Re: [tram] Publication has been requested for draft-ietf-tram-stun-pmtud-07

[Spencer Dawkins at IETF <[e-mail]>]

Hi, Marc,

On Mon, Aug 20, 2018 at 11:08 AM Marc Petit-Huguenin <
[e-mail]> wrote:

> Hi SPencer,
>
> Sorry for the delay on resolving that issue.  See below for my answer.
>
> On 05/15/2018 08:33 AM, Spencer Dawkins at IETF wrote:
> > Hi, Marc,
> >
> > On Mon, May 14, 2018 at 6:50 PM, Marc Petit-Huguenin <
> > [e-mail]> wrote:
> >
>
> [...]
>
> >>
> >>>
> >>> If using authentication in
> >>>
> >>>   UDP-based protocols that want to use any of these mechanisms,
> >>>    including the PMTUD-SUPPORTED attribute, to signal PMTUD
> capabilities
> >>>    MUST ensure that it cannot be used to launch an amplification
> attack.
> >>>    For example, using authentication can ensure this.
> >>>
> >>> is only one way to ensure prevention of amplification attacks, is there
> >> any
> >>> guidance or reference you could point to that would help implementers
> >>> evaluate other approaches?
> >>
> >> It's a good question.  I have to think about that.
> >>
> >
> > Thanks for the quick and thorough responses.
> >
> > I think I'm good on your responses for all my other questions. I'll let
> the
> > working group chew on this one, and let the chairs/shepherd let me know
> > when to request Last Call.
> >
>
> As far as I can tell, there is 3 major ways of preventing source IP
> spoofing at this layer, but I was not able to find a unique reference that
> points to an explanation to these.
>
> So the plan is to add, after some copy-editing with my co-editor, the
> following text in replacement of the "For example, using authentication can
> ensure this." sentence:
>
>
> "  An amplification attack can be prevented using three different
>    techniques:
>
>    o  Authentication, where the source of the packet and the destination
>       share a secret.
>
>    o  3 way handshake with some form of unpredictable cookie.
>
>    o  Make sure that the total size of the traffic potentially generated
>       is lower than the size of the request that generated it."
>
>
> Would that resolve that issue?
>

Yes, it would.

I was hoping there would be a good reference you can point to, but if
there's not, this is helpful.

I might suggest that your first sentence be something like

"An amplification attack can be prevented using techniques such as:"

just in case a security reviewer happens to know of a fourth technique. But
I'll let you and Gonzalo do the right thing, and I'll request Last Call for
your next version.

Thanks for chasing this down!

Spencer


> Thanks.
>
> --
> Marc Petit-Huguenin
> Email: [e-mail]
> Blog: https://marc.petit-huguenin.org
> Profile: https://www.linkedin.com/in/petithug
>
>
>
>