Network Working Group                                          E. Lopez
Internet Draft                                                 Fortinet
Intended status: Informational                                 D. Lopez
Expires: November 2016                                       Telefonica
                                                               L. Dunbar
                                                            J. Strassner
                                                               X. Zhuang
                                                            China Mobile
                                                              J. Parrott
                                                             R Krishnan
                                                               S. Durbha

                                                            May 2, 2016

           Framework for Interface to Network Security Functions

Status of this Memo

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   This Internet-Draft is submitted in full conformance with the
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   The list of current Internet-Drafts can be accessed at

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   This document defines the framework for guiding the functionality
   provided by 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
   in which the packet is associated. This document provides an
   overview of how NSFs are used, and describes how NSF software
   interfaces are controlled and monitored using rulesets. The design
   of these software interfaces must prevent the creation of implied
   constraints on NSF capability and functionality.

Table of Contents

   1. Introduction...................................................3
   2. Conventions used in this document..............................4
   3. Interfaces to Flow-based NSFs..................................4

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   4. Reference Models in Managing Flow-based NSFs...................7
      4.1. NSF Facing (Capability Layer) Interface...................8
      4.2. Client Facing (Service Layer) Interface...................9
      4.3. Vendor Facing Interface...................................9
      4.4. The Network Connecting the Security Controller and NSFs...9
      4.5. Interface to vNSFs.......................................10
   5. Flow-based NSF Capability Characterization....................11
   6. Structure of Rules for governing NSFs.........................15
      6.1. Capability Layer Rules and Monitoring....................15
      6.2. Service Layer Policy.....................................16
   7. Capability Negotiation........................................19
   8. Types of I2NSF clients........................................19
   9. Manageability Considerations..................................20
   10. Security Considerations......................................20
   11. IANA Considerations..........................................20
   12. References...................................................21
      12.1. Normative References....................................21
      12.2. Informative References..................................21
   13. Acknowledgments..............................................22

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. It also describes how I2NSF
   facilitates Software-Defined Networking (SDN) and Network Function
   Virtualization (NVF) control, while avoiding potential constraints
   that could limit the internal functionality and capabilities of

   The I2NSF use cases ([I2NSF-ACCESS], [I2NSF-DC] and [I2NSF-Mobile])
   call for standard interfaces for clients (e.g., applications,
   application controllers, or users), to inform the network what they
   are willing to receive. I2NSF realizes this as a set of security
   rules for monitoring and controlling the behavior of their specific
   traffic. It also provides standard interfaces for them to monitor
   the security functions hosted and managed by service providers.

   [I2NSF-Problem] describes the motivation and the problem space for
   Interface to Network Security Functions.

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2. Conventions used in this document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in RFC-2119 [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.

   BSS:  Business Support System

   Controller: used interchangeably with Service Provider Security
               Controller or management system throughout this

   FW:   Firewall

   IDS:  Intrusion Detection System

   IPS:  Intrusion Protection System

   NSF:  Network Security Functions, defined by [I2NSF-Problem]

   OSS:  Operation Support System

   vNSF: refers to NSF being instantiated on Virtual Machines.

3. Interfaces to Flow-based NSFs

   The emergence of SDN and NFV have resulted in the need to create
   application programming interfaces (APIs) in support of dynamic
   requests from various applications or application controllers.

   Flow-based NSFs [I2NSF-Problem] inspects packets in the order that
   they are received. The Interface to Flow-based NSFs can be generally
   grouped into three types:

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      1) Configuration - deals with the management and configuration of
         the NSF device itself, such as port address configurations.
         Configuration deals with attributes that are relatively

      2) Signaling - which represents logging and query functions
         between the NSF and external systems. Signaling API functions
         may also be defined by other protocols, such as SYSLOG and

      3) Rules Provisioning - used to control the rules that govern how
         packets are treated by the NSFs. Due to the need of
         applications/controllers to dynamically control what traffic
         they need to receive, much of the I2NSF efforts towards
         interface development will be in this area.

   This draft proposes that a rule provisioning interface to NSFs can
   be developed on a packet- or flow-based paradigm. A common trait of
   NSFs is in the processing of packets based on the content
   (header/payload) and/or context (session state, authentication
   state, etc) of the received packets.

   An important concept underlying this framework is the fact that
   attackers do not have standards as to how to attack networks, so it
   is equally important not to constrain NSF developers to offering a
   limited set of security functions. In other words, the introduction
   of I2NSF standards should not make it easier for attackers to
   compromise the network. Therefore, in constructing standards for
   rules provisioning interfaces to NSFs, it is equally important to
   allow support for vendor-specific functions, as this enables the
   introduction of NSFs that evolve to meet new threats. Proposed
   standards for rules provisioning interfaces to NSFs SHOULD NOT:

      - Narrowly define NSF categories, or their roles when implemented
        within a network

      - Attempt to impose functional requirements or constraints,
        either directly or indirectly, upon NSF developers

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      - Be a limited lowest common denominator approach, where
        interfaces can only support a limited set of standardized
        functions, without allowing for vendor-specific functions

      - Be seen as endorsing a best common practice for the
        implementation of NSFs

   By using a packet/flow-based approach to the design of such
   provisioning interfaces, 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.

   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 Event - Condition - Action (ECA) policy

   An Event, when used in the context of policy rules for a flow-based
   NSF, is used to determine whether the condition clause of the Policy
   Rule can be evaluated or not. Here are some examples of I2NSF

     - defining a clause, of the canonical form {variable, operator,
       value}, to represent an Event (e.g., time == 08:00)
     - using an Event object as the variable or the value in the above
       clause (e.g., use one or more attributes from one or more Event
       objects in the comparison clause)
     - using a Collection object to collect Events for aggregation,
       filtering, and/or correlation operations as part of the Event
       clause processing
     - encoding the entire Event expression into an attribute

   A Condition, when used in the context of policy rules for flow-based
   NSFs, is used to determine whether or not the set of Actions in that
   Policy Rule can be executed or not. A condition can be based on
   various combinations of the content (header/payload) and/or the
   context (session state, authentication state, etc) of the received

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     - Packet content values are based on one or more packet headers,
       data from the packet payload, bits in the packet, or something
       derived from the packet;
     - Context values are based on measured and inferred knowledge that
       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 for flow-based NSFs include:

     - Action ingress processing, such as pass, drop, mirroring, etc;
     - Action egress processing, 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. 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 vendor-specific today. The rulesets and software interfaces
   of I2NSF aim to standardize the form and function of profile and
   signature files while supporting vendor-specific functions of each.

4. Reference Models in Managing Flow-based NSFs

   This document only focuses on the framework of rules provisioning
   for and monitoring of flow-based NSFs.

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   The following figure shows various interfaces for managing the
   provisioning & monitoring aspects of flow-based NSFs.

              |      Client or App Controller       |
              | (e.g., Video Conference Ctrl Admin, |
              |  OSS/BSS, or Service Orchestration  |
                         |  Client Facing (Service Layer) Interface
                   |Network Operator mgmt|               +-------------+
                   | Security Controller | < --------- > |   Vendor    |
                   +---------------+-----+ Vendor Facing |   System    |
                                   |         Interface   +-------------+
                                   | NSF Facing (capability) Interface
       |                                                   |
       |                                                   |
   +---+--+         +------+             +------+       +--+---+
   + NSF-1+ ------- + NSF-n+             +NSF-1 + ----- +NSF-m +  . . .
   +------+         +------+             +------+       +------+

   Vendor A                                       Vendor B

                         Figure 1: Multiple Interfaces

4.1. NSF Facing (Capability Layer) Interface

     This is the interface between the Service Provider's management
     system (or Security Controller) and the set of NSFs that are
     selected to enforce the desired network security. This interface
     defines the features available for each NSF that the management
     system can choose to invoke for a particular packet or flow. Note
     that the management system does not need to use all features for a
     given NSF, nor does it need to use all available NSFs. Hence, this
     abstraction enables the same relative features from diverse NSFs
     from different vendors to be selected.

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     This interface is called the Capability Interface in the I2NSF

4.2. Client Facing (Service Layer) Interface

     This interface is for clients or Application Controller to express
     and monitor security policies for their specific flows. The Client
     Facing interface is called the Service Layer Interface in the
     I2NSF context. The I2NSF Service Layer allows the client to define
     and monitor the client specific policies and their execution

     A single client layer policy may need multiple NSFs (or multiple
     instantiations of the same NSF) to achieve the desired

4.3. Vendor Facing Interface

     NSFs provided by different vendors 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 an interface for vendors to register their NSFs indicating
     the capabilities of their NSFs.

     The Registration Interface can be defined statically or
     instantiated dynamically at runtime. If a new functionality that
     is exposed to the user is added to an NSF, the vendor MUST notify
     the network operator's management system or security controller of
     its updated functionality via the Registration Interface.

4.4. The Network Connecting the Security Controller and NSFs

     Most likely the NSFs are not directly attached to the Security
     Controller; for example, NSFs can be distributed across the
     network. The network that connects the Security 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) [MPTCP] and the Stream Control Transmission
     Protocol (SCTP) [RFC3286] will need to be evaluated for
     applicability.  Latency requirements for control message delivery
     must also be evaluated.

     The network connection between the Security Controller and NSFs
     could be:

     - 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
     - Open environments, where some NSFs (virtual or physical) can be
       hosted in external administrative domains or reached via secure
       external network domains.  This requires more restrictive
       security control to be placed over the I2NSF interface.  Not
       only must the information over the I2NSF interfaces use trusted
       channels, such as TLS, SASL (RFC4422), or the combination of the
       two, but also require proper authentication as described in

       Over the Open Environment, I2NSF needs to provide identity
       information, along with additional data that Authentication,
       Authorization, and Accounting (AAA) frameworks can use. This
       enables those frameworks to perform AAA functions on the I2NSF

4.5. Interface to vNSFs

     Even though there is no difference between virtual network
     security functions (vNSF) and physical NSFs from the policy
     provisioning perspective, there are some unique characteristics in
     interfacing to the vNSFs:

     - There could be multiple instantiations of one single NSF that
       has been distributed across a network. When different
       instantiations are visible to the Security Controller, different

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       policies may be applied to different instantiations of an
       individual NSF (e.g., to reflect the different roles that each
       vNSF is designated for).
     - When multiple instantiations of one single NSF appear as one
       single entity to the Security Controller, the policy
       provisioning has to be sent to the NSF's sub-controller, which
       in turn disseminates the polices to the corresponding
       instantiations of the NSF, as shown in the Figure 2 below.
     - Policies to one vNSF may need to be retrieved and moved to
       another vNSF of the same type when client flows are moved from
       one vNSF to another.
     - Multiple vNSFs may share the same physical platform
     - There may be scenarios where multiple vNSFs collectively perform
       the security policies needed.

                          | Security Controller    |
                                   ^        ^
                                   |        |
                       +-----------+        +------------+
                       |                                 |
                       v                                 v
    + - - - - - - - - - - - - - - - +  + - - - - - - - - - - - - - - - +
    |  NSF-A  +--------------+      |  |  NSF-B  +--------------+      |
    |         |Sub Controller|      |  |         |sub Controller|      |
    |         +--------------+      |  |         +--------------+      |
    | + - - - - - - - - - - - - - + |  | + - - - - - - - - - - - - - + |
    | |+---------+     +---------+| |  | |+---------+     +---------+| |
    | || 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

5. 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

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   among them are definitely blurring, due to technological capacity
   increases, integration of platforms, and new threats. At their core:
  . 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.
  . 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.
  . 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.

   To prevent constraints on NSF vendors' 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.

   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".

   Accordingly, the NSF capabilities are characterized by the level of
   packet processing and context that a NSF supports, the profiles and
   the actions that the NSF can apply. The term "context" includes
   anything that can influence the action(s) taken by the NSF, such as
   time of day, location, session state, and events.

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   Vendors can register their NSFs using Packet Content Match
   categories. The IDR 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                            |

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     |               |          ? urg                            |
     |               |          ? window                         |
     |               |            sockstress                     |
     |               | Note: bitmap could be used to             |
     |               |   represent all the fields                |
     |               |                                           |
     | 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: Subject Capability Index

     |      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, ...   |

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     |  Direction    |  Inbound, Outbound                        |
     |  State        |  Authentication State                     |
     |               |  Authorization State                      |
     |               |  Accounting State                         |
     |               |  Session State                            |

                      Table 2: Object 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                          |
     | Signature     |   Flexible Profile/signature URL          |
     |               | Command for Controller to enable/disable  |
     |               |                                           |
                     Table 4: Function Capability Index

6. Structure of Rules for governing NSFs

6.1. Capability Layer Rules and Monitoring

   The purpose of the Capability Layer is to define explicit rules for
   individual NSFs to treat packets, as well as methods to monitor the
   execution status of those functions.

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   [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.

   The functional profiles (or signatures) for NSFs are not present in
   [ACL-MODEL] because the functional profiles are unique to specific
   NSFs. For example, most vendors' IPS/IDS 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 [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.

   The I2NSF "actions" should extend the actions specified by [ACL-
   MODEL] to include applying statistics functions, threat profiles, or
   signature files that clients provide.

   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.

6.2. Service Layer Policy

   This layer is for clients or an Application Controller to express
   and monitor the needed security policies for their specific flows.

   Some Customers may not have security skills. As such, they are not
   able to express requirements or security policies that are precise
   enough. These customers may instead express expectations or intent
   of the functionality desired by their security policies. Customers
   may also express guidelines such as which certain types of
   destinations are not allowed for certain groups. As a result, there
   could be different depths or layers of Service Layer policies. Here
   are some examples of more abstract service layer security Policies:

          o Pass for Subscriber "xxx"
          o enable basic parental control

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          o enable "school protection control"
          o allow Internet traffic from 8:30 to 20:00
          o scan email for malware detection protect traffic to
            corporate network with integrity and confidentiality
          o remove tracking data from Facebook [website =
          o my son is allowed to access facebook from 18:30 to 20:00

   One Service Layer Security Policy may need multiple security
   functions at various locations to achieve the enforcement. Service
   layer Security Policy may need to be updated by clients or
   Application controllers when clients' service requirements have been
   changed. Some service layer policies may not be granted because the
   carrier or Enterprises imposes additional constraints on what a
   client can have. [I2NSF-Demo] describes an implementation of
   translating a set of service layer policies to the Capability Layer
   instructions to NSFs.

   I2NSF will first focus on simple service layer policies that are
   modeled as closely as possible on the Capability Layer.  The I2NSF
   simple service layer should have similar structure as the I2NSF
   capability layer, but with more of a client-oriented expression for
   the packet content, context, and other parts of an ECA policy rule.
   This enables the client to construct an ECA policy rule without
   having to know its detailed structure or syntax.

   There have been several industry initiatives to address network
   policies, such as OpenStack's Group-based Policy (GBP), IETF Policy
   Core Information Model-PCIM [RFC3060, RFC3460], and others. I2NSF
   will not work on general network service policies, but instead will
   define a standard interface for clients/applications to inform the
   Flow-based NSFs on the rules for treating traffic.

   However, the notion of Groups (or roles), Target, Event, Context (or
   Conditions), and Action do cover what is needed for
   clients/applications to express the rules on how their flows can be
   treated by the Flow-Based NSFs in networks.  The goal is to have a
   policy structure that can be mapped to the Capability layer's Event-
   Condition-Action paradigm.

   The I2NSF simple service layer can have the following entities:

       - I2NSF-Groups: This is a collection of users, applications,
          virtual networks, or traffic patterns to which a service

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          layer policy can be applied. An I2NSF-Group may be mapped to
          a client virtual Subnet (i.e. with private address prefix), a
          subnet with public address families, specific applications,
          destinations, or any combination of them with logical
          operators (Logical AND, OR, or NOT). An I2NSF-Group can have
          one or more Policy Rules applied to it.
       - Target. This is used by the application client to identify
          the set of objects to be affected by the policy rules. A
          Target can be mapped to a physical/logical ingress port, a
          set of destinations, or a physical/logical egress port.
       - Policy Rule. A Policy Rule consists of a set of Policy
          Events, Policy Conditions, and Policy Actions. Policy Rules
          are triggered by matching Events. If the Event portion of the
          Policy Rule evaluates to true, then the Condition portion is
          evaluated (otherwise, the Policy Rule terminates and no
          action is taken). If the Condition portion of the Policy Rule
          evaluates to true, then the set of Actions MAY be executed
          and applied to the traffic (otherwise, the Policy Rule
          terminates and no action is taken).
       - Policy Event. This triggers a determination of whether the
          condition portion of a Policy Rule should be evaluated or
       - Policy Condition. This determines when the Policy Actions
          contained in a Policy Rule are to be applied. It can be
          expressed as a direction, a list of L4 ports, time range, or
          a protocol, etc.
       - Policy Action: This is the action applied to the traffic that
          matches the Conditions (and was triggered by the Events). An
          action may be a simple ACL action (i.e. allow, deny,
          mirroring), applying a well known statistics functions (e.g.
          X minutes count, Y hours court), applying client specified
          functions (with URL provided), or may refer to an ordered
          sequence of functions.

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7. Capability Negotiation

     When an NSF can't perform the desired provisioning (e.g., due to
     resource constraints), it MUST inform the controller.

     The protocol needed for this security function/capability
     negotiation may be somewhat correlated to the dynamic service
     parameter negotiation procedure [RFC7297]. The Connectivity
     Provisioning Profile (CPP) template documented in RFC7297, even
     though currently covering only Connectivity requirements (but
     includes security clauses such as isolation requirements, non-via
     nodes, etc.), could be extended as a basis for the negotiation
     procedure. Likewise, the companion Connectivity Provisioning
     Negotiation Protocol (CPNP) could be a candidate to proceed with
     the negotiation procedure.

     The "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.

8. Types of I2NSF clients

   It is envisioned that I2NSF clients include:

   - Application Controller:

        -                 For example, Video Conference Mgr/Controller needs to
          dynamically inform network to allow or deny flows (some of
          which are encrypted) based on specific fields in the packets
          for a certain time span. Otherwise, some flows can't go
          through the NSFs (e.g. FW/IPS/IDS) in the network because the
          payload is encrypted or packets' protocol codes are not
          recognized by those NSFs.

   - Security Administrators

          - Enterprise users and applications

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          - Operator Management System dynamically updates, monitors
            and verifies the security policies to NSFs (by different
            vendors) in a network.
          - Third party system

   - Security functions send requests for more sophisticated functions
     upon detecting something suspicious, usually via a security

9. Manageability Considerations

     Management of NSFs usually includes:

        -               life cycle management and resource management of NSFs

        -               configuration of devices, such as address configuration,
          device internal attributes configuration, etc,

        -               signaling, and

        -               policy rules provisioning.

     I2NSF will only focus on the policy rule provisioning part, i.e.,
     the last bullet listed above.

10. Security Considerations

     Having a secure access to control and monitor NSFs is crucial for
     hosted security service. 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).

11. IANA Considerations

   This document requires no IANA actions. RFC Editor: Please remove
   this section before publication.

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12. References

12.1. Normative References

   [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
             Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC3060] Moore, B, et al, "Policy Core Information Model (PCIM)",
             RFC 3060, Feb 2001.

   [RFC3460] Moore, B. "Policy Core Information Model (PCIM)
             Extensions", RFC3460, Jan 2003.

   [RFC5575] Marques, P, et al, "Dissemination of Flow Specification
             Rules", RFC 5575, Aug 2009.

   [RFC7297] Boucadair, M., "IP Connectivity Provisioning Profile",
             RFC7297, April 2014.

 12.2. Informative References

   [I2NSF-ACCESS] A. Pastor, et al, "Access Use Cases for an Open OAM
             Interface to Virtualized Security Services", <draft-
             pastor-i2nsf-access-usecases-00>, Oct 2014.

   [I2NSF-DC] M. Zarny, et al, "I2NSF Data Center Use Cases", <draft-
             zarny-i2nsf-data-center-use-cases-00>, Oct 2014.

   [I2NSF-MOBILE] M. Qi, et al, "Integrated Security with Access
             Network Use Case", <draft-qi-i2nsf-access-network-usecase-
             00>, Oct 2014

   [I2NSF-Problem] L. Dunbar, et al "Interface to Network Security
             Functions Problem Statement", <draft-dunbar-i2nsf-problem-
             statement-01>, Jan 2015

   [ACL-MODEL] D. Bogdanovic, et al, "Network Access Control List (ACL)
             YANG Data Model", <draft-ietf-net-acl-model-00>, Nov 2014.

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   [gs_NFV] ETSI NFV Group Specification, Network Functions
             Virtualizsation (NFV) Use Cases. ETSI GS NFV 001v1.1.1,

   [NW-2011] J. Burke, "The Pros and Cons of a Cloud-Based Firewall",
             Network World, 11 November 2011

   [SC-MobileNetwork] W. Haeffner, N. Leymann, "Network Based Services
             in Mobile Network", IETF87 Berlin, July 29, 2013.

   [I2NSF-Demo] Y. Xie, et al, "Interface to Network Security Functions
             Demo Outline Design", <draft-xie-i2nsf-demo-outline-
             design-00>, April 2015.

   [ITU-T-X1036] ITU-T Recommendation X.1036, "Framework for creation,
             storage, distribution and enforcement of policies for
             network security", Nov 2007.

13. Acknowledgments

   Acknowledgements to xxx for his review and contributions.

   This document was prepared using

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Authors' Addresses

   Edward Lopez
   899 Kifer Road
   Sunnyvale, CA 94086
   Phone: +1 703 220 0988

   Diego Lopez

   XiaoJun Zhuang
   China Mobile

   Linda Dunbar

   John Strassner

   Joe Parrott

   Ramki Krishnan

   Seetharama Rao Durbha

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