Re: [ntp:questions] Very rapid polling
David Woolley wrote: Danny Mayer wrote: David Woolley wrote: Danny Mayer wrote: There is no way to mark an NTP packet as invalid but then why would you There are several ways of marking a packet as effectively invalid. The real problem is that there is a lot of software out there (including w32time) that will accept packets that the protocol says they should reject. No, there's is no way to mark a packet as invalid. If you mean KOD Leap bits = 11, root dispersion 1 second, stratum = 16. There's probably lots of time sync sw out there that will disregard all of those and only use the four main timestamps to calculate the current time. Terje -- - Terje.Mathisen at tmsw.no almost all programming can be viewed as an exercise in caching ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Very rapid polling
Terje Mathisen wrote: David Woolley wrote: Danny Mayer wrote: David Woolley wrote: Danny Mayer wrote: There is no way to mark an NTP packet as invalid but then why would you There are several ways of marking a packet as effectively invalid. The real problem is that there is a lot of software out there (including w32time) that will accept packets that the protocol says they should reject. No, there's is no way to mark a packet as invalid. If you mean KOD Leap bits = 11, root dispersion 1 second, stratum = 16. There's probably lots of time sync sw out there that will disregard all of those and only use the four main timestamps to calculate the current time. Which is what I said, further up the quote. ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Very rapid polling
David Woolley wrote: gary.limanap...@elisys.co.uk wrote: We are running W32Time on all machines including the servers. The server itself obtains its own time independantly via a hardware clock. This is used to update the CMOS clock from which W32Time then serves out to the Clients. I will take up your suggestion and look into using I'm not aware of any time synchronisation software that uses the RTC clock. They generally use the software clock, which is typically set from the RTC clock on bootup. In any case, w32time, when run without a real server, sends out multiple indications that the time shouldn't be used, so any real implementation of NTP would ignore it (w32time doesn't ignore it). IIRC there is a configuration option for w32time which lets it synchronize periodically to the RTC chip, so this may mb w32time's version of the local clock. Martin -- Martin Burnicki Meinberg Funkuhren Bad Pyrmont Germany ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
[ntp:questions] MSF Outage March 2009
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Re: [ntp:questions] Very rapid polling
Thanks to all of you who responded to my initial post regarding very rapid polling. I have fixed this particular instance with some cooperation from the ISP. However, the generic problem remains and is likely to re-appear. I don't know of a good general solution to this problem because: 1. the KOD packets are generally not effective. Either the remote software does not recognize them or it chooses to ignore them. The KOD method obviously would not work against an attack. 2. Sending any reply at all doubles the network traffic and makes an attack more effective. Therefore, all of the NIST servers log the event and the source ip but do not respond. I think it is not appropriate for a national timing laboratory to knowingly send the wrong time. 3. This sort of stuff is really more general than NTP -- denial of service attacks can use many different protocols and a more general network solution is going to be needed. 4. A serious denial-of-service attack probably requires a botnet to cause real trouble, and fixing that problem might reduce the impact of all denial of service attacks. Judah Levine Time and Frequency Division NIST Boulder ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] ntpd on embedded risc
Harlan Stenn wrote: Assuming you have accurately relayed Dave's POV, Bill, I'd be open to seeing if we can take Dave's policy choice and making it the default choice for a config file knob (mechanism) that would allow folks to get faster convergence. I suspect that the only way this would fly is if the simulator (and Reality) can show that the alternative choice is stable. And the scope of this effort might be larger than (simulating) the behavior on a single machine - it might require analysis on a network of machines. Oh, please let's do this. I have many customers that are willing to put a good deal of money into their infrastructure to guarantee network connectivity, low latency, and anything else it takes to get highly accurate time sync. But after all of that, they have to fight the NTP implementation. blu ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Very rapid polling
jlevine jlev...@boulder.nist.gov writes: Thanks to all of you who responded to my initial post regarding very rapid polling. I have fixed this particular instance with some cooperation from the ISP. However, the generic problem remains and is likely to re-appear. Could you tell us what the problem was? Was it an attack or a misconfiguration or a bug in some program? I don't know of a good general solution to this problem because: 1. the KOD packets are generally not effective. Either the remote software does not recognize them or it chooses to ignore them. The KOD method obviously would not work against an attack. 2. Sending any reply at all doubles the network traffic and makes an attack more effective. Therefore, all of the NIST servers log the event and the source ip but do not respond. I think it is not appropriate for a national timing laboratory to knowingly send the wrong time. 3. This sort of stuff is really more general than NTP -- denial of service attacks can use many different protocols and a more general network solution is going to be needed. 4. A serious denial-of-service attack probably requires a botnet to cause real trouble, and fixing that problem might reduce the impact of all denial of service attacks. Judah Levine Time and Frequency Division NIST Boulder ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
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[ntp:questions] NTP Peering Queries
NTP experts, I have a few queries regarding NTP. I have a following setup. 1. Valid NTP server 2. Device1 where i configure a NTP server with ntp server command. 3. Another Device2 where I configure Device1's IP address in ntp peer config. Question : Will Device2 be synced with Device1's clock ? How does the peer protocol work ? I have the following setup 1. Valid NTP server 2. Device1 where I configure a NTP server with ntp server command. 3. In Device2 I configure Device1's IP in ntp peer command. 4. In Device1 I configure Device2's IP in ntp peer command. Question: How does the peering protocol work here. Does Device1 sync the clock of Device2 ? I have the following setup 1. Device1 where I configure Device2's IP in ntp peer configuration. 2. Device2 where I configure Device1's IP in ntp peer configuration. 3. No ntp server configuration and Device1 and Device2 both are in the same stratum. Question : How does the peer protocol work here ? And Which clock would be used to sync the time ? Thanks Kiran S Shirol ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
