Subject: [Ipsec] Number of Proposals in IKE_SA_INIT exchange for IKE_SA and first CHILD_SA ??

From: wadood <[email-masked]>
Date: Fri, 13 Aug 2004 14:06:17 +0600

hi,

How may proposals Initiator will send in the first exchange i.e.,
IKE_SA_INIT. If Initiator wants to make two SAs i.e., IKE_SA and first
CHILD_SA(piggybacked with IKE_SA) having same cryptographic suite.

Or we can say 
A  single proposal for IKE_SA is sufficed for first CHILD_SA. If
CHILD_SA uses the same cryptographic suite as of IKE_SA.

Any comments/answers will be highly appreciated.

wadood

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From: Yoav Nir <[email-masked]>
Date: Sat, 21 Aug 2004 09:51:52 +0300

You need at least one proposal in an SA payload in message #1, and at 
least one proposal in an SA payload in message #3.

If you do not include an SA payload in message #3, that says that you 
don't want to create a child-SA.

There is no way in the IKEv2 draft to say that you want the same 
cryptosuite for the IKE SA and the child SA

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From: Paul Hoffman / VPNC <[email-masked]>
Date: Sat, 21 Aug 2004 09:31:44 -0700

>cryptosuite for the IKE SA and the child SA

... other than to repeat it in the third message.

--Paul Hoffman, Director
--VPN Consortium

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From: Tero Kivinen <[email-masked]>
Date: Mon, 23 Aug 2004 13:10:41 +0300

> don't want to create a child-SA.

SAi2, and SAr2 are not optional in the current draft, thus there is
no way not to create the child-SA during the initial IKE exchange. 
-- 
[email-masked]

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From: "Yoav Nir" <[email-masked]>
Date: Mon, 23 Aug 2004 15:25:07 +0300

Whoops.  For some reason I though it was possible to make an initial
exchange without creating child SAs.  Was it removed in some recent version
of the draft?

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf Of
Tero Kivinen
Sent: Monday, August 23, 2004 1:11 PM
To: Yoav Nir
Cc: [email-masked]; wadood
Subject: Re: [Ipsec] Number of Proposals in IKE_SA_INIT exchange for IKE_SA
andfirst CHILD_SA ??

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From: Tero Kivinen <[email-masked]>
Date: Mon, 23 Aug 2004 15:39:50 +0300

> exchange without creating child SAs.  Was it removed in some recent version

Lots of people seem to think that there would be option for that, but
there has not been such option, at least draft version 05 didn't have
such option....

It has not been ever explictly said, but the payloads in the pictures
are not optional, and they pictures are not just examples in the draft.
-- 
[email-masked]

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From: "Yoav Nir" <[email-masked]>
Date: Mon, 23 Aug 2004 16:23:54 +0300

Strange that nobody wanted this.  I guess the model is that both IKE SAs and
child SAs are created on demand.  While this is just fine for peer to peer
VPNs, remote access clients usually have a connect button.  When the user
clicks it, it makes sense to create the IKE SA, but what selectors are you
going to put for the child SA?

I suppose it's not really important.   You can use universal selectors or
peer-to-peer selectors. 

-----Original Message-----
From: Tero Kivinen [mailto:[email-masked]] 
Sent: Monday, August 23, 2004 3:40 PM
To: Yoav Nir
Cc: [email-masked]; 'wadood'
Subject: RE: [Ipsec] Number of Proposals in IKE_SA_INIT exchange for IKE_SA
andfirst CHILD_SA ??

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From: "Srinivasa Rao Addepalli" <[email-masked]>
Date: Mon, 23 Aug 2004 07:29:21 -0700

> IKE_SA_INIT

There are two initial exchanges. One is IKE_SA_INIT and another
IKE_AUTH.  In IKE_SA_INIT, you can only have SA payload
for creating IKE SA. You can send multiple proposals with multiple
transforms.  But, they all used to create IKE SA.

>  If Initiator wants to make two SAs i.e., IKE_SA and first

 SAs correspond to IPSec (Child SA) are sent/received as part
of IKE_AUTH exchange. They are different from SAs that are sent in 
IKE_SA_INIT.

If an administrator wants same cryptographic algorithms between these
two SAs, he needs to configure same using his management station. 
As far as protocol is concerned, they are sent as two different SA payloads
in different exchanges.

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From: Tero Kivinen <[email-masked]>
Date: Tue, 24 Aug 2004 11:02:44 +0300

Yoav Nir writes:
> Strange that nobody wanted this.

I think there would be people who would like to have this feature too,
but if we leave it out we can also get rid of one more testing case
and one more option in the protocol. I think the getting rid of one
more option is much more important than this feature, especially when
the first SA comes free in IKEv2, i.e. there is no real extra cost
because of the IPsec SA created.

> I guess the model is that both IKE SAs and

In normal case you put TSi and TSr to any address, and then when the
server assigns an ip-adderss to you, it will also limit your TSi to
match the IP-address it gave to you, and the TSr to match the subnet
which is reachable through it (or, any address, in case it wants
everything to come through VPN). 
-- 
[email-masked]