Network Working Group Y. Nir
Internet-Draft Check Point
Intended status: Standards Track Q. Wu
Expires: November 2, 2011 Huawei
May 1, 2011
An IKEv2 Extension for Supporting ERP
draft-nir-ipsecme-erx-00
Abstract
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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1. Introduction
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.
1.1. Conventions Used in This Document
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].
2. Usage Scenarios
Several scenarios motivated this proposal:
o Multiple tunnels for a single remote access VPN client. Suppose a
company has offices in New York City, Paris, and Shanghai. For
historical reasons, the email server is located in the Paris
office, while most of the servers hosting the company's intranet
are located in Shanghai, and the finance department servers are in
NYC. An employee using remote access VPN may need to connect to
servers from all three locations. While it is possible to connect
to a single gateway, and have that gateway route the requests to
the other gateways (perhaps through site-2-site VPN), this is not
efficient, and it is more desirable to have the client initiate
three different tunnels. It is, however, not desirable to have
the user type in a password three times.
o Roaming. In these days of mobile phones and tablets, users often
move from the wireless LAN in their office, where access may be
granted through 802.1x, to a cellular network where VPN is
necessary and back again. Both the VPN server and the 802.1x
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access point are authenticators that connect to the same AAA
servers. So it makes sense to make the transition smooth, without
requiring user interaction. [SecureBeacon] is an attempt to allow
detecting whether the client should connect using VPN or not.
3. Protocol Outline
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.
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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+]
3.1. Clarification About EAP Codes
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).
4. ERX_SUPPORTED Notification
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 !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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o Protocol ID (1 octet) MUST be 1, as this message is related to an
IKE SA.
o SPI Size (1 octet) MUST be zero, in conformance with section 3.10
of [RFC5996].
o ERX Notify Message Type (2 octets) - MUST be xxxxx, the value
assigned for ERX. TBA by IANA.
o Domain Name (variable) - contains the domain name or realm, as
these terms are used in [RFC5296bis].
5. Security Considerations
TBA
6. IANA Considerations
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".
7. References
7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5296bis]
Wu, W., Cao, Z., Shi, Y., and B. He, "EAP Extensions for
EAP Re-authentication Protocol (ERP)",
draft-ietf-hokey-rfc5296bis-02 (work in progress),
March 2011.
[RFC5996] Kaufman, C., Hoffman, P., Nir, Y., and P. Eronen,
"Internet Key Exchange Protocol: IKEv2", RFC 5996,
September 2010.
7.2. Informative References
[SecureBeacon]
Sheffer, Y. and Y. Nir, "Secure Beacon: Securely Detecting
a Trusted Network", draft-sheffer-ipsecme-secure-beacon
(work in progress), June 2009.
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Authors' Addresses
Yoav Nir
Check Point Software Technologies Ltd.
5 Hasolelim st.
Tel Aviv 67897
Israel
Email: ynir@checkpoint.com
Q. Wu
Huawei Technologies Co., Ltd.
101 Software Avenue, Yuhua District
Nanjing, JiangSu 210012
China
Email: Sunseawq@huawei.com
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