
   9.  Contributing Authors  . . . . . . . . . . . . . . . . . . . .  19
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  19
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  19



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     10.2.  Informative References . . . . . . . . . . . . . . . . .  19
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  21

1.  Introduction

   This document describes the problem statement for Interface to
   Network Security Functions (I2NSF) and summary of the I2NSF use
   cases.  A summary of the I2NSF state of the art in the industries and
   IETF which is relevant to I2NSF work is contained in
   [I-D.hares-i2nsf-gap-analysis].

   The growing challenges and complexity in maintaining a secure
   infrastructure, complying with regulatory requirements, and
   controlling costs are enticing enterprises into consuming network
   security functions hosted by service providers.  The hosted security
   service is especially attractive to small and medium size enterprises
   who suffer from a lack of security experts to continuously monitor,
   acquire new skills and propose immediate mitigations to ever
   increasing sets of security attacks.

   According to [Gartner-2013], the demand for hosted (or cloud-based)
   security services is growing.  Small and medium-sized businesses
   (SMBs) are increasingly adopting cloud-based security services to
   replace on-premises security tools, while larger enterprises are
   deploying a mix of traditional and cloud-based security services.

   To meet the demand, more and more service providers are providing
   hosted security solutions to deliver cost-effective managed security
   services to enterprise customers.  The hosted security services are
   primarily targeted at enterprises (especially small/medium ones), but
   could also be provided to any kind of mass-market customer.  As the
   result, the Network security functions (NSFs) are provided and
   consumed in increasingly diverse environments.  Users of NSFs may
   consume network security services hosted by one or more providers,
   which may be their own enterprise, service providers, or a
   combination of both.  This document also briefly describes the
   following use cases summarized by
   [I-D.pastor-i2nsf-merged-use-cases]:

   o  [I-D.pastor-i2nsf-access-usecases] (I2NSF-Access),

   o  [I-D.zarny-i2nsf-data-center-use-cases](I2NSF-DC), and

   o  [I-D.qi-i2nsf-access-network-usecase] (I2NSF-Mobile).







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2.  Terminology

   ACL:   Access Control List

   B2B:   Business-to-Business

   Bespoke:   Something made to fit a particular person, client or
      company.

   Bespoke security management:   Security management which is make to
      fit a particular customer.

   DC:    Data Center

   FW:    Firewall

   IDS:    Intrusion Detection System

   IPS:    Intrusion Protection System

   NSF:    Network security function.  An NSF is a function that that
      detects unwanted activity and blocks/mitigates the effect of such
      unwanted activity in order to support availability of a network.
      In addition, the NSF can help in supporting communication stream
      integrity and confidentiality.

   Flow-based NSF:    A NSF which inspects network flows according to a
      policy intended for enforcing security properties.  Flow based
      security also means that packets are inspected in the order they
      are received, and without modification to the packet due to the
      inspection process (MAC rewrites, TTL decrement action, or NAT
      inspection or changes).

   Virtual NSF:    A NSF which is deployed as a distributed virtual
      device.

   VNFPool:    Pool of Virtual Network Functions.

3.  Problem Space

   The following sub-section describe the problems and challenges facing
   customers and security service providers when some or all of the
   security functions are no longer physical hosted by the customer's
   administrative domain.

   Security service providers can be internal to the company or external
   security service providers.  For example, an internal IT Security
   group within a large enterprise could act as a security service



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   provider for the enterprise.  In contrast, an enterprise could
   outsource all security services to an external security service
   provider in a global service provider.  In document, the security
   service provider function whether it is internal or external, will be
   denoted as "service provider".

   The "Customer-Provider" relationship may be between any two parties.
   The parties can be in different firms or different domains of the
   same firm.  Contractual agreements may be required in such contexts
   to formally document the customer's security requirements and the
   provider's guarantees to fulfill those requirements.  Such agreements
   may detail protection levels, escalation procedure, alarms reporting,
   etc.  There is currently no standard mechanism to capture those
   requirements.

   A service provider may be a customer of another service provider.

3.1.  Facing Security Service Providers

3.1.1.  Diverse Types of Security Functions

   There are many types of NSFs.  NSFs by different vendors can have
   different features and have different interfaces.  NSFs can be
   deployed in multiple locations in a given network, and perhaps have
   different roles.

   Below are a few examples of security functions and locations or
   contexts in which they are often deployed:

   External Intrusion and Attack Protection:   Examples of this function
      are firewall/ACL authentication, IPS, IDS, and endpoint
      protection.

   Security Functions in a DMZ:   Examples of this function are
      firewall/ACLs, IDS/IPS, authentication and authorization services,
      NAT, forwarding proxies, application, and AAA services.  These
      functions may be physically on-premise in a server provider's
      network at the DMZ spots or at "virtual" DMZ.

   Internal Security Analysis and Reporting:   Examples of this function
      are security logs, event correlation, and forensic analysis.

   Internal Data and Content Protection:   Examples of this function are
      encryption, authorization, and public/private key management for
      internal database.

   Given the diversity of security functions, the contexts in which
   these functions can be deployed, and the constant evolution of these



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   functions, standardizing all aspects of security functions is
   challenging, and most probably not feasible.  Fortunately, it is not
   necessary to standardize all aspects.  For example, from an I2NSF
   perspective, there is no need to standardize on how a firewall
   filters are created or applied.

   What is needed is having a standardized interface to control and
   monitor the rule sets that NSFs use to treat packets traversing
   through.  And standardizing interfaces will provide an impetuous for
   standardizing established security functions.

3.1.2.  Diverse Interfaces to Control NSFS

   To provide effective and competitive solutions and services, Security
   Service Providers may need to utilize multiple security functions
   from various vendors to enforce the security policies desired by
   their customers.

   Since no widely accepted industry standard security interfaces exists
   today, management of NSFs (device and policy provisioning,
   monitoring, etc.) tends to be bespoke security management offered by
   product vendors.  As a result, automation of such services, if it
   exists at all, is also bespoke.  Thus, even in the traditional way of
   deploying security features, there is a gap to coordinate among
   implementations from distinct vendors.  This is the main reason why
   mono-vendor security functions are often deployed and enable in a
   particular network segment.

   A challenge for monitoring is that an NSF cannot monitor what it
   cannot view.  Therefore, enabling a security function (e.g., firewall
   [I-D.ietf-opsawg-firewalls]) does not mean that a network is
   protected.  As such, it is necessary to have a mechanism to monitor
   and provide execution status of NSFs to security and compliance
   management tools.  There exist various network security monitoring
   vendor specific interfaces for forensics and troubleshooting.

3.1.3.  Diverse Interface to monitor the behavior of NSFs

   Obviously, enabling a security function (e.g., firewall
   [I-D.ietf-opsawg-firewalls] does not mean that a network is
   protected.  Therefore, it is necessary to have a mechanism to monitor
   the execution status of NSFs.

3.1.4.  More Distributed NSFs and vNSFs

   The security functions which are invoked to enforce a security policy
   can be located in different equipment and network locations.




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   The European Telecommunications Standards Institute (ETSI) Network
   Function Virtualization (NFV) initiative creates new management
   challenges for security policies to be enforced by distributed,
   virtual, and network security functions (vNSF).

   A vNSF has higher risk of failure, migrating, and state changes as
   their hosting VMs being created, moved, or decommissioned.

3.1.5.  More Demand to Control NSFs Dynamically

   In the advent of SDN (see [I-D.jeong-i2nsf-sdn-security-services]),
   more clients, applications or application controllers need to
   dynamically update their communication policies that are enforced by
   NSFs.  The Security Service Providers have to dynamically update
   control requests to NSFs upon receiving the requests from their
   clients

3.1.6.  Demand for multi-tenancy to control and monitor NSFs

   Service providers may require having several operational units to
   control and monitor the NSFs, especially when NSFs become distributed
   and virtualized.

3.1.7.  Lack of Characterization of NSFs and Capability Exchange

   To offer effective security services, service providers need to
   activate various security functions in NSFs or vNSFs manufactured by
   multiple vendors.  Even within one product category (e.g., firewall),
   security functions provided by different vendors can have different
   features and capabilities.  For example, filters that can be designed
   and activated by a firewall may or may not support IPv6 depending on
   the firewall technology.

   The service provider's management system (or controller) needs a way
   to retrieve the capabilities of service functions by different
   vendors so that it could build an effective security solution.  These
   service function capabilities can be documented in a static manner
   (e.g. a file) or via an interface which access a repository of
   security function capabilities which the NSF vendors dynamically
   update.

   A dynamic capability registration is useful for automation because
   security functions may be subject to software and hardware updates.
   These updates may have implications on the policies enforced by the
   NSFs.

   Today, there is no standard method for vendors to describe the
   capabilities of their security functions.  Without a common technical



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   framework to describe the capabilities of security functions, service
   providers cannot automate the process of selecting NSFs by different
   vendors to accommodate customer's requirements.

3.1.8.  Lack of Mechanism for NSFs to utilize external profiles

   Many security functions depend on signature files or profiles to
   perform (e.g.  IPS/IDS signatures, DOTS filters).  Different policies
   might need different signatures or profiles.  Today, the construction
   and use of black databases can be win-win strategy for all parties
   involved.  There might be Open Source provided signature/profiles
   (e.g. by Snort or others) in the future.

   There is a need to have a standard envelop (i.e. the format) to allow
   NSFs to use external profiles.

3.1.9.  Lack of Mechanisms to accept external alerts to trigger
        automatic configuration changes

   NSF can ask the I2NSF security controller to alter network policy.
   For example, a DDoS alert could trigger a change to routing system to
   send traffic to a traffic scrubbing service to mitigate the DDoS.

   The DDoS protection has the following two parts: a) the configuration
   of signaling of open threats and b) DDoS mitigation.  DOTS controller
   manages the signaling part of DDoS.  I2NSF controller(s) would manage
   the changing to the network policy.  By monitoring the network alerts
   from DDoS, I2NSF can feed a alerts analytics engine that could
   recognize attacks and the I2NSF can implement the needed new
   policies.

   DDoS mitigation is enhanced if the provider's network security
   controller can monitor, analyze, and investigate the abnormal events
   and provide information to the client or change the network
   configuration (see section x) for details on the interfaces.

   [I-D.zhou-i2nsf-capability-interface-monitoring] provides details on
   how monitoring aspects of the flow-based Network Security Functions
   (NSFs) can use the I2NSF interfaces to receive traffic reports and
   enforce policy.

3.1.10.  Lack of mechanism for dynamic key distribution to NSFs

   There is a need for controller to distribute various keys to
   distributed NSFs.  To distribute various keys, the keys must be
   created and managed.  While there is many key management methods and
   key derivation functions (KDF), there is a lack of standard interface
   to provision and manage keys.



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   The keys may be used for message authentication and integrity in
   order to protect data flow.  In addition, keys may be used to secure
   the protocol and messages in the core routing infrastructure.

   As of now there is no much focus on an abstraction for keying
   information that describes the interface between protocols,
   operators, and automated key management.

   The keys may be used for message authentication and integrity in
   order to protect data flow.  In addition, keys may be used to secure
   the protocol and messages in the core routing infrastructure.

   The ability to utilize keys when routing protocols send or receive
   messages will be enhanced by having an abstract key table maintained
   by a security services.  Conceptually, there must be an interface
   defined for routing/signaling protocols to make requests of automated
   key management when it is being used, to notify the protocols when
   keys become available in the key table.

   An abstract key service needs to have three things:

   1.  I2NSF need to design the key table abstraction, the interface
       between key management protocols and routing/other protocols, and
       possibly security protocols at other layers.

   2.  For each routing/other protocol, I2NSF need to define the mapping
       between how the protocol represents key material and the
       protocol-independent key table abstraction.  (If protocols share
       common mechanisms for authentication (e.g.  TCP Authentication
       Option), then the same mapping may be reused.)

   3.  Automated Key management must support both symmetric keys and
       group keys via the service provided by items 1 and 2.

3.1.10.1.  Background on Core Routing Security

   A recommendation from a workshop held by the Internet Architecture
   Board (IAB) held a workshop on the topic of "Unwanted Internet
   Traffic" [RFC4948] suggest since a "simple risk analysis" suggests an
   "ideal attack target of minimal cost but maximal disruption is the
   core routing infrastructure", it is important to "tightening the
   security of the core routing infrastructure".  One of the ways to
   tighten security of the core routing infrastructure is to tighten the
   security of protocol packets on the wire is by protecting the
   messages by use of keys.

   Conceptually, when routing protocols send or receive messages, they
   might need to look up the key to use in this abstract key table.



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   Conceptually, there must be an interface defined for a protocols to
   make requests of automated key management when it is being used; when
   keys become available, they might be made available in the key table.

3.2.  Challenges Facing Customers

   When customers invoke hosted security services, their security
   policies may be enforced by a collection of security functions hosted
   in different domains.  Customers may not have the security skills to
   express sufficiently precise requirements or security policies.
   Usually these customers express the expectations of their security
   requirements or the intent of their security policies.  These
   expectations can be considered customer level security expectations.
   Customers may also desire to express guidelines for security
   management.  Examples of such guidelines are the following:

   o  Which critical communications are to be preserved during critical
      events (DOTS),

   o  Which hosts are to continue service even during severe security
      attacks (DOTS),

   o  Reporting of attacks to CERT (MILE),

   o  Managing network connectivity of systems out of compliance (SACM),

3.2.1.  NSFs from Heterogeneous Administrative Domains

   Many medium and large enterprises have deployed various on-premises
   security functions which they want to continue to deploy.  These
   enterprises want to combine local security functions with remote
   hosted security functions to achieve more efficient and immediate
   counter-measures to both Internet-originated attacks and enterprise
   network-originated attacks.

   Some enterprises may only need the hosted security services for their
   remote branch offices where minimal security infrastructures/
   capabilities exist.  The security solution will consist of NSFs on
   customer networks and NSFs on service provider networks.

3.2.2.  Today's Control Requests are Vendor Specific

   Customers may consume NSFs by multiple service providers.  Customers
   need to express their security requirements, guidelines, and
   expectations to the service providers.  In turn, the service
   providers must translate this customer information into customer
   security policies and associated configuration sets for the set of
   security functions in their network.  Without a standard technical



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   characterizations or a standard interface, the service provide faces
   many challenges.

   Due the lack of standard technical characterizations and a standard
   interfaces, the following problems exists:

   No standard technical characterization and/or APIs  :  Even the most
      common security services there is no standard technical
      characterization or APIs.  Most security services are accessible
      only through disparate, proprietary interfaces (e.g., portals or
      APIs) in whatever format vendors choose to offer.  The service
      provider must the customer's input to these widely varying
      interfaces.

   No standard interface:    Without standard interfaces it is complex
      for customers to update security policies or integrate the
      security functions in their enterprise with the security services
      provided by the security service providers.  This complexity is
      induced by the diversity of the configuration models, policy
      models, and supported management interfaces.  Without a standard
      interface, new innovative security products find a large barrier
      to entry into the market

   Managing by scripts de-jour:    The current practices rely on the use
      of scripts which generate other scripts which the automatically
      run to upload or download configuration changes, log information
      and other things.  These scripts have to be adjusted each time an
      implementation from a different vendor is enabled in a provider
      side.

   Lack of immediate Feedback:    Customers may also require a mechanism
      to easily update/modify their security requirements with immediate
      effect in the underlying involved NSFs.

   Lack of explicit invocation request:    While security agreements are
      in place, security functions may be solicited without requiring an
      explicit invocation means.  Nevertheless, some explicit invocation
      means may be required to interact with a service function.

   To see how standard interfaces could help achieve faster
   implementation time cycles, let us consider a customer who would like
   to dynamically allow an encrypted flow with specific port, src/dst
   addresses or protocol type through the firewall/IPS to enable an
   encrypted video conferencing call only during the time of the call.
   With no commonly accepted interface in place, the customer would have
   to learn about the particular provider's firewall/IPS interface and
   send the request in the provider's required format.




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           +------------+
           | security   |
           | MGT system |
           +----||------+
                ||   proprietary
                ||   or I2NSF standard
   Picture:     ||
   Port 10   +--------+
     --------| FW/IPS |-------------
   Encrypted +--------+
   Video Flow

    Figure 2: Example of non-standard vs. standard interface

   In contrast, if a firewall/IPS interface standard exists, the
   customer would be able to send the request, without having to do the
   extensive preliminary legwork.  A standard interface also helps
   service providers since they could now offer the same firewall/IPS
   interface to represent firewall/IPS services for utilizing products
   from many vendors.  The result is that the service provider has now
   abstracted the firewall/IPS services.  The standard interface also
   helps the firewall/IPS vendors to focus on their core security
   functions or extended features rather than the standard building
   blocks of a management interface.

3.2.3.  Difficulty to Monitor the Execution of Desired Policies

   How a policy is translated into technology-specific actions is hidden
   from the customers.  However, customers still need ways to monitor
   the delivered security service that results from the execution of
   their desired security requirements, guidelines and expectations.

   Today, there is no standard way for customers to get security service
   assurance of their specified security policies properly enforced by
   the security functions in the provider domain.  The customer also
   lacks the ability to perform "what-if" scenarios to assess the
   efficiency of the delivered security service.

3.3.  Difficulty to Validate Policies across Multiple Domains

   One key aspect of a hosted security service with security functions
   located at different premises is the ability to express, monitor and
   verify security policies that combine several distributed security
   functions.  It is crucial to an effective service to be able to take
   these actions via a standard interface.  This standard interface
   becomes more crucial to the hosted security service when NSFs are
   instantiated in Virtual Machines which are sometimes widely




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   distributed in the network and sometimes are combined together in one
   device to perform a set of asks in a service.

   Without standard interfaces and security policy data models, the
   enforcement of a customer-driven security policy remains challenging
   because of the inherent complexity created by the combining the
   invocation of several vendor-specific security functions into a
   multi-vendor, heterogeneous environment.  Each vendor specific
   function may require specific configuration procedures and
   operational tasks.

   Ensuring the consistent enforcement of the policies at various
   domains is also challenging.  Standard data models are likely to
   contribute to ameliorating that issue.

3.4.  Lack of Standard Interface to Inject Feedback to NSF

   Today, many security functions, such as IPS, IDS, DDoS and Antivirus,
   depend heavily on the associated profiles.  They can perform more
   effective protection if they have the up-to-date profiles.  As more
   sophisticated threats arise, enterprises, vendors, and service
   providers have to rely on each other to achieve optimal protection.
   Cyper Threat Alliance (CA, http://cyberthreatalliance.org/) is is one
   of those initiatives that aim at combining efforts conducted by
   multiple organizations.

   Today there is no standard interface to exchange security profiles
   between organizations.

3.5.  Lack of Standard Interface for Capability Negotiation

   There could be situations when the NSFs selected cannot perform the
   policies requested by the Security Controller, due to resource
   constraints.  To support the automatic control in the SDN-era, it is
   necessary to have a set of messages for proper negotiation between
   the Security Controller and the NSFs.

4.  Use Cases

   Standard interfaces for monitoring and controlling the behavior of
   NSFs are essential building blocks for Security Service Providers and
   enterprises to automate the use of different NSFs from multiple
   vendors by their Security management entities.  I2NSF may be invoked
   by any (authorized) client.  Examples of authorized clients are
   upstream applications (controllers), orchestration systems, and
   security portals.





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4.1.  General Use Cases

   User request security services through specific clients (e.g. a
   customer application, the NSP BSS/OSS or management platform) and the
   appropriate NSP network entity will invoke the (v)NSFs according to
   the user service request.  We will call this network entity the
   security controller.  The interaction between the entities discussed
   above (client, security controller, NSF) is shown in the following
   diagram:

                                +----------+
         +-------+              |          |                  +-------+
         |       |  Interface 1 |Security  |   Interface 2    | NSF(s)|
         |Client <------------->           <------------------>       |
         |       |              |Controller|                  |       |
         +-------+              |          |                  +-------+
                                +----------+

                    Figure 2: Interaction between Entities

   Interface 1 is used for receiving security requirements from client
   and translating them into commands that NSFs can understand and
   execute.  The security controller also passes back NSF security
   reports (e.g. statistics) to the client which the control has
   gathered from NSFs.  Interface 2 is used for interacting with NSFs
   according to commands, and collect status information about NSFs.

   Client devices or applications can require the security controller to
   add, delete or update rules in the security service function for
   their specific traffic.

   When users want to get the executing status of security service, they
   can request the information of NSFs from the client.  The security
   controller will collect NSF information through Interface 2,
   consolidate them, and give feedback to client through Interface 1.
   This interface can be used to collect not only individual service
   information, but also aggregated data suitable for tasks like
   infrastructure security assessment.

   Customers may require validating NSF availability, provenance, and
   correct execution.  This validation process, especially relevant for
   vNSFs, includes at least:

   Integrity of the NSF:   by ensuring that the NSF is not compromised;

   Isolation:   by ensuring the execution of the NSF is self-contained
      for privacy requirements in multi-tenancy scenarios.




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   In order to achieve this, the security controller may collect
   security measurements and share them with an independent and trusted
   third party (via the interface 1) in order to allow for attestation
   of NSF functions using the third party added information.

4.2.  Access Networks

   This scenario describes use cases for users (e.g. enterprise user,
   network administrator, and residential user) that request and manage
   security services hosted in the network service provider (NSP)
   infrastructure.  Given that NSP customers are essentially users of
   their access networks, the scenario is essentially associated with
   their characteristics, as well as with the use of vNSFs.

   The Virtual CPE described in [NFVUC] use cases #5 and #7 requires a
   model of access virtualization that includes mobile and residential
   access where the operator may offload security services from the
   customer local environment (E.g. device or terminal) to the operator
   infrastructure supporting the access network.

   These use cases defines the operator interaction with vNSFs through
   automated interfaces, typically by B2B communications.



            Customer   +     Access     +     PoP/Datacenter
                       |                |     +--------+
                       |          ,-----+--.  |Network |
                       |        ,'      |   `-|Operator|
       +-------------+ |       /+----+  |     |Mgmt Sys|
       | Residential |-+------/-+vCPE+----+   +--------+
       +-------------+ |     /  +----+  |  \     |    :
                       |    /           |   \    |     |
           +-------+   |   ;    +----+  |    +----+    |
           | Cloud |---+---+----+ vPE+--+----+ NSF|    |
           +-------+   |   :    +----+  |    +----+    |
                       |    :           |   /          |
            +--------+ |    :   +----+  |  /           ;
            | Mobile |-+-----\--+vEPC+----+           /
            +--------+ |      \ +----+  |          ,-'
                       |       `--.     |      _.-'
                       |           `----+----''
                       +                +


                      Figure 3:  NSF and actors





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   The following are actions required for this access use case:

   vNSF Deployment:   The deployment process consists of instantiating a
      NSF on a Virtualization Infrastructure (NFVI), within the NSP
      administrative domain(s) or with other external domain(s).  This
      is a required step before a customer can subscribe to a security
      service supported in the vNSF.

   vNSF Customer Provisioning:    Once a vNSF is deployed, any customer
      can subscribe to it.  The provisioning lifecycle includes the
      following:

      *  Customer enrollment and cancellation of the subscription to a
         vNSF;

      *  Configuration of the vNSF, based on specific configurations, or
         derived from common security policies defined by the NSP.

      *  Retrieve and list of the vNSF functionalities, extracted from a
         manifest or a descriptor.  The NSP management systems can
         demand this information to offer detailed information through
         the commercial channels to the customer.

4.3.  Cloud Datacenter Scenario

   In a datacenter, network security mechanisms such as firewalls may
   need to be added or removed dynamically for a number of reasons.
   These changes may be explicitly requested by the user, or triggered
   by a pre-agreed upon service level agreement (SLA) between the user
   and the provider of the service.  For example, the service provider
   may be required to add more firewall capacity within a set timeframe
   whenever the bandwidth utilization hits a certain threshold for a
   specified period.  This capacity expansion could result in adding new
   instances of firewalls on existing machines or provisioning a
   completely new firewall instance in a different machine.

   The on-demand, dynamic nature of deployment essentially requires that
   the network security "devices" be in software or virtual form
   factors, rather than in a physical appliance form.  This requirement
   is a provider-side concern.  Users of the firewall service are
   agnostic (as they should) as to whether or not the firewall service
   is run on a VM or any other form factor.  Indeed, they may not even
   be aware that their traffic traverses firewalls.

   Furthermore, new firewall instances need to be placed in the "right
   zone" (domain).  The issue applies not only to multi-tenant
   environments where getting the tenant in the right domain is of
   paramount importance, but also in environments owned and operated by



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   a single organization with its own service segregation policies.  For
   example, an enterprise may mandate that firewalls serving Internet
   traffic and business-to-business (B2B) traffic be separate.  Another
   example is that IPS/IDS services for investment banking and non-
   banking traffic may be need to separated for regulatory reasons.

4.3.1.  On-Demand Virtual Firewall Deployment

   A service provider operated cloud data center could serve tens of
   thousands of clients.  Clients' compute servers are typically hosted
   on virtual machines (VMs), which could be deployed across different
   server racks located in different parts of the data center.  Often it
   is not technically and/or financially feasible to deploy dedicated
   physical firewalls to suit each client's myriad security policy
   requirements.  What is needed is the ability to dynamically deploy
   virtual firewalls for each client's set of servers based on
   established security policies and underlying network topologies.


           ---+-----------------------------+-----
              |                             |
             +---+                         +-+-+
             |vFW|                         |vFW|
             +---+                         +-+-+
               |    Client #1                |  Client #2
            ---+-------+---               ---+-------+---
             +-+-+   +-+-+                 +-+-+   +-+-+
             |vM |   |vM |                 |vM |   |vM |
             +---+   +---+                 +---+   +---+

             Figure 4:  NSF in Data Center

4.3.2.  Firewall Policy Deployment Automation

   Firewall rules setting is often a time consuming, complex and error-
   prone process even within a single organization/enterprise framework.
   It becomes far more complex in provider-owned cloud networks that
   serve myriad customers.

   Firewall rules today are highly tied with ports and addresses of the
   traffic.  This makes it very difficult for clients of cloud data
   center to construct rules for their own traffic as the clients only
   see the virtual networks and the virtual addresses.  The customer-
   visible virtual networks and addresses may be different from the
   actual packets traversing the FWs.

   Even though most vendors support similar firewall features, the
   actual rule configuration key words are different from vendors to



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   vendors, making it difficult for automation.  Automation works best
   when it can leverage a common set of standards that will work across
   NSFs by multiple vendors.  Without automation, it is virtually
   impossible for clients to dynamically specify their desired rules for
   their traffic.

4.3.3.  Client-Specific Security Policy in Cloud VPNs

   Clients of service provider operated cloud data centers need not only
   secure virtual private networks (VPNs) but also virtual security
   functions that enforce the clients' security policies.  The security
   policies may govern communication within the clients' own virtual
   networks as well as communication with external networks.  For
   example, VPN service providers may need to provide firewall and other
   security services to their VPN clients.  Today, it is generally not
   possible for clients to dynamically view (much less change) what,
   where and how security policies are implemented on their provider-
   operated clouds.  Indeed, no standards-based framework that allows
   clients to retrieve/manage security policies in a consistent manner
   across different providers exists.

4.3.4.  Internal network monitoring

   There are many types of internal traffic monitors that may be managed
   by a security controller.  This includes a new class of services
   referred to as DLP, Data Loss Prevention, or Reputation Protection
   Services.  Depending on the class of event, alerts may go to internal
   administrators, or external services.

5.  Management Considerations

   Management of NSFs usually include configuration of devices,
   signaling and policy provisioning.  I2NSF will only focus on the
   policy provisioning part.

6.  IANA Considerations

   No IANA considerations exist for this document.

7.  Security Considerations

   Having a secure access to control and monitor NSFs is crucial for
   hosted security service.  The new NSF security controller introduces
   a new attack surface.  It needs to be resilient to attack and
   recovery from attack needs to be quick and trivial (thus making
   attacking it 'uninteresting').  Therefore, proper secure
   communication channels have to be carefully specified for carrying




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   the controlling and monitoring information between the NSFs and their
   management entity (or entities).

8.  Contributors

   I2NSF is a group effort.  The following people contributed actively
   to the initial use case text: Xiaojun Zhuang (China Mobile), Sumandra
   Majee (F5), Ed Lopez (Fortinet), and Robert Moskowitz (Huawei).

9.  Contributing Authors

   I2NSF has had a number of contributing authors.  The following are
   contributing authors:

   o  Antonio Pastur (Telefonica I+D),

   o  Mohamed Boucadair (France Telecom),

   o  Michael Georgiades (Prime Tel),

   o  Minpeng Qi (China Mobile),

   o  Shaibal Chakrabarty (US Ignite), and

   o  Nic Leymann (Deutsche Telekom).

10.  References

10.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

10.2.  Informative References

   [Gartner-2013]
              Messmer, E., "Gartner: Cloud-based security as a service
              set to take off", October 2013.

   [I-D.hares-i2nsf-gap-analysis]
              Hares, S., Zhang, D., Moskowitz, R., and H. Rafiee,
              "Analysis of Existing work for I2NSF", draft-hares-i2nsf-
              gap-analysis-01 (work in progress), December 2015.






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   [I-D.ietf-netmod-acl-model]
              Bogdanovic, D., Koushik, K., Huang, L., and D. Blair,
              "Network Access Control List (ACL) YANG Data Model",
              draft-ietf-netmod-acl-model-06 (work in progress),
              December 2015.

   [I-D.ietf-opsawg-firewalls]
              Baker, F. and P. Hoffman, "On Firewalls in Internet
              Security", draft-ietf-opsawg-firewalls-01 (work in
              progress), October 2012.

   [I-D.jeong-i2nsf-sdn-security-services]
              Jeong, J., Kim, H., and P. Jung-Soo, "Requirements for
              Security Services based on Software-Defined Networking",
              draft-jeong-i2nsf-sdn-security-services-01 (work in
              progress), March 2015.

   [I-D.lopez-i2nsf-packet]
              Ed, E., "Packet-Based Paradigm For Interfaces To NSFs",
              draft-lopez-i2nsf-packet-00 (work in progress), March
              2015.

   [I-D.pastor-i2nsf-access-usecases]
              Pastor, A. and D. Lopez, "Access Use Cases for an Open OAM
              Interface to Virtualized Security Services", draft-pastor-
              i2nsf-access-usecases-00 (work in progress), October 2014.

   [I-D.pastor-i2nsf-merged-use-cases]
              Pastor, A., Lopez, D., Wang, K., Zhuang, X., Qi, M.,
              Zarny, M., Majee, S., Leymann, N., Dunbar, L., and M.
              Georgiades, "Use Cases and Requirements for an Interface
              to Network Security Functions", draft-pastor-i2nsf-merged-
              use-cases-00 (work in progress), June 2015.

   [I-D.qi-i2nsf-access-network-usecase]
              Wang, K. and X. Zhuang, "Integrated Security with Access
              Network Use Case", draft-qi-i2nsf-access-network-
              usecase-02 (work in progress), March 2015.

   [I-D.zarny-i2nsf-data-center-use-cases]
              Zarny, M., Leymann, N., and L. Dunbar, "I2NSF Data Center
              Use Cases", draft-zarny-i2nsf-data-center-use-cases-00
              (work in progress), October 2014.








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   [I-D.zhou-i2nsf-capability-interface-monitoring]
              Zhou, C., Xia, L., Boucadair, M., and J. Xiong, "The
              Capability Interface for Monitoring Network Security
              Functions (NSF) in I2NSF", draft-zhou-i2nsf-capability-
              interface-monitoring-00 (work in progress), October 2015.

   [RFC4948]  Andersson, L., Davies, E., and L. Zhang, "Report from the
              IAB workshop on Unwanted Traffic March 9-10, 2006",
              RFC 4948, DOI 10.17487/RFC4948, August 2007,
              <http://www.rfc-editor.org/info/rfc4948>.

   [RFC7277]  Bjorklund, M., "A YANG Data Model for IP Management",
              RFC 7277, DOI 10.17487/RFC7277, June 2014,
              <http://www.rfc-editor.org/info/rfc7277>.

Authors' Addresses

   Susan Hares
   Huawei
   7453 Hickory Hill
   Saline, MI  48176
   USA

   Phone: +1-734-604-0332
   Email: shares@ndzh.com


   Linda Dunbar
   Huawei
   5340 Legacy Drive, Suite 175
   Plano, TX  75024
   USA

   Phone: +1-734-604-0332
   Email: ldunbar@huawei.com


   Diego R. Lopex
   Telefonica I+D
   Don Ramon de la Cruz, 82
   Madrid  28006
   Spain

   Email: diego.r.lopez@telefonica.com







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   Myo Zarny
   Goldman Sachs
   30 Hudson Street
   Jersey City, NJ  07302
   USA

   Email: myo.zarny@gs.com


   Christian Jacquenet
   France Telecom
   Rennes, 35000
   France

   Email: Christian.jacquenet@orange.com




































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