Re: [Idr] AD Review of draft-ietf-idr-shutdown-07

"Alvaro Retana (aretana)" <aretana@cisco.com> Mon, 24 April 2017 21:59 UTC

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From: "Alvaro Retana (aretana)" <aretana@cisco.com>
To: Job Snijders <job@instituut.net>
CC: "draft-ietf-idr-shutdown@ietf.org" <draft-ietf-idr-shutdown@ietf.org>, "idr-chairs@ietf.org" <idr-chairs@ietf.org>, Hares Susan <shares@ndzh.com>, "idr@ietf.org" <idr@ietf.org>
Thread-Topic: [Idr] AD Review of draft-ietf-idr-shutdown-07
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Date: Mon, 24 Apr 2017 21:59:47 +0000
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Subject: Re: [Idr] AD Review of draft-ietf-idr-shutdown-07
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On 4/22/17, 6:10 AM, "Job Snijders" <job@instituut.net> wrote:

Job:

Hi!

…
> > C5. Section 4. (Error Handling): “Any erroneous or malformed Shutdown
> > Communication received SHOULD be logged for the attention of the
> > operator and then MAY be discarded.”
> > 
> > C5.1. What does “erroneous or malformed” mean?  I guess this is beyond
> > a bad length, but maybe it refers to invalid UTF-8 sequences, or maybe
> > something different.   ??
>
> Yes, section 2 "A receiving BGP speaker MUST NOT interpret invalid UTF-8
> sequences." So, what a BGP speaker could do is send a hexdumped version
> of the received data to syslog after something like "printf("%02x",
> *p++);", rather then present that data through usual ways (as UTF-8).

Ok, so “erroneous or malformed” just refers to an “invalid UTF-8 sequence”?  If so, then just say that and don’t leave it up to interpretation.


…
> > C5.3. Section 2 already talks about reporting the contents -- I’m
> > assuming the logging requirement here is the same (do whatever you
> > want, but syslog SHOULD be used), right?  If so, then how is the
> > handling of the “erroneous or malformed” information different than
> > that of the one that isn’t?
>
> I envision that in the invalid case one simply logs "received malformed
> shutdown communication", with perhaps a hexdump of what was received,
> and in the normal situation a bgp speaker decodes the string as UTF-8,
> syslogs the result, and perhaps stores it for historic purposes. Do you
> have a suggestion how to clarify?
>
> perhaps, NEW:
>
>     """
>     If an erroneous or malformed Shutdown Communication is received, a
>     message indicating this event SHOULD be logged for the attention of
>     the operator.  An erroneous or malformed Shutdown Communication
>     itself MAY be logged in a hexdump format.
>     """

That text seems fine to me.  


> > C6. Section 5. (IANA Considerations) Why do you want the registry to
> > refer to this document?  There’s nothing in this document that
> > modifies or affects the registry, the policies or the assignments… I
> > think that the Updates tag is enough to show the relationship.
>
> Because 4486 is updated, and 4486 instantiated those entries. I believe
> there is benefit in providing this additional way to show the relation.
> A developer or debugger might go straight to the registry looking for
> just the value mapping, and then be happy to learn that subcode 2 & 4
> could be followed by trailing data which is encoded in a specific way.

That still doesn’t seem needed to me, but I’m happy to let IANA raise a flag if it is an issue for them.



> > C7. Section 6.  (Security Considerations)
> > 
> > C7.1. REQUIRING is not an rfc2119 keyword.  Please work REQUIRED in
> > there instead.
>
> OK, I got that from RFC 5424, so we might need an errata there.

It looks like we do.


…
> > C7.3. In the Shepherd’s write-up [2], Sue wrote: “The Security-ADs
> > will look at the ability to send data which indicates specific details
> > regarding an operator or the operator's topology.”  Given that the
> > operator can put anything in the string, it would be nice if you
> > addressed this concern up front (and not wait for the SEC ADs).  Even
> > if the information is being sent to a “trusted” peer, I think Sue
> > raises an interesting point as “confidential” information may be
> > inadvertently sent out.  One way to address this concern may be with
> > guidance to operators and to reaffirm the fact that while the
> > information is sent only one hop away (to your peer), it can be used
> > as the receiver’s discretion.
> > 
> > [2] https://datatracker.ietf.org/doc/draft-ietf-idr-shutdown/shepherdwriteup/
>
> Interesting point. Do you think XMPP, SMTP, NNTP, and SYSLOG, include
> similar clauses? 

I don’t know, did you look? ;-)

All those protocols were standardized before the IAB/IESG acquired a new taste for privacy.  Take a look at rfc6973 and at this short review [3].

[3] https://ietf.org/edu/tutorials/89-Privacy-Tschofenig.pdf 


> I personally may want to wait for a security AD to
> actually make and argue the point rather then 'preempt' the angle with
> text which borders on legalese.

No need to be too clever when writing this up; all you need is a recognition that secondary use of the data can occur, some recommendations about how to mitigate (by not including too much), and maybe a pointer to rfc6973.


> Following your feedback, we'll post an update shortly.


Thanks!

Alvaro.