RFC 7296 - Internet Key Exchange Protocol Version 2 (IKEv2)

Abstract

This document describes version 2 of the Internet Key Exchange (IKE) protocol. IKE is a component of IPsec used for performing mutual authentication and establishing and maintaining Security Associations (SAs). This document obsoletes RFC 5996, and includes all of the errata for it. It advances IKEv2 to be an Internet Standard.

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/rfc7296.

Copyright Notice

Copyright (c) 2014 IETF Trust and the persons identified as the document authors. All rights reserved.

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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 material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. 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.

Contents

• 1. Introduction
  • 1.1. Usage Scenarios
    • 1.1.1. Security Gateway to Security Gateway in Tunnel Mode
    • 1.1.2. Endpoint-to-Endpoint Transport Mode
    • 1.1.3. Endpoint to Security Gateway in Tunnel Mode
    • 1.1.4. Other Scenarios
  • 1.2. The Initial Exchanges
  • 1.3. The CREATE_CHILD_SA Exchange
    • 1.3.1. Creating New Child SAs with the CREATE_CHILD_SA Exchange
    • 1.3.2. Rekeying IKE SAs with the CREATE_CHILD_SA Exchange
    • 1.3.3. Rekeying Child SAs with the CREATE_CHILD_SA Exchange
  • 1.4. The INFORMATIONAL Exchange
    • 1.4.1. Deleting an SA with INFORMATIONAL Exchanges
  • 1.5. Informational Messages outside of an IKE SA
  • 1.6. Requirements Terminology
  • 1.7. Significant Differences between RFC 4306 and RFC 5996
  • 1.8. Differences between RFC 5996 and This Document
• 2. IKE Protocol Details and Variations
  • 2.1. Use of Retransmission Timers
  • 2.2. Use of Sequence Numbers for Message ID
  • 2.3. Window Size for Overlapping Requests
  • 2.4. State Synchronization and Connection Timeouts
  • 2.5. Version Numbers and Forward Compatibility
  • 2.6. IKE SA SPIs and Cookies
    • 2.6.1. Interaction of COOKIE and INVALID_KE_PAYLOAD
  • 2.7. Cryptographic Algorithm Negotiation
  • 2.8. Rekeying
    • 2.8.1. Simultaneous Child SA Rekeying
    • 2.8.2. Simultaneous IKE SA Rekeying
    • 2.8.3. Rekeying the IKE SA versus Reauthentication
  • 2.9. Traffic Selector Negotiation
    • 2.9.1. Traffic Selectors Violating Own Policy
    • 2.9.2. Traffic Selectors in Rekeying
  • 2.10. Nonces
  • 2.11. Address and Port Agility
  • 2.12. Reuse of Diffie-Hellman Exponentials
  • 2.13. Generating Keying Material
  • 2.14. Generating Keying Material for the IKE SA
  • 2.15. Authentication of the IKE SA
  • 2.16. Extensible Authentication Protocol Methods
  • 2.17. Generating Keying Material for Child SAs
  • 2.18. Rekeying IKE SAs Using a CREATE_CHILD_SA Exchange
  • 2.19. Requesting an Internal Address on a Remote Network
  • 2.20. Requesting the Peer's Version
  • 2.21. Error Handling
    • 2.21.1. Error Handling in IKE_SA_INIT
    • 2.21.2. Error Handling in IKE_AUTH
    • 2.21.3. Error Handling after IKE SA is Authenticated
    • 2.21.4. Error Handling Outside IKE SA
  • 2.22. IPComp
  • 2.23. NAT Traversal
    • 2.23.1. Transport Mode NAT Traversal
  • 2.24. Explicit Congestion Notification (ECN)
  • 2.25. Exchange Collisions
    • 2.25.1. Collisions while Rekeying or Closing Child SAs
    • 2.25.2. Collisions while Rekeying or Closing IKE SAs
• 3. Header and Payload Formats
  • 3.1. The IKE Header
  • 3.2. Generic Payload Header
  • 3.3. Security Association Payload
    • 3.3.1. Proposal Substructure
    • 3.3.2. Transform Substructure
    • 3.3.3. Valid Transform Types by Protocol
    • 3.3.4. Mandatory Transform IDs
    • 3.3.5. Transform Attributes
    • 3.3.6. Attribute Negotiation
  • 3.4. Key Exchange Payload
  • 3.5. Identification Payloads
  • 3.6. Certificate Payload
  • 3.7. Certificate Request Payload
  • 3.8. Authentication Payload
  • 3.9. Nonce Payload
  • 3.10. Notify Payload
    • 3.10.1. Notify Message Types
  • 3.11. Delete Payload
  • 3.12. Vendor ID Payload
  • 3.13. Traffic Selector Payload
    • 3.13.1. Traffic Selector
  • 3.14. Encrypted Payload
  • 3.15. Configuration Payload
    • 3.15.1. Configuration Attributes
    • 3.15.2. Meaning of INTERNAL_IP4_SUBNET and INTERNAL_IP6_SUBNET
    • 3.15.3. Configuration Payloads for IPv6
    • 3.15.4. Address Assignment Failures
  • 3.16. Extensible Authentication Protocol (EAP) Payload
• 4. Conformance Requirements
• 5. Security Considerations
  • 5.1. Traffic Selector Authorization
• 6. IANA Considerations
• 7. References
  • 7.1. Normative References
  • 7.2. Informative References
• Appendix A. Summary of Changes from IKEv1
• Appendix B. Diffie-Hellman Groups
  • B.1. Group 1 - 768-bit MODP
  • B.2. Group 2 - 1024-bit MODP
• Appendix C. Exchanges and Payloads
  • C.1. IKE_SA_INIT Exchange
  • C.2. IKE_AUTH Exchange without EAP
  • C.3. IKE_AUTH Exchange with EAP
  • C.4. CREATE_CHILD_SA Exchange for Creating or Rekeying Child SAs
  • C.5. CREATE_CHILD_SA Exchange for Rekeying the IKE SA
  • C.6. INFORMATIONAL Exchange

Authors

• C. Kaufman, Microsoft
• P. Hoffman, VPN Consortium
• Y. Nir, Check Point
• P. Eronen, Independent
• T. Kivinen, INSIDE Secure

Published: October 2014