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Versions: (draft-nir-ipsecme-p2p) 00 01 02 draft-ietf-ipsecme-ad-vpn-problem

IPsecME Working Group                                           S. Hanna
Internet-Draft                                                   Juniper
Intended status: Informational                                 V. Manral
Expires: January 11, 2013                                             HP
                                                           July 10, 2012

         Auto Discovery VPN Problem Statement and Requirements


   This document describes the problem of enabling a large number of
   systems to communicate directly using IPsec to protect the traffic
   between them.  It them expands on the requirements, for such a

   Manual configuration of all possible tunnels is too cumbersome in
   many such cases.  In other cases the IP address of end points change
   or the end points may be behind NAT gateways, making static
   configuration impossible.  The Auto Discovery VPN solution is
   chartered to address these requirements.

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

   Internet-Drafts are draft documents valid for a maximum of six months
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   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 January 11, 2013.

Copyright Notice

   Copyright (c) 2012 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

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   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
     1.1.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .  3
     1.2.  Conventions Used in This Document  . . . . . . . . . . . .  4
   2.  Use Cases  . . . . . . . . . . . . . . . . . . . . . . . . . .  5
     2.1.  Endpoint-to-Endpoint P2P VPN Use Case  . . . . . . . . . .  5
     2.2.  Gateway-to-Gateway AD VPN Use Case . . . . . . . . . . . .  5
     2.3.  Endpoint-to-Gateway AD VPN Use Case  . . . . . . . . . . .  6
   3.  Inadequacy of Existing Solutions . . . . . . . . . . . . . . .  7
     3.1.  Exhaustive Configuration . . . . . . . . . . . . . . . . .  7
     3.2.  Star Topology  . . . . . . . . . . . . . . . . . . . . . .  7
     3.3.  Proprietary Approaches . . . . . . . . . . . . . . . . . .  8
   4.  Requirements . . . . . . . . . . . . . . . . . . . . . . . . .  9
     4.1.  Gateway and End Point Requirements . . . . . . . . . . . .  9
   5.  Security Considerations  . . . . . . . . . . . . . . . . . . . 10
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 11
   7.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12
   8.  Normative References . . . . . . . . . . . . . . . . . . . . . 13
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14

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1.  Introduction

   IPsec [RFC4301] is used in several different cases, including tunnel-
   mode site-to-site VPNs and Remote Access VPNs.  Host to host
   communication employing transport mode also exists, but is far less
   commonly deployed.

   The subject of this document is the problem presented by large scale
   deployments of IPsec and the requirements on a solution to address
   the problem.  These may be a large collection of VPN gateways
   connecting various sites, a large number of remote endpoints
   connecting to a number of gateways or to each other, or a mix of the
   two.  The gateways and endpoints may belong to a single
   administrative domain or several domains with a trust relationship.

   Section 4.4 of RFC 4301 describes the major IPsec databases needed
   for IPsec processing.  It requires an extensive configuration for
   each tunnel, so manually configuring a system of many gateways and
   endpoints becomes infeasible and inflexible.

   The difficulty is that all the configuration mentioned in RFC 4301 is
   not superfluous.  IKE implementations need to know the identity and
   credentials of all possible peer systems, as well as the addresses of
   hosts and/or networks behind them.  A simplified mechanism for
   dynamically establishing point-to-point tunnels is needed.  Section 2
   contains several use cases that motivate this effort.

1.1.  Terminology

   Endpoint - A device that implements IPsec for its own traffic but
   does not act as a gateway.

   Gateway - A network device that implements IPsec to protect traffic
   flowing through the device.

   Point-to-Point - Direct communication between two parties without
   active participation (e.g. encryption or decryption) by any other

   Hub - The central point in a star topology, generally implemented in
   a gateway

   Spoke - The edge devices in a star topology, implemented in endpoints
   or gateways

   Security Association (SA) - Defined in [RFC4301].

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1.2.  Conventions Used in This Document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in [RFC2119].

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2.  Use Cases

   This section presents the key use cases for large-scale point-to-
   point VPN.

   In all of these use cases, the participants (endpoints and gateways)
   may be from a single organization or from multiple organizations with
   an established trust relationship.  When multiple organizations are
   involved, products from multiple vendors are employed so open
   standards are needed to provide interoperability.  Establishing
   communications between participants with no established trust
   relationship is out of scope for this effort.

2.1.  Endpoint-to-Endpoint P2P VPN Use Case

   Two endpoints wish to communicate securely via a direct, point-to-
   point SA.

   The need for secure endpoint to endpoint communications is often
   driven by a need to employ high-bandwidth, low latency local
   connectivity instead of using slow, expensive links to remote
   gateways.  For example, two users in close proximity may wish to
   place a direct, secure video or voice call without needing to send
   the call through remote gateways, which would add latency to the
   call, consume precious remote bandwidth, and increase overall costs.
   Such a usecase also enables connectivity when both endpoints are
   behind NAT gateways.  Such usecase should allow for seamless
   connectivity even as Endpoints roam, in behing or away from gateways.

   In a hub and spoke topology when two end-points communicate, they
   must use a mechanism for authentication, such that they do not expose
   them to impersonation by the other spoke endpoint.

2.2.  Gateway-to-Gateway AD VPN Use Case

   A typical Enterprise traffic model is Hub and Spoke, with the
   Gateways connecting to each other using IPsec tunnels.

   However for the voice and other rich media traffic that occupies a
   lot of bandwidth and the traffic tromboning to the Hub can create
   traffic bottlenecks on the Hub and can lead to a increase cost.  It
   is for this purpose Spoke-to-Spoke tunnels are dynamically created
   and torn-down.

   The Spoke Gateways can themselves come up and down, getting different
   IP addresses in the process, making th static configuration

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   Also for the reasons of cost and manual error reduction, it is
   desired there be minimal or even no configuration on the Hub as a new
   Spoke Router is added or removed.

   In a hub and spoke topology when two spoke gateways communicate, they
   must use a mechanism for authentication, such that they do not expose
   them to impersonation by the other gateways spoke.

2.3.  Endpoint-to-Gateway AD VPN Use Case

   An endpoint should be able to use the most efficient gateway as it
   roams in the internet.

   A mobile user roaming on the Internet may connect to a gateway, which
   because of roaming is no longer the most efficient gateway to use
   (reasons could be cost/ efficiency/ latency or some other factor).
   The mobile user should be able to discover and then connect to the
   current most efficient gateway without having to reinitiate the

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3.  Inadequacy of Existing Solutions

   Several solutions exist for the problems described above.  However,
   none of these solutions is adequate, as described here.

3.1.  Exhaustive Configuration

   One simple solution is to configure all gateways and endpoints in
   advance with all the information needed to determine which gateway or
   endpoint is optimal and to establish an SA with that gateway or
   endpoint.  However, this solution does not scale in a large network
   with hundreds of thousands of gateways and endpoints, especially when
   multiple organizations are involved and things are rapidly changing
   (e.g. mobile endpoints).  Such a solution is also limited by the
   smallest endpoint/ gateway, as the same exhaustive configuration is
   to be applied on all endpoints/ gateways.  A more dynamic, secure and
   scalable system for establishing SAs between gateways is needed.

3.2.  Star Topology

   The most common way to address this problem today is to use what has
   been termed a "star topology".  In this case one or a few gateways
   are defined as "Hub gateways", while the rest of the systems (whether
   endpoints or gateways) are defined as "spokes".  The spokes never
   connect to other spokes.  They only open tunnels with the core
   gateways.  Also for a large number of gateways in one administrative
   domain, one gateway may be defined as the core, and the rest of the
   gateways and remote access clients connect only to that gateway.

   This solution however does not work when the spokes, get dynamic IP
   address which the "core gateways" cannot be configured with.  It is
   also desired that there is minimal to no configuration on the Hub as
   the number of spokes increases and new spokes are added and deleted

   Another problem with stars and trunks is that it creates a high load
   on the core gateways as well as on the trunk connection.  This load
   is both in processing power and in network bandwidth.  A single
   packet in the trunk scenario can be encrypted and decrypted three
   times.  It would be much preferable if these gateways and clients
   could initiate tunnels between them, bypassing the core gateways.
   Additionally, the path bandwidth to these core gateways may be lower
   than that of the path between the satellites.  For example, two
   remote access users may be in the same building with high-speed wifi
   (for example, at an IETF meeting).  Channeling their conversation
   through the core gateways of their respective employers seems
   extremely wasteful, as well as having lower bandwidth.

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   The challenge is to build a large scale, IPsec protected networks
   that can dynamically change with minimum administrative overhead.

3.3.  Proprietary Approaches

   Several vendors offer proprietary solutions to these problems.
   However, these solutions offer no interoperability between equipment
   from one vendor and another.  This means that they are generally
   restricted to use within one organization, and it is harder to move
   off such solutions as the features are not standardized.  Besides
   multiple organizations cannot be expected to all choose the same
   equipment vendor.

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4.  Requirements

   This section is currently being updated and hence under flux.

4.1.  Gateway and End Point Requirements

   1.  For any network topology (whether Hub-and-Spoke or Full Mesh)
   Gateways/ end points MUST allow for minimal configuration changes
   when a new Gateway or end-point is added, removed or changed.  The
   solution should allow for such configuration on a global basis.

   2.  Gateways/ end-points MUST allow IPsec Tunnels to be setup without
   any configuration changes, even as peer addresses gets updated every
   time the device comes up.

   3.  Gateways MUST allow tunnel binding, such that applications like
   Routing using the tunnels can work seamlessly without any updates to
   the higher level application configuration i.e.  OSPF configuration.

   4.  In a Hub-and-Spoke topology, Spoke Gateways/ en-points MUST allow
   for direct communication with other Spoke Gateways/ end-points, using
   authentication that does not expose them to other Gateway Spoke.

   5.Gateways SHOULD allow for easy handoff of sessions in case end-
   points are roamining and cross policy boundaries.

   6.  Gateways SHOULD allow for easy handoff of a session to another
   gateway, to optimize latency, bandwidth or other factor, based on

   7.  Gateways/ End-points MUST be able to work, behing NAT boxes.

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5.  Security Considerations

   The solution to the problems presented in this draft may involve
   dynamic updates to databases defined by RFC 4301, such as the
   Security Policy Database (SPD) or the Peer Authorization Database

   RFC 4301 is silent about the way these databases are populated, and
   it is implied that these databases are static and pre-configured by a
   human.  Allowing dynamic updates to these databases must be thought
   out carefully, because it allows the protocol to alter the security
   policy that the IPsec endpoints implement.

   One obvious attack to watch out for is stealing traffic to a
   particular site.  The IP address for www.example.com is
   If we add an entry to an IPsec endpoint's SPD that says that traffic
   to is protected through peer Gw-Mallory, then this allows
   Gw-Mallory to either pretend to be www.example.com or to proxy and
   read all traffic to that site.  Updates to this database requires a
   clear trust model.

   More to be added.

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6.  IANA Considerations

   No actions are required from IANA for this informational document.

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7.  Acknowledgements

   Many people have contributed to the development of this problem
   statement and many more will probably do so before we are done with
   it.  While we cannot thank all contributors, some have played an
   especially prominent role.  Yoav Nir, Yaron Scheffer, Jorge Coronel
   Mendoza, Chris Ulliott, and John Veizades wrote the document upon
   which this draft was based.  Geoffrey Huang, Suresh Melam, Praveen
   Sathyanarayan, Andreas Steffen, and Brian Weis provided essential

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8.  Normative References

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

   [RFC4301]  Kent, S. and K. Seo, "Security Architecture for the
              Internet Protocol", RFC 4301, December 2005.

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Authors' Addresses

   Steve Hanna
   Juniper Networks, Inc.
   1194 N. Mathilda Ave.
   Sunnyvale, CA  94089

   Email: shanna@juniper.net

   Vishwas Manral
   Hewlett-Packard Co.
   19111 Pruneridge Ave.
   Cupertino, CA  95113

   Email: vishwas.manral@hp.com

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