Wrapped Encapsulating Security Payload (ESP) for Traffic Visibility
RFC 5840

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Internet Engineering Task Force (IETF)                         K. Grewal
Request for Comments: 5840                             Intel Corporation
Category: Standards Track                                  G. Montenegro
ISSN: 2070-1721                                    Microsoft Corporation
                                                               M. Bhatia
                                                          Alcatel-Lucent
                                                              April 2010

  Wrapped Encapsulating Security Payload (ESP) for Traffic Visibility

Abstract

   This document describes the Wrapped Encapsulating Security Payload
   (WESP) protocol, which builds on the Encapsulating Security Payload
   (ESP) RFC 4303 and is designed to allow intermediate devices to (1)
   ascertain if data confidentiality is being employed within ESP, and
   if not, (2) inspect the IPsec packets for network monitoring and
   access control functions.  Currently, in the IPsec ESP standard,
   there is no deterministic way to differentiate between encrypted and
   unencrypted payloads by simply examining a packet.  This poses
   certain challenges to the intermediate devices that need to deep
   inspect the packet before making a decision on what should be done
   with that packet (Inspect and/or Allow/Drop).  The mechanism
   described in this document can be used to easily disambiguate
   integrity-only ESP from ESP-encrypted packets, without compromising
   on the security provided by ESP.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc5840.

Grewal, et al.               Standards Track                    [Page 1]
RFC 5840               WESP for Traffic Visibility            April 2010

Copyright Notice

   Copyright (c) 2010 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
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   This document may contain material from IETF Documents or IETF
   Contributions published or made publicly available before November
   10, 2008.  The person(s) controlling the copyright in some of this
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   Without obtaining an adequate license from the person(s) controlling
   the copyright in such materials, this document may not be modified
   outside the IETF Standards Process, and derivative works of it may
   not be created outside the IETF Standards Process, except to format
   it for publication as an RFC or to translate it into languages other
   than English.

Table of Contents

   1. Introduction ....................................................3
      1.1. Requirements Language ......................................4
      1.2. Applicability Statement ....................................4
   2. Wrapped ESP (WESP) Header Format ................................5
      2.1. UDP Encapsulation ..........................................8
      2.2. Transport and Tunnel Mode Considerations ...................9
           2.2.1. Transport Mode Processing ...........................9
           2.2.2. Tunnel Mode Processing .............................10
      2.3. IKE Considerations ........................................11
   3. Security Considerations ........................................12
   4. IANA Considerations ............................................13
   5. Acknowledgments ................................................13
   6. References .....................................................14
      6.1. Normative References ......................................14
      6.2. Informative References ....................................14

Grewal, et al.               Standards Track                    [Page 2]
RFC 5840               WESP for Traffic Visibility            April 2010

1.  Introduction

   Use of ESP within IPsec [RFC4303] specifies how ESP packet