Re: [ietf-privacy] [Int-area] NAT Reveal / Host Identifiers

Brandon Williams <brandon.williams@akamai.com> Mon, 09 June 2014 13:47 UTC

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Date: Mon, 09 Jun 2014 09:46:59 -0400
From: Brandon Williams <brandon.williams@akamai.com>
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To: Stephen Farrell <stephen.farrell@cs.tcd.ie>, Dan Wing <dwing@cisco.com>
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Subject: Re: [ietf-privacy] [Int-area] NAT Reveal / Host Identifiers
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Hi Stephen,

On 06/07/2014 09:20 AM, Stephen Farrell wrote:
 > Adding new identifiers with privacy impact, as proposed here, is
 > quite different.

It is not the intention of the authors for this to be a solution draft. 
The draft is intended to describe address sharing use cases and 
deployment scenarios.

Would you please indicate where the draft proposes a new identifier? If 
you are seeing a proposal for protocol changes somewhere in the draft, 
editing work is required in order to either clarify or excise the 
associated text.

Thanks,
--Brandon

On 06/07/2014 09:20 AM, Stephen Farrell wrote:
>
> Hi Dan,
>
> On 07/06/14 02:38, Dan Wing wrote:
>>
>> Stephen,
>>
>> It seems NAPT has become IETF's privacy feature of 2014 because
>> multiple users are sharing one identifier (IP address and presumably
>> randomized ports [RFC6056], although many NAPT deployments use
>> address ranges because of fear of compressing log files).  As a
>> former co-chair of BEHAVE it is refreshing to see the IETF embracing
>> NAPT as a desirable feature.
>
> Embracing seems like significant overstatement to me, but maybe
> that's understandable given how calmly NAT is generally debated.
>
> NATs have both good and bad properties. The slightly better privacy
> is one of the good ones.
>
> Recognising that reality is neither embracing nor refreshing IMO,
> nor does it mean NAPT is (un)desirable overall. (That's an argument
> I only ever watch from the side-lines thanks:-)
>
>> However, if NAPT provides privacy and NAT Reveal removes it, where
>> does that leave a host's IPv6 source address with respect to BCP188?
>>
>> Afterall, an IPv6 address is quite traceable, even with IPv6 privacy
>> addresses (especially as IPv6 privacy addresses are currently
>> deployed which only obtain a new IPv6 privacy address every 24 hours
>> or when attaching to a new network).  If BCP188 does not prevent
>> deployment of IPv6, I would like to understand the additional privacy
>> leakage of IPv4+NAT+NAT_Reveal compared to the privacy leakage of
>> IPv6+privacy_address.
>
> I'm frankly amazed that that's not crystal clear to anyone who
> has read all 2.5 non-boilerplate pages of the BCP. Or even just
> the last two words of the 1-line abstract (hint: those say "where
> possible.")
>
> Yes, source addresses leak information that affects privacy. But
> we do not have a practical way to mitigate that. So therefore
> BCP188 does not call for doing stupid stuff, nor for new laws of
> physics (unlike -04 of the draft we're discussing;-)
>
> Adding new identifiers with privacy impact, as proposed here, is
> quite different.
>
> S.
>
> PS: If someone wants to propose what they think is a practical
> way to mitigate the privacy issues with source addresses, please
> write a draft first and then start a separate thread somewhere.
>
>
>>
>> -d
>>
>
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-- 
Brandon Williams; Senior Principal Software Engineer
Emerging Products Engineering; Akamai Technologies Inc.