I found this as an unsent draft - I hope I didn't send it before. On 3/30/2020 2:01 AM, Ragnar Sundblad wrote:
On 30 Mar 2020, at 08:18, Saku Ytti <saku@ytti.fi> wrote:
On Mon, 30 Mar 2020 at 01:58, Ragnar Sundblad <ragge@kth.se> wrote:
A protocol with varying packet size, as the NTS protected NTP is, can easily have the bad property of having responses larger than the requests if not taken care. Don’t you see that?
Why? Why not pad requests to guarantee attenuation vector until authenticity of packets can be verified?
Right, and NTS does that.
There is more to NTP than NTS. Are y'all seriously recommending that NTP always sends a max-sized packet as a client request so the client/server can send back an identical response? That's just wasting huge amounts of bandwidth to save the possibility of a possibly larger response. And just becase a responbse may be larger, that doesn't necessarily translate into an amplification vector. The alternative seems to be that the client sends a smaller request and is ready when the response from the server is "Send your request again, but this time pad it to NNN bytes so I can respond with the same sized packet"?
Ragnar
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