Re: [v6ops] IPv6-Only Preferred DHCPv4 option

[Fernando Gont <[e-mail]>]

On 4/12/19 17:49, Jen Linkova wrote:
> On Thu, Dec 5, 2019 at 6:53 AM Brian E Carpenter
> <[e-mail]> wrote:
>>
>> As an ex-author of an ex-draft that suggested using IPv6 to tell hosts to avoid IPv4, I'm curious to know whether a draft that suggests using IPv4 to tell hosts to prefer IPv6 will also be accused of being an operational nightmare.
> 
> I hope not and let me explain why I have that hope ;)
> AFAIR the main issue with using IPv6 to signal to the host 'pls turn
> of IPv4' was that many IPv4-only networks might not have IPv6 security
> in place. So an attacker can use IPv6 to a)turn off IPv4 and b) break
> IPv6 by sending a rogue RA.
> 
> What this draft proposes is to use DHCPv4 to signal to the host 'pls
> turn of IPv4' . The same protocol, not IPv6. So there is a shared fate
> here - it the network allows rogue DHCP servers then IPv4 is doomed
> anyway.  But it's all is working over IPv4, no IPv6 involved.

Disclaimer: I haven't red the document.

But based on your description, I would suggest that the subject line is
changed. And that if there's similar wording in the document, that's
changed, too.

An DHCPv4 option to turn off IPv4 is acceptable (the two protocols are
*npt* being entangled). Whereas the subject line makes one thing that
you are using IPv4 to convey IPv6 signals -- where in fact you seem to
be using IPv4 to signal information about IPv4.

I'd bet that simple change in wording will save you a lot of time ;-)


Thanks,
-- 
Fernando Gont
SI6 Networks
e-mail: [e-mail]
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