41–50 of 113 posts
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I had the same thought. Does the world really need another (presumably) stratum-3 server running in Amazon's cluster, when Amazon already runs a pool of stratum-2 servers? ([0-3].amazon.pool.ntp.org).
By my recent reading of the AWS docs, those pool addresses are not run by Amazon. They are DNS names that allow NTP load from AWS to the NTP pool to be distributed more fairly.
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Keeping a table of clients and their last-updated time is probably more expensive than just sending them a response.
Randomly dropping a percentage of requests is stateless.
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Keeping a table of clients and their last-updated time is probably more expensive than just sending them a response.
Randomly dropping a percentage of requests is stateless.
Earlier quoted context omitted.
> Netgear stopped doing it. Netgear issued patches for the devices. Most people never update their server firmware, and we're talking about over 700,000 devices. The university still gets considerable traffic. https://en.wikipedia.org/wiki/NTP_server_misuse_and_abuse#NE...
Can't the university throttle non local connections ? (netgear could have provided the hardware ;)
For what you want to have any effect they'll have to sinkhole/throttle the traffic upstream before it ever reaches them and as a university they are effectively an ISP so that might not even be really possible.
Earlier quoted context omitted.
> Netgear stopped doing it. Netgear issued patches for the devices. Most people never update their server firmware, and we're talking about over 700,000 devices. The university still gets considerable traffic. https://en.wikipedia.org/wiki/NTP_server_misuse_and_abuse#NE...
Can't the university throttle non local connections ? (netgear could have provided the hardware ;)
I do recommend reading the incident report posted above if you have an interest in network operations, it's quite interesting!
part 2: https://blog.pivotal.io/labs/labs/ntp-server-costing-500year...
I wish he'd explained somewhere how they leapt to examining virtualized NTP clients, or what they ultimately did (since there's no part 3 that I can find).
> I wish he'd explained somewhere how they leapt to examining virtualized NTP clients...
I had a hunch [wrongly] that the traffic was caused by a particular operating system. I didn't have enough machines to run the tests on bare-metal, so I virtualized them. And I suspected that virtualization would provide a worst-case scenario (the virtualized clocks would be jittery).
My big surprise was that Windows was a model client (once per day), OS X was good, too, and that FreeBSD was the worst and Ubuntu a close second. It was a complete inversion of what I had expected to find.
> what they ultimately did (since there's no part 3 that I can find).
I never wrote part 3, but now that it seems the post has gained traction on Hacker News I might be inspired to write one. The summary would be as follows:
To reduce your costs by a quarter, use the following lines in your NTP configuration file to throttle overly-aggressive clients (the important directive is `limited`:
``` restrict default limited kod nomodify notrap nopeer discard minimum 0 ```
Here is a description of NTP rate-limiting and why `limited`, `kod`, and `discard` are important: https://www.eecis.udel.edu/~mills/ntp/html/rate.html
Here is my current NTP configuration: https://github.com/cunnie/deployments/blob/95e9c71e882d453ec...
Earlier quoted context omitted.
I wish he'd explained somewhere how they leapt to examining virtualized NTP clients, or what they ultimately did (since there's no part 3 that I can find).
I too was expecting some sort of conclusion.
My bad. Now that the post has been picked up on HN, I'll try to write up a conclusion.
Hats off to everyone contributing to public services like this. My then company wanted to give back ny doing this many years ago and it was an eye opening experience. We had troubles almost immediately with utilization and script kiddies. The company ended up only doing it for a relatively short period and ended up making contributions to projects instead
Thanks, Spooky23. As you pointed out, contributing to the community takes more time than originally expected.