Internet DRAFT - draft-ietf-i2nsf-client-facing-interface-req
draft-ietf-i2nsf-client-facing-interface-req
I2NSF Working Group R. Kumar
Internet-Draft Lilac Cloud
Intended status: Informational A. Lohiya
Expires: November 28, 2018 Juniper Networks
D. Qi
Bloomberg
N. Bitar
S. Palislamovic
Nokia
L. Xia
Huawei
May 27, 2018
Requirements for Client-Facing Interface to Security Controller
draft-ietf-i2nsf-client-facing-interface-req-05
Abstract
This document captures requirements for Client-Facing interface to
the Security Controller as defined by [RFC8327]. 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 the User Community. This
gives ability to decouple policy definition from policy enforcement
on a specific security functional 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 https://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 November 28, 2018.
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Copyright Notice
Copyright (c) 2018 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
(https://trustee.ietf.org/license-info) in effect on the date of
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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 Definition . . 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 Unified Model for Various Network Types . 11
4.2. Requirement for Multi-Tenancy in Client-Facing Interface 12
4.3. Requirement for Authentication and Authorization of
Client-Facing Interface . . . . . . . . . . . . . . . . . 12
4.4. Requirement for Role-Based Access Control (RBAC) in
Client-Facing Interface . . . . . . . . . . . . . . . . . 13
4.5. Requirement to Protect Client-Facing Interface from
Attacks . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.6. Requirement to protect Client-Facing Interface from
Misconfiguration . . . . . . . . . . . . . . . . . . . . 13
4.7. Requirement to Manage Policy Lifecycle with Rich Set of
Controls . . . . . . . . . . . . . . . . . . . . . . . . 14
4.8. Requirement to Define Dynamic Policy Endpoint Group . . . 15
4.9. Requirement to Express Rich Set of Policy Rules . . . . . 17
4.10. Requirement to Express Rich Set of Policy Actions . . . . 18
4.11. Requirement for Consistent Policy Enforcement . . . . . . 19
4.12. Requirement to Detect and Correct Policy Conflicts . . . 20
4.13. Requirement for Backward Compatibility . . . . . . . . . 20
4.14. Requirement for Third-Party Integration . . . . . . . . . 20
4.15. Requirement to Collect Telemetry Data . . . . . . . . . . 20
5. Operational Requirements for the Client-Facing Interface . . 21
5.1. API Versioning . . . . . . . . . . . . . . . . . . . . . 21
5.2. API Extensibility . . . . . . . . . . . . . . . . . . . . 21
5.3. APIs and Data Model Transport . . . . . . . . . . . . . . 21
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5.4. Notification and Monitoring . . . . . . . . . . . . . . . 22
5.5. Affinity . . . . . . . . . . . . . . . . . . . . . . . . 22
5.6. Test Interface . . . . . . . . . . . . . . . . . . . . . 22
6. Security Considerations . . . . . . . . . . . . . . . . . . . 22
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 23
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 23
9. Normative References . . . . . . . . . . . . . . . . . . . . 23
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23
1. Introduction
Programming security policies in a network has been a fairly complex
task that often requires deep knowledge of vendor specific devices
and features. This has been the biggest challenge for both Service
Providers and Enterprises, henceforth named as Security Admins in
this document. This challenge is further amplified due to network
virtualization with security functions deployed in physical and
virtual form factors, henceforth named as network security function
(NSF) in this document, from multiple vendors with proprietary
interfaces.
Even if 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 that requires mapping of
business needs to complex security features with vendor specific
configurations. 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 security functions in either
virtual or physical form to attain the flexibility, elasticity,
performance scale and operational efficiency they require.
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Practically, that often requires different sources (vendor, open
source) to get the best of breed for a given security function.
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 [RFC8327] [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 Policy in
an abstract form with choice of wide variety of NSF as policy
enforcement point. The implementation of security management
applications or controller is out of scope for I2NSF working group.
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 Security 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 [RFC8192]
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
VPN: Virtual Private Network
3. Guiding Principle for Client-Facing Interface Definition
Client-Facing Interface must ensure that a Security Admin can deploy
a NSF from any vendor and should still be able to use the same
consistent interface. In essence, this interface allows a Security
Admin to express a Security Policy enforced on the NSFs to be
independent of vendor and its implementation. 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 vendor
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. To further
complicate the matters, when changes happen in the network topology,
the Security Policy may require modifications accordingly. This may
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be a highly manual task based on network design and becomes
unmanageable in virtualized environment.
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 a particular network topology or the NSF location
in the network
o Not forced to express Security Policy with proprietary vendor
specific interfaces for a given NSF
o Independent of NSF type that will implement a specific Security
Policy; e.g., the interface remains same no matter if a specific
Security Policy is enforced on a stateful firewall, IDP, IDS,
Router or a Switch
o Declarative/Descriptive model instead of Imperative/Prescriptive
model - What security policy need to be expressed (declarative)
instead of how it is implemented (imperative)
o Not dependent on vendors' 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, e.g.
encapsulation, service function chains.
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Note that the rules stated above only apply to the Client-Facing
interface, which a Security Admin 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
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 Enterprises deploy vendor provided
management systems to create Security Policies and any changes to
these Security Policies are made manually over time by Security
Admin. This approach may not be suitable and nor sufficient for
modern highly automated campus network, and data centers that are
largely virtualized and rely on various management systems and
controllers to implement dynamic Security Policies over large number
of NSF in the network.
There are two distinct deployment models for Security Controller.
Although, these have no direct impact on the Client-Facing interface,
but illustrate the overall Security Policy management framework in an
organization and how the Client-Facing interface remain same which is
the main objective of this document. 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
As mentioned above, these models discussed here don't affect the
definition of Client-Facing interface, they do give an overall
context for defining a Security Policy interface based on
abstraction. This can help in implementing a Security Controller.
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 Security Admin'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 their business needs and
objectives.
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 Unified model for various network types (i.e., campus network,
date center, operator core/metro network, etc)
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
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o Policy Actions
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 or required for all use-cases, but should be a good
starting point for a wide variety of use-cases in Service Provider
and Enterprise networks.
A specific implementation may not support all these requirements but
in order to define a base set of requirements which would works for
most use-cases, this document will make an attempt to classify these
requirements in three categories:
MUST: This means, the requirement must be supported by Client-Facing
interface.
RECOMMENDED: This means, we recommend that Client-Facing interface
support this requirement since it might be applicable to large
number of use-cases but some vendor may choose to omit if their
focus is only certain market segments.
MAY: This means, the requirement is not mandatory for Client-Facing
interface but may be needed for specific use-cases.
4.1. Requirement for Unified Model for Various Network Types
In terms of security management/control, different network types have
different focus and requirements. In general, campus network focuses
more on user and device management, as well as the access control
among them. But for data center, more focus are putted on the east-
west traffic control for various application, or workload isolation
with micro-segmentation.
Comparing to campus network and DC network, the other network types,
such as: operator core/metro network, VPN network, are relatively
simple in terms of security policies but still have their own
considerations. Despite their different focus on security policy,
one unified model is still necessary with the benefits of simplicity,
wide applicability and extensibility. More specifically, the unified
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model here means all the policy objects are constructed with the same
structured method in the security policies for all the network types.
We classify this requirement in MUST category.
4.2. Requirement for Multi-Tenancy in Client-Facing Interface
An organization may have internal tenants and might want a framework
wherein each tenant manages its own Security Policies with isolation
from other tenants. This requirement may be applicable to Service
Providers and Large Enterprises so we classify this requirement in
RECOMMENDED category. If an implement does not support this
requirement, it must support a default implicit tenant created by
Security Controller that owns all the Security Policies.
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 able to manage its own Security Policies without
affecting other tenants.
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.
The following objects are needed to fulfill this requirement:
Policy-Tenant: An entity that owns and manages Security Policies
applied to its own asset and 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.
4.3. Requirement for Authentication and Authorization of Client-Facing
Interface
A Security Admin must be authenticated and authorized in order to
manage Security Policies. We classify this requirement in MUST
category since without proper authentication and authorization, the
security posture of entire organization can be easily compromised.
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 [RFC6749],
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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.
4.4. Requirement for Role-Based Access Control (RBAC) in Client-Facing
Interface
A tenant in organization may have multiple users with each user given
certain privileges. Some user such as "Admin" may have all the
permission but other may have limited permissions. We classify this
requirement in RECOMMENDED category since it aligns with Multi-
Tenancy requirement. If this requirement is not supported, a default
privilege must be assigned to all the users.
The following objects are needed to fulfill this requirement:
Policy-Authorization-Role: Defines the permissions assigned to a
user such as creating and managing policies on specified
resources. A user may not be allowed to change existing policies
but only view them.
4.5. Requirement to Protect Client-Facing Interface from Attacks
The interface must be protected against attacks from malicious
clients or a client impersonator. Potential attacks could come from
Botnets, hosts infected with virus or some unauthorized entities.
This requirement is highly RECOMMENDED since it may not be needed if
the entire framework is deployed in very controlled environment. But
if needed, we recommend that Security Controller uses an out-of-band
communication channel for Client-Facing interface. In addition, it
is also recommended that traffic of Client-Facing interface
communication are encrypted; Furthermore, some straightforward
traffic/session control mechanisms (i.e., Rate-limit, ACL, White/
Black list) can be employed on Security Controller to protect against
DDoS flooding attacks.
4.6. Requirement to protect Client-Facing Interface from
Misconfiguration
There must be measures to protect from mis-configured clients.
System and policy parameters validations should be implemented to
detect this. Validation may be based on a set of default parameters
or custom tuned thresholds such as the number of policy changes
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submitted, number of objects requested in a given time interval, etc.
We consider this to be a MUST requirement but implementation aspects
would depend upon each individual API communication.
4.7. Requirement to Manage Policy Lifecycle with Rich Set of Controls
In order to provide more sophisticated and flexible security
framework, there should be a mechanism so that a policy becomes
dynamically active/enforced or inactive based on multiple different
criteria such as Security Admin's manual intervention or some
external event. We consider requirement listed here to be a MUST for
wide variety of use-cases.
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 threat detection. 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 activated by Security Admin manually using a
client interface such as GUI or CLI.
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 configured but gets activated or deactivated upon
specified timing calendar with Security Policy definition.
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
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de-activated when the corresponding session is closed or the flow
becomes inactive for certain time.
A policy could be a composite policy, which 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 Security
Admin 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.
4.8. 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, or combination of them. We refer to such
a subset of the network as a "Policy Endpoint Group". This
requirement is the fundamental building block of Client-Facing
interface; so making it a MUST requirement. But object defined here
may not support all use-cases and may not be required by everyone so
it is left up to vendor whether all or partial set of these object is
supported.
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 "Metadata Driven
Groups". The metadata is a tag associated with endpoint information
such as User, Application, or Device. The mapping from metadata 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 endpoint.
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Client-Facing interface must support Policy Endpoint Groups as a
target for a Security Policy. The following metadata driven groups
MAY be used for configuring Security Polices:
User-Group: This group identifies a set of users based on a tag or
static information such as user-names. The tag identifying users,
is dynamically derived from systems such as Active Directory or
LDAP. For 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 device information. The tag identifying the devices, 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 application names. The tag identifying
applications, 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 locations. Tag may
correspond 1:1 to location. The tag identifying locations 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. Note that
the location can be both the geographic and abstract concept.
Some typical examples for the latter case are: branches and
headquarter for a large enterprise; different data center sites;
private cloud and public cloud.
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4.9. Requirement to Express Rich Set of Policy Rules
The Policy Rules is a central component of any Security Policy but
rule requirements may vary based on use-cases and it is hard to
define a complete set that works for everyone. In order to build a
rich interface, we are going to take a different approach; we will
define the building block of rules and let Security Admin build rules
using these construct so that Security Policies meet their
requirements divided into the following major categories:
Segmentation policies : This set of policies create rules for
communication between two Endpoint Groups. An organization may
restrict certain communication between a set of user and
applications for example. The segmentation policy may be a micro-
segmentation rule between components of complex applications or
related to hybrid cloud deployment based on location.
Threat policies: This set of policies creates rules to prevent
communication with externally or internally identified threats.
The threats may be well knows such as threat feeds from external
sources or dynamically identified by using specialty devices in
the network.
Governance and Compliance policies: This set of policies creates
rules to implement business requirement such as controlling access
to internal or external resources for meeting regulatory
compliance or business objectives.
In order to build a generic rule engine to satisfy diverse set of
Policy Rules, we propose following objects:
Source Policy Endpoint Group: A source target of the Policy Rule.
This may be special object "ALL" if all groups meet this criteria.
Destination Policy Endpoint Group: A destination target of the
Policy Rule. This may be a special object "ALL", if all groups
meet this criteria.
Direction: By default rules are applied in both directions but this
object can be used to make rule definition uni-directional.
Threat Group: An object that represents a set of static or dynamic
threats such as Botnet, GeoIP, URL feeds or virus and malware
signatures detected dynamically. This object can be used as
source or destination target in a rule.
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Match Condition: An object that represents a set of allowed
interactions. It could be as simple as group of application names
or L4 ports allowed between two Endpoint Groups.
Exceptions: In order to greatly simplify Security Admin's task, we
should allow to specify exceptions to the match criteria. E.g.,
we could build a rule that allows all traffic between two groups
except a particular application or threat source.
Actions: Action is what makes rule and Policy work. The Action is
defined in details in next section. We RECOMMEND that there be a
one-to-one mapping between rule and action otherwise if multiple
rules are associated with one action, it may be a difficult to
manage Security Policy lifecycle as they evolve.
4.10. Requirement to Express Rich Set of Policy Actions
Security Admin must be able to configure a variety of actions for a
given Policy Rule. Typically, Security Policy specifies a simple
action of "deny" or "permit" if a particular condition is matched.
Although this may be enough for most use-cases, the I2NSF Client-
Facing interface must provide a more comprehensive set of actions so
that the interface can be used effectively across various security
needs.
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.
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.
Authenticate connection: This action means that whenever a new
connection is established it should be authenticated.
Quarantine/Redirect: This action is useful for threat remediation
purposes. If a security breach or infection point is detected, a
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Security Admin would like to isolate for purpose of remediation or
controlling attack surface.
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, IPS, IDS, honeypot, or VPN,
etc.
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.
4.11. Requirement for Consistent Policy Enforcement
As proposed in this document, the Client-Facing interface MUST be
built using higher-level "User-Constructs" that are independent of
network design and implementations. In order to achieve this goal,
it becomes important that Security Controller functionality becomes
more complex that keep track of various objects that are used to
express Security Policies. The Security Controller MUST evaluate the
Security Policies whenever these objects and network topology change
to make sure that Security Policy is consistently enforced as
expressed.
Although this document does not specify how Security Controller
achieve this and any implementation challenges. It is assumed that
once Security Controller uses Client-Facing interface to accept
Security Policies; it would maintain the security posture as per the
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Security Policies during all changes in network or Endpoints and
other building blocks of the framework.
An event must be logged by Security Controller when a Security Policy
is updated due to changes in it's building blocks such as Endpoint
Group contents or the Security Policy is moved from one enforcement
point to another because the Endpoint has moved in the network. This
may help in debugging and auditing for compliance reasons. The
Security Admin may optionally receive notifications if supported and
desired.
4.12. 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 a newly submitted Security Policy could conflict with
existing Security Policies applied to a set of Policy Endpoint
Groups. This MUST be detected and Security Admin be allowed for
manual correction if needed.
4.13. Requirement for Backward Compatibility
It MUST be possible to add new capabilities to Client-Facing
interface in a backward compatible fashion.
4.14. Requirement for Third-Party Integration
The security framework in a network may require the use of some
special devices such as honeypot, behavioral analytic, or SIEM for
threat detection; the device may provide threat information such as
threat feeds, virus signatures, and malicious file hashes.
The Client-Facing interface must allow Security Admin to include
these devices under Security Controller's Client-Facing interface so
that a Security Policy could be expressed using information from such
devices; basically it allows ability to integrate third part devices
into the Security Policy framework.
4.15. Requirement to Collect Telemetry Data
One of the most important aspect of security is to have visibility
into the network. As threats become more sophisticated, Security
Admin must be able to gather different types of telemetry data from
various NSFs in the network. The collected data could simply be
logged or sent to security analysis engines for application
identification, flow context and behavioral analysis, policy
violations, and for threat detection. Based on the analysis result,
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the security controller can enforce the policy lifecycle management
and automatic optimization.
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.
Client-Facing interface must provide a set of telemetry data
available to Security Admin from Security Controller. The Security
Admin should be able to subscribe and receive to this data set.
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 important since Security Controller could be
deployed by using multiple componenets and different pieces may come
from different vendors; it is difficult to isolate and debug issues
without ability to track each component's operational behavior. Even
if the vendor is same for all the components, it is hard to imagine
that all pieces would be released in lock step by the vendor.
Without API versioning, it is hard to debug and figure out issues
when deploying Security Controller and its components built overtime
across multiple release cycles. Although API versioning does not
guarantee that Security Controller would always work but it helps in
debugging if the problem is caused by an API mismatch.
5.2. API Extensibility
Abstraction and standardization of Client-Facing interface is of
tremendous value to Security Admins 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 SHALL be a way to extend existing APIs or to create a new API
that addresses specific vendors's new NSF functionality.
5.3. APIs and Data Model Transport
The APIs for interface SHALL be derived from the YANG based data
model. The data model for Client-Facing 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
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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 and Monitoring
Client-Facing interface must allow ability to collect various alarms,
events, statistics about enforcement and policy violations from NSFs
in the network. The events and alarms may be associated with a
specific policy or associated with operating conditions of a specific
NSF in general. The statistics may be a measure of potential
Security Policy violations or general data that reflect operational
behavior of a NSF. The events, alarms and statistics may also be
used as an input to automate Security Policy lifecycle management.
5.5. Affinity
Client-Facing interface must allow Security Admin to pass any
additional metadata that a user may want to provide with a Security
Policy e.g., whether the policy needs to be enforced by a very highly
secure NSF with Trusted Platform Module (TPM) chip. Another example
would be, whether or not a policy can be enforced by a multi-tenant
NSF. This would Security Admin control on operating environment
5.6. Test Interface
Client-Facing interface must support 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 existing policies or
if there are enough resources and capability to enforce this policy.
The test interface would provide a mechanism to Security Admin where
policies could be tested in the actual environment before
enforcement.
6. Security Considerations
Client-Facing interface to Security controller must be protected to
make sure that entire security posture is not compromised. This
draft mandates that interface must have proper authentication and
authorization control mechanisms to ward off malicious attacks. The
draft does not specify a particular mechanism as different
organization may have different needs based on their specific
deployment environment and moreover new methods may evolve to better
suit contemporary requirements.
Authentication and authorization alone may not be sufficient for
Client-Facing interface; the interface API must be validated for
proper input to guard against attacks. The type of checks and
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verification may be specific to each interface API, but a careful
consideration must be made to ensure that Security Controller is not
compromised.
We recommend that all attack surface must be examined with careful
consideration of the operating environment and available industry
best practices must be used such as process and standards to protect
security controller against malicious or inadvertent attacks.
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
[RFC8192] Hares, S., Lopez, D., Zarny, M., Jacquenet, C., Kumar, R.,
and J. Jeong, "Interface to Network Security Functions
(I2NSF): Problem Statement and Use Cases", RFC 8192,
DOI 10.17487/RFC8192, July 2017,
<https://www.rfc-editor.org/info/rfc8192>.
[RFC8327] Hargrave, W., Griswold, M., Snijders, J., and N. Hilliard,
"Mitigating the Negative Impact of Maintenance through BGP
Session Culling", BCP 214, RFC 8327, DOI 10.17487/RFC8327,
March 2018, <https://www.rfc-editor.org/info/rfc8327>.
Authors' Addresses
Rakesh Kumar
Lilac Cloud
14435 C Big Basin Way #104
Saratoga, CA 95070
US
Email: rakeshkumarcloud@gmail.com
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Anil Lohiya
Juniper Networks
1133 Innovation Way
Sunnyvale, CA 94089
US
Email: alohiya@juniper.net
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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