Defending against Sequence Number Attacks
draft-ietf-tcpm-rfc1948bis-02

[Ballot comment]
Acronyms should be expanded on first use in the body text.

---

In Section 3 you use "F" and "F()" to denote the PRF. You should pick
one for consistent use.

[Ballot comment]
The SECDIR Review by Joe Salowey  points out a minor typo.
  In section 3 there is a repeated "the" in the first sentence of
  the second paragraph.

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:  (Defending Against Sequence Number Attacks) to Proposed Standard


The IESG has received a request from the TCP Maintenance and Minor
Extensions WG (tcpm) to consider the following document:
- 'Defending Against Sequence Number Attacks'
  as a 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 2011-11-02. 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


  This document specifies an algorithm for the generation of TCP
  Initial Sequence Numbers (ISNs), such that the chances of an off-path
  attacker guessing the sequence numbers in use by a target connection
  are reduced.  This document revises (and formally obsoletes) RFC
  1948, and takes the ISN generation algorithm originally proposed in
  that document to Standards Track.




The file can be obtained via
http://datatracker.ietf.org/doc/draft-ietf-tcpm-rfc1948bis/

IESG discussion can be tracked via
http://datatracker.ietf.org/doc/draft-ietf-tcpm-rfc1948bis/


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

  (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?


David Borman (david.borman@windriver.com) is the document shepherd.
He has personally reviewed this version and believes it is ready for
forwarding to the IESG for publication.



  (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 document has had review in the TCPM working group.  During review
several comments were received and discussed on the mailing list.
The latest version of the document incorporates all the received
comments.  The shepherd has no concerns about the depth or breadth
of review.


  (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?


No concerns.


  (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.


No 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 has not been any resistance to this document.  Most of the
discussion has been around clarification and cleanup of the document.


  (1.f) 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
        entered into the ID Tracker.)


No.


  (1.g) Has the Document Shepherd personally verified that the
        document satisfies all ID nits? (See the Internet-Drafts Checklist
        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?


The warnings by idnits are:

  -- The draft header indicates that this document obsoletes RFC1948, but the
    abstract doesn't seem to directly say this.  It does mention RFC1948
    though, so this could be OK.

  -- The draft header indicates that this document updates RFC793, but the
    abstract doesn't seem to mention this, which it should.

  ** Downref: Normative reference to an Informational RFC: RFC 1321

The first one is handled in the abstract.

The second one is not an issue, RFC793 is mentioned throught the
document; this document provides a new method for determing the
ISN, but does not change the TCP protocol in any other way.

The last is a reference to the MD5 RFC.  Hence, it is reasonable to
list this in the Normative section, even though it is an informational
RFC.



  (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].


The references are properly split, with the comment above about
the MD5 RFC.



  (1.i) Has the Document Shepherd verified that the document IANA
        consideration 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 [RFC5226]. If the
        document describes an Expert Review process has Shepherd
        conferred with the Responsible Area Director so that the IESG
        can appoint the needed Expert during the IESG Evaluation?



The IANA Considerations are present and specify no actions for IANA.



  (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?


Not Applicable.



  (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.


From the abstract:

  This document specifies an algorithm for the generation of TCP
  Initial Sequence Numbers (ISNs), such that the chances of an off-path
  attacker guessing the sequence numbers in use by a target connection
  are reduced.  This document revises (and formally obsoletes) RFC
  1948, and takes the ISN generation algorithm originally proposed in
  that document to Standards Track.



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

Nothing exceptional occurred during the working group process for this
document.


    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?

This document is aimed at decreasing the predictability of the
TCP ISN, to reduce the probability that an off-path attacker can
guess the ISN, which would allow it to compromise the TCP connection.
It does not change how TCP operates, just how the implementation
chooses the ISN for each connection.