Softwire Provisioning Using DHCPv4 over DHCPv6
draft-ietf-dhc-dhcp4o6-saddr-opt-08

[Ballot discuss]
Rich version of this review at:
https://mozphab-ietf.devsvcdev.mozaws.net/D5110


I believe there are security issues as detailed in this review.

DETAIL
S 9.
>      For such an attack to be effective, the attacker would need to know
>      both the client identifier and active IPv4 address lease currently in
>      use by another client.  The risk of this can be reduced by using a
>      client identifier format which is not easily guessable, e.g., by
>      including a time component for when the client identifier was
>      generated (see [I-D.ietf-dhc-rfc3315bis] Section 11.2).

This doesn't seem like a very strong defense. At minimum you need an
analysis of the level of entropy.

I note that an on-path attacker (as RFC 3552 requires us to consider)
will have no real problem with this attack. This seems fairly serious.

[Ballot comment]
S 1.
>      A dynamic provisioning model, such as using DHCPv4 over DHCPv6
>      [RFC7341] (DHCP 4o6) allows much more flexibility in the location of
>      the IPv4-over-IPv6 softwire source address.  In this model, the IPv6
>      address is dynamically communicated back to the service provider
>      allowing the corresponding softwire configuration to be created in
>      the border router (BR).

I'm sure this is obvious to the informed, but it would have helped me
to have explained that the setting here is that the client has v6-only
service and is going to get a v4 address and tunnel that over v6.


S 5.
>              OPTION_DHCP4O6_S46_SADDR (TBD2) with the IPv6 address which
>              the client will use as its softwire source address.
> 
>      Step 4  The server sends a DHCPv6 'DHCPV4-RESPONSE (21)' message.
>              OPTION_DHCPV4_MSG contains a DHCPv4 DHCPACK message.
>              OPTION_DHCP4O6_S46_SADDR with the client's softwire source

Which of these messages contains the client's assigned IPv4 address?
It's the DHCPOFFER, right?

[Ballot comment]

Thanks to everyone involved for the work they did on this document.

I agree with Alissa's request for the addition of privacy considerations.

---------------------------------------------------------------------------

§7.2.1:

>  the client's IPv6 will change.  E.g., if there is an IPv6 re-

Nit: "...the client's IPv6 address will change."

---------------------------------------------------------------------------

§9:

>  For such an attack to be effective, the attacker would need to know
>  both the client identifier and active IPv4 address lease currently in
>  use by another client.  The risk of this can be reduced by using a
>  client identifier format which is not easily guessable, e.g., by
>  including a time component for when the client identifier was
>  generated (see [I-D.ietf-dhc-rfc3315bis] Section 11.2).

I might be missing something here, but my understanding is that DHCP isn't
confidential, and so attackers on the same segment might be able to observe
another client's identifier and IPv4 address in the DHCP traffic itself
(depending on the nature of the networking equipment). Even if
this cannot be easily mitigated, I think it's worth mentioning.

---------------------------------------------------------------------------

§10:

>  IANA is requested to update the entry for DHCPv6 Option S46_BR (90)
>  in the Option Codes table at https://www.iana.org/assignments/
>  dhcpv6-parameters as follows:
>
>  Old entry:
>
>  |    90 | S46_BR                  | No                  | No        |
>
>  New entry:
>
>  |    90 | S46_BR                  | Yes                | No        |

This is a somewhat unconventional way to represent IANA actions. This format
does not make sense in a vacuum; and, more importantly, and will lose meaning
in the case that the corresponding registry table is ever expanded. I also
note that the name is incorrect (S46_BR instead of OPTION_S46_BR), and that
the Reference column is omitted (which is relevant, as I believe the intenion
is to instruct IANA to add this document to the list of references).  Please
consider reformatting as:

  Old Entry:

    Value:            90
    Description:      OPTION_S46_BR
    Client ORO:        No
    Singleton Option:  No
    Reference:        [RFC7598]

  New Entry:

    Value:            90
    Description:      OPTION_S46_BR
    Client ORO:        Yes
    Singleton Option:  No
    Reference:        [RFC7598] [RFCxxxx]


>  IANA is also requested to make a new entry for
>  OPTION_S46_BIND_IPV6_PREFIX (TBD1) in the Option Codes table at
>  https://www.iana.org/assignments/dhcpv6-parameters:
>
>  |  TBD1 |OPTION_S46_BIND_IPV6_PREFIX| Yes              | Yes      |

Similarly:

    Value:            TBD1
    Description:      OPTION_S64_BIND_IPV6_PREFIX
    Client ORO:        Yes
    Singleton Option:  Yes
    Reference:        [RFCxxxx]

[Ballot comment]
I think this document could benefit from some discussion of the privacy considerations associated with the new options specified in the document. E.g., if one were to apply the analysis in RFC 7844, what would the guidance be to clients that want to limit the disclosure of information about themselves? (It might be "don't use DHCP4o6," but even that is worth saying if that's the best advice available.)

[Ballot comment]
Section 7

  It is also a prerequisite that the client has already learned a
  suitable IPv6 prefix to use for its local softwire endpoint using
  DHCPv6, RA/PIO or another mechanism.

I think I'm confused.  Is the OPTION_S46_BIND_IPV6_PREFIX option a way to
obtain the "suitable IPv6 prefix" above?  If so, then "prerequisite" may
not be the best word to use here.

Section 7.2.1

  Across the lifetime of the leased IPv4 address, it is possible that
  the client's IPv6 will change.  E.g., if there is an IPv6 re-
  numbering event.

nit: The last sentence is a sentence fragment.

Section 9

With address-binding mechanisms such as these we also try to consider the
possibility of binding an unexpected address to an unsuspecting recipient,
e.g., to direct a large flow of traffic to a victim unable to process it
all.  I did not see an immediate way for an attacker to do this, since it
would seem like it would either require DHCPv4 to assign the same address
twice or allow a duplicate v6/v4 softwire binding, but I am not sure I have
the full picture in my head yet.  It would be good to include some text on
this class of attacks, even if it is just "redirecting existing flows to an
unsuspecting victim is not possible because ".

IntArea                                                  B. E. Carpenter
Internet-Draft                                        Univ. of Auckland
Intended status: Informational                                  S. Jiang
Expires: November 26, 2013                  Huawei Technologies Co., Ltd
                                                              W. Tarreau
                                                              Exceliance
                                                            May 25, 2013

          Using the IPv6 Flow Label for Server Load Balancing
              draft-ietf-intarea-flow-label-balancing-01

Abstract

  This document describes how the IPv6 flow label as currently
  specified can be used to enhance layer 3/4 load distribution and
  balancing for large server farms.

Status of This Memo

  This Internet-Draft is submitted in full conformance with the
  provisions of BCP 78 and BCP 79.

  Internet-Drafts are working documents of the Internet Engineering
  Task Force (IETF).  Note that other groups may also distribute
  working documents as Internet-Drafts.  The list of current Internet-
  Drafts is at http://datatracker.ietf.org/drafts/current/.

  Internet-Drafts are draft documents valid for a maximum of six months
  and may be updated, replaced, or obsoleted by other documents at any
  time.  It is inappropriate to use Internet-Drafts as reference
  material or to cite them other than as "work in progress."

  This Internet-Draft will expire on November 26, 2013.

Copyright Notice

  Copyright (c) 2013 IETF Trust and the persons identified as the
  document authors.  All rights reserved.

Carpenter, et al.      Expires November 26, 2013                [Page 1]
Internet-Draft        Flow Label Load Balancers                May 2013

  This document is subject to BCP 78 and the IETF Trust& from In Last Call

(Via drafts-lastcall@iana.org): IESG/Authors/WG Chairs:

The IANA Functions Operator has completed its review of draft-ietf-dhc-dhcp4o6-saddr-opt-04. If any part of this review is inaccurate, please let us know.

IANA has a question about one of the actions requested in the IANA Considerations section of this document.

The IANA Functions Operator understands that, upon approval of this document, there are four actions which we must complete.

First, in the Option Codes registry on the Dynamic Host Configuration Protocol for IPv6 (DHCPv6) registry page located at:

https://www.iana.org/assignments/dhcpv6-parameters/

a new option code will be registered as follows:

Value: [ TBD-at-Registration ]
Description: OPTION_S46_BIND_IPV6_PREFIX
Client ORO:
Singleton Option:
Reference: [ RFC-to-be ]

IANA Question --> What should the values be for the parameters Client ORO and Singleton Option?

As this document requests registrations in an Expert Review (see RFC 8126) registry, we will initiate the required Expert Review via a separate request. Expert review will need to be completed before your document can be approved for publication as an RFC.

Second, in the BOOTP Vendor Extensions and DHCP Options registry on the Dynamic Host Configuration Protocol (DHCP) and Bootstrap Protocol (BOOTP) Parameters registry page located at:

https://www.iana.org/assignments/bootp-dhcp-parameters/

a single, new registration will be made as follows:

Tag: [ TBD-at-Registration ]
Name: OPTION_DHCP4O6_S46_SADDR
Data Length:
Meaning:
Reference: [ RFC-to-be ]

IANA Question --> What should the values be for the parameters Data Length and Meaning?

Third, in the Options Codes registry on the Dynamic Host Configuration Protocol (DHCP) and Bootstrap Protocol (BOOTP) Parameters registry page located at:

https://www.iana.org/assignments/bootp-dhcp-parameters/

the existing registration:

Value Description Client ORO Singleton
| 90 | S46_BR | No | No |

Will be changed to:

Value Description Client ORO Singleton
| 90 | S46_BR | Yes | No |

IANA Question --> Should the reference for this registration be changed to [ RFC-to-be ].

Fourth, the authors make the following request:

"IANA is also requested to make a new entry for OPTION_S46_BIND_IPV6_PREFIX (TBD1) in the table at

https://www.iana.org/assignments/dhcpv6-parameters:

| TBD1 |OPTION_S46_BIND_IPV6_PREFIX| Yes | Yes

IANA Question --> Is this the same request as the first request in the IANA Considerations section?

The IANA Functions Operator understands that these are the only actions required to be completed upon approval of this document.

Note:  The actions requested in this document will not be completed until the document has been approved for publication as an RFC. This message is meant only to confirm the list of actions that will be performed.

Thank you,

Sabrina Tanamal
Senior IANA Services Specialist

The following Last Call announcement was sent out (ends 2018-09-07):

From: The IESG
To: IETF-Announce
CC: volz@cisco.com, dhc-chairs@ietf.org, Bernie Volz , dhcwg@ietf.org, draft-ietf-dhc-dhcp4o6-saddr-opt@ietf.org, suresh@kaloom.com
Reply-To: ietf@ietf.org
Sender:
Subject: Last Call:  (Softwire Provisioning using DHCPv4 Over DHCPv6) to Proposed Standard


The IESG has received a request from the Dynamic Host Configuration WG (dhc)
to consider the following document: - 'Softwire Provisioning using DHCPv4
Over DHCPv6'
  as Proposed Standard

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 2018-09-07. 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.

Abstract


  DHCPv4 over DHCPv6 (RFC7341) is a mechanism for dynamically
  configuring IPv4 over an IPv6-only network.  For DHCPv4 over DHCPv6
  to function with some IPv4-over-IPv6 softwire mechanisms and
  deployment scenarios, the operator needs to know the IPv6 address
  that the client will use as the source of IPv4-in-IPv6 softwire
  tunnel.  This address, in conjunction with the client's IPv4 address,
  and (in some deployments) the Port Set ID are used to create a
  binding table entry in the operator's softwire tunnel concentrator.
  This memo defines a DHCPv6 option to convey IPv6 parameters for
  establishing the softwire tunnel and a DHCPv4 option (to be used only
  with DHCP 4o6) to communicate the source tunnel IPv6 address between
  the DHCP 4o6 client and server.  It is designed to work in
  conjunction with the IPv4 address allocation process.

  This document updates "DHCPv6 Options for Configuration of Softwire
  Address and Port-Mapped Clients" (RFC7598), allowing OPTION_S46_BR
  (90) to be enumerated in the DHCPv6 client's ORO request and appear
  directly within subsequent messages sent by the DHCPv6 server.




The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-dhc-dhcp4o6-saddr-opt/

IESG discussion can be tracked via
https://datatracker.ietf.org/doc/draft-ietf-dhc-dhcp4o6-saddr-opt/ballot/


No IPR declarations have been submitted directly on this I-D.

Write up for draft-ietf-dhc-dhcp4o6-saddr-opt(-04).txt:


(1) What type of RFC is being requested (BCP, Proposed Standard,
    Internet Standard, Informational, Experimental, or Historic)? Why
    is this the proper type of RFC? Is this type of RFC indicated in
    the title page header?

Standards Track. This is the proper type as it defines new
options and the steps a used to make use of those options in
provisioning softwires that use DHCPv4 over DHCPv6 (RFC7341).


(2) 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:

This document extends DHCPv4 over DHCPv6 (RFC7341) to provide
some IPv4-over IPv6 softwire mechanisms and deployment scenarios
two additional needed pieces of information. It defines a new
DHCPv6 option to indicate the preferred prefix for the client to
bind its IPv4 configuration to, and a new DHCPv4 option to
indicate the IPv6 address associated with the client's IPv4
configuration, and the procedures to use these options.

Working Group Summary:

This document has been in development, first as an individual
submission in the software WG, and more recently in the DHC WG.
It has undergone about 10 revisions - with more recent changes
being fairly minor.

Document Quality:

The document has had extensive review and input by the working
group and by "DHCP experts" and "Softwires experts".


Personnel:

Bernie Volz is the document shepherd. Suresh Krishnan is the
current responsible AD.


(3) Briefly describe the review of this document that was performed by
    the Document Shepherd. If this version of the document is not
    ready for publication, please explain why the document is being
    forwarded to the IESG.

I read the document thoroughly several times, and submitted
editorial and technical suggestions to the authors, which they
implemented. I believe it is ready for publication.


(4) Does the document Shepherd have any concerns about the depth or
    breadth of the reviews that have been performed?

The document has had a good deal of careful review. However, the
volume of response recently has not been as great as the WG
chairs would have liked, but all responses received were
positive.


(5) Do portions of the document need review from a particular or from
    broader perspective, e.g., security, operational complexity, AAA,
    DNS, DHCP, XML, or internationalization? If so, describe the
    review that took place.

No.


(6) Describe any specific concerns or issues that the Document
    Shepherd has 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.

I think the document is good as written, and serves a useful
purpose.


(7) Has each author confirmed that any and all appropriate IPR
    disclosures required for full conformance with the provisions of
    BCP 78 and BCP 79 have already been filed. If not, explain why?

Yes I have confirmed with the 4 co-authors. They all report they
are not aware of any IPR to disclose.


(8) Has an IPR disclosure been filed that references this document? If
    so, summarize any WG discussion and conclusion regarding the IPR
    disclosures.

No IPR disclosures have been filed.


(9) 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 consensus behind this document and no objections were
raised.


(10) Has anyone threatened an appeal or otherwise indicated extreme
    discontent? If so, please summarise the areas of conflict in
    separate email messages to the Responsible Area Director. (It
    should be in a separate email because this questionnaire is
    publicly available.)

No.


(11) Identify any ID nits the Document Shepherd has found in this
    document. (See http://www.ietf.org/tools/idnits/ and the
    Internet-Drafts Checklist). Boilerplate checks are not enough;
    this check needs to be thorough.

There are none.


(12) Describe how the document meets any required formal review
    criteria, such as the MIB Doctor, media type, and URI type
    reviews.

N/A


(13) Have all references within this document been identified as
    either normative or informative?

Yes.


(14) 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 plan for their
    completion?

No.


(15) Are there downward normative references references (see RFC
    3967)? If so, list these downward references to support the Area
    Director in the Last Call procedure.

No.


(16) Will publication of this document change the status of any
    existing RFCs? Are those RFCs listed on the title page header,
    listed in the abstract, and discussed in the introduction? If the
    RFCs are not listed in the Abstract and Introduction, explain
    why, and point to the part of the document where the relationship
    of this document to the other RFCs is discussed. If this
    information is not in the document, explain why the WG considers
    it unnecessary.

Yes and the RFC being updated is listed in the title page
header - it is a minor update to RFC7598.


(17) Describe the Document Shepherd's review of the IANA
    considerations section, especially with regard to its consistency
    with the body of the document. Confirm that all protocol
    extensions that the document makes are associated with the
    appropriate reservations in IANA registries. Confirm that any
    referenced IANA registries have been clearly identified. Confirm
    that newly created IANA registries include a detailed
    specification of the initial contents for the registry, that
    allocations procedures for future registrations are defined, and
    a reasonable name for the new registry has been suggested (see
    RFC 5226).

There are IANA actions and they are compatible with DHC WG IANA
actions and adds an option to each of the DHCPv4 (BOOTP) and
DHCPv6 option registries.


(18) List any new IANA registries that require Expert Review for
    future allocations. Provide any public guidance that the IESG
    would find useful in selecting the IANA Experts for these new
    registries.

There are no new registries.


(19) Describe reviews and automated checks performed by the Document
    Shepherd to validate sections of the document written in a formal
    language, such as XML code, BNF rules, MIB definitions, etc.

There are no such parts to the document.