Network Working Group L. Dunbar
Internet Draft Huawei
Intended status: Informational M. Zarny
Expires: August 2015 Goldman Sachs
C. Jacquenet
France Telecom
S. Chakrabarty
US Ignite
February 4, 2015
Interface to Network Security Functions Problem Statement
draft-dunbar-i2nsf-problem-statement-02.txt
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Abstract
This draft describes the motivation, focused use cases, and the
problem statement for Interface to Network Security Functions.
Table of Contents
1. Introduction...................................................3
1.1. Motivation................................................3
1.2. Impact from Network Function Virtualization...............4
1.3. Network Security Functions under Consideration............4
1.4. The scope of the proposed work............................5
2. Conventions used in this document..............................7
3. Focused Use Cases..............................................8
4. Problem Space.................................................10
5. The Benefits..................................................11
6. Related industry initiatives..................................12
6.1. Related IETF WGs.........................................12
6.2. Relationship with ETSI NFV...............................13
6.3. OpenStack Firewall/Security as a Service.................14
6.4. Security as a Service by Cloud Security Alliance.........14
6.5. Productive Eco-system with Open Source Communities.......14
7. Security Policies/functions negotiation.......................15
8. Conclusion and Recommendation.................................15
9. Manageability Considerations..................................16
10. Security Considerations......................................16
11. IANA Considerations..........................................16
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12. References...................................................16
12.1. Normative References....................................16
12.2. Informative References..................................16
13. Acknowledgments..............................................17
1. Introduction
This draft describes the motivation, focused use cases, and the
problem statement for Interface to Network Security Functions.
In the context of I2NSF, the term "Virtual Network Security
Function" is used frequently to emphasize the point that the
entities that consume the Network Security functions don't own or
host them. Those network security functions can be achieved by
physical appliances, or by VMs instantiated on servers.
1.1. Motivation
Enterprises are increasingly consuming network functions, especially
the network security related functions that are not hosted at their
promises. Some of the reasons driving up this demand are the desire
(and the necessity) to:
- Implement stringent security functions at branch offices where
minimal security infrastructures/capabilities exist;
- Provide interfaces for clients, and/or applications to
dynamically alter security policies;
- Maintain consistent security policies across a large number of
sites and devices.
According to [Gartner-2013], the demand for cloud-based security
services is growing. Small and medium-sized businesses (SMBs) are
increasingly adopting cloud-based security services to replace on-
premises security tools, while larger enterprises are deploying a
mix of traditional and cloud-based security services.
To efficiently meet the dynamic demand of security functions
requests from clients, it is desirable to have mechanisms to:
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- Specify concrete security rules (or attributes) for security
functions hosted and managed by third party, and
- Have standardized mechanisms for clients, users, or
applications to request/negotiate/validate security functions
that are not physically located on the local premises.
Despite their increasing popularity, most common cloud security
services do not yet have industry standards by which users/clients
can request their desired services. (The "user-provider"
relationship may exist between two different firms or between
different domains of the same firm.)
1.2. Impact from Network Function Virtualization
The ETSI Network Function Virtualization (NFV) initiative brings out
another management challenges for security policies to be enforced
by distributed (virtual) network security functions (vNSF). Those
trends require a standard interface to express, monitor, and manage
the security policies on distributed security functions that may be
running on different premises.
1.3. Network Security Functions under Consideration
There are many network functions being deployed and new ones are
popping up with business and application demands. In order to have a
concrete context for the protocols discussion, we start with the
following network security related functions:
- Firewall
- Intrusion Detection System/ Intrusion Prevention System
(IDS/IPS)
The reason for starting with security-related functions is due to
the wide acceptance of security functions that are not running on
customer/enterprise premises. Numerous security vendors are now
leveraging cloud based models to deliver security solutions. This
shift has occurred for a variety of reasons including greater
economies of scale, streamlined delivery mechanisms, and the demand
of business and applications for more sophisticated security
functions that they do not have. Consumers, enterprise clients as
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well as applications are embracing the business model of requesting
for security functions that do not run on their own premises on
demand, also known as Network Security as a Service.
1.4. The scope of the proposed work
The Interface to vNSF (I2NSF) initiative is to identify how to
express, monitor, and manage the security policies on distributed
security functions that may be running on different premises. I2NSF
also allows clients to communicate their specific security policies
(request/monitor/report) to security functions.
There are two aspects of the I2NSF work:
- Service Layer, which is for clients to express, monitor, or
manage their desired security policies for their designated
traffic.
This layer will leverage the existing protocols in RESTconf,
AAA, SACM, and security policy expression using Role Based
Access Control (RBAC), Mandatory Access Control (MAC), or
Attribute based access control (ABAC).
- Functional layer, which is to specify the proper interface to
the individual security functions or function instances when
overall policies are enforced by a collection of security
functions located in multiple premises.
The Interface to Network Security Functions (I2NSF) initiative aims
at improving the dynamic allocation and operation of network
security functions by documenting a global framework that would
include protocol-based control and management interfaces, along with
adequate data models. The information required for the provisioning,
the configuration and the operation of network security functions
will be exchanged through the said interfaces and protocols. The
I2NSF initiative will also take into account the need for co-
existing with legacy configuration and management systems used to
allocate and operate network security functions, whether they are
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embedded in network devices or virtualized in data center
environments, for example. The standard Interface to
request/negotiate/allocate/operate (Virtual) Network Security
Functions (I2NSF) is one of the necessary tools for operators and
service providers to offer network security functions as a service
to their corporate clients.
It is envisioned that clients of the I2NSF interfaces include
Application Gateway, Security Administrator, service orchestration
systems, even some security functions requests for more
sophisticated functions when detect something suspicious.
Various aspects to I2NSF include:
- The mechanism for clients (applications) to
request/negotiate/validate security policies that are enforced by
security functions physically located in different premises, or
administrative domain.
- Information/data model to configure and monitor the newly
instantiate virtual security functions (NFV initiative).
The "requester <-> provider" relationship has different connotations
in different scenarios:
- Client <-> Provider relationship, i.e. client requesting some
network functions from its provider;
- Inter-domain, e.g. Domain A <-> Domain B relationship, i.e. one
operator domain requesting some network functions from another
operator domain, where "A" and "B" can be from same operator or
different operators; or
- Application Gateways <-> Network relationship, i.e. an application
gateway (e.g. cluster of servers) requesting some security
policies for their designated traffic.
The security functions offered by third party need Bi-directional
periodic communications among multiple entities for policies
negotiation, validation, potentially re-directing traffic to higher
level security functions, etc. Therefore, the service requires
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programmatic interfaces or protocol exchange, whereas API is
conventionally associated with functional calls on one system.
The objective of the proposed work is to standardize the protocols
(or the interface) and architecture for Requester and Provider to
negotiate the functions needed as well as the associated attributes
or security policies.
The proposed protocols between requester and provider can be used
for the following scenarios:
- A Client requests a certain network security function from a
provider
- The provider fulfills the request for example, by instantiating
an instance of the service in question, or configures
additional rules in an already provisioned vNSF.
2. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC-2119 [RFC2119].
In this document, these words will appear with that interpretation
only when in ALL CAPS. Lower case uses of these words are not to be
interpreted as carrying RFC-2119 significance.
Cloud DC: The data centers that are not on premises of enterprises
yet have the compute/storage resources that can be
requested or purchased by the enterprises. What the
enterprises actually get is Virtual Data Centers.
DC: Data Center
Domain: The term "Domain" in this draft has different
connotations in different scenarios:
Client <-> Provider relationship, i.e. client requesting
some network functions from its provider;
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Domain A <-> Domain B relationship, i.e. one operator
domain requesting some network functions
from another operator domain; or
Applications <-> Network relationship, i.e. an
application (e.g. cluster of servers)
requesting some functions from network, etc.
Virtual Network Function: In the context of I2NSF, the term
"Virtual Network Function" is used frequently to
emphasize the point that the entities that consume the
Network functions, mostly L4-L7 functions, don't own or
host them. Those network functions can be achieved by
physical appliances, or by VMs instantiated on common
compute servers (i.e. the ETSI NFV defined Virtualized
network functions).
Virtual Security Function: a security function that can be requested
by one domain but may be owned or managed by another
domain.
Cloud-based security functions: used interchangeably with the
"Virtual Security Functions" in this draft.
3. Focused Use Cases
Many use cases have been described by [I2NSF-ACCESS], [I2NSF-DC] and
the [I2NSF-Mobile]. To make I2NSF more focused, we will start with
one use case that is described by all three use case drafts.
Enterprises, residential, and mobile customers are increasingly
consuming network functions, especially the network security related
functions that are not running on their premises. The ETSI Network
Function Virtualization (NFV) initiative brings out another
management challenges for security policies to be enforced by
distributed (virtual) network security functions (vNSF). Those
trends require a standard interface to express, monitor, and manage
the security policies on distributed security functions that may be
running on different premises.
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One key aspect of those multiple premises hosted security functions
is to have standard ways to express, monitor and verify security
policies among distributed and virtual security functions.
The standard ways (I2NSF) to express security policies makes it
possible for Application Gateway, e.g. Video Conference Controller,
to dynamically inform the network security controller to have some
specific encrypted flows by-passing some FW/IPS/IDS for a specific
time span. Otherwise, some flows can't go through the FW/IPS/IDS
because the payload is encrypted. Or require manually configuring a
wide set of port ranges for calls to pass through (ex: ports 50,000
to 50,999) if there is a firewall placed in the middle of any
enterprise deployment (very common for defense in depth postures).
This causes a bigger attack surface area. I2NSF can dynamically
create pinhole firewalls rules that are only active for when the
call media session is alive. Once the session is over the pinhole
policy is removed.
The standard interface (I2NSF) also makes it possible for Cloud DC
to offer Virtual Firewall Function On Demand service.
Clients of cloud data center not only need virtual networks to
interconnect their virtual compute/storage resources, but they also
need virtual firewall services to enforce the proper communication
policies. VPN clients, especially branch office access points, may
need firewalls that are hosted by the VPN provider to be integrated
with the VPN service.
Per [NW-2011], A cloud-based firewall is different from an on-
premise one (aside from its location) in three key areas:
scalability, availability and extensibility.
- Scalability: Cloud-based firewalls are designed to serve
multiple customers and their increasing demand. Unlike with an
on-premise firewall, upgrading a cloud-based firewall-e.g.,
for greater throughput-should be transparent to enterprise
users.
- Availability: Cloud-based firewall providers tend to offer
extremely high availability through their highly redundant and
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resilient data centers. In contrast, most enterprises may not
be able to offer "carrier-grade" high availability.
- Extensibility: Enterprises looking for vendor diversity can
subscribe to cloud-based firewalls from different providers.
Furthermore, additional features can be added more seamlessly,
transparently.
4. Problem Space
Many vendors already offer Security as a Service in the cloud.
However, all their solutions are proprietary, with different
interfaces and different modes of operation.
There are no common interfaces/mechanisms for clients or
applications to monitor or verify the required security policies or
security functions. There is a lack of user-friendly service
(policy) template.
I2NSF will only focus on the following problem spaces:
- Security Policy Layer, which is for clients to express,
monitor, verify the needed security policies for their
specific flows.
Proper language has to be identified between clients and
network security function controllers. This layer will
leverage the existing protocols in RESTconf, AAA, SACM, and
security policy expression using Role Based Access Control
(RBAC), Mandatory Access Control (MAC), or Attribute-based
access control (ABAC).
- Capability (or Functional) Layer, which specifies the
information/data models to Security functions/devices (virtual
& physical). This layer will leverage the existing protocols
and data models defined by I2RS, Netconf, and NETMOD.
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There are many other problems associated with Security Function on
Demand that are out of the scope of I2NSF:
- Diverse security services:
The I2NSF will only cover Firewall and IPS/IDS, may be
extending to other security functions after re-chartering.
- Scalability:
Not only diverse CPU/memory needed for different security
functions can be difficult to manage, but the solution itself
may have some limits, e.g. maximum number of firewall rules.
- Availability:
The requested security functions or security policies might not
be fulfilled. The negotiation protocol is not in the scope of
I2NSF.
- Converting policies to vendor-specific configurations
- Dynamic features update
5. The Benefits
The goal of I2NSF is to specify standard mechanisms for clients to
request security functions or security policies from another domain.
The framework allows the clients to view, request, and/or verify the
security functions/policies offered by different providers. This
framework can make it easy for a cluster of devices requiring the
similar security policies to have consistent policies across
multiple sites.
The network service providers, with their physical access to a vast
number of enterprises and consumers, are very well positioned to
provide the "Security Function on Demand" services. The providers
can act as security function brokers to their directly connected
domains. They can offer a service catalog and standard mechanisms by
which enterprises (or applications) can query request, or/and verify
the needed security functions or policies.
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With the standard interfaces for clients to request the needed
security functions and policies, network operators can leverage
their current VPN to enterprises and access to a vast population of
end users to offer a set of consolidated Security solutions and
policies. The IETF can play an instrumental role in defining this
common interface and framework for network operators.
6. Related industry initiatives
6.1. Related IETF WGs
IETF NETCONF: I2NSF should consider using Netconf protocol for
capability layer to communicate the security data models to the
designated security functions.
NETMOD ACL Model: draft-ietf-netmod-acl-model-00 describes the very
basic attributes for access control. I2NSF will extend the ACL data
model to be more comprehensive, for example, extend to multiple
actions and policies, and describes various services associated with
the security functions under consideration.
For Firewall, I2NSF will specify the information model associated
with various services of FW, such as stateful or deep packet
inspection, packet/flow/stream filtering and redirect (remote and
local), etc.
In addition, I2NSF has to specify the needed information model for
the monitoring/reporting of FW.
I2RS: I2RS is thinking how to create interface between data and
control plane, essentially be able to run an application like BGP
somewhere else and then communicate the instruction to data plane
how to act. I2NSF is looking specifically into expressing security
policies in two layers. I2NSF should leverage the protocols
developed by I2RS. I2NSF is only to develop the additional
information models and data models for distributed security
functions, like FW and IPS/IDS. The Policy structure specified by
http://datatracker.ietf.org/doc/draft-hares-i2rs-bnp-info-model/ can
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be used by I2NSF to be extended to include recursive actions to
other security functions.
IETF SFC is about mechanism of chaining together service functions
while treating service functions as black box; VNFpool is about the
reliability and availability of the virtualized network functions.
But none of them address how service functions are requested, or how
service functions are fulfilled.
Both SFC and VNFpool don't cover in-depth specification (e.g. rules
for the requested FW) for clients to request its needed functions.
In SFC & VNFpool, FW function is a black box, that is treated in
same way as Video Optimization function. SFC/VNFpool don't cover the
negotiation part, e.g. Client needs Rule x/y/z for FW, but the
Provider can only offer x/z.
IETF SACM (Security Assessment and Continuous Monitoring) specifies
the mechanisms to assess end point security. The end points can be
routers, switches, clustered DB, installed piece of software. SACM
is about "How to encode that policy in a manner where assessment can
be automated". For examples:
- a Solaris 10 SPARC or Window 7 system used in a environment
that requires adherence to a policy of Mission Critical
Classified.
- rules like "The maximum password age must be 30 days" and
"The minimum password age must be 1 day"
IETF midcom, nsis, pcp, (arguably) SOCKS have done some work that
have some aspects related to or can be used by I2NSF.
6.2. Relationship with ETSI NFV
We believe that the I2NSF is one of the enabling tools for Network
Security as a Service (NSaaS), which is a subset of VNF as a Service
(VNFaaS) specified by ETSI NFV Group Specification Use Cases
[gs_NFV]. The main benefits of virtualized network functions are
increased flexibility to efficiently share the resources, and
decreased setup and management costs. NFV defines the architecture
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to pool together many virtual network functions to be managed and
consumed collectively.
NFV, with its heavy representation from service provider side, can
define more detailed service model for VNFaaS and setting
requirement for IETF's narrowly scoped I2NSF interface.
6.3. OpenStack Firewall/Security as a Service
Open source projects like OpenStack and CloudStack have begun to
tackle the issues of interfaces to security functions but much work
remains. There are many pieces of open sourced code, and there are a
lot of areas not covered. The combined contributed source code is
not comprehensive.
OpenStack completed the Firewall as a Service project and specified
the set of APIs for Firewall services:
http://docs.openstack.org/admin-guide-
cloud/content/fwaas_api_abstractions.html
OpenStack has defined the APIs for managing Security Groups:
http://docs.openstack.org/admin-guide-
cloud/content/securitygroup_api_abstractions.html
The attributes defined by OpenStack Firewall/Security as a Service
are very primitive. However they can be the basis of the information
model for the I2NSF IETF initiative.
6.4. Security as a Service by Cloud Security Alliance
https://cloudsecurityalliance.org/research/secaas/#_get-involved
SaaS by CSA is at the initial stage of defining the scope of work.
6.5. Productive Eco-system with Open Source Communities
Our goal is to form a Collaborative Loop from IETF to Industry
Open Source Communities (as Dave Ward said at IETF 91 Lunch
session).
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Open-source initiatives are not to be considered as an alternative
to formal standardization processes. On the contrary, they are
complementary, with the former acting as an enabler and
accelerator of the latter. Open-source provides an ideal mechanism
to quick prototyping and validating contending proposals, and
demonstrating the feasibility of disruptive ideas that could
otherwise not be considered. In this respect, open-source
facilitates the engagement in the standardization process of small
(and typically more dynamic) players such as start-ups and
research groups, that would see better opportunities of being
heard and a clearer rewards to their efforts. An open-source
approach is extremely useful as well for the production of open
reference implementations of the standards at the same (or even
faster) pace they are defined. The availability of such reference
implementations translate into much simpler interoperability and
conformance assessments for both providers and users, and can
become the basis for incremental differentiation of a common
solution, thus allowing a cooperative competition ("coopetition")
model.
7. Security Policies/functions negotiation
The protocol needed for this security function/policies negotiation
may be somewhat correlated to the dynamic service parameter
negotiation procedure [RFC7297]. The CPP template documented in
RFC7297, even though currently covering only Connectivity, could be
extended as a basis for the negotiation procedure. Likewise, the
companion CPNP protocol could be a candidate to proceed with the
negotiation procedure.
The "security as a service" would be a typical example of the kind
of (CPP-based) negotiation procedures that could take place between
a corporate customer and a service provider. However, more security
specific parameters have to be considered by this proposed work.
8. Conclusion and Recommendation
The I2NSF aims at providing standard interfaces for clients to
express, monitor, and manage their desired security policies, which
can be instantiated on devices at different premises.
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9. Manageability Considerations
TBD.
10. Security Considerations
TBD
11. IANA Considerations
This document requires no IANA actions. RFC Editor: Please remove
this section before publication.
12. References
12.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC7297] Boucadair, M., "IP Connectivity Provisioning Profile",
RFC7297, April 2014.
12.2. Informative References
[I2NSF-ACCESS] A. Pastor, et al, "Access Use Cases for an Open OAM
Interface to Virtualized Security Services", <draft-
pastor-i2nsf-access-usecases-00>, Oct 2014.
[I2NSF-DC] M. Zarny, et al, "I2NSF Data Center Use Cases", <draft-
zarny-i2nsf-data-center-use-cases-00>, Oct 2014.
[I2NSF-MOBILE] M. Qi, et al, "Integrated Security with Access
Network Use Case", <draft-qi-i2nsf-access-network-usecase-
00>, Oct 2014
[gs_NFV] ETSI NFV Group Specification, Network Functions
Virtualizsation (NFV) Use Cases. ETSI GS NFV 001v1.1.1,
2013.
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[Boucadair-framework] M. Boucadair, et al, "Differentiated Service
Function Chaining Framework", < draft-boucadair-service-
chaining-framework-00>; Aug 2013
[Gartner-2013] E. Messmer, "Gartner: Cloud-based security as a
service set to take off", Network World, 31 October 2013
[NW-2011] J. Burke, "The Pros and Cons of a Cloud-Based Firewall",
Network World, 11 November 2011
[SC-MobileNetwork] W. Haeffner, N. Leymann, "Network Based Services
in Mobile Network", IETF87 Berlin, July 29, 2013
[Application-SDN] J. Giacomonni, "Application Layer SDN", Layer 123
ONF Presentation, Singapore, June 2013
13. Acknowledgments
Acknowledgements to Andy Malis for his review and contributions.
This document was prepared using 2-Word-v2.0.template.dot.
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Authors' Addresses
Linda Dunbar
Huawei Technologies
5340 Legacy Drive, Suite 175
Plano, TX 75024, USA
Phone: (469) 277 5840
Email: ldunbar@huawei.com
Myo Zarny
Goldman Sachs
30 Hudson Street
Jersey City, NJ 07302
Email: myo.zarny@gs.com
Christian Jacquenet
France Telecom
Rennes 35000
France
Email: Christian.jacquenet@orange.com
Shaibal Chakrabarty
US Ignite
1776 Massachusetts Ave NW, Suite 601
Washington, DC 20036
Phone: (214) 708 6163
Email: shaibalc@us-ignite.org
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