Encrypted Signaling Transport Modes for the Host Identity Protocol
draft-ietf-hip-over-hip-06

[Ballot comment]
The document should state that hiding HIP control packets inside ESP will make it impossible to build NATs or other middleboxes that look inside the HIP packets to do something useful. There used to be a proposal called SPINAT that did this, allowing ESP to go through NATs without UDP encapsulation. SPINAT isn't used anywhere anymore AFAIK, and the one implementation that exists isn't in open source. So this is not a big deal, but for completeness the impact should be noted.

[Ballot discuss]
I think it would be useful for the document to talk about what happens when there's a NAT, and what the interaction with the HIP NAT traversal mechanisms is. Do you run UDP-ESP-TCP?

[Ballot comment]
1) It would have helped me had the packet figures from RFC 5201 were added here (assume I'm getting it right):

The HIP header values for the R1 packet:

      IP ( HIP ( [ R1_COUNTER, ]
                PUZZLE,
                DIFFIE_HELLMAN,
                HIP_TRANSFORM,
                HOST_ID,
                [ ECHO_REQUEST_SIGNED, ]
->              [ HIP_TRANSPORT_MODE,]
                HIP_SIGNATURE_2 )
                <, ECHO_REQUEST_UNSIGNED >i)

Not sure if it's exactly in the right place.  This would make it clear that the transport mode is signed.  Same for I2:

  IP ( HIP ( [R1_COUNTER,]
                SOLUTION,
                DIFFIE_HELLMAN,
                HIP_TRANSFORM,
                ENCRYPTED { HOST_ID } or HOST_ID,
->              [ HIP_TRANSPORT_MODE, ]
                [ ECHO_RESPONSE_SIGNED ,]
                HMAC,
                HIP_SIGNATURE
                <, ECHO_RESPONSE_UNSIGNED>i ) )

2) Sec 4.2: Difficult to parse the sentence Lars has a discuss on.

3) Why SHOULD the TCP originator use the source port they said they'd use? I could understand a MUST or with NATs a MAY but can't figure why SHOULD?

[Ballot discuss]
This is similar to Peter's:  Does the HIP base exchange protect against down grade attacks?  I think it does, but wanted to verify.  If it's part of the base exchange (I1, R1, I2, R2) then the HIP_SIGNATURE is over R1 and I2.

[Ballot comment]
The OPS-DIR review performed by David Black pointed to the following problem:

The draft is somewhat inconsistent about support for a HIP node policy that requires use of an encrypted transport for HIP signaling.  Section 3.3 provides an essential building block, the error signaling mechanism to indicate that an encrypted transport is required and none was proposed.  On the other hand, Section 5 is unclear with respect to this class of policy in that it strongly recommends (SHOULD) fallback to a non-encrypted HIP connection but requires (MUST) that "messages that are intended to be sent only encrypted" not be sent unencrypted.  If the "messages that are intended to be sent only encrypted" are all HIP messages after the base exchange, these two requirements appear to be in conflict.

I suggest adding a short explanation to Section 5 of what would be reasonable vs. unreasonable policy for "messages that are intended to be sent only encrypted", and how to use the Section 3.3 error report when a failed encrypted connection is recovered by attempting to fall back to an unencrypted connection when HIP node policy requires encryption of all signaling after the base exchange.

The change was agreed by the document editor and the OPS-DIR reviewer and needs to find its way either in a revised I-D or in a note to the RFC Editor.

[Ballot comment]
The OPS-DIR review performed by David Black pointed to the following problem:

The draft is somewhat inconsistent about support for a HIP node policy that requires use of an encrypted transport for HIP signaling.  Section 3.3 provides an essential building block, the error signaling mechanism to indicate that an encrypted transport is required and none was proposed.  On the other hand, Section 5 is unclear with respect to this class of policy in that it strongly recommends (SHOULD) fallback to a non-encrypted HIP connection but requires (MUST) that "messages that are intended to be sent only encrypted" not be sent unencrypted.  If the "messages that are intended to be sent only encrypted" are all HIP messages after the base exchange, these two requirements appear to be in conflict.

I suggest adding a short explanation to Section 5 of what would be reasonable vs. unreasonable policy for "messages that are intended to be sent only encrypted", and how to use the Section 3.3 error report when a failed encrypted connection is recovered by attempting to fall back to an unencrypted connection when HIP node policy requires encryption of all signaling after the base exchange.

The change was agreed by the document editor and the OPD-DIR reviewer and needs to find its way either in a revised I-D or in a note to the RFC Editor.

[Ballot comment]
I was surprised to see no discussion of TCP-AO.

---

I agree with the Discuss about downgrade attacks. These seem to be particularly open in the mobility/multi-homing case described in Section 6.

[Ballot discuss]
Given that bootstrapping of secure communication depends on transmission of the HIP_TRANSPORT_MODE parameter during HIP base exchange, I'm surprised that the security considerations do not discuss the possibility of downgrade attacks.

IANA has a question about the IANA Actions in this document.

IANA understands that, upon approval of this document, there are three
IANA Actions which need to be completed.

First, in the HIP Parameters Type subregistry of the Host Identity
Protocol (HIP) Parameters registry located at:

http://www.iana.org/assignments/hip-parameters/hip-parameters.xml#hip-parameters-8

A new Parameter Type will be assigned as follows:

Value:
Parameter Type: HIP_TRANSPORT_MODE
Length:
Refere3nce: [ RFC-to-be ]

IANA Question --> What is the length of the HIP_TRANSPORT_MODE parameter
type?

Second, IANA is to create a new "HIP Transport Modes" under the "Host
Identity Protocol (HIP) Parameters" registry located at:

http://www.iana.org/assignments/hip-parameters/hip-parameters.xml#hip-parameters-8

Initial values for the new transport mode registry are as follows:

Identifier name: Value: Reference:
RESERVED 0 [ RFC-to-be ]
DEFAULT 1 [ RFC-to-be ]
ESP 2 [ RFC-to-be ]
ESP-TCP 3 [ RFC-to-be ]

New assignments in this registry require IETF Review.

Third, in the HIP Notification Message Type subregistry of the Host
Identity Protocol (HIP) Parameters registry located at:

http://www.iana.org/assignments/hip-parameters/hip-parameters.xml#hip-parameters-8

A new assignment is to be made as follows:

Value:
Notify Message Type: HIP_TRANSPORT_MODE
Reference: [ RFC-to-be ]

IANA understands that these are the only actions that need to be
completed upon approval of this document.

[Ballot comment]
INTRODUCTION, paragraph 2:
>        Host Identity Protocol Signaling Message Transport Modes

  I think this title sets a record for most number of consecutive nouns.
  Can we maybe stick a verb and an object in there to improve clarity?


Section 4.2., paragraph 4:
>    Since TCP provides reliable transport, the HIP messages sent over TCP
>    MUST NOT be retransmitted for the purpose of achieving reliable
>    transmission.

  Does this mean that HIP messages may be retransmitted for other
  purposes? Or it this phrasing inaccurate?

[Ballot discuss]
Section 4.2., paragraph 1:
>    If the ESP-TCP mode is selected, the host with the larger HIT
>    (calculated as defined in Section 6.5 of [RFC5201]) MUST start to
>    listen for an incoming TCP connection on the encrypted connection on
>    the port it used in the Port field of the transport mode parameter.

  DISCUSS: TCP listens on IP address/port number tuples. What's the IP
  address to listen on here? (I don't understand what you mean by "on
  the encrypted connection".)

State changed to In Last Call from Last Call Requested.

The following Last Call Announcement was sent out:

From: The IESG
To: IETF-Announce
CC:
Reply-To: ietf@ietf.org
Subject: Last Call:  (Host Identity Protocol Signaling Message Transport Modes) to Experimental RFC


The IESG has received a request from the Host Identity Protocol WG (hip)
to consider the following document:
- 'Host Identity Protocol Signaling Message Transport Modes'
  as an Experimental RFC

The IESG plans to make a decision in the next few weeks, and solicits
final comments on this action. Please send substantive comments to the
ietf@ietf.org mailing lists by 2011-03-01. Exceptionally, comments may be
sent to iesg@ietf.org instead. In either case, please retain the
beginning of the Subject line to allow automated sorting.

The file can be obtained via
http://datatracker.ietf.org/doc/draft-ietf-hip-over-hip/

IESG discussion can be tracked via
http://datatracker.ietf.org/doc/draft-ietf-hip-over-hip/

(1.a) Who is the Document Shepherd for this document? Has the
Document Shepherd personally reviewed this version of the
document and, in particular, does he or she believe this
version is ready for forwarding to the IESG for publication?

Gonzalo Camarillo is the document shepherd and considers this document
is ready to be forwarded to the IESG.

(1.b) Has the document had adequate review both from key WG members
and from key non-WG members? Does the Document Shepherd have
any concerns about the depth or breadth of the reviews that
have been performed?

The WG has thoroughly reviewed it.

(1.c) Does the Document Shepherd have concerns that the document
needs more review from a particular or broader perspective,
e.g., security, operational complexity, someone familiar with
AAA, internationalization, or XML?

The document has been reviewed by the security experts in the HIP WG.

(1.d) Does the Document Shepherd have any specific concerns or
issues with this document that the Responsible Area Director
and/or the IESG should be aware of? For example, perhaps he
or she is uncomfortable with certain parts of the document, or
has concerns whether there really is a need for it. In any
event, if the WG has discussed those issues and has indicated
that it still wishes to advance the document, detail those
concerns here. Has an IPR disclosure related to this document
been filed? If so, please include a reference to the
disclosure and summarize the WG discussion and conclusion on
this issue.

The document shepherd does not have such concerns.

(1.e) How solid is the WG consensus behind this document? Does it
represent the strong concurrence of a few individuals, with
others being silent, or does the WG as a whole understand and
agree with it?

There is a solid consensus behind this document.

(1.f) Has anyone threatened an appeal or otherwise indicated extreme
discontent? If so, please summarize the areas of conflict in
separate email messages to the Responsible Area Director. (It
should be in a separate email because this questionnaire is
entered into the ID Tracker.)

No.

(1.g) Has the Document Shepherd personally verified that the
document satisfies all ID nits? (See
http://www.ietf.org/ID-Checklist.html and
http://tools.ietf.org/tools/idnits/.) Boilerplate checks are
not enough; this check needs to be thorough. Has the document
met all formal review criteria it needs to, such as the MIB
Doctor, media type, and URI type reviews? If the document
does not already indicate its intended status at the top of
the first page, please indicate the intended status here.

The document passes ID nits.

(1.h) Has the document split its references into normative and
informative? Are there normative references to documents that
are not ready for advancement or are otherwise in an unclear
state? If such normative references exist, what is the
strategy for their completion? Are there normative references
that are downward references, as described in [RFC3967]? If
so, list these downward references to support the Area
Director in the Last Call procedure for them [RFC3967].

All the normative references are RFCs.

(1.i) Has the Document Shepherd verified that the document's IANA
Considerations section exists and is consistent with the body
of the document? If the document specifies protocol
extensions, are reservations requested in appropriate IANA
registries? Are the IANA registries clearly identified? If
the document creates a new registry, does it define the
proposed initial contents of the registry and an allocation
procedure for future registrations? Does it suggest a
reasonable name for the new registry? See [RFC2434]. If the
document describes an Expert Review process, has the Document
Shepherd conferred with the Responsible Area Director so that
the IESG can appoint the needed Expert during IESG Evaluation?

The IANA Considerations section is correct.

(1.j) Has the Document Shepherd verified that sections of the
document that are written in a formal language, such as XML
code, BNF rules, MIB definitions, etc., validate correctly in
an automated checker?

The draft does not contain formal language.

(1.k) The IESG approval announcement includes a Document
Announcement Write-Up. Please provide such a Document
Announcement Write-Up. Recent examples can be found in the
"Action" announcements for approved documents. The approval
announcement contains the following sections:

Technical Summary
Relevant content can frequently be found in the abstract
and/or introduction of the document. If not, this may be
an indication that there are deficiencies in the abstract
or introduction.

This document specifies two transport modes for Host Identity
Protocol (HIP) signaling messages that allow conveying them over
encrypted connections initiated with the Host Identity Protocol.

Working Group Summary
Was there anything in the WG process that is worth noting?
For example, was there controversy about particular points
or were there decisions where the consensus was
particularly rough?

The consensus behind this draft was solid.

Document Quality
Are there existing implementations of the protocol? Have a
significant number of vendors indicated their plan to
implement the specification? Are there any reviewers that
merit special mention as having done a thorough review,
e.g., one that resulted in important changes or a
conclusion that the document had no substantive issues? If
there was a MIB Doctor, Media Type, or other Expert Review,
what was its course (briefly)? In the case of a Media Type
Review, on what date was the request posted?

Implementations of HIP-based overlays will intend to include this
functionality.

Personnel
Who is the Document Shepherd for this document? Who is the
Responsible Area Director? If the document requires IANA
experts(s), insert 'The IANA Expert(s) for the registries
in this document are .'

The document shepherd was Gonzalo Camarillo.
The Responsible Area Director was Ralph Droms.