Re: [secdir] [v6ops] Secdir last call review of draft-ietf-v6ops-transition-ipv4aas-11

[Christian Huitema <[e-mail]>]

On 12/13/2018 2:09 PM, JORDI PALET MARTINEZ wrote:
> Hi Christian,
>
> Thanks a lot for your review.
>
> Please see below in-line.
>
> I'm working in a new version according to the comments got from the ops review as well, so will be able to integrate yours very quickly.
>
> Regards,
> Jordi
>  
>  
>
> -----Mensaje original-----
> De: v6ops <[e-mail]> en nombre de Christian Huitema <[e-mail]>
> Fecha: jueves, 13 de diciembre de 2018, 21:50
> Para: <[e-mail]>
> CC: <[e-mail]>, <[e-mail]>, <[e-mail]>
> Asunto: [v6ops] Secdir last call review of draft-ietf-v6ops-transition-ipv4aas-11
>
>     Reviewer: Christian Huitema
>     Review result: Has Issues
>     
>     I have reviewed draft-ietf-v6ops-transition-ipv4aas-11 as part of the
>     security directorate's ongoing effort to review all IETF documents
>     being processed by the IESG.  These comments were written primarily for
>     the benefit of the security area directors.  Document editors and WG chairs
>     should treat these comments just like any other last call comments.
>     
>     The summary of the review is "ready with issue".
>     
>     The document describes solution for providing "IPv4 as a service", i.e.
>     provision of IPv4 as a service over an IPv6 only network.
>     It calls this support "transition as a service".
>     
>     For various reasons, IETF working groups have standardized not just one but
>     five different mechanisms for providing this transition: 464XLAT [RFC6877],
>     Dual-Stack Lite [RFC6333], Lightweight 4over6 (lw4o6) [RFC7596],
>     MAP-E [RFC7597], and MAP-T [RFC7599]. (I am sure that Monty Python could have
>     produced a nice sketch about that.) The purpose of the draft is to
>     state how home routers (a.k.a. customer premise equipment, CPE) should
>     inform local devices about which of the mechanisms are available, which
>     should be preferred, and what parameters should be used when deploying
>     the chosen services. This is done using the DHCPv6 "S46" option
>     specified in RFC 8026.
>     
>     The draft also makes specific recommendation regarding the use of the UPnP and
>     PCP services, by requiring specific error codes when a requested port mapping 
>     is not available through the specified transition technology.
>     
>     The security section briefly points to the "Basic Requirements for IPv6
>     Customer Edge Routers" specified in RFC 7084, and to the security
>     section of each of the RFC describing the security technologies, and implicitly
>     argues that there are no other security issues. I think that is insufficient.
>     
>     The draft introduces a reliance on the DHCPv6 "S46" option for assessing the
>     relative priority of different transition technologies. An attacker could spoof
>     the DHCPv6 response, and direct client traffic to a different technology than
>     selected by the service provider. This could be used, for example, to capture
>     IPv4 traffic in an IPv6 network and send it to a route chosen by the attacker.
>     The attack might also be used in a dual stack network that does not support
>     any transition technology. I don't understand how this attack is mitigated.
>
> Not sure if you will suggest here that we should say something about the security considerations already mention in RFC8026. In general all those are generic DHCPv6 security considerations I think.

Basically, the devices should be programmed to ignore DHCPv6 if they
have another more secure way of getting their configuration data. Plus,
apply general defense against DHCPv6 hacks in the network, etc. I
understand that your draft is meant to inform the building of CPEs, but
its effect is generalization of an unsafe mechanism.


>     
>     Nits:
>     
>     The introduction uses the acronym WAN without spelling out "Wide Area Network". 
>     Also, WAN is used as substitute for local Internet Service Provider network. We could
>     debate whether such networks are always "wide area", by opposition to say
>     "metropolitan" or "regional". This is the same convention used in RFC 7084 that
>     this document updates. It is arguably defined by reference, but spelling it out
>     would be nice.
>  
> Will do.
>
>    
>     The comparison with RFC7084 section includes a mangled sentence: 
>     
>        This document doesn't include support for 6rd ([RFC5969]), because as
>        in an IPv6-in-IPv4 tunneling.
>
> Typo, sorry the correct sentence was:
>        This document doesn't include support for 6rd ([RFC5969]), because is
>        an IPv6-in-IPv4 tunneling.

       This document doesn't include support for 6rd ([RFC5969]), because it is
       an IPv6-in-IPv4 tunneling.

>     
>     Please rephrase. Please also rephrase the next sentence, for similar reasons:
>     
>        Regarding DS-LITE [RFC6333], this document includes slightly
>        different requirements, because the PCP ([RFC6887]) support and the
>        prioritization of the transition mechanisms, including dual-stack.
>
> I think it is much clear this way:
>
>        Regarding DS-LITE [RFC6333], this document includes slightly
>        different requirements, related to the support of PCP ([RFC6887]),
>        IGD-PCP IWF [RFC6970] and the prioritization of the transition 
>        mechanisms, including dual-stack.  

OK.


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