Re: [IPsec] draft-fluhrer-qr-ikev2 AUTH issue

Paul Wouters <paul@nohats.ca> Fri, 18 August 2017 15:27 UTC

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Date: Fri, 18 Aug 2017 11:26:55 -0400
From: Paul Wouters <paul@nohats.ca>
To: Tero Kivinen <kivinen@iki.fi>
cc: "ipsec@ietf.org WG" <ipsec@ietf.org>, Vukasin Karadzic <vukasin.karadzic@gmail.com>, "Scott Fluhrer (sfluhrer)" <sfluhrer@cisco.com>
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Subject: Re: [IPsec] draft-fluhrer-qr-ikev2 AUTH issue
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On Thu, 17 Aug 2017, Tero Kivinen wrote:

>> Basically, we are in the case where "Have PPK" is not yet known.
>
> I think the discussion earlier was that we solve this by policy, where
> responder is configured BEFORE initiator.

I thought about this a few times, and after some discussions with
myself, I agree that you are right.

> I.e., if responder sees
> initiator that says PPK is supported (meaning initiator has PPK) then
> responder is safe to assume that it has also been configured PPK for
> that ID. Anyways if this guess turns out to be wrong, it can then
> fail the exchange later, and mark that peer as not having PPK when it
> reconnects, i.e., add peer IP-address to temporary list saying that if
> connection comes from this IP-address, and says it has supports PPK,
> we do not have PPK for it, so fall back to standard IKE.

That is a terrible hack. It will likely not work well with NAT, when
the client mind end up with a new exchange on a different NAT port,
so you cannot tell whether this is 1 client behind NAT or 2 clients
behind NAT. But I see how we can just call this a "misconfiguration"
and I don't mind it not working.

> Anyways this kind of text needs to be added to the protocol draft.

Yes.

So I agree with Tero. And I guess our code is already doing this.

Paul