Re: [v6ops] RFC6459 "IPv6 in 3GPP" - the IID in the LL address

[Alexandre Petrescu <[e-mail]>]

Le 11/07/2017 à 08:51, [e-mail] a écrit :
> Hi Alex,
> 
> Please see inline.
> 
> Cheers,
> Med
> 
>> -----Message d'origine-----
>> De : Alexandre Petrescu [mailto:[e-mail]]
>> Envoyé : lundi 10 juillet 2017 18:28
>> À : BOUCADAIR Mohamed IMT/OLN; [e-mail]
>> Objet : Re: [v6ops] RFC6459 "IPv6 in 3GPP" - the IID in the LL address
>>
>>
>>
>> Le 10/07/2017 à 16:58, [e-mail] a écrit :
>>> Re-,
>>>
>>> Please see inline.
>>>
>>> Cheers,
>>> Med
>>>
>>>> -----Message d'origine-----
>>>> De : Alexandre Petrescu [mailto:[e-mail]]
>>>> Envoyé : lundi 10 juillet 2017 16:46
>>>> À : BOUCADAIR Mohamed IMT/OLN; [e-mail]
>>>> Objet : Re: [v6ops] RFC6459 "IPv6 in 3GPP" - the IID in the LL address
>>>>
>>>>
>>>>
>>>> Le 10/07/2017 à 16:16, [e-mail] a écrit :
>>>>> Alex,
>>>>>
>>>>> I'm focusing on this part of your answer.
>>>>>
>>>>> Please see inline.
>>>>>
>>>>> Cheers, Med
>>>>>
>>>>>> -----Message d'origine----- De : Alexandre Petrescu
>>>>>> [mailto:[e-mail]] Envoyé : lundi 10 juillet
>>>>>> 2017 15:51 À : BOUCADAIR Mohamed IMT/OLN; [e-mail] Objet :
>>>>>> Re: [v6ops] RFC6459 "IPv6 in 3GPP" - the IID in the LL address
>>>>>>
>>>>>> Med,
>>>>>>
>>>>>>
>>>>>>>> This has consequences on privacy, and may impact
>>>>>>>> interoperability when DHCPv6-PD is used later in the process.
>>>>>>>
>>>>>>> [Med] I don't follow you here. There is no privacy concern out
>>>>>>> there. The IID used when forming a global IPv6 address will be
>>>>>>> selected by the terminal; no assumption is made about those
>>>>>>> bits.
>>>>>>
>>>>>> There is a privacy concern: if the operator enforces the UE to
>>>>>> always use the network-assigned IID then that UE is trackable.
>>>>>>
>>>>>
>>>>> [Med] I'm not sure what you mean by "trackable" in this context. If
>>>>> you mean that "a UE can be identified by the network", then an UE is
>>>>> always identified by the network it connects to!
>>>>
>>>> YEs, and I thought that is a device-specific identifier like the IMEI,
>>>> not the link-local address.
>>>>
>>>>> At the IP level, an UE is identified by the bits of the IPv6 prefix,
>>>>>    not IID bits.
>>>>
>>>> Well - by the IP address.
>>>
>>> [Med] No. I reiterate my answer: it is identified by the prefix not the
>> full IPv6 address.  Policies at the network are enforced based on the
>> prefix, not the full IPv6 address.
>>>
>>>>
>>>>> Further, a network does not need IP-related information to identify
>>>>> an UE.
>>>>
>>>> I agree, so why does it want to impose an IID to the UE?
>>>
>>> [Med] This is an optimization to avoid DAD.
>>
>> Ok about LL, but how about the GUA?
> 
> [Med] No problem at that front either (reading from the 3GPP spec):
> 
> ==
> Since the GGSN guarantees that the Prefix is unique, the MS does not need to perform any Duplicate Address Detection on addresses it creates.
> ==
> 
>    If the network uses a GUA same as
>> the UE then there should be DAD for that GUA.
> 
> [Med] Idem as above, the spec is clear:
> 
> ==
> The GGSN shall not generate any globally unique IPv6 addresses for itself using the Prefix assigned to the MS in the Router Advertisement.
> ==
> 
>>
>> I dont think there is any spec that tells that the network MUST NOT
>> assign a GUA on its interface towards the UE.
> 
> [Med] See for example, 3GPP TS. 29.061
> 
>>
>>
>>
>>>>> I still don't see any privacy concern in supplying an IID to an UE
>>>>> to be used for forming its link-local address.
>>>>
>>>> Err...
>>>>
>>>> It's because the supplied IID is very much like an IEEE MAC 48bit
>>>> address.
>>>
>>> [Med] This is a link-local address not a GUA. So, not sure to understand
>> your point.
>>
>> I can understand your point about GUA privacy vs LL privacy.
> 
> [Med] OK.

Med - why there is no answer to my DHCPv6 PD Solicit?  I am using a GUA 
without the IID from the operator.

Alex

>