TCP Encapsulation of IKE and IPsec Packets
RFC 8229

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Internet Engineering Task Force (IETF)                          T. Pauly
Request for Comments: 8229                                    Apple Inc.
Category: Standards Track                                      S. Touati
ISSN: 2070-1721                                                 Ericsson
                                                               R. Mantha
                                                           Cisco Systems
                                                             August 2017

               TCP Encapsulation of IKE and IPsec Packets

Abstract

   This document describes a method to transport Internet Key Exchange
   Protocol (IKE) and IPsec packets over a TCP connection for traversing
   network middleboxes that may block IKE negotiation over UDP.  This
   method, referred to as "TCP encapsulation", involves sending both IKE
   packets for Security Association establishment and Encapsulating
   Security Payload (ESP) packets over a TCP connection.  This method is
   intended to be used as a fallback option when IKE cannot be
   negotiated over UDP.

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 7841.

   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/rfc8229.

Pauly, et al.                Standards Track                    [Page 1]
RFC 8229       TCP Encapsulation of IKE and IPsec Packets    August 2017

Copyright Notice

   Copyright (c) 2017 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1. Introduction ....................................................3
      1.1. Prior Work and Motivation ..................................4
      1.2. Terminology and Notation ...................................5
   2. Configuration ...................................................5
   3. TCP-Encapsulated Header Formats .................................6
      3.1. TCP-Encapsulated IKE Header Format .........................6
      3.2. TCP-Encapsulated ESP Header Format .........................7
   4. TCP-Encapsulated Stream Prefix ..................................7
   5. Applicability ...................................................8
      5.1. Recommended Fallback from UDP ..............................8
   6. Connection Establishment and Teardown ...........................9
   7. Interaction with NAT Detection Payloads ........................11
   8. Using MOBIKE with TCP Encapsulation ............................11
   9. Using IKE Message Fragmentation with TCP Encapsulation .........12
   10. Considerations for Keep-Alives and Dead Peer Detection ........12
   11. Middlebox Considerations ......................................12
   12. Performance Considerations ....................................13
      12.1. TCP-in-TCP ...............................................13
      12.2. Added Reliability for Unreliable Protocols ...............14
      12.3. Quality-of-Service Markings ..............................14
      12.4. Maximum Segment Size .....................................14
      12.5. Tunneling ECN in TCP .....................................14
   13. Security Considerations .......................................15
   14. IANA Considerations ...........................................16
   15. References ....................................................16
      15.1. Normative References .....................................16
      15.2. Informative References ...................................17

Pauly, et al.                Standards Track                    [Page 2]
RFC 8229       TCP Encapsulation of IKE and IPsec Packets    August 2017

   Appendix A. Using TCP Encapsulation with TLS ......................18
   Appendix B. Example Exchanges of TCP Encapsulation with TLS .......19
     B.1. Establishing an IKE Session ................................19
     B.2. Deleting an IKE Session ....................................21
     B.3. Re-establishing an IKE Session .............................22