Re: [IPsec] FW: I-D Action:draft-nir-ipsecme-childless-00.txt

[Gaurav Poothia <[e-mail]>]

Hello Yoav,
Are you suggesting that in this scenario the initiator will not tear down the IKE SA on getting a CHILD SA specific error (NO_PROPOSAL_CHOSEN) for the AUTH exchange response ?
Shouldn't the IKE SA also be torn down because while the error notify doesn't explicitly fail the AUTH there is no explicit indication of success either.
Or did you have a response in mind that had all the relevant IKE SA related payloads intact and a single error notify for the CHILD SA?


BTW perhaps the authors should consider motivating scenario ( c ) where it is the responder that wants a childless IKE SA instead of the initiator, with usage scenarios or alternatively consider making it an explicit non-goal.
I was under the impression it's the initiator that requests this feature and the responder might/might not oblige based on whether it implements the extension.

From: [e-mail] [mailto:[e-mail]] On Behalf Of Yoav Nir
Sent: Monday, July 06, 2009 6:15 AM
To: 'Raghunandan P (raghup)'; Raj Singh
Cc: [e-mail]
Subject: Re: [IPsec] FW: I-D Action:draft-nir-ipsecme-childless-00.txt

Hi Raghu

I think in scenario (c) the initiator will propose a full child SA proposal, and the responder will accept the IKE SA and reply with a NO_PROPOSAL_CHOSEN for the child SA.



________________________________
From: Raghunandan P (raghup) [mailto:[e-mail]]
Sent: Monday, July 06, 2009 1:43 PM
To: Yoav Nir; Raj Singh
Cc: [e-mail]
Subject: RE: [IPsec] FW: I-D Action:draft-nir-ipsecme-childless-00.txt

Hi Yoav/Raj,

I think its a good idea for the initiator to announce its capabilities about supporting just IKE SA without child SA. The responder will then act accordingly.  Hence, this would make 4 scenarios:
[IKE_SA_ONLY] is the mode that will tell whether the device supports bringing up IKE SA only or not.

       Initiator                          Responder             Result
---------------------------------------------------------------------------------------------------------
 a)  IKE_SA_ONLY              IKE_SA_ONLY                  Bring up the IKE SA

 b)  IKE_SA_ONLY            Does not support            Send a Notify with INVALID_SYNTAX
                                           IKE_SA_ONLY

c)  Does not support             IKE_SA_ONLY           IKE and child SA would be brought UP
     IKE_SA_ONLY

d) Does not support           Does not support          IKE and child SA would be brought UP.
     IKE_SA_ONLY                  IKE_SA_ONLY

My question is related to the scenario c) discussed above.
Is the result to bring up IKE and IPSec SA  or would the responder send a Notify with INVALID_SYNTAX to the initiator since responder wants to bring up IKE SA only and not the child SA.

It might be good to add a Notify (IKE_SA_ONLY) than the VID.

Regards
Raghu

________________________________
From: [e-mail] [mailto:[e-mail]] On Behalf Of Yoav Nir
Sent: Monday, July 06, 2009 1:54 PM
To: 'Raj Singh'
Cc: [e-mail]
Subject: Re: [IPsec] FW: I-D Action:draft-nir-ipsecme-childless-00.txt
Inline with <ynir>

________________________________
From: [e-mail] [mailto:[e-mail]] On Behalf Of Raj Singh
Sent: Sunday, July 05, 2009 5:02 AM
To: Yoav Nir
Cc: [e-mail]
Subject: Re: [IPsec] FW: I-D Action:draft-nir-ipsecme-childless-00.txt

Hi Yoav,

Please find my input inline <Raj>.

With Regards,
Raj
On Sun, Jul 5, 2009 at 2:33 AM, Yoav Nir <[e-mail]<mailto:[e-mail]>> wrote:
Hi Raj

The ordinary thing for a responder to do with unrecognized Notifies/VIDs is to ignore them. So the only responder that will behave as you suggest is one that supports this extension, but is configured not to.
<Raj> Yes, if responder understands childless IKE_AUTH from initiator, it will behave as mentioned in my previous mail, if NOT and it does not support childless IKE_AUTH [only responder not supporting childless extention], then initiator will notice missing childless notify/VID and can stop the transactions for the SA. But it will help responders, supporting this extentions and applying policies.


At least for the remote access client, it makes sense for a client that faces both supporting and non-supporting gateways to have a "dummy" proposal for a useless child SA, for example ICMP from the client to the gateway. It doesn't really matter if the proposal is accepted or rejected, because the client does not need the traffic.
 <Raj> What's the usecase ?
<ynir> the usecase is that the client needs an IKE SA, but can't get it unless it negotiates a child SA - that's what you have now before implementing our draft.


In any case, an initiator that insists on a childless IKE SA contacting a gateway that does not support the extension is a misconfiguration. I don't believe we should go to great lengths (especially the new critical payload that Yaron is proposing) to save work in such a misconfiguration case.
<Raj> How it can be a misconfiguration, The gateway can put some policy to enable/disable childless IKE_AUTH based on "load" on gateway. Yes, i agree, new crittical payload, we can avoid.
<ynir> Well, we could add our own "critical" bit to the notify/VID. If that is on, the responder can either reply with a similar notification/VID, or else some error notify (NO_PROPOSAL_CHOSEN or a new one of our own)



If we do think it's important, the "right" way is for the Initiator to send the VID, for the responder to only send the VID if it (a) supports the extension *and* (b) has seen the VID from the initiator. We could even require that the initiator be prepared to continue with a non-supporting gateway, but I'm not sure that's a good idea.
<Raj> The whole idea is:
initiator to send childless notify/VID when it want to bring up "ONLY" IKE SA i.e. it is not hit by traffic or "dummy" payload. This will avoid unnecessary processing of IKE_SA_INIT at responder when responder does not support childless IKE_AUTH. This is most likely usecase of chiless IKE_AUTH in VPN scenarios.
The behavior remains similar as mentioned in my previous mail except "critical" bit as it needs to define new payload type which even i want to avoid. Its just a simple notify/VID payload with no associated data and easing the work at initiator and responder. Its can see goodness in idea.
When initiator has dummy proposal  ready, the initiator need not to send childless notify/VID payload.


________________________________________
From: Raj Singh [[e-mail]<mailto:[e-mail]>]
Sent: Friday, July 03, 2009 16:51
To: Yoav Nir
Cc: [e-mail]<mailto:[e-mail]>
Subject: Re: [IPsec] FW: I-D Action:draft-nir-ipsecme-childless-00.txt

Hi Yoav,

Mostly the Initiator will decide that it wants to bring UP only IKE SA without child SA.
But currently there is no notify/VID from Initiator to Responder to indicate that initiator wants to bring only IKE SA. Even if responder does not supports "childless IKE_AUTH", it will process IKE_SA_INIT, involding CPU intensive D-H calculations, and send IKE_SA_INIT response without "childless VID" payload.

By introducing a notify/VID payload from Initiator that it wants to bring UP only IKE SA without child SA wil ease the processing ar Responder side. If responder does not support "childless IKE_AUTH", it can send INVALID_SYNTAX. Then, Initiator will wait for "Child SA" info to be available to bring UP both IKE and child SA, normally as mentioned in RFC 4306.

Thanks,
Raj
On Thu, Jul 2, 2009 at 1:42 AM, Yoav Nir <[e-mail]<mailto:[e-mail]><mailto:[e-mail]<mailto:[e-mail]>>> wrote:
Hi all.

This is the fourth iteration of this draft.  New in this iteration
 - Another co-author
 - Changed the name, so that this item is considered in the rechartering discussion
 - Fixed some notation and some discussion based on comments from the list

Yoav
________________________________________
From: [e-mail]<mailto:[e-mail]><mailto:[e-mail]<mailto:[e-mail]>> [[e-mail]<mailto:[e-mail]><mailto:[e-mail]<mailto:[e-mail]>>] On Behalf Of [e-mail]<mailto:[e-mail]><mailto:[e-mail]<mailto:[e-mail]>> [[e-mail]<mailto:[e-mail]><mailto:[e-mail]<mailto:[e-mail]>>]
Sent: Wednesday, July 01, 2009 12:15
To: [e-mail]<mailto:[e-mail]><mailto:[e-mail]<mailto:[e-mail]>>
Subject: I-D Action:draft-nir-ipsecme-childless-00.txt

A New Internet-Draft is available from the on-line Internet-Drafts directories.

      Title           : A Childless Initiation of the IKE SA
      Author(s)       : Y. Nir, et al.
      Filename        : draft-nir-ipsecme-childless-00.txt
      Pages           : 7
      Date            : 2009-07-01

This document describes an extension to the IKEv2 protocol that
allows an IKE SA to be created and authenticated without generating a
child SA.

A URL for this Internet-Draft is:
http://www.ietf.org/internet-drafts/draft-nir-ipsecme-childless-00.txt

Internet-Drafts are also available by anonymous FTP at:
ftp://ftp.ietf.org/internet-drafts/

Below is the data which will enable a MIME compliant mail reader
implementation to automatically retrieve the ASCII version of the
Internet-Draft.



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