[time] Fwd: [time-dev] NTP survey

Ishan Vaishnavi I.Vaishnavi
Fri Feb 12 14:46:19 UTC 2010

Ryan, How do you propose to choose nodes "randomly" ?

Well, I have already started "walking the tree" as a first attempt. So, 
if any of you own an NTP server now is a good time to set the 
permissions so that it replies to all requests over the next 2 weeks. 
The IP addresses are 192.16.201.*

If anyone has a list of all pool server ip addresses, please do mail 
them to me.
Ryan Malayter wrote:
> On Mon, Feb 8, 2010 at 8:16 AM, Ishan Vaishnavi <I.Vaishnavi at cwi.nl> wrote:
>> Any pointers, helpful suggestion, articles are welcome.
> I would make a suggestion for your survey, and that would be not to
> rely soley on "walking the tree" of known ntp associations as previous
> surveys have done. GPS is now cheap, and there are a lot more
> "disconnected" NTP hierarchies out there than there were previously.
> Also, I would suspect there are a lot more systems which are
> configured to not respond to NTP management packets (as that is now
> the default configuration in many NTP distributions).
> So I think that leaves random scanning for NTP servers. Of course,
> randomly knocking on UDP port 123 is considered somewhat rude, and
> would look a lot like a machine infected with a virus/trojan/rootkit
> to your ISP. I would think you would need some coordination with your
> provider, and having reverse DNS and informational web pages as was
> done in previous surveys would be a necessity.
> However, by random scanning, you can get a pretty decent statistical
> estimate about the total state of NTP on the Internet that might not
> be achiveable with other methods that relied upon a "seed list" of NTP
> servers.

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