Subject: Re: [ntpwg] I-D Action: draft-ietf-ntp-network-time-security-04.txt

From: Tapio Sokura <[email-masked]>
Date: Fri, 04 Jul 2014 15:24:34 +0300

On 4.7.2014 12:24, [email-masked] wrote:
> http://tools.ietf.org/html/draft-ietf-ntp-network-time-security-04

I haven't been following the development of the draft before so this
could be an old issue, but here goes anyway: Has consideration been
given to averting DoS amplification attacks? It looks like the
client_cert/server_cert message combination might allow a decent
amplification factor, without the (spoofed) client needing to supply any
specific per-association state to the server.

If the server keeps tabs on clients that have sent a client_assoc
message and responds to client_cert requests only from them, an attacker
could just as well send a forged client_assoc first and then a forged
client_cert. Of course this gets more complicated for the attacker and
lessens the aplification factor so he might turn to something else.

I don't know if it needs to be in the document, but acknowledging the
possibility of using DANE for authenticating the server certificate
should not be forgotten.

  Tapio
_______________________________________________
ntpwg mailing list
[email-masked]
http://lists.ntp.org/listinfo/ntpwg