[rnijveld]

I agree that amplification and reflection definitely are worries, which is why we are working towards NTS becoming a default on the internet. NTS would prevent responses by a server from a spoofed packet and at the same time would make sure that NTP clients can finally start trusting their time instead of hoping that there are no malicious actors anywhere near them. You can read about it on our blog as well: https://tweedegolf.nl/en/blog/122/a-safe-internet-requires-s...

One thing to note about amplification: amplification has always been something that NTP developers have been especially sensitive to. I would say though that protocols like QUIC and DNS have far greater amplification risks. Meanwhile, our server implementation forces that responses can never be bigger than the requests that initiated them, meaning that no amplification is possible at all. Even if we would have allowed bigger responses, I cannot imagine NTP responses being much bigger than two or three times their related request. Meanwhile I've seen numbers for DNS all the way up to 180 times the request payload.

As for your worries: I think being a little cautious keeps you alert and can prevent mistakes, but I also feel that we've gone out of our way to not do anything crazy and hopefully we will be a net positive in the end. I hope you do give us a try and let us know if you find anything suspicious. If you have any feedback we'd love to hear it!

[dfc]

> I cannot imagine NTP responses being much bigger than two or three times their related request.

I think you must be limiting your imagination to ntp requests related to setting the time. There are a lot of other commands in the protocol used for management and metrics. The `monlist` command was good for 200x amplification. https://blog.cloudflare.com/understanding-and-mitigating-ntp...

[rnijveld]

Ah right! I always forget about that since we don’t implement the management protocol in ntpd-rs. I think it’s insane that stuff should go over the same socket as the normal time messages. Something I don’t ever see us implementing.

[syncsynchalt]

Thank you for your considered response!

I hadn't heard about NTS and I'm rolling it out to my fleet of timeservers now.