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Versions: (draft-kumar-i2nsf-client-facing-interface-req) 00 01 02 03 04 05

I2NSF Working Group                                             R. Kumar
Internet-Draft                                                 A. Lohiya
Intended status: Informational                          Juniper Networks
Expires: October 28, 2017                                          D. Qi
                                                               Bloomberg
                                                                N. Bitar
                                                         S. Palislamovic
                                                                   Nokia
                                                                  L. Xia
                                                                  Huawei
                                                          April 26, 2017


    Requirements for Client-Facing Interface to Security Controller
            draft-ietf-i2nsf-client-facing-interface-req-01

Abstract

   This document captures requirements for Client-Facing interface to
   Security Controller.  The interface is expressed using objects and
   constructs understood by Security Admin as opposed to vendor or
   device specific expressions associated with individual product and
   feature.  This document identifies a broad set of requirements needed
   to express security policies based on User-constructs which are well
   understood by User Community.  This gives ability to decouple policy
   definition from policy enforcement on a specific element, be it a
   physical or virtual.

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 October 28, 2017.







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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
   (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
   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.  Conventions Used in this Document . . . . . . . . . . . . . .   4
   3.  Guiding principle for Client-Facing Interface defintion . . .   5
     3.1.  User-construct based modeling . . . . . . . . . . . . . .   5
     3.2.  Basic rules for Client-Facing Interface definition  . . .   6
     3.3.  Deployment Models for Implementing Security Policies  . .   7
   4.  Functional Requirements for the Client-Facing Interface . . .  10
     4.1.  Requirement for Multi-Tenancy in client interface . . . .  11
     4.2.  Requirement for Authentication and Authorization of
           client interface  . . . . . . . . . . . . . . . . . . . .  12
     4.3.  Requirement for Role-Based Access Control (RBAC) in
           client interface  . . . . . . . . . . . . . . . . . . . .  12
     4.4.  Requirement to protect client interface from attacks  . .  12
     4.5.  Requirement to protect client interface from
           misconfiguration  . . . . . . . . . . . . . . . . . . . .  12
     4.6.  Requirement to manage policy lifecycle with diverse needs  13
     4.7.  Requirement to define dynamic policy Endpoint group . . .  14
     4.8.  Requirement to express rich set of policy rules . . . . .  15
     4.9.  Requirement to express rich set of policy actions . . . .  16
     4.10. Requirement to express policy in a generic model  . . . .  18
     4.11. Requirement to detect and correct policy conflicts  . . .  18
     4.12. Requirement for backward compatibility  . . . . . . . . .  18
     4.13. Requirement for Third-Party integration . . . . . . . . .  18
     4.14. Requirement to collect telemetry data . . . . . . . . . .  19
   5.  Operational Requirements for the Client-Facing Interface  . .  19
     5.1.  API Versioning  . . . . . . . . . . . . . . . . . . . . .  19
     5.2.  API Extensiblity  . . . . . . . . . . . . . . . . . . . .  19
     5.3.  APIs and Data Model Transport . . . . . . . . . . . . . .  20
     5.4.  Notification  . . . . . . . . . . . . . . . . . . . . . .  20
     5.5.  Affinity  . . . . . . . . . . . . . . . . . . . . . . . .  20
     5.6.  Test Interface  . . . . . . . . . . . . . . . . . . . . .  20



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   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  20
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  21
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  21
   9.  Normative References  . . . . . . . . . . . . . . . . . . . .  21
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  21

1.  Introduction

   Programming security policies in a network has been a fairly complex
   task that often requires very deep knowledge of vendor specific
   device and features.  This has been the biggest challenge for both
   Service Provider and Enterprise, henceforth named as Security Admin
   in this document.  This challenge is further amplified due to network
   virtualization with security functions deployed in physical and
   virtual form factor, henceforth named as network security function
   (NSF) in this document, from multiple vendors with proprietary
   interface.

   Even if a Security Admin deploys a single vendor solution with one or
   more security appliances across its entire network, it is still very
   difficult to manage security policies due to complexity of security
   features, and mapping of business requirements to vendor specific
   configuration.  The Security Admin may use vendor provided management
   systems to provision and manage security policies.  But, the single
   vendor approach is highly restrictive in today's network for
   following reasons:

   o  An organization may not be able to rely on a single vendor because
      the changing security requirements may not align with vendor's
      release cycle.

   o  A large organization may have a presence across different sites
      and regions; which means, it may not be possible to deploy same
      solution from the same vendor because of regional regulatory and
      compliance policy.

   o  If and when an organization migrates from one vendor to another,
      it is almost impossible to migrate security policies from one
      vendor to another without complex and time consuming manual
      workflows.

   o  An organization may deploy multiple network security functions in
      virtual and physical forms to attain the flexibility, elasticity,
      performance scale, and operational efficiency they require.
      Practically, that often requires different sources (vendor, open
      source) to get the best of breed for any such security function.





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   o  An organization may choose all or part of their assets such as
      routers, switches, firewalls, and overlay-networks as policy
      enforcement points for operational and cost efficiency.  It would
      be highly complex to manage policy enforcement with different tool
      set for each type of device.

   In order to facilitate deployment of security policies across
   different vendor provided NSFs, the Interface to Network Security
   Functions (I2NSF) working group in the IETF is defining a Client-
   Facing interface to Security Controller [I-D. ietf-i2nsf-framework]
   [I-D. ietf-i2nsf-terminology].  Deployment facilitation should be
   agnostic to the type of device, be it physical or virtual, or type of
   enforcement point.  Using these interfaces, it becomes possible to
   write different kinds of security management applications (e.g.  GUI
   portal, template engine, etc.) allowing Security Admin to express
   security policies in an abstract form with choice of wide variety of
   NSF for policy enforcement.  The implementation of security
   management applications or controller is completely out of the scope
   of the I2NSF working group, which is only focused on interface
   definition.

   This document captures the requirements for Client-Facing interface
   that can be easily used by Security Admin without a need for
   expertise in vendor and device specific feature set.  We refer to
   this as "User-construct" based interfaces.  To further clarify, in
   the scope of this document, the "User-construct" here does not mean
   some free-from natural language input or an abstract intent such as
   "I want my traffic secure" or "I don't want DDoS attacks in my
   network"; rather the User-construct here means that policies are
   described using expressions such as application names, application
   groups, device groups, user groups etc. with a vocabulary of verbs
   (e.g., drop, tap, throttle), prepositions, conjunctions,
   conditionals, adjectives, and nouns instead of using standard
   n-tuples from the packet header.

2.  Conventions Used in this Document

   BSS:  Business Support System

   CLI:  Command Line Interface

   CMDB:  Configuration Management Database

   Controller:  Used interchangeably with Security Controller or
      management system throughout this document

   CRUD:  Create, Retrieve, Update, Delete




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   FW:  Firewall

   GUI:  Graphical User Interface

   IDS:  Intrusion Detection System

   IPS:  Intrusion Protection System

   LDAP:  Lightweight Directory Access Protocol

   NSF:  Network Security Function, defined by
      [I-D.ietf-i2nsf-problem-and-use-cases]

   OSS:  Operation Support System

   RBAC:  Role Based Access Control

   SIEM:  Security Information and Event Management

   URL:  Universal Resource Locator

   vNSF:  Refers to NSF being instantiated on Virtual Machines

3.  Guiding principle for Client-Facing Interface defintion

   Client-Facing Interface must ensure that a Security Admin can deploy
   any NSF from any vendor and should still be able to use the same
   consistent interface.  In essence, this interface must allow a
   Security Admin to express security policies independent of how NSFs
   are implemented in their deployment.  Henceforth, in this document,
   we use "security policy management interface" interchangeably when we
   refer to Client-Facing interface.

3.1.  User-construct based modeling

   Traditionally, security policies have been expressed using
   proprietary interface.  The interface is defined by a vendor based on
   proprietary command line text or a GUI based system with
   implementation specific constructs such IP address, protocol and
   L4-L7 information.  This requires Security Admin to translate their
   business objectives into vendor provided constructs in order to
   express a security policy.  But, this alone is not sufficient to
   render a policy in the network; the admin must also understand
   network and application design to locate a specific policy
   enforcement point to make sure policy is effective.  This may be
   highly manual task based on specific network design and may become
   unmanageable in virtualized networks.




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   The User-construct based framework does not rely on lower level
   semantics due to problem explained above, but rather uses higher
   level constructs such as User-group, Application-group, Device-group,
   Location-group, etcetera.  A Security Admin would use these
   constructs to express a security policy instead of proprietary
   implementation or feature specific constructs.  The policy defined in
   such a manner is referred to User-construct based policies in this
   draft.  The idea is to enable Security Admin to use constructs they
   understand best in expressing security policies which simplify their
   tasks and help avoiding human errors in complex security
   provisioning.

3.2.  Basic rules for Client-Facing Interface definition

   The basic rules in defining the Client-Facing interfaces are as
   follows:

   o  Not dependent on particular Network topology or the NSF location
      in the network

   o  Not requiring deep knowledge of proprietary features and
      capabilities supported in the deployed NSFsa€

   o  Independent of NSF type that will implement the user security
      policy be it a stateful firewall,IDP, IDS, Router, Switch

   o  Declarative/Descriptive model instead of Imperative/Prescriptive
      model - What security policy need to be enforced (declarative)
      instead of how it is implemented (imperative)

   o  Not dependent on any specific vendor implementation or form-factor
      (physical, virtual) of the NSF

   o  Not dependent on how a NSF becomes operational - Network
      connectivity and other hosting requirements.

   o  Not dependent on NSF control plane implementation (if there is
      one) E.g., cluster of NSFs active as one unified service for scale
      and/ or resilience.

   o  Not depending on specific data plane implementation of NSF i.e.
      Encapsulation, Service function chains.

   Note that the rules stated above only apply to the Client-Facing
   interface, which a user would use to express a high level policy.
   These rules do not apply to the lower layers e.g.  Security
   Controller that convert higher level policies into lower level
   constructs.  The lower layers may still need some intelligence such



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   as topology awareness, capability of the NSF and its functions,
   supported encapsulations etc. to convert and apply the policies
   accurately on the NSF.

3.3.  Deployment Models for Implementing Security Policies

   Traditionally, medium and large Enterprise deploy management systems
   to manage their statically defined security policies.  This approach
   may not be suitable nor sufficient for modern automated and dynamic
   data centers that are largely virtualized and rely on various
   management systems and controllers to dynamically implement security
   policies over any types of NSF.

   There are two different deployment models in which the Client-Facing
   interface referred to in this document could be implemented.  These
   models have no direct impact on the Client-Facing interface, but
   illustrate the overall security policy and management framework and
   where various processing functions reside.  These models are:

   a.  Policy management without an explicit management system for
       control of NSFs.  In this deployment, Security Controller acts as
       a NSF management system; it takes information passed over Client-
       Facing interface and translates into data on I2NSF NSF-facing
       interface.  The NSF-Facing interface is implemented by NSF
       vendors; this would usually be done by having an I2NSF agent
       embedded in the NSF.  This deployment model is shown in Figure 1.

























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                            RESTful API
                    SUPA or I2NSF Policy Management
                                  ^
                                  |
    Client-Facing Interface       |
    (Independent of individual    |
     NSFs, devices,and vendors)|
                                  |
                    ------------------------------
                   |                              |
                   |       Security Controller    |
                   |                              |
                    ------------------------------
                         |                 ^
                         |   I2NSF         |
    NSF Interface        |   NSF-facing    |
    (Specific to NSFs)   |   Interface     |
                     ..............................
                         |                 |
                         v                 |


                   -------------     -------------
                  | I2NSF Agent |   | I2NSF Agent |
                  |-------------|   |-------------|
                  |             |---|             |
                  |     NSF     |   |     NSF     |
        NSFs      |             |   |             |
    (virtual       -------------\   /-------------
       and               |       \ /       |
    physical)            |        X        |
                         |       / \       |
                   -------------/   \-------------
                  | I2NSF Agent |   | I2NSF Agent |
                  |-------------|   |-------------|
                  |             |---|             |
                  |     NSF     |   |     NSF     |
                  |             |   |             |
                   -------------     -------------


              Figure 1: Deployment without Management System

   b.  Policy management with an explicit management system for control
       of NSFs.  This model is similar to the model above except that
       Security Controller interacts with a vendor's dedicated
       management system that proxy I2NSF NSF-Facing interfaces as NSF




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       may not support NSF-Facing interface.  This is a useful model to
       support legacy NSF.  This deployment model is shown in Figure 2.


                            RESTful API
                    SUPA or I2NSF Policy Management
                                  ^
                                  |
    Client-facing Interface       |
    (Independent of individual    |
     NSFs,devices,and vendors) |
                                  |
                    ------------------------------
                   |                              |
                   |       Security Controller    |
                   |                              |
                    ------------------------------
                         |                 ^
                         |   I2NSF         |
    NSF Interface        |   NSF-facing    |
    (Specific to NSFs)   |   Interface     |
                     ..............................
                         |                 |
                         v                 |
                    ------------------------------
                   |                              |
                   |      I2NSF Proxy Agent /     |
                   |      Management System       |
                   |                              |
                    ------------------------------
                         |                 ^
                         |  Proprietary    |
                         |  Functional     |
                         |  Interface      |
                     ..............................
                         |                 |
                         v                 |

                   -------------     -------------
                  |             |---|             |
                  |     NSF     |   |     NSF     |
        NSFs      |             |   |             |
    (virtual       -------------\   /-------------
       and               |       \ /       |
    physical)            |        X        |
                         |       / \       |
                   -------------/   \-------------
                  |             |---|             |



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                  |     NSF     |   |     NSF     |
                  |             |   |             |
                   -------------     -------------


     Figure 2: Deployment with Management System or I2NSF Proxy Agent

   Although the deployment models discussed here don't necessarily
   affect the definition of Client-Facing interface, they do give an
   overall context for defining a security policy interface based on
   abstraction.

4.  Functional Requirements for the Client-Facing Interface

   As stated in the guiding principle for defining the I2NSF Client-
   Facing interface, the security policies and the Client-Facing
   interface shall be defined from user's or client's perspective and
   abstracted away from type of NSF, NSF specific implementation,
   controller implementation, network topology, controller NSF-Facing
   interface.  Thus, the security policy definition shall be
   declarative, expressed using User-construct, and driven by how
   Security Admin view security policies from definition, communication
   and deployment perspective.

   Security Controller's' implementation is outside the scope of this
   document and the I2NSF working group.

   In order to express and build security policies, high level
   requirement for Client-Facing interface is as follows:

   o  Multi-Tenancy

   o  Authentication and Authorization

   o  Role-Based Access Control (RBAC)

   o  Protection from Attacks

   o  Protection from Misconfiguration

   o  Policy Lifecycle Management

   o  Dynamic Policy Endpoint Groups

   o  Policy Rules

   o  Policy Actions




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   o  Generic Policy Model

   o  Policy Conflict Resolution

   o  Backward Compatibility

   o  Third-Party Integration

   o  Telemetry Data

   The above requirements are by no means a complete list and may not be
   sufficient for all use-cases and all Security Admins, but should be a
   good starting point for a wide variety of use-cases in Service
   Provider and Enterprise networks.

4.1.  Requirement for Multi-Tenancy in client interface

   A Security Admin may have internal tenants and might want a framework
   wherein each tenant manages its own security policies with isolation
   from other tenants.

   A Security Admin may be a cloud service provider with multi-tenant
   deployment, where each tenant is a different customer.  Each tenant
   or customer must be allowed to manage its own security policies.

   It should be noted that tenants may have their own tenants, so a
   recursive relation may exist.  For instance, a tenant in a Cloud
   Service Provider may have multiple departments or organizations that
   need to manage their own security rules for compliance.

   Some key concepts are listed below and used throughout the document
   hereafter:

   Policy-Tenant:  An entity that owns and manages the security policies
      applied on its resources.

   Policy-Administrator:  A user authorized to manage the security
      policies for a Policy-Tenant.

   Policy-User:  A user within a Policy-Tenant who is authorized to
      access certain resources of that tenant according to the
      privileges assigned to it.









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4.2.  Requirement for Authentication and Authorization of client
      interface

   Security Admin MUST authenticate to and be authorized by Security
   Controller before they are able to issue control commands and any
   policy data exchange commands.

   There must be methods defined for Policy-Administrator to be
   authenticated and authorized to use Security Controller.  There are
   several authentication methods available such as OAuth, XAuth and
   X.509 certificate based; the authentication may be mutual or single-
   sided based on business needs and outside the scope of I2NSF.  In
   addition, there must be a method o authorize the Policy-Administrator
   to perform certain action.  It should be noted that, Policy-
   Administrator authentication and authorization to perform actions
   could be part of Security Controller or outside; this document does
   not mandate any specific implementation but requires that such a
   scheme must be implemented.

4.3.  Requirement for Role-Based Access Control (RBAC) in client
      interface

   Policy-Authorization-Role represents a role assigned to a Policy-User
   that determines whether a user has read-write access, read-only
   access, or no access for certain resources.  A User can be mapped to
   a Policy-Authorization-Role using an internal or external identity
   provider or mapped statically.

4.4.  Requirement to protect client interface from attacks

   The interface must be protections from attacks, malicious or
   otherwise, from clients or a client impersonator.  Potential attacks
   could come from Botnets, hosts infected with virus or some
   unauthorized entity.  It is recommended that Security Controller use
   a dedicated IP interface for Client-Facing communications and those
   communications should be carried over an isolated out-of-band
   network.  In addition, it is recommended that traffic between clients
   and Security controller be encrypted.  Furthermore, some
   straightforward traffic/session control mechanisms (i.e., Rate-limit,
   ACL, White/Black list) can be employed on Security Controller to
   defend against DDoS flooding attacks.

4.5.  Requirement to protect client interface from misconfiguration

   There must be protections from mis-configured clients.  System and
   policy validations should be implemented to detect this.  Validation
   may be based on a set of default parameters or custom tuned




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   thresholds such as the number of policy changes submitted, number of
   objects requested in a given time interval, etc.

4.6.  Requirement to manage policy lifecycle with diverse needs

   In order to provide more sophisticated security framework, there
   should be a mechanism so that a policy becomes dynamically active/
   enforced or inactive based on Security Admin's manual intervention or
   some external event.

   One example of dynamic policy management is when Security Admin pre-
   configures all the security policies, but the policies get activated
   or deactivated based on dynamic threats.  Basically, a threat event
   may activate certain inactive policies, and once a new event
   indicates that the threat has gone away, the policies become inactive
   again.

   There are following ways for dynamically activating policies:

   o The policy may be dynamically activated by Security Admin or
   associated management entity

   o The policy may be dynamically activated by Security Controller upon
   detecting an external event or an event from I2NSF monitoring
   interface

   o The policy can be statically configured but activated or
   deactivated upon policy attributes, such as timing calendar

   Client-Facing interface should support the following policy
   attributes for policy enforcement:

   Admin-Enforced:  A policy, once configured, remains active/enforced
      until removed by Security Admin.

   Time-Enforced:  A policy configuration specifies the time profile
      that determines when the policy is to be activated/enforced.
      Otherwise, it is de-activated.

   Event-Enforced:  A policy configuration specifies the event profile
      that determines when the policy is to be activated/enforced.  It
      also specifies the duration attribute of that policy once
      activated based on event.  For instance, if the policy is
      activated upon detecting an application flow, the policy could be
      de-activated when the corresponding session is closed or the flow
      becomes inactive for certain time.





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   A policy could be a composite policy, that is composed of many rules,
   and subject to updates and modification.  For the policy maintenance,
   enforcement, and audit-ability purposes, it becomes important to name
   and version Security Policy.  Thus, the policy definition SHALL
   support policy naming and versioning.  In addition, the i2NSF Client-
   Facing interface SHALL support the activation, deactivation,
   programmability, and deletion of policies based on name and version.
   In addition, it should support reporting operational state of
   policies by name and version.  For instance, a client may probe
   Security Controller whether a Security Policy is enforced for a
   tenant and/or a sub-tenant (organization) for audit-ability or
   verification purposes.

4.7.  Requirement to define dynamic policy Endpoint group

   When Security Admin configures a Security Policy, it may have
   requirement to apply this policy to certain subsets of the network.
   The subsets may be identified based on criteria such as Users,
   Devices, and Applications.  We refer to such a subset of the network
   as a "Policy Endpoint Group".

   One of the biggest challenges for a Security Admin is how to make
   sure that a Security Policy remain effective while constant changes
   are happening to the "Policy Endpoint Group" for various reasons
   (e.g., organizational, network and application changes).  If a policy
   is created based on static information such as user names,
   application, or network subnets; then every time this static
   information change, policies need to be updated.  For example, if a
   policy is created that allows access to an application only from the
   group of Human Resource users (HR-users group), then each time the
   HR-users group changes, the policy needs to be updated.

   We call these dynamic Policy Endpoint Groups "Meta-data Driven
   Groups".  The meta-data is a tag associated with endpoint information
   such as User, Application, or Device.  The mapping from meta-data to
   dynamic content could come from a standards-based or proprietary
   tools.  Security Controller could use any available mechanisms to
   derive this mapping and to make automatic updates to policy content
   if the mapping information changes.  The system SHOULD allow for
   multiple, or sets of tags to be applied to a single network object.

   Client-Facing policy interface must support endpoint groups for
   expressing a Security Policy.  The following meta-data driven groups
   MAY be used for configuring security polices:

   User-Group:  This group identifies a set of users based on a tag or
      on static information.  The tag to identify user is dynamically
      derived from systems such as Active Directory or LDAP.  For



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      example, an organization may have different User-groups, such as
      HR-users, Finance-users, Engineering-users, to classify a set of
      users in each department.

   Device-Group:  This group identifies a set of devices based on a tag
      or on static information.  The tag to identify device is
      dynamically derived from systems such as configuration management
      database (CMDB).  For example, a Security Admin may want to
      classify all machines running a particular operating system into
      one group and machines running a different operating system into
      another group.

   Application-Group:  This group identifies a set of applications based
      on a tag or on static information.  The tag to identify
      application is dynamically derived from systems such as CMDB.  For
      example, a Security Admin may want to classify all applications
      running in the Legal department into one group and all
      applications running in the HR department into another group.  In
      some cases, the application can semantically associated with a VM
      or a device.  However, in other cases, the application may need to
      be associated with a set of identifiers (e.g., transport numbers,
      signature in the application packet payload) that identify the
      application in the corresponding packets.  The mapping of
      application names/tags to signatures in the associated application
      packets should be defined and communicated to the NSF.  The
      Client-Facing Interface shall support the communication of this
      information.

   Location-Group:  This group identifies a set of location tags.  Tag
      may correspond 1:1 to location.  The tag to identify location is
      either statically defined or dynamically derived from systems such
      as CMDB.  For example, a Security Admin may want to classify all
      sites/locations in a geographic region as one group.

4.8.  Requirement to express rich set of policy rules

   The security policy rules can be as simple as specifying a match for
   the user or application specified through "Policy Endpoint Group" and
   take one of the "Policy Actions" or more complicated rules that
   specify how two different "Policy Endpoint Groups" interact with each
   other.  The Client-Facing interface must support mechanisms to allow
   the following rule matches.

   Policy Endpoint Groups: The rule must allow a way to match either a
   single or a member of a list of "Policy Endpoint Groups".






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   There must be a way to express a match between two "Policy Endpoint
   Groups" so that a policy can be effective for communication between
   two groups.

   Direction:  The rule must allow a way to express whether Security
      Admin wants to match the "Policy Endpoint Group" as the source or
      destination.  The default should be to match both directions, if
      the direction rule is not specified in the policy.

   Threats:  The rule should allow the security administrator to express
      a match for threats that come either in the form of feeds (such as
      Botnet feeds, GeoIP feeds, URL feeds, or feeds from a SIEM) or
      speciality security appliances.  Threats could be identified by
      Tags/names in policy rules.  The tag is a label of one or more
      event types that may be detected by a threat detection system.

   The threat could be from malware and this requires a way to match for
   virus signatures or file hashes.

4.9.  Requirement to express rich set of policy actions

   Security Admin must be able to configure a variety of actions within
   a security policy.  Typically, security policy specifies a simple
   action of "deny" or "permit" if a particular condition is matched.
   Although this may be enough for most of the simple policies, the
   I2NSF Client-Facing interface must also provide a more comprehensive
   set of actions so that the interface can be used effectively across
   various security functions.

   Policy action MUST be extensible so that additional policy action
   specifications can easily be added.

   The following list of actions SHALL be supported:

   Permit:  This action means continue processing the next rule or allow
      the packet to pass if this is the last rule.  This is often a
      default action.

   Deny:  This action means stop further packet processing and drop the
      packet.

   Drop connection:  This action means stop further packet processing,
      drop the packet, and drop connection (for example, by sending a
      TCP reset).

   Log:  This action means create a log entry whenever a rule is
      matched.




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   Authenticate connection:  This action means that whenever a new
      connection is established it should be authenticated.

   Quarantine/Redirect:  This action may be relevant for event driven
      policy where certain events would activate a configured policy
      that quarantines or redirects certain packets or flows.  The
      redirect action must specify whether the packet is to be tunneled
      and in that case specify the tunnel or encapsulation method and
      destination identifier.

   Netflow:  This action creates a Netflow record; Need to define
      Netflow server or local file and version of Netflow.

   Count:  This action counts the packets that meet the rule condition.

   Encrypt:  This action encrypts the packets on an identified flow.
      The flow could be over an IPSEC tunnel, or TLS session for
      instance.

   Decrypt:  This action decrypts the packets on an identified flow.
      The flow could be over an IPSEC tunnel, or TLS session for
      instance.

   Throttle:  This action defines shaping a flow or a group of flows
      that match the rule condition to a designated traffic profile.

   Mark:  This action defines traffic that matches the rule condition by
      a designated DSCP value and/or VLAN 802.1p Tag value.

   Instantiate-NSF:  This action instantiates an NSF with a predefined
      profile.  An NSF can be any of the FW, LB, IPS, IDS, honeypot, or
      VPN, etc.

   WAN-Accelerate:  This action optimizes packet delivery using a set of
      predefined packet optimization methods.

   Load-Balance:  This action load balances connections based on
      predefined LB schemes or profiles.

   The policy actions should support combination of terminating actions
   and non-terminating actions.  For example, Syslog and then Permit;
   Count and then Redirect.

   Policy actions SHALL support any L2, L3, L4-L7 policy actions.







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4.10.  Requirement to express policy in a generic model

   Client-Facing interface SHALL provide a generic metadata model that
   defines once and then be used by appropriate model elements any
   times, regardless of where they are located in the class hierarchy,
   as necessary.

   Client-Facing interface SHALL provide a generic context model that
   enables the context of an entity, and its surrounding environment, to
   be measured, calculated, and/or inferred.

   Client-Facing interface SHALL provide a generic policy model that
   enables context-aware policy rules to be defined to change the
   configuration and monitoring of resources and services as context
   changes.

   Client-Facing interface SHALL provide the ability to apply policy or
   multiple sets of policies to any given object.  Policy application
   process SHALL allow for nesting capabilities of given policies or set
   of policies.  For example, an object or any given set of objects
   could have application team applying certain set of policy rules,
   while network team would apply different set of their policy rules.
   Lastly, security team would have an ability to apply its set of
   policy rules, being the last policy to be evaluated against.

4.11.  Requirement to detect and correct policy conflicts

   Client-Facing interface SHALL be able to detect policy "conflicts",
   and SHALL specify methods on how to resolve these "conflicts"

   For example: two clients issues conflicting set of security policies
   to be applied to the same Policy Endpoint Group.

4.12.  Requirement for backward compatibility

   It MUST be possible to add new capabilities to Client-Facing
   interface in a backward compatible fashion.

4.13.  Requirement for Third-Party integration

   The security policies in a network may require the use of specialty
   devices such as honeypots, behavioral analytics, or SIEM in the
   network, and may also involve threat feeds,virus signatures, and
   malicious file hashes as part of comprehensive security policies.

   The Client-Facing interface must allow Security Admin to configure
   these threat sources and any other information to provide integration
   and fold this into policy management.



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4.14.  Requirement to collect telemetry data

   One of the most important aspect of security is to have visibility
   into the networks.  As threats become more sophisticated, Security
   Admin must be able to gather different types of telemetry data from
   various devices in the network.  The collected data could simply be
   logged or sent to security analysis engines for behavioral analysis,
   policy violations, and for threat detection.

   The Client-Facing interface MUST allow Security Admin to collect
   various kinds of data from NSFs.  The data source could be syslog,
   flow records, policy violation records, and other available data.

   Detailed Client-Facing interface telemetry data should be available
   between clients and Security Controller.  Clients should be able to
   subscribe and receive these telemetry data.

   client should be able to receive notifications when a policy is
   dynamically updated.

5.  Operational Requirements for the Client-Facing Interface

5.1.  API Versioning

   Client-Facing interface must support a version number for each
   RESTful API.  This is very important because the client application
   and the controller application may come from different vendors.  Even
   if the vendor is same, it is hard to imagine that two different
   applications would be released in lock step.

   Without API versioning, it is hard to debug and figure out issues if
   an application breaks.  Although API versioning does not guarantee
   that applications will always work, it helps in debugging if the
   problem is caused by an API mismatch.

5.2.  API Extensiblity

   Abstraction and standardization of Client-Facing interface is of
   tremendous value to Security Admin as it gives them the flexibility
   of deploying any vendor's NSF without need to redefine their policies
   if or when a NSF is changed.

   If a vendor comes up with new feature or functionality that can't be
   expressed through the currently defined Client-Facing interface,
   there must be a way to extend existing APIs or to create a new API
   that is relevant for that NSF vendor only.





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5.3.  APIs and Data Model Transport

   The APIs for client interface must be derived from the YANG based
   data model.  The YANG data model for client interface must capture
   all the requirements as defined in this document to express a
   security policy.  The interface between a client and controller must
   be reliable to ensure robust policy enforcement.  One such transport
   mechanism is RESTCONF that uses HTTP operations to provide necessary
   CRUD operations for YANG data objects, but any other mechanism can be
   used.

5.4.  Notification

   Client-Facing interface must allow Security Admin to collect various
   alarms and events from the NSF in the network.  The events and alarms
   may be either related to security policy itself or related to NSF
   where the policy is implemented.  The events and alarms could also be
   used as an input to the security policy for autonomous handling as
   specified in a given security policy.

5.5.  Affinity

   Client-Facing interface must allow Security Admin to pass any
   additional metadata that a user may want to provide for a security
   policy e.g. certain security policy needs to be implemented only on a
   very highly secure NSF with Trusted Platform Module (TPM) chip.  A
   user may require Security Controller not to share the NSF with other
   tenant, this must be expressed through the interface API.

5.6.  Test Interface

   Client-Facing interface must allow Security Admin ability to test a
   security policy before it is enforced e.g. a user may want to verify
   whether the policy creates any potential conflicts with the existing
   policies or if there are even resources to enforce the policy.  The
   test policy would provide such a capability without actually applying
   the policies.

6.  Security Considerations

   Client-Facing interface to Security controller must be protected to
   ensure that entire security posture is not compromised.  This draft
   mandates that interface must have proper authentication and
   authorization with Role Based Access Controls to address multi-
   tenancy requirement.  The draft does not specify a particular
   mechanism as different organization may have different needs based on
   their deployment.  This has been discussed extensively in this draft.




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   Authentication and authorization alone may not be sufficient for
   Client-Facing interface; the interface API must be validated for
   proper inputs to guard against attacks.  The type of checks and
   verification may be specific to each interface API, but a careful
   consideration must be made to ensure that Security Controller is not
   compromised.

7.  IANA Considerations

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

8.  Acknowledgements

   The authors would like to thank Adrian Farrel, Linda Dunbar and Diego
   R.Lopez from IETF I2NSF WG for helpful discussions and advice.

   The authors would also like to thank Kunal Modasiya, Prakash T.
   Sehsadri and Srinivas Nimmagadda from Juniper networks for helpful
   discussions.

9.  Normative References

   [I-D.ietf-i2nsf-problem-and-use-cases]
              Hares, S., Lopez, D., Zarny, M., Jacquenet, C., Kumar, R.,
              and J. Jeong, "I2NSF Problem Statement and Use cases",
              draft-ietf-i2nsf-problem-and-use-cases-15 (work in
              progress), April 2017.

Authors' Addresses

   Rakesh Kumar
   Juniper Networks
   1133 Innovation Way
   Sunnyvale, CA  94089
   US

   Email: rkkumar@juniper.net


   Anil Lohiya
   Juniper Networks
   1133 Innovation Way
   Sunnyvale, CA  94089
   US

   Email: alohiya@juniper.net




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   Dave Qi
   Bloomberg
   731 Lexington Avenue
   New York, NY  10022
   US

   Email: DQI@bloomberg.net


   Nabil Bitar
   Nokia
   755 Ravendale Drive
   Mountain View, CA  94043
   US

   Email: nabil.bitar@nokia.com


   Senad Palislamovic
   Nokia
   755 Ravendale Drive
   Mountain View, CA  94043
   US

   Email: senad.palislamovic@nokia.com


   Liang Xia
   Huawei
   101 Software Avenue
   Nanjing, Jiangsu  210012
   China

   Email: Frank.Xialiang@huawei.com

















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