| Network Working Group | Y. Nir |
| Internet-Draft | Check Point |
| Intended status: Standards Track | Q. Wu |
| Expires: November 02, 2011 | Huawei |
| May 01, 2011 |
An IKEv2 Extension for Supporting ERP
draft-nir-ipsecme-erx-00
This document describes an extension to the IKEv2 protocol that allows an IKE Security Association (SA) to be created and authenticated using the EAP Re-authentication Protocol extension as described in RFC 5296 and its bis document.
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IKEv2, as specified in [RFC5996], allows authentication of the initiator using an EAP method. This is described in section 2.16. Using EAP significantly increases the count of round-trips required to establish the IPsec SA, and also may require user interaction. This makes it inconvenient to allow a single remote access client to create multiple IPsec tunnels with multiple IPsec gateways that belong to the same domain.
The EAP Re-authentication Protocol (ERP), as descripted in [RFC5296bis], allows an EAP peer to authenticate to multiple authenticators, while performing the full EAP method only once. Subsequent authentications require fewer round-trips and no user interaction.
Bringing these two technologies together allows a remote access IPsec client to create multiple tunnels with different gateways that belong to a single domain, as well as using the keys from other contexts of using EAP, such as network access within the same domain, to transparently connect to VPN gateways within this domain.
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 [RFC2119].
Several scenarios motivated this proposal:
Supporting ERX requires an EAP payload in the first IKE_AUTH request. This is a deviation from the rules in RFC 5996, so support needs to be indicated through a Notify payload in the IKE_SA_INIT response. This Notify replaces the EAP-Initiate/Re-auth-Start message of ERX, and therefore contains the domain name, as specified in section 5.3.1.1 of [RFC5296bis].
A supporting initiator that has unexpired keys for this domain will send the EAP_Initiate/Re-auth message in an EAP payload in the first IKE_AUTH request.
The responder sends the EAP payload content to a backend AAA server, and receives the rMSK and an EAP-Finish/Re-auth message. If forwards that to the initiator in an EAP payload within the first IKE_AUTH response.
The initiator then sends an additional IKE_AUTH request, that includes the AUTH payload which has been calculated using the rMSK in the role of the MSK as described in sections 2.15 and 2.16 or [RFC5996]. The responder replies similarly, and the IKE_AUTH exchange is finished.
The following figure is adapted from appendixes C.1 and C.3 of RFC 5996, with most of the optional payloads removed. Note that the EAP_Initiate/Re-auth message replaces the IDi payload.
init request --> SA, KE, Ni,
init response <-- SA, KE, Nr,
N[ERX_SUPPORTED]
first request --> EAP(EAP_Initiate/Re-auth),
[[N(HTTP_CERT_LOOKUP_SUPPORTED)], CERTREQ+],
[IDr],
[CP(CFG_REQUEST)],
SA, TSi, TSr,
[V+][N+]
first response <-- IDr, [CERT+], AUTH,
EAP(EAP-Finish/Re-auth),
[V+][N+]
last request --> AUTH
last response <-- AUTH,
[CP(CFG_REPLY)],
SA, TSi, TSr,
[V+][N+]
Section 3.16 of [RFC5996] enumerates the EAP codes in EAP messages which are carried in EAP payloads. The enumeration goes only to 4. It is not clear whether that list is supposed to be exhaustive or not.
To clarify, an implementation supporting this specification MUST accept and transmit EAP messages with at least the codes for Initiate and Finish (5 and 6).
The Notify payload is as described in [RFC5996]
1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! Next Payload !C! RESERVED ! Payload Length !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! Protocol ID ! SPI Size ! ERX Notify Message Type !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! Domain Name !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
TBA
IANA is requested to assign a notify message type from the status types range (16418-40959) of the "IKEv2 Notify Message Types" registry with name "ERX_SUPPORTED".
| [1] | Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. |
| [2] | Kaufman, C, Hoffman, P, Nir, Y and P Eronen, "Internet Key Exchange Protocol: IKEv2", RFC 5996, September 2010. |
| [3] | Wu, W, Cao, Z, Shi, Y and B He, "EAP Extensions for EAP Re-authentication Protocol (ERP)", Internet-Draft draft-ietf-hokey-rfc5296bis-02, March 2011. |
| [1] | Sheffer, Y. and Y. Nir, "Secure Beacon: Securely Detecting a Trusted Network", Internet-Draft draft-sheffer-ipsecme-secure-beacon, June 2009. |