Re: [IPsec] Genart last call review of draft-ietf-ipsecme-split-dns-12

[Tommy Pauly <tpauly@xxxxxxxxx>]

Hi Christer,

Thanks for the review! Some responses inline.

Best,

Tommy

On Aug 16, 2018, at 11:25 PM, Christer Holmberg <christer.holmberg@xxxxxxxxxxxx> wrote:

Reviewer: Christer Holmberg
Review result: Ready with Nits

I am the assigned Gen-ART reviewer for this draft. The General Area
Review Team (Gen-ART) reviews all IETF documents being processed
by the IESG for the IETF Chair.  Please treat these comments just
like any other last call comments.

For more information, please see the FAQ at

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Document: draft-ietf-ipsecme-split-dns-12
Reviewer: Christer Holmberg
Review Date: 2018-08-16
IETF LC End Date: 2018-08-24
IESG Telechat date: Not scheduled for a telechat

Summary: The document is well written, and almost ready for publication. I have
a couple of questions that I would like the authors to address.

Major issues: N/A

Minor issues:

Q1:

Section 3.1 contains some SHOULD-do statements, e.g.,:

"the initiator SHOULD also include one or more INTERNAL_IP4_DNS and
INTERNAL_IP6_DNS attributes in the CFG_REQUEST"

"the initiator SHOULD also include one or more INTERNAL_DNS_DOMAIN attributes
in the CFG_REQUEST."

Is there a reason for not using MUST instead of SHOULD?

In general, the CFG_REQUEST attributes are a bit loose—they're hints more than requirements.

From section 3.15.1 of RFC7296:

   The CFG_REQUEST and CFG_REPLY pair allows an IKE endpoint to request
   information from its peer.  If an attribute in the CFG_REQUEST
   Configuration payload is not zero-length, it is taken as a suggestion
   for that attribute.  The CFG_REPLY Configuration payload MAY return
   that value, or a new one.  It MAY also add new attributes and not
   include some requested ones.  Unrecognized or unsupported attributes
   MUST be ignored in both requests and responses.

So, the CFG_REPLY MUST have a DNS server to go along with the DNS domain, but I left the SHOULD in spirit of the fact that the CFG_REQUEST is more of a suggestion.

That being said, if others in the WG would like to see this be a MUST, I'm fine with that as well. I don't think we should have the responder error out if it doesn't see both, however.

Q2:

Section 3.2 says:

"the initiator SHOULD behave as if Split DNS configurations are not supported
by the server."

Again, is there a reason for not using MUST?

This one could be a MUST. The one exception I could see is if the initiator was statically configured with some split DNS domains to use as split domains

In case the responder didn't provide any in the CFG_REPLY, it should still use those and not send all DNS queries inside the tunnel. I wouldn't want this

MUST to disable the static configuration workarounds that implementations have done prior to allowing split DNS to be negotiated.

Nits/editorial comments:

Q3:

Is there a need for the "Background" section? Since the text is related to what
is described in the "Introduction", could the the text be moved there?

The main new points that the Background section adds on top of the Introduction are:

- The prior art for split DNS in IKEv1

- The fact that this is currently mainly seen in enterprise VPN deployments

These points could indeed be moved to the introduction. I had felt they fit better as "background" since they're not essential to the description of the protocol, but give context that is relevant now (and may be less so in the future).

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