One document matched: draft-nir-ike-qcd-02.txt
Differences from draft-nir-ike-qcd-01.txt
Network Working Group Y. Nir
Internet-Draft Check Point
Intended status: Standards Track F. Detienne
Expires: February 7, 2009 P. Sethi
Cisco
August 6, 2008
A Quick Crash Detection Method for IKE
draft-nir-ike-qcd-02
Status of this Memo
By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
This Internet-Draft will expire on February 7, 2009.
Abstract
This document describes an extension to the IKEv2 protocol that
allows for faster detection of SA desynchronization using a saved
token.
When an IPsec tunnel between two IKEv2 peers is disconnected due to a
restart of one peer, it can take as much as several minutes for the
other peer to discover that the reboot has occurred, thus delaying
recovery. In this text we propose an extension to the protocol, that
allows for recovery immediately following the restart.
Nir, et al. Expires February 7, 2009 [Page 1]
Internet-Draft Quick Crash Detection August 2008
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Conventions Used in This Document . . . . . . . . . . . . 3
2. RFC 4306 Crash Recovery . . . . . . . . . . . . . . . . . . . 3
3. Protocol Outline . . . . . . . . . . . . . . . . . . . . . . . 4
4. Formats and Exchanges . . . . . . . . . . . . . . . . . . . . 5
4.1. Notification Format . . . . . . . . . . . . . . . . . . . 5
4.2. Passing a Token in the AUTH Exchange . . . . . . . . . . . 5
4.3. Replacing Tokens After Rekey or Resumption . . . . . . . . 7
4.4. Presenting the Token in an INFORMATIONAL Exchange . . . . 7
5. Token Generation and Verification . . . . . . . . . . . . . . 8
5.1. A Stateless Method of Token Generation . . . . . . . . . . 8
5.2. Token Lifetime . . . . . . . . . . . . . . . . . . . . . . 9
6. Backup Gateways . . . . . . . . . . . . . . . . . . . . . . . 9
7. Alternative Solutions . . . . . . . . . . . . . . . . . . . . 9
7.1. Initiating a new IKE SA . . . . . . . . . . . . . . . . . 9
7.2. Birth Certificates . . . . . . . . . . . . . . . . . . . . 9
8. Interaction with Session Resumption . . . . . . . . . . . . . 10
9. Operational Considerations . . . . . . . . . . . . . . . . . . 11
9.1. Who should implement this specification . . . . . . . . . 11
9.2. Response to unknown child SPI . . . . . . . . . . . . . . 12
10. Security Considerations . . . . . . . . . . . . . . . . . . . 13
10.1. QCD Token Handling . . . . . . . . . . . . . . . . . . . . 13
10.2. QCD Token Transmission . . . . . . . . . . . . . . . . . . 13
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 14
13. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . . 14
13.1. Changes from draft-nir-ike-qcd-01 . . . . . . . . . . . . 14
13.2. Changes from draft-nir-ike-qcd-00 . . . . . . . . . . . . 14
13.3. Changes from draft-nir-qcr-00 . . . . . . . . . . . . . . 14
14. References . . . . . . . . . . . . . . . . . . . . . . . . . . 15
14.1. Normative References . . . . . . . . . . . . . . . . . . . 15
14.2. Informative References . . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15
Intellectual Property and Copyright Statements . . . . . . . . . . 17
Nir, et al. Expires February 7, 2009 [Page 2]
Internet-Draft Quick Crash Detection August 2008
1. Introduction
IKEv2, as described in [RFC4306] has a method for recovering from a
reboot of one peer. As long as traffic flows in both directions, the
rebooted peer should re-establish the tunnels immediately. However,
in many cases the rebooted peer is a VPN gateway that protects only
servers, or else the non-rebooted peer has a dynamic IP address. In
such cases, the rebooted peer will not be able to re-establish the
tunnels. Section 2 describes how recovery works under RFC 4306, and
explains why it takes several minutes.
The method proposed here, is to send a token in the IKE_AUTH exchange
that establishes the tunnel. That token can be stored on the peer as
part of the IKE SA. After a reboot, the rebooted implementation can
re-generate the token, and send it to the non-rebooted peer so as to
delete the IKE SA. Deleting the IKE SA results is a quick re-
establishment of the IPsec tunnels. This is described in Section 3.
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].
The term "token" refers to an octet string that an implementation can
generate using only the IKE SPIs as input. A conforming
implementation MUST be able to generate the same token from the same
input even after rebooting.
The term "token maker" refers to an implementation that generates a
token and sends it to the peer in the IKE_AUTH exchange.
The term "token taker" refers to an implementation that stores such a
token or a digest thereof, after receiving it in an IKE_AUTH
exchange.
2. RFC 4306 Crash Recovery
When one peer reboots, the other peer does not get any notification,
so IPsec traffic can still flow. The rebooted peer will not be able
to decrypt it, however, and the only remedy is to send an unprotected
INVALID_SPI notification as described in section 3.10.1 of [RFC4306].
That section also describes the processing of such a notification:
"If this Informational Message is sent outside the context of an
IKE_SA, it should be used by the recipient only as a "hint" that
something might be wrong (because it could easily be forged)."
Nir, et al. Expires February 7, 2009 [Page 3]
Internet-Draft Quick Crash Detection August 2008
Since the INVALID_SPI can only be used as a hint, the non-rebooted
peer has to determine whether the IPsec SA, and indeed the parent IKE
SA are still valid. The method of doing this is described in section
2.4 of [RFC4306]. This method, called "liveness check" involves
sending a protected empty INFORMATIONAL message, and awaiting a
response. This procedure is sometimes referred to as "Dead Peer
Detection" or DPD.
Section 2.4 does not mandate how many times the liveness check
message should be retransmitted, or for how long, but does recommend
the following: "It is suggested that messages be retransmitted at
least a dozen times over a period of at least several minutes before
giving up on an SA". Clearly, implementations differ, but all will
take a significant amount of time.
3. Protocol Outline
Supporting implementations will send a notification, called a "QCD
token", as described in Section 4.1 in the last packets of the
IKE_AUTH exchange. These are the final request and final response
that contain the AUTH payloads. The generation of these tokens is a
local matter for implementations, but considerations are described in
Section 5. Implementations that send such a token will be called
"token makers".
A supporting implementation receiving such a token SHOULD store it as
part of the IKE SA. Implementations that support this part of the
protocol will be called "token takers". Section 9.1 has
considerations for which implementations need to be token takers, and
which should be token makers. Implementation that are not token
takers will silently ignore QCD tokens.
When a token maker receives a protected IKE request message with
unknown IKE SPIs, it MUST generate a new token that is identical to
the previous token, and send it to the requesting peer in an
unprotected IKE message as described in Section 4.4.
When a token taker receives the QCD token in an unprotected
notification, it MUST verify that the TOKEN_SECRET_DATA matches the
token stored in the matching the IKE SA. If the verification fails,
or if the IKE SPIs in the message do not match any existing IKE SA,
it SHOULD log the event. If it succeeds, it MUST delete the IKE SA
associated with the IKE_SPI fields, and all dependant child SAs.
This event MAY also be logged. The token taker MUST accept such
tokens from any address, so as to allow different kinds of high-
availability configuration of the token maker.
Nir, et al. Expires February 7, 2009 [Page 4]
Internet-Draft Quick Crash Detection August 2008
A supporting token taker MAY immediately create new SAs using an
Initial exchange, or it may wait for subsequent traffic to trigger
the creation of new SAs.
There is ongoing work on IKEv2 Session Resumption [resumption]. See
Section 8 for a short discussion about this protocol's interaction
with session resumption.
4. Formats and Exchanges
4.1. Notification Format
The notification payload called "QCD token" is formatted as follows:
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 ! QCD Token Notify Message Type !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! !
~ TOKEN_SECRET_DATA ~
! !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
o Protocol ID (1 octet) MUST contain 1, as this message is related
to an IKE SA.
o SPI Size (1 octet) MUST be zero, in conformance with [RFC4306].
o QCD Token Notify Message Type (2 octets) - MUST be xxxxx, the
value assigned for QCD token notifications. TBA by IANA.
o TOKEN_SECRET_DATA (16-128 octets) contains a generated token as
described in Section 5.
4.2. Passing a Token in the AUTH Exchange
For clarity, only the EAP version of an AUTH exchange will be
presented here. The non-EAP version is very similar. The figures
below are based on appendix A.3 of [RFC4718].
Nir, et al. Expires February 7, 2009 [Page 5]
Internet-Draft Quick Crash Detection August 2008
first request --> IDi,
[N(INITIAL_CONTACT)],
[[N(HTTP_CERT_LOOKUP_SUPPORTED)], CERTREQ+],
[IDr],
[CP(CFG_REQUEST)],
[N(IPCOMP_SUPPORTED)+],
[N(USE_TRANSPORT_MODE)],
[N(ESP_TFC_PADDING_NOT_SUPPORTED)],
[N(NON_FIRST_FRAGMENTS_ALSO)],
SA, TSi, TSr,
[V(SIR_VID)]
[V+]
first response <-- IDr, [CERT+], AUTH,
EAP,
[V(SIR_VID)]
[V+]
/ --> EAP
repeat 1..N times |
\ <-- EAP
last request --> AUTH
[N(QCD_TOKEN)]
last response <-- AUTH,
[N(QCD_TOKEN)]
[CP(CFG_REPLY)],
[N(IPCOMP_SUPPORTED)],
[N(USE_TRANSPORT_MODE)],
[N(ESP_TFC_PADDING_NOT_SUPPORTED)],
[N(NON_FIRST_FRAGMENTS_ALSO)],
SA, TSi, TSr,
[N(ADDITIONAL_TS_POSSIBLE)],
[V+]
Note that the QCD_TOKEN notification is marked as optional because it
is not required by this specification that every implementation be
both token maker and token taker. If only one peer sends the QCD
token, then a reboot of the other peer will not be recoverable by
this method. This may be acceptable if traffic typically originates
from the other peer.
In any case, the lack of a QCD_TOKEN notification MUST NOT be taken
as an indication that the peer does not support this standard.
Conversely, if a peer does not understand this notification, it will
simply ignore it. Therefore a peer MAY send this notification
freely, even if it does not know whether the other side supports it.
Nir, et al. Expires February 7, 2009 [Page 6]
Internet-Draft Quick Crash Detection August 2008
The QCD_TOKEN notification is related to the IKE SA and MUST follow
the AUTH payload and precede the Configuration payload and all
payloads related to the child SA.
4.3. Replacing Tokens After Rekey or Resumption
After rekeying an IKE SA, the IKE SPIs are replaced, so the new SA
also needs to have a token. If only the responder in the rekey
exchange is the token maker, this can be done before within the
CREATE_CHILD_SA exchange. If the initiator is a token maker, then we
need an extra informational exchange.
The following figure shows the CREATE_CHILD_SA exchange for rekeying
the IKE SA. Only the responder sends a stateless token.
request --> SA, Ni, [KEi]
response <-- SA, Nr, [KEr], N(QCD_TOKEN)
If the initiator is also a token maker, it SHOULD soon initiate an
INFORMATIONAL exchange as follows:
request --> N(QCD_TOKEN)
response <--
For session resumption, as specified in [resumption], the situation
is similar. The responder, which is necessarily the peer that has
crashed, SHOULD send a new ticket within the protected payload of the
IKE_SESSION_RESUME exchange. If the Initiator is also a token maker,
it needs to send a QCD_TOKEN in a separate INFORMATIONAL exchange.
4.4. Presenting the Token in an INFORMATIONAL Exchange
This QCD_TOKEN notification is unprotected, and is sent as a response
to a protected IKE request, which uses an IKE SA that is unknown.
request --> N(INVALID_IKE_SPI), N(QCD_TOKEN)+
If child SPIs are persistently mapped to IKE SPIs as described in
Section 9.2, we may get the following exchange in response to an ESP
or AH packet.
request --> N(INVALID_SPI), N(QCD_TOKEN)+
The QCD_TOKEN and INVALID_IKE_SPI notifications are sent together to
support both implementations that conform to this specification and
implementations that don't. Similar to the description in section
Nir, et al. Expires February 7, 2009 [Page 7]
Internet-Draft Quick Crash Detection August 2008
2.21 of [RFC4306], The IKE SPI and message ID fields in the packet
headers are taken from the protected IKE request.
To support a periodic rollover of the secret used for token
generation, the token taker MUST support at least four QCD_TOKEN
notifications in a single packet. The token is considered verified
if any of the QCD_TOKEN notifications matches. The token maker MAY
generate up to four QCD_TOKEN notifications, based on several
generations of keys.
If the QCD_TOKEN verifies OK, an empty response MUST be sent. If the
QCD_TOKEN cannot be validated, a response SHOULD NOT be sent.
Section 5 defines token verification.
5. Token Generation and Verification
No token generation method is mandated by this document. A method is
documented in Section 5.1, but only serves as an example.
The following lists the requirements from a token generation
mechanism:
o Tokens MUST be at least 16 octets long, and no more than 128
octets long, to facilitate storage and transmission. Tokens
SHOULD be indistinguishable from random data.
o It should not be possible for an external attacker to guess the
QCD token generated by an implementation. Cryptographic
mechanisms such as PRNG and hash functions are RECOMMENDED.
o The token maker, MUST be able to re-generate or retrieve the token
based on the IKE SPIs even after it reboots.
5.1. A Stateless Method of Token Generation
This describes a stateless method of generating a token:
o At installation or immediately after the first boot of the IKE
implementation, 32 random octets are generated using a secure
random number generator or a PRNG.
o Those 32 bytes, called the "QCD_SECRET", are stored in non-
volatile storage on the machine, and kept indefinitely.
o The TOKEN_SECRET_DATA is calculated as follows:
TOKEN_SECRET_DATA = HASH(QCD_SECRET | SPI-I | SPI-R)
o If key rollover is required by policy, the implementation MAY
periodically generate a new QCD_SECRET and keep up to 3 previous
generations. When sending an unprotected QCD_TOKEN, as many as 4
Nir, et al. Expires February 7, 2009 [Page 8]
Internet-Draft Quick Crash Detection August 2008
notification payloads may be sent, each from a different
QCD_SECRET.
5.2. Token Lifetime
The token is associated with a single IKE SA, and SHOULD be deleted
by the token taker when the SA is deleted or expires. More formally,
the token is associated with the pair (SPI-I, SPI-R).
6. Backup Gateways
Making crash detection and recovery quick is a worthy goal, but since
rebooting a gateway takes a non-zero amount of time, many
implementations choose to have a stand-by gateway ready to take over
as soon as the primary gateway fails for any reason.
If such a configuration is available, it is RECOMMENDED that the
stand-by gateway be able to generate the same token as the active
gateway. if the method described in Section 5.1 is used, this means
that the QCD_SECRET field is identical in both gateways. This has
the effect of having the crash recovery available immediately.
7. Alternative Solutions
7.1. Initiating a new IKE SA
Instead of sending a QCD token, we could have the rebooted
implementation start an Initial exchange with the peer, including the
INITIAL_CONTACT notification. This would have the same effect,
instructing the peer to erase the old IKE SA, as well as establishing
a new IKE SA with fewer rounds.
The disadvantage here, is that in IKEv2 an authentication exchange
MUST have a piggy-backed Child SA set up. Since our use case is such
that the rebooted implementation does not have traffic flowing to the
peer, there are no good selectors for such a Child SA.
Additionally, when authentication is asymmetric, such as when EAP is
used, it is not possible for the rebooted implementation to initiate
IKE.
7.2. Birth Certificates
Birth Certificates is a method of crash detection that has never been
formally defined. Bill Sommerfeld suggested this idea in a mail to
the IPsec mailing list on August 7, 2000, in a thread discussing
Nir, et al. Expires February 7, 2009 [Page 9]
Internet-Draft Quick Crash Detection August 2008
methods of crash detection:
If we have the system sign a "birth certificate" when it
reboots (including a reboot time or boot sequence number),
we could include that with a "bad spi" ICMP error and in
the negotiation of the IKE SA.
We believe that this method would have some problems. First, it
requires Alice to store the certificate, so as to be able to compare
the public keys. That requires more storage than does a QCD token.
Additionally, the public-key operations needed to verify the self-
signed certificates are more expensive for Alice.
We believe that a symmetric-key operation such as proposed here is
more light-weight and simple than that implied by the Birth
Certificate idea.
8. Interaction with Session Resumption
Session Resumption, specified in [resumption] proposes to make
setting up a new IKE SA consume less computing resources. This is
particularly useful in the case of a remote access gateway that has
many tunnels. A failure of such a gateway would require all these
many remote access clients to establish an IKE SA either with the
rebooted gateway or with a backup gateway. This tunnel re-
establishment should occur within a short period of time, creating a
burden on the remote access gateway. Session Resumption addresses
this problem by having the clients store an encrypted derivative of
the IKE SA for quick re-establishment.
What Session Resumption does not help, is the problem of detecting
that the peer gateway has failed. A failed gateway may go undetected
for as long as the lifetime of a child SA, because IPsec does not
have packet acknowledgement, and applications cannot signal the IPsec
layer that the tunnel "does not work". Before establishing a new IKE
SA using Session Resumption, a client MUST ascertain that the gateway
has indeed failed. This could be done using either a liveness check
(as in RFC 4306) or using the QCD tokens described in this document.
A remote access client conforming to both specifications will store
QCD tokens, as well as the Session Resumption ticket, if provided by
the gateway. A remote access gateway conforming to both
specifications will generate a QCD token for the client. When the
gateway reboots, the client will discover this in either of two ways:
1. The client does regular liveness checks, or else the time for
some other IKE exchange has come. Since the gateway is still
down, the IKE times out after several minutes. In this case QCD
Nir, et al. Expires February 7, 2009 [Page 10]
Internet-Draft Quick Crash Detection August 2008
does not help.
2. Either the primary gateway or a backup gateway (see Section 6) is
ready and sends a QCD token to the client. In that case the
client will quickly re-establish the IPsec tunnel, either with
the rebooted primary gateway, the backup gateway as described in
this document or another gateway as described in [resumption]
The full combined protocol looks like this:
Initiator Responder
----------- -----------
HDR, SAi1, KEi, Ni -->
<-- HDR, SAr1, KEr, Nr, [CERTREQ]
HDR, SK {IDi, [CERT,]
[CERTREQ,] [IDr,]
AUTH, N(QCD_TOKEN)
SAi2, TSi, TSr,
N(TICKET_REQUEST)} -->
<-- HDR, SK {IDr, [CERT,] AUTH, SAr2, TSi,
TSr, N(TICKET_OPAQUE)
[,N(TICKET_GATEWAY_LIST)]}
---- Reboot -----
HDR, {} -->
<-- HDR, N(QCD_Token)
HDR, Ni, N(TICKET_OPAQUE),
[N+,], SK {IDi, [IDr,]
SAi2, TSi, TSr,
[CP(CFG_REQUEST)]} -->
<-- HDR, SK {IDr, Nr, SAr2, [TSi, TSr],
[CP(CFG_REPLY)]}
9. Operational Considerations
9.1. Who should implement this specification
Throughout this document, we have referred to reboot time
alternatingly as the time that the implementation crashes and the
time when it is ready to process IPsec packets and IKE exchanges.
Depending on the hardware and software platforms and the cause of the
reboot, rebooting may take anywhere from a few seconds to several
Nir, et al. Expires February 7, 2009 [Page 11]
Internet-Draft Quick Crash Detection August 2008
minutes. If the implementation is down for a long time, the benefit
of this protocol extension is reduced. For this reason critical
systems should implement backup gateways as described in Section 6.
Note that the lower-case "should" in the previous sentence is
intentional, as we do not specify this in the sense of RFC 2119.
Implementing the "token maker" side of QCD makes sense for IKE
implementation where protected connections originate from the peer,
such as inter-domain VPNs and remote access gateways. Implementing
the "token taker" side of QCD makes sense for IKE implementations
where protected connections originate, such as inter-domain VPNs and
remote access clients.
To clarify the requirements:
o A remote-access client MUST be a token taker and MAY be a token
maker.
o A remote-access gateway MAY be a token taker and MUST be a token
maker.
o An inter-domain VPN gateway MUST be both token maker and token
taker.
In order to limit the effects of DoS attacks, a token taker SHOULD
limit the rate of QCD_TOKENs verified from a particular source.
If excessive amounts of IKE requests protected with unknown IKE SPIs
arrive at a token maker, the IKE module SHOULD revert to the behavior
described in section 2.21 of [RFC4306] and either send an
INVALID_IKE_SPI notification, or ignore it entirely.
9.2. Response to unknown child SPI
After a reboot, it is more likely that an implementation receives
IPsec packets than IKE packets. In that case, the rebooted
implementation will send an INVALID_SPI notification, triggering a
liveness check. The token will only be sent in a response to the
liveness check, thus requiring an extra round-trip.
To avoid this, an implementation that has access to non-volatile
storage MAY store a mapping of child SPIs to owning IKE SPIs, or to
generated toekns. If such a mapping is available and persistent
across reboots, the rebooted implementation SHOULD respond to the
IPsec packet with an INVALID_SPI notification, along with the
appropriate QCD_Token notifications. A token taker SHOULD verify the
QCD token that arrives with an INVALID_SPI notification the same as
if it arrived with the IKE SPIs of the parent IKE SA.
However, a persistent storage module might not be updated in a timely
manner, and could be populated with IKE SPIs that have already been
Nir, et al. Expires February 7, 2009 [Page 12]
Internet-Draft Quick Crash Detection August 2008
rekeyed. A token taker MUST NOT take an invalid QCD Token sent along
with an INVALID_SPI notification as evidence that the peer is either
malfunctioning or attacking, but it SHOULD limit the rate at which
such notifications are processed.
10. Security Considerations
10.1. QCD Token Handling
Tokens MUST be hard to guess. This is critical, because if an
attacker can guess the token associated with the IKE SA, she can tear
down the IKE SA and associated tunnels at will. When the token is
delivered in the IKE_AUTH exchange, it is encrypted. When it is sent
again in an unprotected notification, it is not, but that is the last
time this token is ever used.
An aggregation of some tokens generated by one peer together with the
related IKE SPIs MUST NOT give an attacker the ability to guess other
tokens. Specifically, if one peer does not properly secure the QCD
tokens and an attacker gains access to them, this attacker MUST NOT
be able to guess other tokens generated by the same peer. This is
the reason that the QCD_SECRET in Section 5.1 needs to be
sufficiently long.
The QCD_SECRET MUST be protected from access by other parties.
Anyone gaining access to this value will be able to delete all the
IKE SAs for this token maker.
The QCD token is sent by the rebooted peer in an unprotected message.
A message like that is subject to modification, deletion and replay
by an attacker. However, these attacks will not compromise the
security of either side. Modification is meaningless because a
modified token is simply an invalid token. Deletion will only cause
the protocol not to work, resulting in a delay in tunnel re-
establishment as described in Section 2. Replay is also meaningless,
because the IKE SA has been deleted after the first transmission.
10.2. QCD Token Transmission
A token maker MUST NOT send a QCD token in an unprotected message for
an existing IKE SA. This implies that a conforming QCD token maker
MUST be able to tell whether a particular pair of IKE SPIs represent
a valid IKE SA.
This requirement is obvious and easy in the case of a single gateway.
However, some implementations use a load balancer to divide the load
between several physical gateways. It MUST NOT be possible even in
Nir, et al. Expires February 7, 2009 [Page 13]
Internet-Draft Quick Crash Detection August 2008
such a configuration to trick one gateway into sending a QCD token
for an IKE SA which is valid on another gateway.
11. IANA Considerations
IANA is requested to assign a notify message type from the error
types range (43-8191) of the "IKEv2 Notify Message Types" registry
with name "QUICK_CRASH_DETECTION".
12. Acknowledgements
We would like to thank Hannes Tschofenig and Yaron Sheffer for their
comments about Session Resumption.
13. Change Log
This section lists all changes in this document
NOTE TO RFC EDITOR : Please remove this section in the final RFC
13.1. Changes from draft-nir-ike-qcd-01
o Removed stateless method.
o Added discussion of rekeying and resumption.
o Added discussion of non-synchronized load-balanced clusters of
gateways in the security considerations.
o Other wording fixes.
13.2. Changes from draft-nir-ike-qcd-00
o Merged proposal with draft-detienne-ikev2-recovery [recovery]
o Changed the protocol so that the rebooted peer generates the
token. This has the effect, that the need for persistent storage
is eliminated.
o Added discussion of birth certificates.
13.3. Changes from draft-nir-qcr-00
o Changed name to reflect that this relates to IKE. Also changed
from quick crash recovery to quick crash detection to avoid
confusion with IFARE.
o Added more operational considerations.
o Added interaction with IFARE.
Nir, et al. Expires February 7, 2009 [Page 14]
Internet-Draft Quick Crash Detection August 2008
o Added discussion of backup gateways.
14. References
14.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4306] Kaufman, C., "Internet Key Exchange (IKEv2) Protocol",
RFC 4306, December 2005.
[RFC4718] Eronen, P. and P. Hoffman, "IKEv2 Clarifications and
Implementation Guidelines", RFC 4718, October 2006.
14.2. Informative References
[recovery]
Detienne, F., Sethi, P., and Y. Nir, "Safe IKE Recovery",
draft-detienne-ikev2-recovery (work in progress),
July 2008.
[resumption]
Sheffer, Y., Tschofenig, H., Dondeti, L., and V.
Narayanan, "IPsec Gateway Failover Protocol",
draft-sheffer-ipsec-failover (work in progress),
July 2008.
Authors' Addresses
Yoav Nir
Check Point Software Technologies Ltd.
5 Hasolelim st.
Tel Aviv 67897
Israel
Email: ynir@checkpoint.com
Nir, et al. Expires February 7, 2009 [Page 15]
Internet-Draft Quick Crash Detection August 2008
Frederic Detienne
Cisco Systems, Inc.
De Kleetlaan, 7
Diegem B-1831
Belgium
Phone: +32 2 704 5681
Email: fd@cisco.com
Pratima Sethi
Cisco Systems, Inc.
O'Shaugnessy Road, 11
Bangalore, Karnataka 560027
India
Phone: +91 80 4154 1654
Email: psethi@cisco.com
Nir, et al. Expires February 7, 2009 [Page 16]
Internet-Draft Quick Crash Detection August 2008
Full Copyright Statement
Copyright (C) The IETF Trust (2008).
This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors
retain all their rights.
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Intellectual Property
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at
ietf-ipr@ietf.org.
Nir, et al. Expires February 7, 2009 [Page 17]
| PAFTECH AB 2003-2026 | 2026-04-24 00:23:09 |