[ipv6hackers] an interesting DHCPv6 DoS

[Tore Anderson]

* Mark ZZZ Smith

> One other question though, it also shouldn't be asking for a IA-NA
> unless you have the M bit (Managed Address bit) switched on in RAs.
> If you do have it switched on, it would be interesting whether
> switching it off (just leaving the O bit switched on) would stop the
> CPE asking for IA-NAs in its DHCPv6 requests.

I'm not sure this is correct. RFC 6204 implies that a router may start
DHCPv6 before having even seen an RA:

   WPD-5:  If the IPv6 CE router initiates DHCPv6 before receiving a
           Router Advertisement, it MUST also request an IA_NA option in
           DHCPv6.

While this has been taken out of RFC 7084, I see no language there that
forbids a router from requesting IA_NA before it has seen an RA with M=1.

Tore