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Re: [Ntp] Details of the fragmentation attacks against NTP and port randomization

Watson Ladd <watsonbladd@gmail.com> Tue, 11 June 2019 01:25 UTC

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From: Watson Ladd <watsonbladd@gmail.com>
Date: Mon, 10 Jun 2019 18:24:53 -0700
Message-ID: <CACsn0cngYO=u40pzDcL7uj5OC=HQ16czXdvK-rA4LthER3_WSw@mail.gmail.com>
To: Danny Mayer <mayer@ntp.org>
Cc: Fernando Gont <fgont@si6networks.com>, Ask Bjørn Hansen <ask@develooper.com>, ntp@ietf.org
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Subject: Re: [Ntp] Details of the fragmentation attacks against NTP and port randomization
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On Mon, Jun 10, 2019, 4:26 PM Danny Mayer <mayer@ntp.org> wrote:

>
> On 6/7/19 6:56 AM, Fernando Gont wrote:
> > On 5/6/19 05:45, Ask Bjørn Hansen wrote:
> >>
> >>> On Jun 5, 2019, at 10:41 AM, Danny Mayer <mayer@pdmconsulting.net
> >>> <mailto:mayer@pdmconsulting.net>> wrote:
> >>>
> >>> Furthermore the attacker doesn't know the server being used by the NTP
> >>> client so the IP address of that server will be invalid as well.
> >> This doesn’t seem right. There are much much less NTP servers in the
> >> world than there are clients. Even an attacker wildly guessing will have
> >> a limited scope of guessing (versus “every possible IP”).
> > Indeed, this is plain wrong. e.g. see the analysis in RFC5927 and
> RFC4953.
> >
> Actually he is right. Not all NTP clients are also servers. It has
> nothing to do with whether or not to randomize the source port.
>

Who is right about what? I am confused and I dont think I'm the only one.


> Danny
>
>
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