IPv4 and IPv6 Greynets
draft-baker-v6ops-greynet-05

[Ballot comment]
Question based on this statement:

  It has been observed [RFC5157] that address scanning is less
  effective in IPv6 [RFC2460] networks, as there are more addresses to
  scan.  The observation is of limited value, in that there are other
  approaches to identifying IPv6 systems, such as reading the
  'Received:' lines in SMTP envelopes.  Such attacks can be limited by
  the use of Privacy Addresses [RFC4941], which periodically change,
  rendering such historical information less useful, but the fact is
  that such analytic methods exist.  Greynets are a tool that can be
  used to isolate and analyze them.

Is there any deployment experience that indicates greynets provide useful information in IPv6, where the traffic to be captured by the greynet may come from seeding information about "lit" IPv6 addresses rather than address or prefix scanning?

(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?

Tim Chown. Yes I have reviewed the document and I believe that it is ready 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 been presented to and discussed within the WG. For the scope of the document the level of review seems appropriate.

(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 further review is required.

It is possible (and in my view desirable) that experience from implementations using certain combination(s) of techniques described in the text may lead to an additional draft where a more specific protocol is described - that is beyond the scope of this text though, which is acting as a 'call to arms' for such implementations.

>>> (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.

I'm not aware of any filing. My view is that such a dynamic approach for greynets would be very useful for IPv4 (where reserving large enough address blocks for traditional darknets is becoming less feasible) and would also be a very natural mechanism for IPv6 where all subnets are naturally sparsely populated/lit.

(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?

The document has been discussed favourably in WG meetings. Discussion on the WG list has been very light, with only minor nitpicking, but that can be taken as a sign of no major issues.

(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 document passes all ID nit tests perfectly. I do not believe any other formal review is required.

(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 document meets the reference requirements.

(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?

There are no IANA considerations relevant to the text.

(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?

There is no use of such 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

The document first describes the darknet model for detecting possible malicious activity on a network and then explains the value of static greynets given the decreasing capability within IPv4 networks to reserve a large enough contiguous block of address space for classic darknet detection purposes. The text describes in general terms a new approach to deploying dynamic greynets in which a router's behaviour can be augmented to forward information (packets) to a collector based on various heuristics as described in the document. It does not try to prescribe specific forwarding methods or heuristics, rather the text should be seen as encouraging implementation and testing. The dynamic forwarding mechanism is applicable both to IPv4 networks where address space is limited, or to IPv6 networks where subnets are naturally sparsely populated. The most obvious forwarding trigger is where a router receives no ARP/ND response for a packet it is forwarding to a subnet, but additional triggers may also be defined whereby packets may be forwarded to the collector, e.g. on failure of a uRPF check.

Working Group Summary

There were no objections raised at all to the ideas presented in the draft.
Document Quality

The document is well written and clear.

I have a student who has implemented the dynamic greynet as described in the text, under Linux, supporting IPv4 and IPv6 traffic. Our implementation used UDP encapsulation for packet forwarding, but other methods could equally be used. In our case we used a web-based GUI to search the database of forwarded (collected) data, with a simplistic search by src/dst IP/port providing interesting information. Our implementation only forwarded packets based on one heuristic (no reply to ARP/ND), but where multiple heuristics are used some additional information may need to be conveyed in the forwarding mechanism, but that is beyond the scope of this text. I am not aware (as yet) of vendor intention to implement, but our own implementation shows the idea appears both viable and useful.