[ipv6hackers] Win7 - no managed flag, DHCP address released?!?

Jim Small jim.small at cdw.com
Thu Oct 18 16:07:55 CEST 2012

Hi Karl,

> [I sent this to the IETF list and they suggested I repost it here.]
> I have just seen the following demonstrated.
> Two routers, short RA interval, both sending RAs for the same prefix,
> both with the autoconf flag set, one with the managed flag set and one
> without.

What if autoconf flag isn't set?  Curious as that could be an interesting DoS tactic.

> A Windows 7 host gets an address via DHCPv6 when the RA with the
> managed
> flag comes around - and DROPS IT when an RA without the managed flag
> comes past.
> This is not the valid lifetime expiring normally. I was not able to
> determine whether the Windows host is actually sending a DHCPv6 release
> as well, but it is most certainly dropping the address from the
> interface.

Would be interesting to see a network capture showing all traffic to/from routers and host.
> I will be trying to do my own tests to confirm (or not) this behaviour,
> but has anyone else seen it? Or seen it with other operating systems?

Haven't run into this - please share the results!
> If it is indeed happening, this behaviour seems very badly broken to me.
> I don't feel the relevant RFCs can reasonably be interpreted as
> supporting this behaviour.

Might need more info before going back to IETF.


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