Re: I-D Action: draft-fgont-6man-rfc4941bis-01.txt

[Brian E Carpenter <[e-mail]>]

On 27/03/2018 21:35, Fernando Gont wrote:
> On 03/26/2018 11:52 PM, Brian E Carpenter wrote:
>>>>
>>>>> 6. Temporary addresses are *not* disabled by default.
>>>>
>>>> Specifically, this text was removed:
>>>>
>>>>> Consequently, the use of temporary addresses SHOULD be disabled by	
>>>>> default in order to minimize potential disruptions.
>>>>
>>>> My concern is that the disruptions ("some applications may not behave
>>>> robustly if temporary addresses are used") haven't gone away, and the
>>>> cause may be very hard for ordinary users to diagnose. In fact, I
>>>> think some of the cases of help desks advising users to switch off
>>>> IPv6 derive from recently shipped operating systems that enable
>>>> temporary addresses by default. I've disabled them on a couple of
>>>> Windows 10 laptops for this reason.
>>>
>>> Through what impact of using privacy addresses?  What are the problematic applications?
>>
>> I don't know what the 4941 authors were thinking of. 
> 
> I guess they were referring to long-lived connections?

Probably. What I'm complaining about is services that have some
sort of reputation system based on individual /128s. Temporary
addresses do create a behaviour pattern that doesn't exist for
IPv4 clients.

> 
> 
>> The example
>> I've seen is mentioned below: a service that considers frequent
>> changes of IP address to be a sign of illicit activity.
> 
> This is tricky already, anyway. With happy-eyeballs sort of behavior,
> this can already happen (one connection happens over v4, and a
> subsequent happens over v6).
> 
> I do believe that, for all such cases, giving apps more control (and
> awareness!) regarding v6 addressing and what they can do about it is
> needed. But that would be out of cope for this particular document, I think.
> 
> That said, we could add a comment about this issue in this document.
> Thoughts?

Yes, an explanation of this side-effect issue would help. Also perhaps,
replace the old "off by default" text by a requirement that it must be
easy for the user to disable temporary addresses if they cause problems.
IMHO, netsh interface ipv6 set privacy state=disabled store=persistent
doesn't count as "easy" for a normal user.

There are real scenarios where "on by default" can be a problem.
Here are some fragments of the real world:
http://kb.tableau.com/articles/Issue/identifying-and-disabling-temporary-ipv6-addresses
https://lonesysadmin.net/2018/01/23/disable-windows-ipv6-temporary-addresses/

   Brian

> 
> 
>> (Remember, my concern is only about the default configuration
>> and the resulting puzzlement of ordinary users and help desks.)
> 
> Another part of the problem here is that you cannot hint the network
> about what to do. e.g., see draft-gont-6man-managing-slaac-policy
> 
> Thanks!
> 
> Cheers,
>