David L. Mills wrote:

David,

There are copious examples of that happening right now on the NIST and USNO servers. What would you suggest we do to stop it? See the paper

Mills, D.L., J. Levine, R. Schmidt and D. Plonka. Coping with overload on the Network Time Protocol public servers. Proc. Precision Time and Time Interval (PTTI) Applications and Planning Meeting (Washington DC, December 2004), 5-16.

Full text is at www.eecis.udel.edu/~mills/papers.html.

Dave

I read the referenced paper with great interest. I noticed that little attention was paid to the idea of tracking down perpetrators and taking actions ranging from asking the perpetrator to cease and desist to asking the courts to intervene. There was an exchange of messages on this newsgroup a few months ago on this topic. A system administrator at HP's (formerly Digital's) Western Research Laboratory complained the his NTP server was being beaten up by clients sending requests at a rate of 1 PPS. The clients appeared to all be served by a single ISP. He was not interested in spending the small amount of time required to identify the IP addresses of the perpetrators and to ask the ISP to shut them down. There was no reply to my suggestion that since this was a Denial of Service attack he should request assistance from his legal department.

The reference implementation of ntpd contributes to the deluge in a small way! Running a Motorola Oncore as a reference clock causes my home server to query its internet servers every 16 seconds. It's nothing I would do by choice; they serve only as a sanity check on my Oncore reference clock There does not appear to be any way of turning this feature off short of modifying the code.

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