Re: [Insipid] Mirja Kühlewind's No Objection on draft-ietf-insipid-logme-marking-12: (with COMMENT)

Mirja Kühlewind <ietf@kuehlewind.net> Tue, 14 August 2018 16:48 UTC

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To: "Arun Arunachalam (carunach)" <carunach@cisco.com>
Cc: The IESG <iesg@ietf.org>, "draft-ietf-insipid-logme-marking@ietf.org" <draft-ietf-insipid-logme-marking@ietf.org>, "insipid-chairs@ietf.org" <insipid-chairs@ietf.org>, "Gonzalo Salgueiro (gsalguei)" <gsalguei@cisco.com>, "insipid@ietf.org" <insipid@ietf.org>, "Dawes, Peter, Vodafone Group" <Peter.Dawes@vodafone.com>
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From: =?UTF-8?Q?Mirja_K=c3=bchlewind?= <ietf@kuehlewind.net>
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Date: Tue, 14 Aug 2018 18:47:24 +0200
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Subject: Re: [Insipid] =?utf-8?q?Mirja_K=C3=BChlewind=27s_No_Objection_on_dra?= =?utf-8?q?ft-ietf-insipid-logme-marking-12=3A_=28with_COMMENT=29?=
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Hi Arun, hi Peter,

please see below.

On 14.08.2018 16:51, Arun Arunachalam (carunach) wrote:
> Hi Mirja,
>
> Thanks for taking the time to review and sharing feedback!
>
> Please see inline.
>
>> On Aug 13, 2018, at 12:24 PM, Mirja Kühlewind <ietf@kuehlewind.net 
>> <mailto:ietf@kuehlewind.net>> wrote:
>>
>> Mirja Kühlewind has entered the following ballot position for
>> draft-ietf-insipid-logme-marking-12: No Objection
>>
>> When responding, please keep the subject line intact and reply to all
>> email addresses included in the To and CC lines. (Feel free to cut this
>> introductory paragraph, however.)
>>
>>
>> Please refer to https://www.ietf.org/iesg/statement/discuss-criteria.html
>> for more information about IESG DISCUSS and COMMENT positions.
>>
>>
>> The document, along with other ballot positions, can be found here:
>> https://datatracker.ietf.org/doc/draft-ietf-insipid-logme-marking/
>>
>>
>>
>> ----------------------------------------------------------------------
>> COMMENT:
>> ----------------------------------------------------------------------
>>
>> A couple of quick comments/questions:
>>
>> 1) How do you know that both endpoints are "log me" enabled? I guess 
>> because of
>> the requirement that all messages of a dialog must have the marker, 
>> you cannot
>> just add it and see if the other end is able to apply it to its 
>> responses…?
>
>
> It is not possible for the originating endpoint to determine whether 
> the terminating endpoint or intermediary supports “log me” prior to 
> setting up a dialog.
> If the originating endpoint sent an INVITE with logme marker and 
> received a provisional or final response with logme marker then it can 
> infer that one or more of the intermediaries in the call signaling 
> path (or) the terminating endpoint supports "log me".

Okay, this does makes sense to me, however, it is a bit contradicting to 
the normative requirement in Section 3.2:
"If a request or response is "log me" marked, then all re-transmissions 
of the request or response MUST be similarly "log me" marked. "

Maybe you can clarify this and maybe also spell out more explicitly in 
the document what you just explained above.

>
>
>
>>
>> 2) Sec 3.2: "firstly because it is configured to
>>   do so, or secondly because it has detected that a dialog is being
>>   "log me" marked, causing it to maintain state to ensure that all
>>   requests and responses in the dialog are similarly "log me" marked."
>> I was first quite confused by this sentence because I though the 
>> second case
>> meant that intermediates needs to ensure that all messages are marked
>> correctly. However, I guess the second case is when the other ends is
>> configured to do marking, one needs to reply with the marking as 
>> well. I think
>> I was mainly confused by the word "detects". Maybe it's worth to further
>> clarify this sentence…?
>
> We can rephrase as:
>    A user agent or intermediary adds a "log me" marker in an unmarked
>    request or response in two cases:firstly because it is configured to
>    add the marking to a dialog-creating request, or secondly because 
> it has
>    received a dialog-creating request that is being "log me" marked, 
> causing it to
>    maintain state to ensure that all requests and responses in the 
> dialog are
>    similarly "log me" marked.

Thanks! Much better for me!

>
>
>>
>> 3) Section 4.6 feels a little misplace but I not sure where it belong 
>> otherwise
>> (maybe section 3 or 5?). Or maybe move section 4.5 in an own section 
>> later in
>> the doc…?
>
>
> We added "4.6 Error Handling” under Section 4 since this section talks 
> about endpoint and intermediary behavior. Error handling needs to be 
> implemented in SIP entities, and we could reword the beginning of 4.6. 
> to: "The two error types that SIP entities must handle are defined in 
> Section 5, a missing marker error and an error of "log me" marking 
> that begins mid-dialog."
>
> Or if needed, we could move it as first part of Section 5 and rename 
> this section as "5. Error Handling” and make “5.1 Error cases” as a 
> sub-section.
I'd prefer this solution. But it's just an editorial comment, so I leave 
it to you.

>
> Please let us know your preference.
>
>>
>> 4) Also Section 4.6: "It MUST NOT forward the "log me" marker"
>> Does it mean an intermediate MUST remove the marker if an error is 
>> detected? Is
>> that safe given the proxy scenarios? If at all I would recommend to 
>> use MAY
>> here, I guess…
>
> If the proxy is logme aware then it is expected to remove logme marker 
> in error scenarios. It is safe to remove. The objective is to stop the 
> propagation of incorrect marking as soon as possible.

I have the feeling that this could be more explicitly spelled out in the 
doc and maybe also providing further guidance when it is actually safe 
to remove a marking would be really good.

>
>>
>> 5) Sec 8.1.:
>> "An end user or network administrator MUST give permission for a
>>   terminal to perform "log me" marking in the context of regression
>>   testing or troubleshooting a problem. "
>> and
>> "The configuration of a SIP intermediary to perform
>>   "log me" marking on behalf of a terminal MUST be authorized by the
>>   network administrator."
>> I'm actually not sure what these normative sentences mean for an
>> implementation. Is this maybe rather "An implementation MUST provide a
>> configuration to active logging and logging MUST be disabled by 
>> default.”?
>
> We can rephrase as:
>
>   “Log me” marking MUST be disabled by default both at the endpoints 
> and intermediaries and MUST be enabled only by authorized users.
>    For example, an end user or network administrator must give 
> permission for a terminal that supports “log me” marking in order to 
> initiate marking.
>    Similarly, a network administrator must enable a configuration at 
> the SIP intermediary to perform "log me" marking on behalf of a 
> terminal that doesn’t
>    support “log me” marking. The permission MUST be limited to only 
> specific calls of interest that are originated in a given time duration.
Yes, thanks!

>>
>> 6) Section 8.2:
>> "If SIP requests and responses are exchanged with an external network
>>   with which there is no agreement to pass "log me" marking, then the
>>   "log me" marking is removed."
>> Should this be normative, maybe:
>> "If SIP requests and responses are exchanged with an external network
>>   with which there is no agreement to pass "log me" marking, then the
>>   "log me" marking SHOULD be removed at the network border."
>> Or MUST?
>
> The last sentence in section 3.4.2 says “However, since a "log me" 
> marker may cause a SIP entity to log
> the SIP header and body of a request or response, if no agreement 
> exists between peer networks then the
>  "log me" marker MUST be removed at a network boundary.”
>
> So we can add a few words in 8.2 to say:
> "If SIP requests and responses are exchanged with an external network 
> with which there is no agreement to
> pass "log me" marking, then the "log me" marking is removed as 
> mandated in section 3.4.2."

Thanks, adding the reference really helps!
>
>
>>
>> 7) Also a related question: Should a network perform ingress 
>> filtering/removal
>> of "log me" markers?
>
> Yes, this scenario is discussed in Section 4.5.2.5.

Yes, the scenarios is fine but providing guidance that ingress filtering 
should be done, should probably be also discussed in the security 
considerations section.

Mirja


>
>>
>> 8) Nit:
>> Sec 2: I guess the following sentence was coped and pasted from 
>> RFC8123 and
>> should be removed for this doc: "Rather than describing interoperability
>>   requirements, they are used to describe requirements to be satisfied
>>   by the "log me" marking solution.”
>
> Yes, we will remove it.
>
> Thanks!
> Peter & Arun
>
>>
>>
>