Re: [ntp:questions] ntp-4.2.6p5 on Win 7 x64
Nick m...@privacy.net wrote: On Fri, 18 Jul 2014 23:16:57 +, jimp wrote: Nick m...@privacy.net wrote: snip This performance is marginal for WSJTX. I need 10ms offset or less after 15 minutes. What make you think that? I see a lot of WSJTX signals that are within +/- .5 seconds and occasionally some over a second off and they still decode. Most seem to be +/- .3 seconds. We are talking about this aren't we: http://physics.princeton.edu/pulsar/K1JT/wsjtx.html Yes we are. My spec was based only on experience using JT65B on HF using the old XP box which easily syncs within 10ms, and on which decodes are rock solid. http://www.vhfdx.de/wsjt/wsjt_user_470.pdf says... You will need a method of setting your computer clock to an accuracy of one second or better, and keeping it set. Many operators use an internet clock-setting program, while others use a GPS or WWVB receiver. Thank you for helping me realise the extent of my own ignorance! Though I agree ntp should be doing a lot better than you are seeing. Yes. I'll keep digging. FWIW, the largest offset I've seen WSJT-X decode is 3.5 seconds and lots of DX stations are in the 1 to 2 second range. BTW, if you are not using it, JT-utilities is very handy. http://hamapps.com/ -- Jim Pennino ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ntp-4.2.6p5 on Win 7 x64
Nick m...@privacy.net wrote: snip This performance is marginal for WSJTX. I need 10ms offset or less after 15 minutes. What make you think that? I see a lot of WSJTX signals that are within +/- .5 seconds and occasionally some over a second off and they still decode. Most seem to be +/- .3 seconds. We are talking about this aren't we: http://physics.princeton.edu/pulsar/K1JT/wsjtx.html Though I agree ntp should be doing a lot better than you are seeing. -- Jim Pennino ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Can NTP sync within 1ms
Rob nom...@example.com wrote: j...@specsol.spam.sux.com j...@specsol.spam.sux.com wrote: The listeners should enjoy a smooth reception while driving around. So of course there should be no time lag between the modulation signals of the different transmitters. Experts in the field tell us we should be within 12us. Unless I fat fingered the calculator, that means the difference in distance between transmitters relative to the receiver can be no more than 3.6 km. 300 meters per microsecond; it is the law... The goal is not to have 12us difference in arrival time, but to be within 12us for transmission time. What good does that do you? And regarding smooth reception while driving around, have you ever heard of multipath or the capture effect? -- Jim Pennino ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Can NTP sync within 1ms
Rob nom...@example.com wrote: David Woolley david@ex.djwhome.demon.invalid wrote: On 27/04/14 17:28, Rob wrote: We are setting up a co-channel diversity network. That means multiple FM transmitters that are transmitting the same signal on the same frequency on different sites, where the receive areas partly overlap. This problem has already been solved using COFDM (aka DAB) and it is much more tolerant of fading that is inevitable with co-channel transmitters than your system. It is not FM broadcast, it is (NB)FM communication. Which makes all of this even more irrelvant as communications circuits usually bandwidth limit to around 3.5 kHz. The listeners should enjoy a smooth reception while driving around. So of course there should be no time lag between the modulation signals of the different transmitters. Experts in the field tell us we should be within 12us. Your transmitters will have to be contained within a circle of 3.6km, reduced by the timing errors in the modulation at 0.3km/microsecond. This turns out to be not the case. Networks like this have been operating for decades, only those were constructed using analog leased lines so there was no relation to ntp, soundcards etc. Just what part, given your original conditions, is not true about this? -- Jim Pennino ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Can NTP sync within 1ms
Rob nom...@example.com wrote: Jochen Bern jochen.b...@linworks.de wrote: [Resend to list, rather than non-working(?) sender e-mail address] On -10.01.-28163 20:59, Rob wrote: We are setting up a co-channel diversity network. That means multiple FM transmitters that are transmitting the same signal on the same frequency on different sites, where the receive areas partly overlap. The listeners should enjoy a smooth reception while driving around. So of course there should be no time lag between the modulation signals of the different transmitters. Experts in the field tell us we should be within 12us. I'm afraid I don't get it yet. You're trying to sync waveforms on the HF side (~100 MHz?) instead of switching between two transmitters on the AF side (couple kHz, with that much more leeway for the sync), a la perfectly normal car radio with RDS AF and dual tuners, because ... ? It is not an FM broadcast system, it is an amateur radio repeater system with wide area coverage. Similar systems are in use, or at least have been in use, in repeater systems used by emergency services, taxi companies, etc. Of course it is possible to use different transmitters and find some way to switch the receivers. It is also possible to use a mobile phone to communicate. But amateur radio is about experimenting and self-education, and we just want to see if it can be done. In fact, it already has been done by another group using a different system setup, and we want to see if it can be done this way as well. It is all made irrelevant by a combination of channel bandwidth and the capture effect. http://en.wikipedia.org/wiki/Capture_effect Unless there is a huge difference in transmission times, no one is going to notice unless they are somewhere where the signal strength of multiple transmitters is roughly equal and then your major problem will be picket fencing, not audio synchronization. -- Jim Pennino ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Can NTP sync within 1ms
Rob nom...@example.com wrote: j...@specsol.spam.sux.com j...@specsol.spam.sux.com wrote: Rob nom...@example.com wrote: j...@specsol.spam.sux.com j...@specsol.spam.sux.com wrote: The listeners should enjoy a smooth reception while driving around. So of course there should be no time lag between the modulation signals of the different transmitters. Experts in the field tell us we should be within 12us. Unless I fat fingered the calculator, that means the difference in distance between transmitters relative to the receiver can be no more than 3.6 km. 300 meters per microsecond; it is the law... The goal is not to have 12us difference in arrival time, but to be within 12us for transmission time. What good does that do you? And regarding smooth reception while driving around, have you ever heard of multipath or the capture effect? Well, smooth reception must be explained as communication is possible, not with the HIFI quality expected from a broadcast station. What I mean is that you can drive around and receive the signal all over the place, even when you drive out of range of one transmitter into the range of the next. It works perfectly when the capture effect results in reception of one transmitter, and in the area where two transmitters are equal in strength it requires suitable synchronization to still have good communication. Picket fencing makes it irrelevant. I did not come up with the 12us figure, I would have guessed it a bit higher. The figure comes from different experts in the field. The people that designed and deployed such systems in the world of emergency services etc. Are you sure that figure is NOT for data communications? Most emergency services have voice and data these days. We can now try it in amateur radio because the advances in technology have made things like GPSDOs and fast network connections affordable. I don't see where that is relevant to anything here. -- Jim Pennino ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Can NTP sync within 1ms
Rob nom...@example.com wrote: j...@specsol.spam.sux.com j...@specsol.spam.sux.com wrote: Your transmitters will have to be contained within a circle of 3.6km, reduced by the timing errors in the modulation at 0.3km/microsecond. This turns out to be not the case. Networks like this have been operating for decades, only those were constructed using analog leased lines so there was no relation to ntp, soundcards etc. Just what part, given your original conditions, is not true about this? It turns out to be working even though there are differences in path lengths, but for it to be working well one must not start off with a large difference in modulation timing. The goal is to be within 12us. Why? What would you see as a timing difference given no correction? What is your definition of working well? How do you avoid picket fencing? -- Jim Pennino ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Can NTP sync within 1ms
Rob nom...@example.com wrote: j...@specsol.spam.sux.com j...@specsol.spam.sux.com wrote: Rob nom...@example.com wrote: j...@specsol.spam.sux.com j...@specsol.spam.sux.com wrote: Rob nom...@example.com wrote: j...@specsol.spam.sux.com j...@specsol.spam.sux.com wrote: The listeners should enjoy a smooth reception while driving around. So of course there should be no time lag between the modulation signals of the different transmitters. Experts in the field tell us we should be within 12us. Unless I fat fingered the calculator, that means the difference in distance between transmitters relative to the receiver can be no more than 3.6 km. 300 meters per microsecond; it is the law... The goal is not to have 12us difference in arrival time, but to be within 12us for transmission time. What good does that do you? And regarding smooth reception while driving around, have you ever heard of multipath or the capture effect? Well, smooth reception must be explained as communication is possible, not with the HIFI quality expected from a broadcast station. What I mean is that you can drive around and receive the signal all over the place, even when you drive out of range of one transmitter into the range of the next. It works perfectly when the capture effect results in reception of one transmitter, and in the area where two transmitters are equal in strength it requires suitable synchronization to still have good communication. Picket fencing makes it irrelevant. This precisely makes it a requirement to synchronize the audio. When this is not done, there will be extreme jitter in the audio which makes it unintelligible. What surprises me is that the audio has to be synchronized so well. But we are just going to do that, or approach it as closely as possible. Nope, it is precisely what makes synchronized audio irrelevant. If you have picket fencing, you have no intelligible audio no matter what you do at the transmitters. I did not come up with the 12us figure, I would have guessed it a bit higher. The figure comes from different experts in the field. The people that designed and deployed such systems in the world of emergency services etc. Are you sure that figure is NOT for data communications? Most emergency services have voice and data these days. Emergency services don't use NBFM systems anymore. At least not here. The networks I am talking about were deployed between the seventies and nineties of last century. Then what the hell are you talking about? We can now try it in amateur radio because the advances in technology have made things like GPSDOs and fast network connections affordable. I don't see where that is relevant to anything here. I am ending this discussion, I only answered the question what are you trying to do and I don't need to account for our experiment to you or anyone else on this group. No, you don't. You can ignore any comments by people with over half a century of experience and go off and waste your time tilting at windmills. -- Jim Pennino ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Using NTP to calibrate sound app
David Taylor david-tay...@blueyonder.co.uk.invalid wrote: On 27/01/2013 19:33, unruh wrote: On 2013-01-27, no-...@no-place.org no-...@no-place.org wrote: [] In case you are wondering, my app is a professional piano tuning app. The standard in this industry is that tuning devices should be accurate to 12 parts per million. I know that is probably overkill for tuning pianos, but that is what the professionals expect from their equipment. Ah. I would expect 1 cent, which is more like 500PPM. 1% (10,000 ppm) is a 4.4 cycles per second beat at 440 Hz! Completely unacceptable. You want an imperceptible beat, ideally, well under 1 Hz. Agreed that 12 ppm is overkill. The general rule of thumb for metrology is that your instrument should be at least an order of magnitude better than the allowable error, i.e. if your allowed error is 1%, your instrument should be capable of measuring to an accuracy of at least 0.1% for the measurement to be meaningful. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ANN: UK GPS Jamming update
Dennis Ferguson dennis.c.fergu...@gmail.com wrote: On 28 Mar, 2012, at 08:26 , David J Taylor wrote: Just wondering: 1) Is the UK govt doing this? The notice is from a UK Government agency. 2) Is the USA doing anything similar? I would be surprised if they were not, but they may have more remote areas to carry out such tests. White Sands Missile Range, maybe. You can't fly over it, and a friend who lives in New Mexico and owns a plane tells me there is a standing warning for pilots flying around it to avoid relying on GPS for navigation. He has also heard of pilots doing that who have seen their position, as reported by GPS, suddenly shift by 50 miles. Quite frequently in the High desert in SOCAL in the Ft Irwine/Edwards AFB area; the FAA puts out notices when it is to happen. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] GPS Jammers in Use by Criminals - Warping Time for Fraud Suggested
Richard B. Gilbert rgilber...@comcast.net wrote: On 2/22/2012 5:16 PM, David Woolley wrote: An article in the Metro, the free morning paper on the London commuter transport network, suggests that criminals may be using GPS jamming equipment to warp the time on financial systems to allow the commission of fraud. GPS is not the only source of time! In the U.S. 60 cycle Alternating Current is the standard and the source of time. It's not going to give you the nanoseconds but very few people could even explain what a nanosecond is let alone needing nanosecond resolution. There are very few civilian systems where absolute time accuracy greater than 1 second is an operational requirement and none that I can think of where sub-microsecond absolute time accuracy is an operational requirement. Although I can't find the source of that article, the BBC has an article, presumably from the same underlying source, addressing another point in that that article, that GPS jammers are increasingly being used to defeat GPS based car tracking systems. If anyone wants to track my car's location, you're welcome. And I hope that no one dies of boredom! In this case what is being jammed is position, not time, and this is so smarter car thieves can defeat systems like LoJack. This is a much easier case as all that has to be jammed is the GPS in the car being stolen. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] GPS Jammers in Use by Criminals - Warping Time for Fraud Suggested
E-Mail Sent to this address will be added to the BlackLists Null@blacklist.anitech-systems.invalid wrote: j...@specsol.spam.sux.com wrote: In this case what is being jammed is position, not time, and this is so smarter car thieves can defeat systems like LoJack. This is a much easier case as all that has to be jammed is the GPS in the car being stolen. LoJack is a radio beacon, it transmits a ID#, but no location information. Well, I did say systems LIKE LoJack, but if you want to be anal about it, how about systems like OnStar which do send location information? ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] GPS Jammers in Use by Criminals - Warping Time for Fraud Suggested
Rick Jones rick.jon...@hp.com wrote: Richard B. Gilbert rgilber...@comcast.net wrote: On 2/22/2012 5:16 PM, David Woolley wrote: An article in the Metro, the free morning paper on the London commuter transport network, suggests that criminals may be using GPS jamming equipment to warp the time on financial systems to allow the commission of fraud. GPS is not the only source of time! In the U.S. 60 cycle Alternating Current is the standard and the source of time. It's not going to give you the nanoseconds but very few people could even explain what a nanosecond is let alone needing nanosecond resolution. Wasn't there something about an experiment to relax the frequency requirements on the power grid in North America? And the financial services types may not be at the nanosecond level, but they (think they) are at the microsecond level. rick jones The absolute frequency accuracy in the US has never been anywhere close to the microsecond level. What was guaranteed was the long term average would be 60 Hz so things like clocks with synchronous motors would be within a few seconds over day long periods. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Accuracy of NTP - Advice Needed
Danny Mayer ma...@ntp.org wrote: On 12/29/2011 8:38 PM, Dennis Ferguson wrote: On 29 Dec, 2011, at 23:26 , Terje Mathisen wrote: Danny Mayer wrote: No, they use synchronized Cesium atomic clocks for time accuracy. GPS is only used to get a fix on the location and I'm not sure that 10's of centimeters is good enough for what they are trying to prove. I'd have to look closely at the methods used and the data to even have a clue as to what is needed and I have touched that stuff in years. Danny, how do you think they keep those atomic clocks synchronized? How do they _verify_ that they actually stay in sync (to a single-digit ns level) over the entire length of the experiment(many months)? Even Hydrogen Masers won't give you that performance over a year or so, you have to have some way to sync them either to each other or to UTC. Yes, they use GPS to compare the clocks to each other. One of the articles I read even identified the GPS receiver they use. I think it was a Septentrio PolaRx3eTR PRO (or maybe the older model which that one replaced). Those receivers take a 10 MHz and 1 PPS reference in from the atomic clock so that they can produce GPS carrier phase measurements with respect to the local clock's time. Making these measurements simultaneously at both locations gives you data you can post-process to determine the time difference between the two clocks, independent of the GPS system time. The GPS signals are used only as markers that can be measured at both locations. They used Septentrio PolaRx2e GPS receivers in both places along with a Symmetricom Cs4000 Cs atomic clock. All of this raises additional questions for which I'd have to dig into the references for answers. For example, both ends are underground and they are likely to use heavy shielding around the sites of the source and target so how are they even getting a GPS signal through in the first place? Are they getting signal or did they set up an external antenna in which case they would have to also figure out the distance of the antenna from the receiver (which part of the antenna?). This is not an easy physics experiment and the errors involved can easily overwhelm the result. Given the size of a GPS antenna, which part they measure from is down in the noise level. And yes, if you actually were to read all the documents available, you would find the antennas are outside and they did measure the distance to the antenna. How else would they be able to know were the expirement was in relation to a known point, i.e. the antenna, and the time delay down the coax if they didn't make such measurements. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Accuracy of NTP - Advice Needed
Danny Mayer ma...@ntp.org wrote: On 12/27/2011 11:45 PM, Greg Hennessy wrote: On 2011-12-28, Danny Mayer ma...@ntp.org wrote: On 12/27/2011 9:08 PM, John Hasler wrote: Danny writes: GPS is not used for this kind of thing, they are too inaccurate, so it doesn't matter. They use atomic clocks. The requirement is for synchronization. They use common view GPS. That's not good enough for experiments like this. In what way is it not good enough? The neutrinos are apparently arriving about 60 nanoseconds early, the distance is known, through GPS to 10's of centimeters, and the time is synchronized, again through GPS (although a second method is used as a double check) to about 1 nanosecond. In what fashion is it 'not good enough'? No, they use synchronized Cesium atomic clocks for time accuracy. GPS is only used to get a fix on the location and I'm not sure that 10's of centimeters is good enough for what they are trying to prove. I'd have to look closely at the methods used and the data to even have a clue as to what is needed and I have touched that stuff in years. Danny Why don't you read some of the available literature before you make an even bigger fool of yourself with your arm-waving guesses and conjecture? -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Accuracy of NTP - Advice Needed
Danny Mayer ma...@ntp.org wrote: On 12/28/2011 12:09 AM, j...@specsol.spam.sux.com wrote: Danny Mayer ma...@ntp.org wrote: On 12/27/2011 8:48 PM, j...@specsol.spam.sux.com wrote: Danny Mayer ma...@ntp.org wrote: On 12/24/2011 8:10 PM, j...@specsol.spam.sux.com wrote: John Hasler jhas...@newsguy.com wrote: The open sky nearest the OPERA detector is straight up through 1400m of rock. Jim Pennino writes: And the easiest open sky to get to is horizontally down the tunnel to the entrance which is next to a freeway. Yes, the entrance is next to a freeway. The entrance to the LNGS facility where the OPERA detector is located is near the middle of the 10 km long Gran Sasso highway tunnel. The bottom line is that the only thing that is relevant is how easy it is to get to a GPS antenna with an open view of the sky. Everything else is bloviation. GPS is not used for this kind of thing, they are too inaccurate, so it doesn't matter. They use atomic clocks. Danny How do you measure distance with an atomic clock? That's a complex question. GPS (even the military version) is not accurate enough. Danny No, it is not complex; you can't measure distance with an atomic clock. An atomic clock is used to measure time intervals. As for GPS, it is pretty trivial these days to determine an absolute location to parts of a centimeter for a fixed location. There's no such thing as an absolute location. See Einstein. Danny Absolute within the frame of reference of GPS, which in case you didn't know, is the Earth. See Spot run. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Accuracy of NTP - Advice Needed
Danny Mayer ma...@ntp.org wrote: On 12/28/2011 12:17 AM, unruh wrote: On 2011-12-28, Danny Mayer ma...@ntp.org wrote: On 12/24/2011 8:10 PM, j...@specsol.spam.sux.com wrote: John Hasler jhas...@newsguy.com wrote: The open sky nearest the OPERA detector is straight up through 1400m of rock. Jim Pennino writes: And the easiest open sky to get to is horizontally down the tunnel to the entrance which is next to a freeway. Yes, the entrance is next to a freeway. The entrance to the LNGS facility where the OPERA detector is located is near the middle of the 10 km long Gran Sasso highway tunnel. The bottom line is that the only thing that is relevant is how easy it is to get to a GPS antenna with an open view of the sky. Everything else is bloviation. GPS is not used for this kind of thing, they are too inaccurate, so it doesn't matter. They use atomic clocks. No they do not. They use GPS. As has been discussed here gps can be made accurate to a few ns. GPS is used by radio astronomers to synchronize very long baseline arrays. (Yes, I also thought that gps was not accurate enough. I was wrong) As a fellow astrophysicist you know that you don't just use GPS for this like you would finding your way around the streets of Vancouver. This is way beyond those kind of calculations. Of course in astrophysics even 1 km is below the noise level... Danny Well, you got a small clue. Do you think the GPS equipment used came from Best Buy or that perhaps it is a bit more sophisticated, costly, and accurate than consumer equipment? -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Accuracy of NTP - Advice Needed
Danny Mayer ma...@ntp.org wrote: On 12/24/2011 8:10 PM, j...@specsol.spam.sux.com wrote: John Hasler jhas...@newsguy.com wrote: The open sky nearest the OPERA detector is straight up through 1400m of rock. Jim Pennino writes: And the easiest open sky to get to is horizontally down the tunnel to the entrance which is next to a freeway. Yes, the entrance is next to a freeway. The entrance to the LNGS facility where the OPERA detector is located is near the middle of the 10 km long Gran Sasso highway tunnel. The bottom line is that the only thing that is relevant is how easy it is to get to a GPS antenna with an open view of the sky. Everything else is bloviation. GPS is not used for this kind of thing, they are too inaccurate, so it doesn't matter. They use atomic clocks. Danny How do you measure distance with an atomic clock? -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Accuracy of NTP - Advice Needed
Greg Hennessy greg.henne...@cox.net wrote: The bottom line is that the only thing that is relevant is how easy it is to get to a GPS antenna with an open view of the sky. Everything else is bloviation. GPS is not used for this kind of thing, they are too inaccurate, so it doesn't matter. They use atomic clocks. GPS is indeed used for the measurement of the time of flight in the CERN and Fermilab experiments. You should read the papers. They use GPS to get time to the order of nanosecond accuracy. What a concept; someone that actually read the papers instead of just pulling crap out their ass and arm waving. Prepare to be inundated with drivel for actually knowing something. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Accuracy of NTP - Advice Needed
Danny Mayer ma...@ntp.org wrote: On 12/27/2011 8:48 PM, j...@specsol.spam.sux.com wrote: Danny Mayer ma...@ntp.org wrote: On 12/24/2011 8:10 PM, j...@specsol.spam.sux.com wrote: John Hasler jhas...@newsguy.com wrote: The open sky nearest the OPERA detector is straight up through 1400m of rock. Jim Pennino writes: And the easiest open sky to get to is horizontally down the tunnel to the entrance which is next to a freeway. Yes, the entrance is next to a freeway. The entrance to the LNGS facility where the OPERA detector is located is near the middle of the 10 km long Gran Sasso highway tunnel. The bottom line is that the only thing that is relevant is how easy it is to get to a GPS antenna with an open view of the sky. Everything else is bloviation. GPS is not used for this kind of thing, they are too inaccurate, so it doesn't matter. They use atomic clocks. Danny How do you measure distance with an atomic clock? That's a complex question. GPS (even the military version) is not accurate enough. Danny No, it is not complex; you can't measure distance with an atomic clock. An atomic clock is used to measure time intervals. As for GPS, it is pretty trivial these days to determine an absolute location to parts of a centimeter for a fixed location. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Accuracy of NTP - Advice Needed
Rob nom...@example.com wrote: j...@specsol.spam.sux.com j...@specsol.spam.sux.com wrote: Again, were do you see the word few in what I wrote? That makes the statement so meaningless. Every distance can be measured in feet. If I had written exactly the same thing with the exception of using the word meters instead of the word feet, would you then get the point or would it still go whooshing over your head? -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Accuracy of NTP - Advice Needed
John Hasler jhas...@newsguy.com wrote: unruh writes: They require ns accuracy in the timing and m accuracy in the distance. And the timing is not simply gps ( although they could have gotten that wrong) but then that timing has to be brought down into the mine a km or so below ground and horizontally and that also has to be surveyed for the distance. The NOvA detector is not in a mine so it should be possible to site the GPS receiver directly above it and drop a cable straight down. The same should be possible at the Fermi end. You could set up both timing chains at Fermilab (using indentical components including cable lengths if you want to be fanatical), calibrate them against each other for delay from antenna to output, and then pack one up and ship it up north (of course there may be good reasons not to do it this way). The surveying should be easier than in Europe: there's no mountain range in the way. That's the common misconception of the geology. Basically the lab is in a tunnel in the side of a mountain and is no more a km underground than is the lobby of a 20 story hotel 20 stories underground. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Accuracy of NTP - Advice Needed
unruh un...@invalid.ca wrote: On 2011-12-24, j...@specsol.spam.sux.com j...@specsol.spam.sux.com wrote: John Hasler jhas...@newsguy.com wrote: unruh writes: They require ns accuracy in the timing and m accuracy in the distance. And the timing is not simply gps ( although they could have gotten that wrong) but then that timing has to be brought down into the mine a km or so below ground and horizontally and that also has to be surveyed for the distance. The NOvA detector is not in a mine so it should be possible to site the GPS receiver directly above it and drop a cable straight down. The same should be possible at the Fermi end. You could set up both timing chains at Fermilab (using indentical components including cable lengths if you want to be fanatical), calibrate them against each other for delay from antenna to output, and then pack one up and ship it up north (of course there may be good reasons not to do it this way). The surveying should be easier than in Europe: there's no mountain range in the way. That's the common misconception of the geology. Basically the lab is in a tunnel in the side of a mountain and is no more a km underground than is the lobby of a 20 story hotel 20 stories underground. But it is a few km inside the mountain. Is a mine in Denver not underground just because Denver is 1600 m above sea level? The issue is that most people don't seem to be able to understand how to get an accurate position of a location that is vertically under a km or so of dirt, yet horizontally feet from wide open sky and GPS signals. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Accuracy of NTP - Advice Needed
John Hasler jhas...@newsguy.com wrote: Jim Pennino writes: The issue is that most people don't seem to be able to understand how to get an accurate position of a location that is vertically under a km or so of dirt, yet horizontally feet from wide open sky and GPS signals. The open sky nearest the OPERA detector is straight up through 1400m of rock. And the easiest open sky to get to is horizontally down the tunnel to the entrance which is next to a freeway. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Accuracy of NTP - Advice Needed
John Hasler jhas...@newsguy.com wrote: The open sky nearest the OPERA detector is straight up through 1400m of rock. Jim Pennino writes: And the easiest open sky to get to is horizontally down the tunnel to the entrance which is next to a freeway. Yes, the entrance is next to a freeway. The entrance to the LNGS facility where the OPERA detector is located is near the middle of the 10 km long Gran Sasso highway tunnel. The bottom line is that the only thing that is relevant is how easy it is to get to a GPS antenna with an open view of the sky. Everything else is bloviation. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Accuracy of NTP - Advice Needed
unruh un...@invalid.ca wrote: On 2011-12-24, j...@specsol.spam.sux.com j...@specsol.spam.sux.com wrote: unruh un...@invalid.ca wrote: On 2011-12-24, j...@specsol.spam.sux.com j...@specsol.spam.sux.com wrote: John Hasler jhas...@newsguy.com wrote: unruh writes: They require ns accuracy in the timing and m accuracy in the distance. And the timing is not simply gps ( although they could have gotten that wrong) but then that timing has to be brought down into the mine a km or so below ground and horizontally and that also has to be surveyed for the distance. The NOvA detector is not in a mine so it should be possible to site the GPS receiver directly above it and drop a cable straight down. The same should be possible at the Fermi end. You could set up both timing chains at Fermilab (using indentical components including cable lengths if you want to be fanatical), calibrate them against each other for delay from antenna to output, and then pack one up and ship it up north (of course there may be good reasons not to do it this way). The surveying should be easier than in Europe: there's no mountain range in the way. That's the common misconception of the geology. Basically the lab is in a tunnel in the side of a mountain and is no more a km underground than is the lobby of a 20 story hotel 20 stories underground. But it is a few km inside the mountain. Is a mine in Denver not underground just because Denver is 1600 m above sea level? The issue is that most people don't seem to be able to understand how to get an accurate position of a location that is vertically under a km or so of dirt, yet horizontally feet from wide open sky and GPS signals. A few feet? I assume that was a misprint for a few km. Where do you see the words few feet in what I wrote? The bottom line is that the only thing that is relevant is the path to the GPS antenna with a clear view of the sky. Everything else is bloviation. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Accuracy of NTP - Advice Needed
unruh un...@invalid.ca wrote: On 2011-12-25, j...@specsol.spam.sux.com j...@specsol.spam.sux.com wrote: John Hasler jhas...@newsguy.com wrote: The open sky nearest the OPERA detector is straight up through 1400m of rock. Jim Pennino writes: And the easiest open sky to get to is horizontally down the tunnel to the entrance which is next to a freeway. Yes, the entrance is next to a freeway. The entrance to the LNGS facility where the OPERA detector is located is near the middle of the 10 km long Gran Sasso highway tunnel. The bottom line is that the only thing that is relevant is how easy it is to get to a GPS antenna with an open view of the sky. Yes. 5km away horizontally or 1.5km away vertically. Distance is not automatically a metric of ease. But bloviate away. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Accuracy of NTP - Advice Needed
John Hasler jhas...@newsguy.com wrote: Richard B. Gilbert wrote: How do you tag a neutrino so that you can say with assurance that the the neutrino that left Cern is the same neutrino that arrives at Sasso? Jim Pennino writes: By sending them in a pulse of a known width. It should be noted, however, that you cannot observe the same neutrino twice. In fact, no neutrinos at all are observed at the Cern end: just the protons that produce the pions that produce the neutrinos. An upcoming experiment at Fermilab will observe neutrinos at both ends (the far end will be in Minnesota). And your point would be? -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] NTP Denial of Service attack 29 November 2011
Rob nom...@example.com wrote: Rich schmidt.r...@gmail.com wrote: Someone is at war with USNO NTP service. They could be students, who knows? But all of the offending addresses traced to Chinese sites. In order to continue to provide NTP to US customers, USNO elected to block Chinese networks at the /8 level whenever we were able to trace the attacks to those networks. Note that there are 2,605 known Chinese CIDR blocks. It takes some time to implement that block list, and it requires considerable horsepower. When it comes to making a choice between staying online and denying USNO NTP to China, we must unfortunately make the more secure choice. Yeah, sure. But where you went over the line is when you recommended others to do the same. Your local solutions to your particular problems are not to be recommended to be used by the rest of the world. I highly disagree. Anyone can recommend anything they want. It is up to the individual to evaluate the recommendation and decide if the recommendation makes any sense for that individual's particular situation. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Questions about joining pool.ntp.org
unruh un...@wormhole.physics.ubc.ca wrote: On 2011-08-31, Uwe Klein u...@klein-habertwedt.de wrote: David J Taylor wrote: How does this square with those who claim 4ns from their GPS devices? Pfft. The defining document is rather old I guess. A lot happened in between. ( I looked into GPS in my diploma thesis ~1987 and not much after that ) The GPS sattelites with their onboard clocks, etc are also rather old. And I do not see how you can get timing accuracies of 2ns when your positional accuracy is 5m. I Think that that 2ns is someone's advertising bunf that totally misunderstood the technical arguments and simply looked through the documents for the smallest time figure they could find without caring what it referred to. That document I mentioned talked about a gps receiver in 2003 which claimed 2ns accuracy. And was hundereds of ns different from a survey grade instrument. Goto http://en.wikipedia.org/wiki/Global_Positioning_System Look at References #81 and follow the links to the paper. On page 31: Since USNO has been successful in predicting UTC to within about 10 ns, combining these two independent error sources yields a real-time potential uncertainty for UTC available from GPS at about the 14-ns level. There is much detail on how he gets to that number. This is from 1997, so some of the numbers may be better by now, in particular the ability of USNO in predicting UTC. However, only 19 of the 31 satellites in orbit as of May 2010 are post 1997. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Questions about joining pool.ntp.org
Rob nom...@example.com wrote: unruh un...@wormhole.physics.ubc.ca wrote: And we keep hearing about the UK jamming GPS for hours at a time in regions of the UK. Yes, we keep hearing about that from the UK. But what about other countries, probably they do the same thing but we don't hear about it because there are no nice bulletins posted to usenet about their tests. If you want to know about them, you need to check NOTAM's (Notice to Airmen) published by the FAA. The last tests of any appreciable extent I know of were in 2006 and centered on military test areas in California, New Mexico, Nevada, and Florida. If you regularly check NOTAM's, you will occasionally see notices of possible GPS outage for short periods around military test areas in the South Western desert areas. The general public and most posters to comp.protocols.time.ntp don't hear about them because essentially no one but pilots care or could be effected. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Questions about joining pool.ntp.org
Harlan Stenn st...@ntp.org wrote: GPS can be done very affordably and can offer great time. There are several *potential* pitfalls: - It is *possible* for the US Gov't to detune the GPS system (locally or in-general). Since GPS is now increasingly used for human safety things, the costs/risks for doing this have gone up significantly so this risk may now be more of a threat than a reality GPS aviation navigation is now so deeply entrenched that if you live near a major airport the US Gov't detunes GPS, you will have much bigger things to worry about than the current time and should start filling things with water... -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Secure NTP
Uwe Klein uwe_klein_habertw...@t-online.de wrote: j...@specsol.spam.sux.com wrote: Richard B. Gilbert rgilber...@comcast.net wrote: Didn't I just see an announcement that GPS was going to be jammed in order to test something or other? Yeah, it happens quite often on a scheduled basis in limited areas. Hmm, it should not be all that difficult to set up a limited reach GPS WAAS/EGNOS impostor. elsewher: Bruce Schneier ( security guy ): http://www.schneier.com/blog/archives/2008/09/gps_spoofing.html uwe OK, so the bad guy sets up the stuff for a GPS spoofer and parks it next to the targeted building where high dollar value stuff goes on in hopes of tweeking their system clocks and stealing a fortune. First issue; a big bucks operation is likely in a multi-story building with the GPS antenna on the roof and GPS antennas have low sensitivity looking down. Our bad guys just happen to know something about antenna patterns, so they obtained some high power RF amplifiers to make sure their signal dominates. So, after carefully syncing their spoofer to the real time, because if they don't, the time jump will just be rejected, the bad guys start cranking up the output power until their signal dominates. At that point they start slowly changing the time to something else. Meanwhile, inside the building where NTP was set up by someone with a clue that bothered to read the documentation, the target client computers notice that the GPS source is different than all the other sources and decide the GPS source has failed and ignore the GPS data. Drat that NTP voting alogorithm. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Secure NTP
Uwe Klein uwe_klein_habertw...@t-online.de wrote: j...@specsol.spam.sux.com wrote: At that point they start slowly changing the time to something else. Meanwhile, inside the building where NTP was set up by someone with a clue if you go by the questions placed here on occasion that assumption is not a given ;-) that bothered to read the documentation, the target client computers notice that the GPS source is different than all the other sources and decide the GPS source has failed and ignore the GPS data. Drat that NTP voting alogorithm. engineering is a management of negatives ( positives is for weenies ) If I had that clocker job (not likely) I would disable all but one source and spoof the remaining in advance. my guess is that even most high profile setups won't complain about being reduced to a single source for time. You are talking about an inside job and neither NPT authentication nor any other software based tool is able to do much about that. If you are already inside, there are easier and more direct ways to steal than messing with system clocks. I deal with an organization where the correct time is modestly (in terms of what NTP can do) important. It is important to them that all systems are within about 0.25 seconds of the real time. The local division I support has three systems set up as NTP servers and a stand alone GPS NTP box to provide time for all the division client systems. The three NTP servers get their time from the local GPS NTP box as well as other GPS NTP boxes and CDMA NTP boxes located at other corporate sites hundreds of miles away on the private corporate network and additionally from several public NTP servers on the Internet. Spoof that. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Secure NTP
Chris Albertson albertson.ch...@gmail.com wrote: On Mon, Mar 28, 2011 at 8:56 AM, j...@specsol.spam.sux.com wrote: OK, so the bad guy sets up the stuff for a GPS spoofer and parks it next to the targeted building where high dollar value stuff goes on in hopes of tweeking their system clocks and stealing a fortune. The best application of GPS signal spoofing would be at sea. You could ship your jammer/spoofer as cargo and have it steer the ship off course. After a day or two of being subtly off course the error could add up to hundreds of miles. then you meet it at some point and even if the ship transmits an SOS the location will be far from the real location and the authorities will respond to some place you are not. However a competent ships captain would periodically check GPS using some other method, maybe even celestial navigation. For this to work, your spoofer has to spoof 4 satellites as well as know its actual position independant of GPS so the ship is steered to somewhere that you can find it. Most civilian ships these days have neither the people or equipment to do celestial navigation. And all of this is pointless as once the ship is any significant distance at sea as all you have to do is attack the ship from a faster boat that is well armed. Google Somali pirates. For truck hijacking a simple jammer is used to disable any GPS tracking. A spoofed gps could never fool a driver into thinking he is 100 miles away and driving off road. Even a totally confused and lost truck driver knows he is on a road. So GPS tracking is AFU. All that means is the trucking compay is unable to say for sure the driver didn't spend a couple of hours at the boobie bar. It doesn't do much for you unless you intend to steal the entire truck and keep it for long that the cops become involved. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Secure NTP
Richard B. Gilbert rgilber...@comcast.net wrote: On 3/25/2011 11:40 AM, j...@specsol.spam.sux.com wrote: Uwe Kleinuwe_klein_habertw...@t-online.de wrote: j...@specsol.spam.sux.com wrote: If you specify the server by IP address, how does that happen and who would bother to do it? The $something trading solutions that require exact timematch ( remember the recent rush of ntp users requiring u-second global time match ) over a set of widely distributed hosts allow fraud in various ways if you can manipulate the time for some select host. One more time, if time is critical to your operation you do NOT have one and only one NTP server. You have serveral servers with local GPS and CDMA NTP boxes. Let's see you spoof the Internet, GPS, and CDMA all at the same time. Any two would be sufficient! Nope, Assuming you had three independant sources of NTP information, you would have to spoof two of them identically, which is virtually impossible for anything less than a government, or two of the three would just appear to be failed. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Secure NTP
E-Mail Sent to this address will be added to the BlackLists Null@blacklist.anitech-systems.invalid wrote: Richard B. Gilbert wrote: j...@specsol.spam.sux.com wrote: Let's see you spoof the Internet, GPS, and CDMA all at the same time. Any two would be sufficient! GPS Jamming could take out the GPS and CDMA. Granted, but that is not spoofing nor would it cause the time of anything to become incorrect by some amount. Also, jamming both GPS and CDMA would likely greatly arouse the ire of the powers that be. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Secure NTP
David Woolley david@ex.djwhome.demon.invalid wrote: j...@specsol.spam.sux.com wrote: One more time, if time is critical to your operation you have several sources to include local GPS and CDMA NTP boxes. You missed an important point, your CEO must also have a current science background. Most UK CEOs, at least, have an arts background, and are quite likely to lead to solutions with no local time receivers, because they require capital expenditure. Yeah, that is a possible scenario; total stupidity in charge. But you don't need a science background to understand that if accurate time keeping has an economic impact on your organization, you had better keep it accurate. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Secure NTP
Uwe Klein uwe_klein_habertw...@t-online.de wrote: j...@specsol.spam.sux.com wrote: One more time, if time is critical to your operation you do NOT have one and only one NTP server. One more time, the times of well designed protocolls and infrastructure software are gone ;-) Today the PHB and his idiot savant minions rule. You have serveral servers with local GPS and CDMA NTP boxes. Let's see you spoof the Internet, GPS, and CDMA all at the same time. Pfft. you don't have to. The GFC is not only witness to the haphazard portfolio of products traded but also the (lack of) basic understanding brought to financial infrastructure. IMHO, It is not well designed with an eye on faulttolerance, congestion, ... uwe Non sequitur. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Secure NTP
unruh un...@wormhole.physics.ubc.ca wrote: On 2011-03-25, j...@specsol.spam.sux.com j...@specsol.spam.sux.com wrote: Miroslav Lichvar mlich...@redhat.com wrote: On Thu, Mar 24, 2011 at 05:01:07PM -0700, Chris Albertson wrote: Security is so that you know you are not being spoofed. Or if you are providing the time so that you can prove to your users that you are who you claim to be and are not spoofing them. There is the chance that someone might impersonate one of your servers or a server you use. and then make a computer's clock be set to the wrong time. Again who cares if you only use your computer to serf the web and read emails but what if you were a bank processing ATM or visa card transactions or worse a computer routing trans or airplanes or controlling stop lights. There is one important thing I haven't seen mentioned here. A MITM doesn't need to modify the NTP packets to seriously degrade your timekeeping. He can exploit the PLL instability when undersampled and by dropping and delaying the packets (up to maxdist, 1.5s by default) he can fairly quickly throw your clock off and let you drift away. In addition to the authentication, it's important to monitor reachability of the peers. One more time, if time is critical to your operation you have several sources to include local GPS and CDMA NTP boxes. I do not understand. If you do not want to use the authentication, don't. Noone is forcing you to. We really do not care if you have thought through your security or not. But at this point it sounds like you are on a crusade against having the authentication in ntpd, and that is bizarre. If you think it adds nothing, do not use it. Or if it offends you to have something in a program you do not use, then rewrite ntpd to remove the sections that are offensive to you and use that. And learn once again that you may not completely understand everyone else in the world. You must really have your panties in a bunch if asking what good is NTP authentication becomes a crusade in your mind. As far as I can see, given the way NTP works and the number of available and independant sources, authentication may make you feel good about it, but has no added value. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Secure NTP
Maarten Wiltink maar...@kittensandcats.net wrote: j...@specsol.spam.sux.com wrote in message news:5lpu58-278@mail.specsol.com... Uwe Klein uwe_klein_habertw...@t-online.de wrote: [...] The $something trading solutions that require exact timematch ( remember the recent rush of ntp users requiring u-second global time match ) over a set of widely distributed hosts allow fraud in various ways if you can manipulate the time for some select host. One more time, if time is critical to your operation you do NOT have one and only one NTP server. You have serveral servers with local GPS and CDMA NTP boxes. Let's see you spoof the Internet, GPS, and CDMA all at the same time. I'll solve (the subproblems of) the big problems just like the little problems. One at a time. That there are other lines of defence is no reason to neglect any one of them. Every single one is there in case the other ones fail. Any and all of the other ones. You do not improve security by stacking the lemon meringue walls higher, or thicker. Groetjes, Maarten Wiltink You do not improve secuity by worrying about, and spending time on, imaginary threats. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Secure NTP
Chris Albertson albertson.ch...@gmail.com wrote: On Fri, Mar 25, 2011 at 8:40 AM, j...@specsol.spam.sux.com wrote: Let's see you spoof the Internet, GPS, and CDMA all at the same time. Summary of above argument: You can't spoof my system, therefor other systems can't be spoofed. Nope. Try reading it again, this time for comprehension. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Secure NTP
Richard B. Gilbert rgilber...@comcast.net wrote: On 3/27/2011 5:45 PM, j...@specsol.spam.sux.com wrote: E-Mail Sent to this address will be added to the BlackListsNull@blacklist.anitech-systems.invalid wrote: Richard B. Gilbert wrote: j...@specsol.spam.sux.com wrote: Let's see you spoof the Internet, GPS, and CDMA all at the same time. Any two would be sufficient! GPS Jamming could take out the GPS and CDMA. Granted, but that is not spoofing nor would it cause the time of anything to become incorrect by some amount. Also, jamming both GPS and CDMA would likely greatly arouse the ire of the powers that be. Didn't I just see an announcement that GPS was going to be jammed in order to test something or other? Yeah, it happens quite often on a scheduled basis in limited areas. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Secure NTP
Chris Albertson albertson.ch...@gmail.com wrote: On Thu, Mar 24, 2011 at 4:18 PM, j...@specsol.spam.sux.com wrote: Hal Murray hal-use...@ip-64-139-1-69.sjc.megapath.net wrote: In article ghps58-1a@mail.specsol.com, j...@specsol.spam.sux.com writes: When I see questions like this my first response is Why all the bother?. There is nothing secret or proprietary about the time of day. Since all NTP servers provide UTC, the service reveals nothing about the machine other than the fact that the clock is correct. If you don't want your resources utilized by outsiders, you just block access to the NTP port for everyone but your own clients as a blocked port uses less resources than denying an unsucessful authorization does. Am I missing something?? Yes. The encryption also verifies that you are talking to the server you think you are talking to rather than an imposter. If you specify the server by IP address, how does that happen and who would bother to do it? The most obvious and easy way is that I cut the wire that goes from your house to your ISP and place a computer (and modems) at the cut point. It can change any bit in any packet. I would not bother with your house but a bank, maybe. Childish fantasy that shows zero understanding of how such things work. If I could make transactions that were backdated I could make a lot of money even if only slightly back dated by 10 seconds. Yeah, if you could do that, but you can't. IP hijacking will disrupt a lot more than just NTP. It can but, that is up to the hijacker. A man in the middle attack can filter network packets and change only the bits he wants changed Yeah, right, like the time in NTP packets. If your server and its clients are on a corporate network, which is the usual case for having one's own server, how does this happen? Outsider has taken control of a computer that lives inside your network If that happens you have a lot more to worry about then the time on some client machines, like your total lack of competence. In general your arguments follows a common mistake. It is equivalent to I can't figure it out so therefor it can't happen. It is never valid to argue it's imposable because I can't figure any way to. To claim something is imposable you need something that is very much like a mathematical proof. I never claimed it is impossible to disrupt an NTP server. My arguement is that if the correct time is important it is trival to ensure that with a proper setup and without jumping through hoops. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Secure NTP
Steve Kostecke koste...@ntp.org wrote: On 2011-03-25, j...@specsol.spam.sux.com j...@specsol.spam.sux.com wrote: Chris Albertson albertson.ch...@gmail.com wrote: On Thu, Mar 24, 2011 at 2:26 PM, j...@specsol.spam.sux.com wrote: When I see questions like this my first response is Why all the bother?. There is nothing secret or proprietary about the time of day. Security is so that you know you are not being spoofed. Or if you are providing the time so that you can prove to your users that you are who you claim to be and are not spoofing them. The question was about clients authenticating to the server. NTP Authentication authenticates the server to the clients. It is not a client access control mechanism. Yeah, I know, I should not have put to between the words authenticating and server. It would be impossible to spoof a proper NTP setup where time is critical. If time is critical, a proper setup would have multiple servers as well as multiple independent, local sources like GPS and CDMA. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Secure NTP
Uwe Klein uwe_klein_habertw...@t-online.de wrote: j...@specsol.spam.sux.com wrote: If you specify the server by IP address, how does that happen and who would bother to do it? The $something trading solutions that require exact timematch ( remember the recent rush of ntp users requiring u-second global time match ) over a set of widely distributed hosts allow fraud in various ways if you can manipulate the time for some select host. One more time, if time is critical to your operation you do NOT have one and only one NTP server. You have serveral servers with local GPS and CDMA NTP boxes. Let's see you spoof the Internet, GPS, and CDMA all at the same time. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Secure NTP
Miroslav Lichvar mlich...@redhat.com wrote: On Thu, Mar 24, 2011 at 05:01:07PM -0700, Chris Albertson wrote: Security is so that you know you are not being spoofed. Or if you are providing the time so that you can prove to your users that you are who you claim to be and are not spoofing them. There is the chance that someone might impersonate one of your servers or a server you use. and then make a computer's clock be set to the wrong time. Again who cares if you only use your computer to serf the web and read emails but what if you were a bank processing ATM or visa card transactions or worse a computer routing trans or airplanes or controlling stop lights. There is one important thing I haven't seen mentioned here. A MITM doesn't need to modify the NTP packets to seriously degrade your timekeeping. He can exploit the PLL instability when undersampled and by dropping and delaying the packets (up to maxdist, 1.5s by default) he can fairly quickly throw your clock off and let you drift away. In addition to the authentication, it's important to monitor reachability of the peers. One more time, if time is critical to your operation you have several sources to include local GPS and CDMA NTP boxes. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Secure NTP
Yessica yessima...@gmail.com wrote: Hello! I am installing an NTP server, but requires authentication for that clients can be synchronized with the server, and also that authentication should be with public and private keys. Let me know if I can work with certificates issued by any authority or can only use the certificates generated by the ntp-keygen. Thank you very much! I hope you can answer. PS: I'm working with ntp v4 When I see questions like this my first response is Why all the bother?. There is nothing secret or proprietary about the time of day. Since all NTP servers provide UTC, the service reveals nothing about the machine other than the fact that the clock is correct. If you don't want your resources utilized by outsiders, you just block access to the NTP port for everyone but your own clients as a blocked port uses less resources than denying an unsucessful authorization does. Am I missing something?? -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Secure NTP
Hal Murray hal-use...@ip-64-139-1-69.sjc.megapath.net wrote: In article ghps58-1a@mail.specsol.com, j...@specsol.spam.sux.com writes: When I see questions like this my first response is Why all the bother?. There is nothing secret or proprietary about the time of day. Since all NTP servers provide UTC, the service reveals nothing about the machine other than the fact that the clock is correct. If you don't want your resources utilized by outsiders, you just block access to the NTP port for everyone but your own clients as a blocked port uses less resources than denying an unsucessful authorization does. Am I missing something?? Yes. The encryption also verifies that you are talking to the server you think you are talking to rather than an imposter. If you specify the server by IP address, how does that happen and who would bother to do it? IP hijacking will disrupt a lot more than just NTP. If your server and its clients are on a corporate network, which is the usual case for having one's own server, how does this happen? -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Secure NTP
Chris Albertson albertson.ch...@gmail.com wrote: On Thu, Mar 24, 2011 at 2:26 PM, j...@specsol.spam.sux.com wrote: When I see questions like this my first response is Why all the bother?. There is nothing secret or proprietary about the time of day. Security is so that you know you are not being spoofed. Or if you are providing the time so that you can prove to your users that you are who you claim to be and are not spoofing them. The question was about clients authenticating to the server. See below. There is the chance that someone might impersonate one of your servers or a server you use. and then make a computer's clock be set to the wrong time. Again who cares if you only use your computer to serf the web and read emails but what if you were a bank processing ATM or visa card transactions or worse a computer routing trans or airplanes or controlling stop lights. If I were smart enough to remotely control a computer's time, then I could maybe make stock trades with an effective trade date of four hours ago. I could make a fortune. If the time on a client is that important, you run multiple local servers with backup like a GPS NTP box and you don't depend on getting the time across the Internet. If the time on a client is only kind of important, you still run multiple servers, which means a majority of your servers would have to be spoofed in sync before it would have any effect on the clients. If your clients and server are on your local network, it is not very likely your servers are going to be spoofed, and if it is you have bigger issues than the time of day. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] UK report on GPS vulnerabilities seems to overlook NTP
JohnAllen johnbenal...@gmail.com wrote: Maybe I read this too quickly, but the report published today by the UK Royal Academy of Engineering (see http://www.raeng.org.uk/news/publications/list/reports/RAoE_Global_Navigation_Systems_Report.pdf and also the BBC coverage at http://www.bbc.co.uk/news/science-environment-12668230) seems to be saying that many organisations are vulnerable to GPS failures because their IT systems rely on GPS for precise time. Can this be true? I would have thought that most systems are using NTP, and synchronising with diverse enough time sources that unavailable or incorrect GPS time would not cause short-term problems. The relevant part of the report is on pages 13-14, where it says: GNSS timing is important for telecommunications applications. Synchronous technologies are much more efficient than asynchronous technologies but require a time source with appropriate accuracy, stability and reliability to operate effectively or at all, and GNSS can provide this. While ground-based clocks are accurate enough for this purpose (especially with the availability of chip scale atomic clocks (CSAC)), the synchronisation of many such clocks is problematic. GPS allows the derivation of synchronised UTC through resolving the signals from a number of satellites at a known position. Only a ‘good guess’ of the current time is required and quartz clocks have therefore been adequate for this process making synchronous time keeping significantly more cost effective. The use of time can be split into three clear and separate aspects: frequency control, time of day and common epoch (usually UTC) time slot alignment (also known as ‘Phase’). Stability of radio communications transmission, constant digital traic low, time slot alignment and traditional services over next generation Ethernet based infrastructure are some of the features that good time and timing bring to communications networks. Financial systems increasingly need precise time stamping to prioritise trades and to provide an audit trail. NTP is not mentioned anywhere in the report. Nor would I expect it to be. There is a big difference between keeping a computer's time of day clock set to the current time (NTP) and maintaining timing or frequency control in a telecom system. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] UK report on GPS vulnerabilities seems to overlook NTP
unruh un...@wormhole.physics.ubc.ca wrote: On 2011-03-08, j...@specsol.spam.sux.com j...@specsol.spam.sux.com wrote: JohnAllen johnbenal...@gmail.com wrote: Maybe I read this too quickly, but the report published today by the UK Royal Academy of Engineering (see http://www.raeng.org.uk/news/publications/list/reports/RAoE_Global_Navigation_Systems_Report.pdf and also the BBC coverage at http://www.bbc.co.uk/news/science-environment-12668230) seems to be saying that many organisations are vulnerable to GPS failures because their IT systems rely on GPS for precise time. Can this be true? I would have thought that most systems are using NTP, and synchronising with diverse enough time sources that unavailable or incorrect GPS time would not cause short-term problems. The relevant part of the report is on pages 13-14, where it says: GNSS timing is important for telecommunications applications. Synchronous technologies are much more efficient than asynchronous technologies but require a time source with appropriate accuracy, stability and reliability to operate effectively or at all, and GNSS can provide this. While ground-based clocks are accurate enough for this purpose (especially with the availability of chip scale atomic clocks (CSAC)), the synchronisation of many such clocks is problematic. GPS allows the derivation of synchronised UTC through resolving the signals from a number of satellites at a known position. Only a ???good guess??? of the current time is required and quartz clocks have therefore been adequate for this process making synchronous time keeping significantly more cost effective. The use of time can be split into three clear and separate aspects: frequency control, time of day and common epoch (usually UTC) time slot alignment (also known as ???Phase???). Stability of radio communications transmission, constant digital traic low, time slot alignment and traditional services over next generation Ethernet based infrastructure are some of the features that good time and timing bring to communications networks. Financial systems increasingly need precise time stamping to prioritise trades and to provide an audit trail. NTP is not mentioned anywhere in the report. Nor would I expect it to be. There is a big difference between keeping a computer's time of day clock set to the current time (NTP) and maintaining timing or frequency control in a telecom system. And exactly what is that difference? While ntp is perhaps too slow to respond to local frequency changes, how do you see the difference between keeping a computer's idea of local time accurate from keeping a telecom's idea of local time accurate? Most telecom systems care very little that it is exactly 12:34:56 Tuesday and a lot that the leading edge of the XYZ sync pulse occurs every ABC milliseconds and is DEF milliseconds wide, for example. The difference is the difference between time and timing. Some systems don't care what the time of day is at all but do care about timing. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] UK report on GPS vulnerabilities seems to overlook NTP
Uwe Klein uwe_klein_habertw...@t-online.de wrote: Chris Albertson wrote: NTP simply is not good enough for use in a tower so it is not used. And why would they use it when all towers by definition have a clear view of the sky IMHO the basic concept of your system is broken when you have sync to such high requirements and need external infrastructure to achieve this. this then is an extremely fickle system that lacks robustness. uwe Then every system ever made that has the concept of a master timing clock, including TV and the computer you are working on, is an extremely fickle system that lacks robustness. The concept hasn't changed over the years, just that we have progressed from R/C oscillators to crystal oscillators to GPS. Perhaps you think we would be better off if such systems had a master crystal osillator somewhere with coax to every remote system to keep them all in sync? -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] National time standard differences
unruh un...@wormhole.physics.ubc.ca wrote: On 2010-02-10, David J Taylor david-tay...@blueyonder.delete-this-bit.and-this-part.co.uk.invalid wrote: David Woolley da...@ex.djwhome.demon.invalid wrote in message news:hksmaf$1c...@news.eternal-september.org... David J Taylor wrote: I remember the flying of caesium or other atomic clocks round the world, and that folks had to invoke relativistic corrections. Were these better than microseconds as well? That's called Navstar (GPS) and GPS position solutions do have to include a general relativity correction to the satellite clocks. Not today's GPS, but some forty or more years ago: http://www.hp.com/hpinfo/abouthp/histnfacts/timeline/hist_60s.html 1964: The highly accurate HP 5060A cesium-beam atomic clocks gain worldwide recognition as the flying clocks when they are flown from Palo Alto to Switzerland to compare time as maintained by the U.S. Naval Observatory in Washington, D.C. to time at the Swiss Observatory in Neuchatel. The atomic clock was designed to maintain accuracy for 3000 years with only one second of error. The cesium-beam standard becomes the standard for international time. I had wondered what accuracy was obtained - i.e. how far was each nation out - and whether relativistic corrections had been needed for these flying clock tests. 1 sec/3000years is 1 part in 10^-11. The gravitational redshift is gh/c^2 (g is gravity acceln on earth, h the height of the flight, and c vel of light) which is 10^-12 -- ie below ( but not by much) the accuracy of the clock. The velocity correction is 1/2 v^2/c^2 which is again about 1 part in 10^12. Ie, both corrections are smaller (but not much) than the uncertainty in the clock rate. If the plane flew at Mach 2, rather than well below Mach 1, you could get that velocity correction up the accuracy and one would have to take special relativity into account. Since the flight probably lasted say 10 hr, which is 10 sec, th eclocks would have been out by about 1usec. Assuming that the clocks could then have been synchronized, that would mean that US and Switzerland time have been out by about 1usec. (Why they would fly from Palo Alto when the time standard is in Washington DC I have no idea). Probably because the clocks came out of the HP Palo Alto office? -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Can or should the NTP protocol eventually serve timezone data?
David Woolley da...@ex.djwhome.demon.co.uk.invalid wrote: j...@specsol.spam.sux.com wrote: David Woolley da...@ex.djwhome.demon.co.uk.invalid wrote: j...@specsol.spam.sux.com wrote: What about all the systems that don't use Olson? I'm only aware of one that doesn't require the system administrator to manually configure for any zone that that doesn't match the (historic) US rules, and that is the Windows NT family. HP-UX to name just one mainstream OS doesn't use Olson. I'm not familiar with HP-UX, but SCO OpenServer doesn't, however SCO OpenServer falls into my other category, than in which the rules for the local timezone have to be entered by the system administrator. Are you saying that HP-UX has centrally distributed rule sets? HP-UX uses tztab, which is a file format developed by HP. http://www.informatik.uni-frankfurt.de/doc/man/hpux/tztab.4.html While HP's system functions overall like most others, the data isn't Olson. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Can or should the NTP protocol eventually serve timezone data?
Rob nom...@example.com wrote: E-Mail Sent to this address will be added to the BlackLists n...@blacklist.anitech-systems.invalid wrote: ... and, what do all those millions of embedded systems do now to get time zone data? They don't. DST support is usually hardwired, manually configured or nonexistent. The user has to set the clock himself twice a year or at best has to manually enter the start- and end moments. Or worst, live with incorrect changeover dates (hardwired to US standard). Newer stuff tends to run a version of Linux or FreeBSD and you get updates as patches from the maker. The Axis Communications video encoders and cameras are all that way. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Can or should the NTP protocol eventually serve timezone data?
John Hasler j...@dhh.gt.org wrote: Jim Pennino writes: Newer stuff tends to run a version of Linux or FreeBSD and you get updates as patches from the maker. Downloaded automatically as needed? What happens when the maker goes bust, shuts down their server, or decides the product is obsolete? The same as any other product, much like the heater/air conditioner on my house that I replaced because parts were no longer available. What is this obsession with automatic download some people seem to have? There have been hundreds and hundreds of patches to each and every OS I run since the last patch to any time zone information. Having one more patch for time zones out of hundreds of others is insignificant. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Can or should the NTP protocol eventually serve timezone data?
John Hasler j...@dhh.gt.org wrote: I wrote: I don't know of any distribution that provides an easy way arrange for automatic updates of a single file. Null writes: Why would rsync not work? It would work fine but it seems like overkill and is not universally available. ...or a cron task for wget crontab /tasks.crontab @monthly wget 'ftp://ftp.eu.openbsd.org/pub/OpenBSD/distfiles/DateTime-TimeZone*.tar.gz' Whatever works. I'm just proposing that the file be made available at a standard location on a well-known set of distributed servers. For what kind of system? While the zoneinfo database, also known as the Olson database, is probably the most common, it is hardly the only system used. The information in general has been freely available for years. General information: http://www.twinsun.com/tz/tz-link.htm -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Can or should the NTP protocol eventually serve timezone data?
John Hasler j...@dhh.gt.org wrote: I wrote: I'm just proposing that the file be made available at a standard location on a well-known set of distributed servers. Jim Pennino writes: For what kind of system? Any. While the zoneinfo database, also known as the Olson database, is probably the most common, it is hardly the only system used. The Olson database is the only one it makes sense to distribute. What about all the systems that don't use Olson? The information in general has been freely available for years. But only in an ad-hoc fashion. True, the most generally available format is Olson and not everything uses Olson. If you limit the problem to Olson, the problem was solved years ago at: ftp://elsie.nci.nih.gov/pub/ Since 1976 there have been 2 changes to the timezone rules in the US. The European history is about the same. The odds are any system you are running today will have been in a trash heap for years before the rules change for your location again. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Can or should the NTP protocol eventually serve timezone data?
David Woolley da...@ex.djwhome.demon.co.uk.invalid wrote: j...@specsol.spam.sux.com wrote: What about all the systems that don't use Olson? I'm only aware of one that doesn't require the system administrator to manually configure for any zone that that doesn't match the (historic) US rules, and that is the Windows NT family. HP-UX to name just one mainstream OS doesn't use Olson. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Can or should the NTP protocol eventually serve timezone data?
John Hasler j...@dhh.gt.org wrote: Jim Pennino writes: If you limit the problem to Olson, the problem was solved years ago at: ftp://elsie.nci.nih.gov/pub/ Until they have a budget cut, a server reorganization, decide the traffic is excessive, or just get bored. You are still ignoring the fact that all the real OS vendors provide patches. Since 1976 there have been 2 changes to the timezone rules in the US. There have been two changes to Federal DST rules. There also have been DST and/or time zone changes affecting part or all of at least three states. How many changes have effected YOU since 1976? The European history is about the same. The odds are any system you are running today will have been in a trash heap for years before the rules change for your location again. The Debian tzdata package has been updated 34 times in the last three years due to changes in the timezone data. Yeah, for the entire planet. How many changes have effected YOU since 1976? -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Can the line audio out of HF radio be used to sync ntp. Trying to get a cheap ($) radio method.
David Woolley da...@ex.djwhome.demon.co.uk.invalid wrote: Nathaniel Homier wrote: Thank you for the ideas. There were many and I think I will start with the audio drivers first. But I will keep an eye on the serial/gps solution as well. You may find that you need SSB capability on the HF receiver. Not for any WWV station. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Can the line audio out of HF radio be used to sync ntp. Trying to get a cheap ($) radio method.
Nathaniel Homier n...@universal-mechanism.org wrote: On Fri, 01 May 2009 21:15:02 +, jimp wrote: David Woolley da...@ex.djwhome.demon.co.uk.invalid wrote: You may find that you need SSB capability on the HF receiver. Not for any WWV station. We can use the synchronous detector to even out the signal and select the sideband which has the least noise. Can is not the same as need, it would take more than SSB capability on the HF receiver to implement this and SSB capability does not guarantee a synchronous detector. In my experience, there are more problems with signal fade with WWV stations then sideband noise. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Why can't clocks do inital synchronization?
David J Taylor david-tay...@blueyonder.neither-this-bit.nor-this-bit.co.uk wrote: j...@specsol.spam.sux.com wrote: [] You do understand there are lots of environments where it takes an act of God to be allowed to replace vendor utilities with self compiled versions, don't you? Not a problem with Windows, fortunately. G David What planet do you people live on? I have one client that will not even allow Windows critical security updates to be installed until a extensive formal test is done to prove the updates won't effect operations. This is hardly a unique operation. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Why can't clocks do inital synchronization?
David J Taylor david-tay...@blueyonder.neither-this-bit.nor-this-bit.co.uk wrote: j...@specsol.spam.sux.com wrote: [] What planet do you people live on? I have one client that will not even allow Windows critical security updates to be installed until a extensive formal test is done to prove the updates won't effect operations. This is hardly a unique operation. Well, I can appreciate that makes sense, as I have known some updates to affect normal operations, although in those circumstances I used to recommend separate PCs for Internet operations. I don't recall ever seeing a report of NTP causing problems with normal operations. David Nor would I ever expect to. The point is LOTS of places have extensive procedures in place that must be followed before any software on production systems can be changed, including applying vendor supplied and recommended patches. While I have free reign to do anything I want with my systems, such is not the case for many of my client's systems. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Why can't clocks do inital synchronization?
David J Taylor david-tay...@blueyonder.neither-this-bit.nor-this-bit.co.uk wrote: j...@specsol.spam.sux.com wrote: [] The point is LOTS of places have extensive procedures in place that must be followed before any software on production systems can be changed, including applying vendor supplied and recommended patches. While I have free reign to do anything I want with my systems, such is not the case for many of my client's systems. Oh, indeed, but I might ask why my client was still running, or had chosen to install in the first place, such outdated versions of software, before taking on those systems. But that's life, I suppose. Cheers, David Solaris 10 Update 6 IS the latest release of Solaris and the provided NTP is nowhere near the latest downloadable version of NTP. I would have to check, but I am pretty sure the same is true for HP-UX. Not everyone runs Linux nor do they usually choose a OS for a rather obscure feature like NTP. To get back to the original topic, it seems to me if one really cares about absolute time, having just one hardware clock is not a very robust solution no matter what OS or version of NTP is being used. I have one client that does care and has GPS timeserver appliances at several sites with all the sites using all the NTP servers as potential sources so failing a major catastrophe at all sites, there is redundancy. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Why can't clocks do inital synchronization?
Andy Helten andy.hel...@dot21rts.com wrote:
Heiko Gerstung wrote:
Juergen Perlinger schrieb:
Hi everybody,
One of the things that can be annoying is that NTPD cannot do an initial
synchronization from (most) reference clocks over a difference of more than
4 hours.
The reason is that 'refclock_process()' calls 'clocktime()' which in turn
will only accept time stamps that are in a hard-coded window of +/- 4h
around the sample time (== system time). This makes it impossible for
systems to recover from a loss of power if there is no battery-backup
driven hardware clock.
I appreciate the fact that there are clock signals that do not transmit year
information (IRIG-B, as far as I know...) and that clocks using such
signals require some processing of the kind 'clocktime()' does.
But it's still a nuisance if you have a DCF77 or a GPS clock and the system
does not synchronize after boot just because the CMOS is backed by a
GoldCap capacitor instead of a real battery. (And getting different
hardware is *not* an option for some of us!)
I think that the normal panic threshold ('tinker panic') should be the only
limit for the acceptance of time stamps, and a disabled panic threshold
would permit the system to synchronize even without a backup CMOS clock.
While changing the behavior of NTPD wouldn't be too hard to implement I
would like to know *why* the clock processing is implemented the way it is.
Does anybody know an could enlighten me?
Juergen, did you see the -g command line switch? This one will allow for
a one-time correction of the clock even if offsets are greater than the
panic threshold value.
Regards,
Heiko
No, I don't believe any flag or tinker can disable this behavior. This
question is referring to the use of the CLOSETIME macro as a rough
sanity check on the ref clock's time. In order to truly change this
behavior you would need to redefine the CLOSETIME macro and recompile.
On the other hand, we dealt with this problem by always setting system
time to the ref clock's time prior to starting up NTP. For us, this
required writing a simple piece of C code that was integrated with our
application that starts NTP. That was the only solution I found without
modifying NTP (and that was not considered a desirable option).
Andy
Have you never heard of calling ntpdate before starting the NTP daemon?
--
Jim Pennino
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Re: [ntp:questions] Why can't clocks do inital synchronization?
Unruh unruh-s...@physics.ubc.ca wrote: j...@specsol.spam.sux.com writes: Have you never heard of calling ntpdate before starting the NTP daemon? uh, ntpdate is severely depricated, and ntpd -g is what is supposed to be used. If ntpd -g fails it is a bug. Uhh, lots of mainline 'nix's don't have a -g option to ntpd and still have ntpdate, e.g. Solaris 10. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Why can't clocks do inital synchronization?
Richard B. Gilbert rgilber...@comcast.net wrote: j...@specsol.spam.sux.com wrote: Unruh unruh-s...@physics.ubc.ca wrote: j...@specsol.spam.sux.com writes: Have you never heard of calling ntpdate before starting the NTP daemon? uh, ntpdate is severely depricated, and ntpd -g is what is supposed to be used. If ntpd -g fails it is a bug. Uhh, lots of mainline 'nix's don't have a -g option to ntpd and still have ntpdate, e.g. Solaris 10. So download the reference implementation from ntp.org and build your own! Both Sun's own development tools and gcc and other Gnu stuff are available in Solaris. Sun's development tools are a separate download from the web site. You do understand there are lots of environments where it takes an act of God to be allowed to replace vendor utilities with self compiled versions, don't you? -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Local time and NTP server time
Melanie Pfefer [EMAIL PROTECTED] wrote: Hello when I specify for example a ntp that is located in a different Time Zone, how ntp records my local time? It doesn't as ntp always uses UTC. Conversion to local time is up to the system. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] How can it be :05 in one place and :30 in another place?
Gretchen Baxter [EMAIL PROTECTED] wrote: Hi, I went to http://www.timeanddate.com/worldclock/ I saw that it was 10:35 in New York but in Adelaide it was 1:05 PM and in New Delhi 8:05. How can that be? Gretchen While most time zones differ from UTC by an integer number of hours, there are some that do not. See: http://www.worldtimezone.com/time/wtzstandard.php?sorttb=Citylistsw=forma=12h -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] list posts in UTF-8
Ryan Malayter [EMAIL PROTECTED] wrote: On Sun, Oct 26, 2008 at 2:48 PM, Unruh [EMAIL PROTECTED] wrote: That may be what you expect, but you can get it 1usec (1 micro second). Is there something wrong with the mail gateway and Unicode? I posted my message as text/plain with charset=UTF-8, which has been an IETF standard for more than a decade. And my message does, in fact, appear correct with UTF-8 characters such as l (Greek Small Letter Mu, Unicode 03BC) in the list archives at: https://lists.ntp.org/pipermail/questions/2008-October/020235.html However, all replies to my message were in 7-bit charset=us-ascii, which of course mangles the non-ASCII chasracters. So is it the pipermail gateway that is not Unicode compliant, or is it the MUAs of the respondents that is at fault? If it is the list itself... well, isn't it absurd to restrict content of a mailing list to 7-bit us-ascii? It is 2008, not 1988. Regards, This is usenet, not a mailing list. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] list posts in UTF-8
Richard B. Gilbert [EMAIL PROTECTED] wrote: [EMAIL PROTECTED] wrote: Ryan Malayter [EMAIL PROTECTED] wrote: On Sun, Oct 26, 2008 at 2:48 PM, Unruh [EMAIL PROTECTED] wrote: That may be what you expect, but you can get it 1usec (1 micro second). Is there something wrong with the mail gateway and Unicode? I posted my message as text/plain with charset=UTF-8, which has been an IETF standard for more than a decade. And my message does, in fact, appear correct with UTF-8 characters such as l (Greek Small Letter Mu, Unicode 03BC) in the list archives at: https://lists.ntp.org/pipermail/questions/2008-October/020235.html However, all replies to my message were in 7-bit charset=us-ascii, which of course mangles the non-ASCII chasracters. So is it the pipermail gateway that is not Unicode compliant, or is it the MUAs of the respondents that is at fault? If it is the list itself... well, isn't it absurd to restrict content of a mailing list to 7-bit us-ascii? It is 2008, not 1988. Regards, This is usenet, not a mailing list. There IS a mailing list for those who prefer mail to news or for those who don't have access to news. Comcast has announced that it will no longer offer access to net news effective 28 October 2008. Yeah, there are lots of groups with a mail gateway. That doesn't change the fact the base is a usenet news group. -- Jim Pennino Remove .spam.sux to reply. ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
