Re: [questions] Fwd: Usage of ntpdsim
On 03/04/2023 17:34, Arturs Laizans wrote: > Documentation there provides such test script to be used: > > #!/bin/bash > rm -f ./ntpstats/* > ntpdsim -C .001 -T 400 -W 1 -c ./ntp.conf, > I know that the comma is included on the web page, but I suspect its author was pursuing punctuation correctness rather than ndptsim syntactical correctness. I suggest retrying without the trailing comma.
Re: [questions] Local ST 1 (GPS/GNSS) servers are consistently offset from internet ST1/2
Hans is right, but the huff'n'puff filter can alleviate that, provided that the slower direction of the link is not permanently fully loaded, such that there are times when the latency is the same in both directions. On 3 December 2022 20:22:59 CET, MAYER Hans wrote: > >Is your Internet connection symmetric? Is upload and download speed the same? >If not this is the reason. > >// Hans > > > > >sent from my mobile device > > >From: vom513 >Sent: Saturday, December 3, 2022 7:53:55 PM >To: NTP Questions mailing list >Subject: [questions] Local ST 1 (GPS/GNSS) servers are consistently offset >from internet ST1/2 > >Hello all, > >This has been bugging me for a bit - but not enough till now to post a message >:) > >I have two boxes here at home (this is “hobbyist” grade gear, not big >commercial appliances). My hardware is: > >SyncBOX - https://www.worldtimesolutions.com/products/gps_time_server.html >This is connected to a small “Jetway” x86 mini PC via DB9 / real UART > serial. > >UPUTronics Pi Hat - https://thepihut.com/products/raspberry-pi-gps-hat >It’s on a Pi obviously (3B I think) > >Both of these appear to be very stable. I graph the offset in MRTG and they >both average about +/- 1-2 us. > >However - when I compare them each individually to a list of about 10 public >ST1 and ST2 servers, they both are averaging about -3.5 ms offset. I did this >with ntpdate -q and punched the values into Excel. > >To also back this data up - I feed a public pool member with these two guys - >and my graphs on the server management page also show ~ -3.5 ms offset. > >(These are the same box…) > >https://www.ntppool.org/scores/216.143.11.126 >https://www.ntppool.org/scores/2607:ff70:11::10 > >Also - ignore the scatter up above 0. I recently set prefer on both these >guys to nail them down and track the pool graphs. > >So while I guess 3ms isn’t the end of the world, I’m just scratching my head >as to why both my boxes are consistent with this offset from the “world”. > >I suppose I could config both to offset by this amount in their config, but >that seems a bit heavy handed. I’d much rather understand why they both >converge at this offset. > >Thanks in advance for any info and clue. > >PS: Something I just thought of before I hit send… Both of these are behind my >home cable modem. And while the jitter is actually pretty good, I know there >is inherent latency and jitter in most current DOCSIS networks. I think >DOCSIS 3.1 has some really nice bufferbloat / latency / jitter “fixes” (AQM I >think it’s called) - but my provider isn’t there yet (and I’m on Docsis 3.0 >anyway). Could this be it ? >-- >This is questions@lists.ntp.org >Subscribe: questions+subscr...@lists.ntp.org >Unsubscribe: questions+unsubscr...@lists.ntp.org > > > >
Re: [ntp:questions] Failed to set ntp: NTP not supported
On 01/05/2021 09:59, Viesturs Veckalns wrote: > I experience the following problem in Ubuntu 20.04: > > > v@v-VirtualBox:~$ sudo timedatectl set-ntp on > [sudo] password for v: > Failed to set ntp: NTP not supported > > > I created a relevant question in > https://askubuntu.com/questions/1335281/failed-to-set-ntp-ntp-not-supported > > What could I debug? > This appears to be a systemd question, not an ntp question. I suggest asking on a systemd-related forum. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] [META] Please Report Dissolved Boxes Spam to Google.
On 26/04/2019 11:03, David Woolley wrote: > Recently I've been religiously reporting the Case Solutions spam that > is appearing on the newsgroup side of this combined list and > newsgroup, with no effect. > > The spam is being injected via Google, but their groups-abuse email > address appears to be broken, so there is only the web interface > available to submit reports, and it does not allow free text reports. > > My guess is that Google will only care when multiple independent > reports are seen for individual postings, which will not typically > happen because this is a niche newsgroup. > > Could I therefore implore anyone receiving this, who has a Google > account, not to kill file Case Solutions, but to also report all their > spam to Google. > > If an anyone knows how to get a real human, with at least the half > brain needed to recognize this as serious abuse, at Google onto > solving the case, even better. > > I paraphrased the spammers tag to get past existing kill files. I have not been receiving any such spam ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Issues trying to sync to NIST public servers
On 03/02/2019 00:39, François Meyer wrote: > > In case NIST servers are hard to reach, a metrologically defendable > fallback could be to use ntp servers from another national metrology > institute which would provide the same traceability to UTC. I agree that this is a sensible answer from a technical perspective. However has anyone else done this and passed SEC scrutiny? Remember that US law is rules-based, not principles-based. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Regular spike_detect on syslog
On 16/09/18 14:15, Sean Austin Critica wrote: > > > Can I directly observe these sources and see which ones are stable > (maybe by dumping them periodically, remotely from a machine with a > known stable clock)? The OS in this case is RedHat EL 7. > > > "Directly observe": no. But you can look at the kernel log to see which clock source the OS has selected: # dmesg | grep clocksource [ 0.00] clocksource: refined-jiffies: mask: 0x max_cycles: 0x, max_idle_ns: 7645519600211568 ns [ 0.00] clocksource: hpet: mask: 0x max_cycles: 0x, max_idle_ns: 79635855245 ns [ 0.053021] clocksource: jiffies: mask: 0x max_cycles: 0x, max_idle_ns: 764504178510 ns [ 0.181027] clocksource: Switched to clocksource hpet [ 0.198695] clocksource: acpi_pm: mask: 0xff max_cycles: 0xff, max_idle_ns: 2085701024 ns [ 0.906180] clocksource: tsc: mask: 0x max_cycles: 0x2879c5f06f2, max_idle_ns: 440795220049 ns [ 1.931401] clocksource: Switched to clocksource tsc You can then look in your CPU's manual to determine whether the selected clocksource is influenced by SpeedStep (or whatever dynamic CPU speed changes are called these days). HTH, Jan ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Regular spike_detect on syslog
On 16/09/18 13:24, Sean Austin Critica wrote: > > > I’m running on bare metal HP Gen9 blade. I have started looking at the > BIOS settings and as far as I can tell there are a lot of options that > affect CPU frequency and they are turned on. > > > > I will check tomorrow if ‘Spread Spectrum’ is available and is turned > on as I don’t have access to the machine right now. > I assume that yours is a Class A device, where the need to resort to spread spectrum is less (because the Class A EMC requirements aren't as strict as the Class B requirements which apply to consumer devices), so you may not find this option in the BIOS, in which case your problem is caused by something else. > > I do know that settings like Intel Turbo Boost, and dynamic power > control are on. Although HP support says that they are not aware of > any settings that impact NTP on the host. > > > Whereas these options do modulate the clock frequency, they do so with the knowledge of the operating system. The OS is therefore able to take that into account in its timekeeping (for example by selecting a timekeeping clock source that remains constant notwithstanding Turbo Boost and all the rest of it). ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Regular spike_detect on syslog
On 15/09/18 22:55, Mike Cook wrote: > Maybe your server is frequency shifting . Check your BIOS settings . Sean: plug "bios spread spectrum" into your favourite search engine for more info. You want to disable that for accurate timekeeping. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] 1000s offset between GPS module and NTP servers
On 23/01/17 17:43, Lloyd Dizon wrote: > > On Mon, Jan 23, 2017 at 4:54 PM, Jan Ceuleers > <jan.ceule...@computer.org <mailto:jan.ceule...@computer.org>> wrote: > > Could you show us the relevant extracts from your ntp.conf file > related > to the GPS source? That is: at least the server line and any fudge > lines? > > > enable mode7 > (etc) Okay, your offset isn't caused by a fudge factor. I'm out. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] 1000s offset between GPS module and NTP servers
On 23/01/17 12:25, Lloyd Dizon wrote: > I've installed a GPS module on a Raspberry Pi and I'm getting 1000ms > offsets between the GPS readings and network NTPs. Could you show us the relevant extracts from your ntp.conf file related to the GPS source? That is: at least the server line and any fudge lines? ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Security announcements
On 24/11/16 04:39, Harlan Stenn wrote: > Announcements are supposed to be automatically sent to the announce > list, which should cause them to appear on questions@ and hackers@. > > We'll dig. Thanks Harlan. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
[ntp:questions] Security announcements
Guys, Come on, why do I have to read about ntpd security patches in the press? Why are they not posted here? Thanks, Jan ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Help verifying accuracy of NTP server
On 02/12/15 21:00, Joachim Fabini wrote: > NTP algorithms rely on symmetric connection delay but DSL delay is > commonly highly asymmetrical. In measurements for my setup (VDSL; > 8Mbit/s DL, 768kbit/s UL), the VDSL one-way delay at low packet payload > averages 12ms for DL and 6ms for UL. Very surprising if you consider the > DL/UL capacity ratio of larger than 10:1. For what it's worth, this is what my VDSL2 modem is telling me: Extended Port Status = Bme: 1 Port: 1 Downstream line rate: 37792 kbps Upstream line rate: 4960 kbps Bearer0 Downstream payload rate: 0 kbps Bearer1 Downstream payload rate: 30064 kbps Bearer0 Upstream payload rate: 0 kbps Bearer1 Upstream payload rate: 4048 kbps Downstream attainable payload rate: 34368 kbps Downstream attainable line rate: 46112 kbps Downstream Training Margin: 9.5 dB Downstream Line Protection (Bearer1 Path): 3.0 DMT Symbols Upstream Line Protection (Bearer1 Path): 1.0 DMT Symbols Near-end ITU Vendor Id: 0xb500494b4e530200 Far-end ITU Vendor Id: 0xb500494b4e530200 Downstream delay: 9.7 ms Upstream delay: 5.4 ms Tx total power -7.9 dbm FE Tx total power 10.8 dbm VDSL Estimated Loop Length : 1901 ft G.Hs Estimated Near End Loop Length : 3187 ft G.Hs Estimated Far End Loop Length :1881 ft Current framing mode: 0x10 Bandplan Type...: 2 No. of Upstream Bands...: 2 No. of Downstream Bands.: 2 Line Type: 0x0020 So 9.7ms down and 5.4ms up. These account for the coding, interleaving and transmission delay; they don't yet account for the delay incurred by the layers above (but this delay should be the same in both directions). So do these numbers merit being called highly asymmetrical? I suppose so, but they're also pretty small in comparison with delays deeper in the network and they don't end up causing appreciable asymmetry in the end-to-end paths to and from internet-based NTP servers. Jan ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] VMWare as a NTP server
On 01/06/15 14:45, Louis Demers wrote: Hello, What is your opinion about using a VM as NTP server? Don't do it if you need accuracy. If you can't run ntpd on the bare metal (e.g. for security reasons, or because the platform doesn't support it) and if you can't justify dedicating a small box to ntpd then I assume that accuracy won't be a significant factor for you. ntpd will probably still work when run in a VM, but the stability of the clock (and therefore the accuracy of the time served) will be far worse than running ntpd on the bare metal of the same machine. Jan ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ntpq authentication problem
On 28/02/15 08:48, catherine.wei1...@gmail.com wrote: I still have a doubt: the key file is generated on my PC (as the first ntp server) , when I copied it to the box(client), and I changed the box's ntp server to a second server 3.cn.pool.ntp.org or some other ntp servers. The authentication still passes. Why is that? ntpq talks directly to the ntpd process over the network. If you run ntpq without specifying where the server is located it talks to ntpd on localhost. Which time sources ntpd uses is immaterial. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ntpq authentication problem
On 28/02/15 03:47, catherine.wei1...@gmail.com wrote: Is there anything wrong in my operation? Thank you. Only thing I can think of is that the keys file might not be owned by root. Is it? ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ntpq authentication problem
On 27/02/15 10:54, catherine.wei1...@gmail.com wrote: However, when I run ntpq : ~ # ntpq ntpq :config addserver 192.168.1.101 minpoll 3 maxpoll 4 burst Keyid: 5 MD5 Password:(password corresponding to keyid 5 in /etc/ntp.keys) ***Server disallowed request (authentication?) I don't know why this happens? Do I need some other configurations? Thank you so much. I found that the permissions on the ntp.keys file matter. They should be 600. (I wrote all this in my email to you and the list on the 11th of Feb; both points (that you need a controlkey and that you need to set the permissions on the keys file) were included). Final point: when you're done and you got it working, throw away your keys file and generate a new-one, because now everybody in the world knows your keys. HTH, Jan ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Pool server gone wild
On 20/02/15 18:46, Roger wrote: On Fri, 20 Feb 2015 12:45:54 +, Roger invalid@invalid.invalid wrote: After about 11 minutes it has dropped one, leaving 6 servers. I'll continue to monitor and report back. Just to recap, I now have this in my ntp.conf: pool 0.uk.pool.ntp.org pool 1.uk.pool.ntp.org pool 2.uk.pool.ntp.org pool 3.uk.pool.ntp.org After five hours ntpd is using the same 6 servers. Perhaps because all of the peerstats have been less than 3 milli- seconds ntpd is quite happy even though the reach of one of the servers isn't always 377. Using dig on a sample of the pool it seems that DNS queries to the pool only ever return 4 entries. So if ntpd relies on there being around 10 servers for some of its monitoring capabilities to kick in then we seem to have a bit of a disconnect. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] [Is deze mail veilig?] [Is this e-mail safe?] [Cet e-mail est-il sans danger?] Re: Pool server gone wild
On 20/02/15 18:49, Rob wrote: Why not just: pool pool.ntp.org That should be enough. It returns only 2 servers (at the moment, and on my system): root@hobbiton:~# dig pool.ntp.org ; DiG 9.9.5-3ubuntu0.2-Ubuntu pool.ntp.org ;; global options: +cmd ;; Got answer: ;; -HEADER- opcode: QUERY, status: NOERROR, id: 7739 ;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 13, ADDITIONAL: 25 ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 4096 ;; QUESTION SECTION: ;pool.ntp.org. IN A ;; ANSWER SECTION: pool.ntp.org. 146 IN A 85.201.95.107 pool.ntp.org. 146 IN A 213.189.188.3 ;; AUTHORITY SECTION: . 36537 IN NS f.root-servers.net. . 36537 IN NS b.root-servers.net. . 36537 IN NS j.root-servers.net. . 36537 IN NS h.root-servers.net. . 36537 IN NS m.root-servers.net. . 36537 IN NS c.root-servers.net. . 36537 IN NS k.root-servers.net. . 36537 IN NS d.root-servers.net. . 36537 IN NS g.root-servers.net. . 36537 IN NS a.root-servers.net. . 36537 IN NS l.root-servers.net. . 36537 IN NS i.root-servers.net. . 36537 IN NS e.root-servers.net. ;; ADDITIONAL SECTION: a.root-servers.net. 300936 IN A 198.41.0.4 a.root-servers.net. 301233 IN 2001:503:ba3e::2:30 b.root-servers.net. 300942 IN A 192.228.79.201 b.root-servers.net. 317560 IN 2001:500:84::b c.root-servers.net. 300974 IN A 192.33.4.12 c.root-servers.net. 304383 IN 2001:500:2::c d.root-servers.net. 110366 IN A 199.7.91.13 d.root-servers.net. 121013 IN 2001:500:2d::d e.root-servers.net. 112934 IN A 192.203.230.10 f.root-servers.net. 101758 IN A 192.5.5.241 f.root-servers.net. 107135 IN 2001:500:2f::f g.root-servers.net. 110990 IN A 192.112.36.4 h.root-servers.net. 11 IN A 128.63.2.53 h.root-servers.net. 116217 IN 2001:500:1::803f:235 i.root-servers.net. 110930 IN A 192.36.148.17 i.root-servers.net. 114101 IN 2001:7fe::53 j.root-servers.net. 111931 IN A 192.58.128.30 j.root-servers.net. 118767 IN 2001:503:c27::2:30 k.root-servers.net. 112005 IN A 193.0.14.129 k.root-servers.net. 8040IN 2001:7fd::1 l.root-servers.net. 111937 IN A 199.7.83.42 l.root-servers.net. 113806 IN 2001:500:3::42 m.root-servers.net. 300975 IN A 202.12.27.33 m.root-servers.net. 302827 IN 2001:dc3::35 ;; Query time: 36 msec ;; SERVER: 127.0.1.1#53(127.0.1.1) ;; WHEN: Fri Feb 20 19:57:58 CET 2015 ;; MSG SIZE rcvd: 800 ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
[ntp:questions] Authenticated TLS constraints in ntpd
I'd like to draw this list's attention to an idea that Reyk Floeter floated, namely to use TLS to help sanity-check NTP timestamps: http://marc.info/?l=openbsd-techm=142356166731390w=2 ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] leapseconds.list updates and ntpd
On 10/02/15 18:19, Harlan Stenn wrote: walter.preunin...@gmail.com writes: Either I have missed it, or it is not there. My question is 'does ntpd have to be restarted after a new leapseconds.list file has been downloaded?' No. The code looks for an updated file (daily, I think, more often as we get closer to an expiration). See check_leap_file() in ntpd/ntp_util.c . I've also experimented with using an ntpq :config command to force the daemon to re-read the leapseconds file, and that also seems to work. That is: strace shows that the daemon does indeed read the file upon receiving the :config command from ntpq, but I haven't verified anything beyond that. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] leapseconds.list updates and ntpd
On 10/02/15 21:01, Brian Inglis wrote: Use ntpq -c rv to check the leap second file has been updated and a pending leap second recognized: $ ntpq -crv associd=0 status=0419 leap_none, sync_uhf_radio, 1 event, leap_armed, version=ntpd 4.2.6p5@1.2349-o Jul 30 11:55:08 (UTC+02:00) 2012 (2), processor=x86, system=Windows, leap=00, stratum=1, precision=-21, rootdelay=0.000, rootdisp=0.455, refid=GPS, reftime=d884e05f.b1f7560d Tue, Feb 10 2015 19:54:07.695, clock=d884e06a.5c64e486 Tue, Feb 10 2015 19:54:18.360, peer=14134, tc=4, mintc=3, offset=0.033, frequency=0.900, sys_jitter=0.037, clk_jitter=0.019, clk_wander=0.000, tai=35, leapsec=20150701, expire=20151228 I confirm that the ntpq method works. So impatient types who can't wait for the (reportedly daily) check mentioned by Harlan can use that to activate the new leapseconds file immediately and without restarting the daemon. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Does ntpq have an equivalent to ntpdc's fudge command?
On 11/02/15 07:57, catherine.wei1...@gmail.com wrote: Hi, I also have a similar problem. In the newest ntp version 4.2.8p1, the ntpdc is deprecated, what can I do if I still want to use it? Since in our system, many ntpdc commands have been used. Can I resolve it by adding some configuration? Thank you. The replacement is to use ntpq. Within ntpq you can issue :config commands. Pretty much anything that you can specify in the ntp.conf file can be specified this way. So for example: the experiment I did yesterday (discussed in another thread) was to use ntpq to force re-reading the leapseconds file. This was done by issuing the following within ntpq: :config leapfile /var/lib/ntp/leap-seconds.list Of course, as was the case with ntpdc, you will first have to specify a keyid and corresponding passwd. Note that ntpq uses the controlkey. Also, for the benefit of others who might be setting up keys for the first time, note that the permissions of the keys file are important; 600 works for me. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] [Is deze mail veilig?] [Is this e-mail safe?] [Cet e-mail est-il sans danger?] Re: Shared PPS source/Multiple PPS sources
On 07/02/15 10:29, Rob wrote: I presume you meant this followup to the multi PPS sources to a single system and then it is not true either, of course our systems have at least 4 cores and they can service multiple interrupts at the same time. On a single-core system I'd invert one of the PPS signals and then appropriately fudge the offset so that the two interrupts do not compete with each other. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] [Is deze mail veilig?] [Is this e-mail safe?] [Cet e-mail est-il sans danger?] Re: Shared PPS source/Multiple PPS sources
On 07/02/15 19:10, William Unruh wrote: Except I would not trust the gps to make the length of the pulse EXACTLY 1ms to the nanosecond say. Ie, the pulse length could vary by the 10usec. But I have not tested this and it may well depend on the manufacturer. The pulse length is usually there to make sure that the interrupt hardware sees the pulse, and the manufacturer of the gps may not decide it is worth making the pulse length exact. That is a fair point. The result would be high jitter. Still worth a go though, since an inverter is cheap (and one might be needed anyway for level conversion purposes). If the device does not provide a programmable offset, that is (as Mike Cook suggested). ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] NTP 4.2.8 for Windows, not branded
On 09/01/15 15:58, trackeroft...@gmail.com wrote: Hello, I'm looking for compiled NTP 4.2.8 for Windows. I know Meinberg's version but unfortunately it is branded. Does anybody know such binary package? I want to avoid compiling it by myself if I can. best regards Johny Johny, What Meinberg have done is to (1) compile ntpd and (2) wrap it into an installer. Because the upstream ntpd does not include a Windows installer. It would also be possible to just take the binaries (for example the ones David makes available), manually put them in the right places on the Windows machine, manually set the thing up as a service, etc. In other words, to manually do the work of an installer. Your choice. HTH, Jan ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Soekris net4501 help....
On 21/12/14 14:08, David Taylor wrote: I have been the fortunate recipient of a Soekris net4501, but although I've written a Compact Flash card image it doesn't boot, from the CF card, although the V1.23 BIOS appears to work. I may not spend too long on this but could anyone point me to a known working image? I used m0n0wall net45xx-1.236.img as a test. David, Don't give up until you've asked here: http://lists.soekris.com/mailman/listinfo/soekris-tech Jan ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Number of Stratum 1 Stratum 2 Peers
On 14/12/14 03:28, Harlan Stenn wrote: Not that easy - unless you are one of the lucky few to have encrypted access to a NIST source, when it may be automatic. http://www.ietf.org/timezones/data/leap-seconds.list Added to the Wiki at http://support.ntp.org/bin/view/Support/ConfiguringNTP The IETF also serve their content over SSL if anyone thinks this increases the level of trust one can have in that content. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Number of Stratum 1 Stratum 2 Peers
On 12/03/2014 02:58 PM, Brian Utterback wrote: I still think that it takes four to guarantee a majority but I don't have proof of that. Someday I will spend some time to either prove or disprove it, but alas, time is something I don't generally have extra to spend. But you are better off with one than two from an operational standpoint. It takes three servers *at all times* to enable clients to use majority voting. So if you want to guard against a single failure (i.e. not a single falseticker, a single server that goes offline), then you need four. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Thoughts on KOD
On 07/07/2014 04:04 PM, Danny Mayer wrote: I have no particular preference for the immutable time stamp value to pick. Could be zero, could be some other meaningful value (such as 0xeee4baadeee4baad - twice Eek! Bad!). KOD already sets a timestamp that is the requesters timestamp. See my previous response. It's better than your idea since it is gradual. Danny, (What's with the mine is better than yours thing?) I'm not sure why sending the requester's timestamp back to him is better than an immutable timestamp. The effect of the former is slow drift, the effect of the latter is (I suspect) no lock at all due to the lack of passage of time. So I think that the latter is more likely to catch the admin's eye. If there is an admin. Jan ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Thoughts on KOD
On 07/06/2014 08:42 AM, Rob wrote: Harlan Stenn st...@ntp.org wrote: Discussion appreciated. I think it is best to remove KOD from ntpd. It does not serve a useful purpose, because precisely the kind of clients that you want to say goodbye to, do not support it. In real life it has either no effect at all, or it even has a negative effect because the client does not understand it and re-tries the request sooner than it would when no reply was sent at all. Seconded. I recommend providing motivation for the undesired clients to stop using the server, by the server sending a regular response indicating that it is not synchronised or replying in some other way that has no timekeeping value to the offending client. Another way would be to use a bogus fixed timestamp that is in the past (i.e. one that suggests that there is no passage of time on the server). My recommendation is based on the assumption, yet to be verified in practice, that this server behaviour won't result in worse client behaviour than would be the case if the server just served the client's request as normal. Jan ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Thoughts on KOD
On 07/06/2014 11:23 AM, Rob wrote: Jan Ceuleers jan.ceule...@computer.org wrote: I recommend providing motivation for the undesired clients to stop using the server, by the server sending a regular response indicating that it is not synchronised or replying in some other way that has no timekeeping value to the offending client. Well, that is what KOD actually is. Sorry, I was not clear. By a 'regular' response I mean one that has a non-zero stratum value. I had actually forgotten that a stratum value of zero indicates that the server is not synchronised (as it is a collision with LI=3, which also means that). So I guess I'm dropping my first suggestion. The second-one stands: pick a non-zero stratum value and report an immutable time stamp. Note that the stratum field occupies 8 bits in the packet format, but currently only values between 0 and 15 are defined (where we have seen that a value of 0 is not uniformly understood by real-life clients). So the choice of stratum value should be in the range 1-15. I have no particular preference for the immutable time stamp value to pick. Could be zero, could be some other meaningful value (such as 0xeee4baadeee4baad - twice Eek! Bad!). Jan ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] MSF Anthorn, UK down
On 06/09/2014 05:50 PM, Marc-Andre Alpers wrote: Hello! Why have such important service no backup transmitter/antenna like DCF77? Whereas DCF77 might have a backup transmitter (I don't know), I observe DCF77 being down very often, albeit for short durations (5-10 mins). When I do receive it the signal is strong, so I don't think my observations are due to being too far away (I'm in Northern Belgium). Morale: don't put all your eggs in one basket. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Can NTP sync within 1ms
On 04/28/2014 07:37 PM, Henry Hallam wrote: On Mon, Apr 28, 2014 at 10:14 AM, William Unruh un...@invalid.ca wrote: Not sure why they would need a lower cutoff, except that it would allow the ancient telephone receivers to comply. Certainly one can make cheap receivers now that go a lot lower than 300Hz. Because 3.1 kHz of bandwidth is cheaper for the telcos to trunk than 3.4 kHz. Not really. The reason is that DC is used for signalling (e.g. on/off-hook, hookflash, pulse dialing). Way OT tho. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Attn Linux distributors - pse include PPS
On 04/24/2014 09:31 PM, Rob wrote: all that is required to get PPS working is to fetch the source package of ntpd for the distribution and recompile it while that single file has been added. e.g. on Ubuntu that file is present in the package pps-tools. So please, on your build systems, make sure that the package pps-tools or whatever other source used for timepps.h is installed during the compilation of ntpd. It makes the use of PPS much easier, as one does not have to find how to successfully compile a package from source on that particular system. And it will not be causing trouble when updates appear. The following bug report exists about this problem in Ubuntu's problem tracker. https://bugs.launchpad.net/ubuntu/+source/ntp/+bug/826873 If this issue affects you, please visit that page and say so. This will raise the priority of the problem and the likelihood of it being fixed in the near term. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Quality vs. Quantity
On 03/24/2014 03:53 PM, Paul wrote: On Mon, Mar 24, 2014 at 12:26 AM, Danny Mayer ma...@ntp.org wrote: That's a misconception. While I trust Richard Schmidt in what he says, that's is not what you think he says. It's hard to misinterpret 590SG load balancers and : It is the load balancer's duty to assign each incoming NTP request to one of the available servers, balancing the load by round-robin, weighted round-robin, least active connections, or other algorithm. Each NTP server returns packets to the load balancer for forwarding back to the requestor. But I wonder what an active connection is in this context, since NTP sits atop UDP. Do the load balancers track whether an association has been mobilised, and if so do they ensure that a particular client is always served by the same server, at least if the poll interval is reasonable? Jan ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Quality vs. Quantity
On 03/24/2014 04:58 PM, Paul wrote: On Mon, Mar 24, 2014 at 11:18 AM, Jan Ceuleers jan.ceule...@computer.org mailto:jan.ceule...@computer.org wrote: But I wonder what an active connection is in this context, since NTP sits atop UDP. These are IP based not TCP/IP. So there's even less of a notion of connection. And in fact the point of the paper is using PTP with the end result that the intra-farm errors should (it's four years later maybe they are) be in the nano-seconds. Yes, that's true. The OP wanted to know about NTP clusters, so I guess there are two lessons here: - either do what NIST did and ensure that your NTP cluster servers are so closely synced with each other that they are indistinguishable by clients; - or ensure that your load balancer ensures an association between clients and servers which persists for long enough (given the poll interval, probably to be multiplied by a safe factor, e.g. 3). Jan ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Indirect GPS time source options
On 03/14/2014 08:12 AM, E-Mail Sent to this address will be added to the BlackLists wrote: Olivier Drouin wrote: The thing with CDMA is that it looks like it'll not be around for many years and I haven't seen any equipement for 4g, hspa, LTE, etc... IIRC, HSPA, UMB, UMTS, EVDO and EVDV are all CDMA based 3G? LTE run with GSM or CDMA? Informative white paper here: https://www.aventasinc.com/whitepapers/WP-Timing-Sync-LTE-SEC.pdf Among other things, it compares the timing requirements of a number of cellular technologies. Warning: it also tries to sell you PTP grand master equipment. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] enable pps not working from ntp.conf
On 01/09/2014 06:15 PM, Dennis Golden wrote: I give up. I see some of you able to post nicely formatted information. What news reader are you using. I'm using pan2. Your messages as seen here were properly formatted. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
[ntp:questions] GPS Weakness Could Sink Wireless
Interesting Light Reading article on the degree to which infrastructure (in casu wireless networks) is dependent on GPS timing signals, how little is needed to jam GPS (intentionally or otherwise), and what the impact of such jamming would be. It also talks about how PTP might or might not mitigate some of these issues. http://www.lightreading.com/mobile/mobile-security/were-jamming-gps-weakness-could-sink-wireless/d/d-id/706895 ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] PPS only configuration
Guys, Can you stop talking about email and news formatting and get back to discussing NTP already? Please? Thanks, Jan ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Win7: ntpd adjusting time backwards
On 12/23/2012 01:11 AM, Hal Murray wrote: Fascinating to see you have less delay on the slower upstream! The queuing delays depend upon the traffic. You control that. The delays I quoted are fixed delays linked to the modulation, encoding and other parameters used on my VDSL2 line (the physical layer, if you like). Another contributor suggested that the greater downstream delay than the upstream delay may be due to interleaving, and this sounds like a good hypothesis. Queuing delays come on top. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Win7: ntpd adjusting time backwards
On 12/11/2012 12:49 PM, David Taylor wrote: Sorry: catching up. What happens if the link to the Internet is rather asymmetrical? For example, here I am stuck with 30 Mb/s down, but only 3 Mb/s up. The actual bitrate is not so important. True: it determines the time a packet spends on the wire. But more important is (or can be) the amount of time a packet spends in various queues before actually being sent. This time varies with instantaneous network load, and with the size of the queue. Google for bufferbloat, and apologies if everyone here already knows all of this. Having said that: there can indeed be asymmetrical transmission delays that are linked to the technology being used. My VDSL2 modem tells me that the downstream delay is 14.1ms and the upstream delay is 4.4ms. The ratio of these numbers is not equal to the ratio of the downstream and upstream bitrates (which are 16544 kbit/s and 2056 kbit/s respectively). So note also that the downstream delay is greater than the upstream delay, although the downstream bitrate is higher. HTH, Jan ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ntp stops running
On 08/13/2012 11:18 PM, Ali Nikzad wrote: unable to bind to wildcard address 0.0.0.0 - another process may be running - EXITING So is another process already running? ___ 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
On 08/03/11 19:39, unruh wrote: 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? GPS is used not only for navigation and time-of-day synchronisation, but also as a source of frequency signals for use by synchronous (e.g. SDH) or plesiosynchronous (e.g. PDH) networks. Jan ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] GPX18x LVC 3.50 firmware - high serial delay problem workround
On 16/01/11 09:11, Chris Albertson wrote: No, if it is not _processed right at the UTC second it is pointless. The Motorola GPS allows you to adjust the timing of the pulse to account for delay in the antenna feed line and serial line. I was also thinking about avoiding interrupt collisions. In an ideal world, if the PPS interrupt occurs exactly at the UTC second it is going to coincide with the system's timer interrupt, is it not? That's even if the system has only one PPS source. So if the GPS receiver is capable of shifting its PPS signal in time, why not shift it to a quiet part of the second in interrupt terms, and then fudge that away in ntpd? Cheers, Jan ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] GPX18x LVC 3.50 firmware - high serial delay problem workround
On 16/01/11 11:25, Rob wrote: Jan Ceuleersjanspam.ceule...@skynet.be wrote: I was also thinking about avoiding interrupt collisions. In an ideal world, if the PPS interrupt occurs exactly at the UTC second it is going to coincide with the system's timer interrupt, is it not? That's even if the system has only one PPS source. You assume that system's timer interrupt is somehow being synchronized with the UTC second. You're right. What then about the case of multiple PPS sources? ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] NTP client with ability to write Windows NT system time to hardware clock?
Piece of feedback below. On 11/12/10 13:07, Brolin Empey wrote: I run Windows 7 Professional IA-32 with RealTimeIsUniversal=1 on brolin-V13, my Dell Vostro V13 laptop. This means brolin-V13’s hardware clock (RTC) runs in UTC, as it should, instead of the local time zone, as Microsoft still uses for the completely illogical default configuration. RealTimeIsUniversal=1 is /finally/ fixed and fully working beginning in Windows Vista SP2 + Windows 7, but there is still a problem: When RealTimeIsUniversal=0, which is also used when the RealTimeIsUniversal key does not exist, Windows 7 writes the Windows NT system time to the hardware clock during the shut down process. When RealTimeIsUniversal=1, though, the Windows NT system time is never written to the hardware clock. Consequently, I have to boot Ubuntu from a USB flash drive (brolin-V13 has no optical disc drive (ODD).), then use ntpdate-debian + hwclock to synchronise the Linux system clock with an NTP server on the Internet, then write the sufficiently-accurate-for-me Linux system time to the hardware clock so Windows 7 will set the Windows NT system clock from the accurate time in the hardware clock. After some time (at least 1 week, not sure.), though, my hardware clock is approximately 2 minutes behind the correct time from an NTP server, but Windows 7 never writes the Windows NT system time to the hardware clock when RealTimeIsUniversal=1, so I have to use my Ubuntu USB flash drive again. I know the proper solution is to get Microsoft to change Windows 7 so it can write the Windows NT system time to the hardware clock even when RealTimeIsUniversal=1, but that has not yet happened. I have at least asked a Microsoft employee about it, though, so they know users (well, at least 1 user. :)) want the feature. I can use w32time to force a synchronisation, but then I have to do that every time I boot Windows 7. brolin-V13 travels with me between home and work, so it is not always running. Maybe this causes the hardware clock to fall behind, but I do not think I can prevent having to shut down and boot brolin-V13 on a daily basis. Since I do not know if Microsoft will ever enable Windows 7 to write the Windows NT system time to the hardware clock when RealTimeIsUniversal=1, the next best solution is probably to write a hwclock.exe application for Windows NT, but I am hoping someone has already implemented this functionality in an application such as an NTP client. Googling “hwclock.exe” returns lots of noise because some malware uses this file name, but I have not found any real hwclock.exe equivalent to hwclock used on Linux. So, is there an NTP client or any other application for Windows NT which can write the Windows NT system time to the hardware clock so I do not have to write hwclock.exe for Windows NT? Thanks for reading, Brolin There's no way I'm going to read all that. If you have a question for us, please can you put it a little more succinctly? Thanks. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] LTC Timecode Generator
On 11/10/10 00:44, Chris H wrote: Does anyone have any info on how if possible to make a Linux computer, synced to GPS become an LTC (Broadcast EBU SMTPE) master clock generator? The LTC page on Wikipedia [1] includes a link to a project on Sourceforge aimed at encoding and decoding LTC in software under Linux. [1]: http://en.wikipedia.org/wiki/Linear_timecode Jan ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Simple but good NTP server
Maarten Wiltink wrote: Why did you get 4801s? I recall reading here that the 4501 was no longer for sale, but Soekris' own website offers them. I didn't get them specifically for timing purposes, but rather to act as a platform on which to build my own access routers (with added DSL and wifi peripherals). Not the cheapest way of doing that (which would be to get a Linksys box and run openwrt), but fun nonetheless. Jan ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Simple but good NTP server
Terje Mathisen wrote: The canonical DIY ntp server would be to base them on phk's choice, the Soekris single-board computer: http://phk.freebsd.dk/soekris/pps/ Since this board has a hw counter capable of accurately timing the PPS signals,Poul-Henning got it to run at sub-us accuracy, using a cheap timing GPS. A few more points: - It does not explicitly say so at the page above, but the Soekris model that Poul-Henning used was the 4501. I've only got 4801s and they're not as good for timing. - The results shown on the above page are of a 4501 that has been significantly hacked by adding a Rubidium oscillator to the mix. Not for the faint hearted and not cheap either. - The net4501 costs €136 for the board and case. Add €15 for the power supply. Then add around €100 for a GPS riming receiver and another $1700 for the Rubidium standard. Admittedly the latter is optional if your needs are modest. Cheers, Jan ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] OT: high-accuracy atomic clock to be attached outside of the International Space Station
unruh wrote: They have high accuracy atomic clocks orbiting up there already (GPS, Galileo,...) What is significant about this? Firstly, the linked press release talks about certain physics experiments which can presumably only be carried out in orbit and which require highly accurate clocks. Secondly though, is the ISS able to receive GPS signals in order to remove the need for its own high-accuracy clock? Assuming that the accuracy that results would still be good enough? I'm asking because I wouldn't expect GPS/Galileo/GLONASS to have been designed with in-orbit receivers in mind. Jan ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] NTP absolute accuracy?
David Lord wrote: How do you get the time difference between your GPS and system time? Include the GPS in your ntp.conf, but mark it with noselect on the server line. ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] NTP absolute accuracy?
David J Taylor wrote: For those without wide-bandwidth academic connections - those folks on cable or ADSL - how good is an equal split round trip assumption? I calculated this for my case once (3840 kbit/s down and 512 kbit/s up). The difference in transmission time due only to the different bitrates was about 1.2ms in my case. This is however only the best case, because it assumes that the uplink is not saturated. If it is, and if you are able to prioritise your upstream NTP packets over all other traffic, then you need to add half of the transmission latency of the average upstream packet to the above 1.2ms. To give you some idea, assuming that the uplink is saturated due to a file upload (i.e. MTU-sized packets), this brings the difference in latency to 14.4ms (including the above 1.2ms). If you cannot control upstream priority queuing, then the upstream latency depends on the total size of your upstream queue, which may add several MTU-sized packet transmission times to the difference (in my case, 26.5ms times three plus 1.2ms). This is then really the worst case, because it assumes that the downlink is not saturated so that there is no queueing on the ISP's side. Cheers, Jan ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Unable to get time from the internet using NTP
Dew Wrobel wrote: I have to setup a couple of servers that will get their time from the internet. [...] When I start NTP, the start up hands with ntpdate trying to get the time from the servers. I have verified that the server names do verify in DNS. Do I need to pick a different set of servers? Any idea/suggestions would be greatly appreciatd. Dew, A few questions to help figure out what is going on. What error messages, if any, are emitted? How do you determine that it isn't working? Can you manually execute ntpdate pool.ntp.org ? If ntpdate succeeds where ntpd itself fails, the culprit is most likely your firewall configuration. You need to permit both inbound and outbound traffic on UDP port 123. If you conclude that things aren't working from ntpq -p, have you waited long enough for ntpd to achieve synchronisation? Without iburst on your server lines it can take quite a while for sync to be acquired. Cheers, Jan ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Testing Sync Across Several Systems
T wrote: We have about 50 Linux/Solaris/Windows boxes running ntpd at several different sites. Some of the systems from time to time go out of sync. My question is there a way to test ntpd machines are all in sync with the master server? The easiest way I can think of is to poll those machines using ntpd from a monitoring host. This monitoring host's ntpd.conf contains, for each of your to-be-monitored boxes, a line like the following: server box1thru50.domain.tld noselect So that's about 50 lines like the above, in addition to your normal server lines (since the monitoring host itself also needs to be synced to the master server). (In fact, it might _be_ the master server). The noselect option on the server lines tells your monitoring host to only poll that box but never to try syncing to it itself. Then you can inspect the state of play using ntpq: ntpq -p monitoringhost.domain.tld This assumes that the to-be-monitored boxes have static IP addresses (or else you would need to restart the monitoring host's ntpd periodically). It also assumes (I've never tried it) that ntpd will scale to the number of hosts that you want to monitor. If you need anything more elaborate, google for ntp survey. There is a periodic project run by Brazilian academics whose toolset you might be able to reuse. Cheers, Jan ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Testing Sync Across Several Systems
T wrote: Got a couple of quests here. He had box1thru50.domain.tld What does the .tld mean? I dropped that in the configuration file... Is the .INIT. in the refid field a problem? These are all Solaris boxes... Tom, Replace the box1thru50.domain.tld with the DNS names of your 50 boxes. If they're not in DNS, and you know their static IP addresses you can specify those instead. The .INIT. means that your monitoring host has not received any NTP packets from these machines at all yet. Two things to check: - wait a while (order of magnitude: 15 minutes) and see if it changes; - make sure that the firewall settings on those boxes allow inbound and outbound UDP traffic on port 123. Cheers, Jan ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] NTP - best practice if there is a local stratum 2 server
Dave wrote: But setting the time from the local server is also going to be cause a problem if that server fails for some reason. What I do here (in my home network) is make the NFS server also an NTP server, and make sure that the NFS clients prefer the NFS/NTP server over any others. (In fact: I configure those NFS clients to have only one NTP server, and that's the NFS server). This way, as long as the NFS server is up, chances are that its NTP server will also be up. Cheers, Jan ___ 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?
Joe wrote: Timezone data is fairly dynamic. It makes sense to have some form of network service to update timezone data. Does anyone know if there have been any proposals about a standardized timezone update protocol, or reasons why there should not be one? Since NTP is well established, maybe it could be expanded to include timezone data? I recognise the need for resolving this problem. What I know most about is the world of telecoms operators. Contrary to the advice most of us (chimeheads who hang out here) would give them, there are a lot of network operators who observe local time at lower layers than the presentation layer. This can include things like: - call detail records: local time is needed to apply the right tariffs where they depend on time-of-day. I would argue that the CDRs emitted by the network elements should use UTC timestamps, where the time is localised only by the rating system. However, many network operators have the network elements observe local time, causing all sorts of grief in respect of transitions to and from daylight savings time. - logfiles: similar point. Correlation of events across multiple network elements is problematic, particularly when they've been timestamped in local time, particularly if the network spans multiple time zones. So the challenge is to keep tens of thousands of network elements (routers, ATM switches, telephone exchanges etc) aware of when to switch to/from DST during their lifetime of multiple years. Wouldn't it be great if we could do this without manual interventions, or scripts, or even cron jobs? If local time were used only on equipment that has a presentation layer (OSS and BSS), then this would reduce the size of the problem by at least one if not two orders of magnitude. (The above does not address the point as to whether or not NTP should be used to distribute time zone information though). Cheers, Jan ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Garmin 18 LVC: whether to fudge
Brian Utterback wrote: Decreased bandwidth means increased latency. The two are related. Only indirectly so. There are at least two components to the higher latency on the ADSL uplink as compared to the downlink. A minor component is the fact that the lower bitrate means that equal-sized packets are in flight longer on the uplink than they are on the downlink. The main component is however that there is a transmit queue in the CPE that packets take a while to get through before actually being sent up the link, particularly under load. So this component is not only dominant, it is also variable with upstream load. One way to get around that is to set up multiple transmit queues for different flows, perhaps based on TOS marking. This way, NTP packets, when suitably marked, can be made to bypass the transmit queue for best-effort traffic. Cheers, Jan ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Power-saving patch to NTP
Unruh wrote: I am totally confused. The cpu is in sleep mode. The cpu is not doing anything. ntp is NOT running. ntp cannot wake up the cpu because ntp is not running. Only external events can wake up the cpu, and ntp is not an external event. So, once the cpu is woken up, and ntp can run, what does it matter if ntp then runs? Ntp runs whenever one of the pieces of hardware it watches reports an event. One of those is the once-per-second wakeup call. But as I said elsewhere in this thread, I don't think that the important thing is ntpd's own power footprint, but rather the implications of the platform's attempts at saving power. Or as someone else put it: the basic assumptions ntpd makes of the behaviour of the platform (hardware and OS) while it's _not_ running (i.e. between invocations of itself). Cheers, Jan ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Power-saving patch to NTP
David Woolley wrote: packet shows up, which with laptops I know will considerably degrade the I'm not convinced this is even about laptops. I think it is about PDAs, or about embedded systems that may run for a year on a couple of AA bateries, or may run on small photocell arrays. I think that the lesswatts.org initiative (which should of course have been called fewerwatts.org but that's another story) is about reducing the power consumption of _all_ hardware that runs Linux, including laptops, desktops, servers, embedded devices etc. I also think that ntpd runs on a sizeable percentage of all such hardware that's in service out there. But that's not why I raised the question here. Ntpd's once-per-second interrupt is nothing compared with the hundreds-to-thousands of wakeups per second initiated by certain poorly-written hardware device drivers. I just wanted to prompt a discussion on understanding the implications of Red Hat's patch. Application writers do (I think) have a responsibility to the planet to verify/justify their application's impact on the platform's total power consumption (and the lesswatts.org website provides tools for doing that, e.g. powertop), but as I said I don't think that ntpd is an especially power-hungry application. The lesswatts.org site also mentions a range of other power-saving measures in recent Linux kernels, including the bunching together of wakeup events. Some applications have no need for very precise timers, they just want to be woken up more-or-less-2s-from-now. The kernel is then able to schedule a bunch of these imprecise timers at the same time such that the number of wakeups is minimised. Clearly ntpd does need precision and therefore probably must not use this new class of imprecise timers, but I also don't know whether anyone knows if the existence of the imprecise timers has a knock-on effect on the precision of the standard timers. On the other hand, perhaps ntpd _can_ use the imprecise timers provided it also has access to an accurate platform time stamp when the timer fires. Cheers, Jan ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Power-saving patch to NTP
Bill, Bill Unruh wrote: Now of course I suspect that the kernel has to wake itself even more often than once a second (eg the timer interrupt) and if it did not, the effect on the time discipline would be pretty bad. The Linux kernel has recently gone tickless, meaning that it only schedules a wakeup for itself at the first time that it knows a timer will expire. A quick intro on that can be found here: http://www.lesswatts.org/documentation/silicon-power-mgmnt/#ticklessidle Cheers, Jan ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Power-saving patch to NTP
David Woolley wrote: Have they considered the resulting increased processing time, and more importantly, variability in processing time of gettimeofday? That's why I'm raising the question here. If anyone on the ntpd team has contacts at Red Hat, a brief discussion about this would be of considerable help. KR, Jan ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
[ntp:questions] Power-saving patch to NTP
I came across the following page: http://www.lesswatts.org/projects/powertop/known.php which says the following on ntpd: By default, the ntp time synchronization daemon will wake up once per second, and will make the kernel do work on it's behalf even more. Red Hat has created a patch to ntp to fix this issue and ships it in their rawhide and FC7 ntp packages. You can download this patch from the Fedora cvs server. Has anyone here looked at that patch? Does it compromise correctness of the algorithms? Thanks, Jan ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Multicast question
Martin Burnicki wrote: I'd expect that either the kernel routed multicast packets to all interfaces (isn't that what routers do with multicasts, contrarily to broadcasts?), or the application would send an individual packet on each interface. Routers have to be told (by means of multicast protocols such as IGMP) which interfaces to replicate multicast packets onto. Jan ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] NTP vs chrony comparison (Was: oscillations in ntp clock synchronization)
David, David Woolley wrote: ISTR that time stamps on financial transactions are required to be within two seconds of the correct time. With NTP that standard is not too difficult to meet. In 2006, it turns out that it was 3 seconds http://tf.nist.gov/general/pdf/2125.pdf, NIST is a US government institution; might there perhaps be different laws or regulations elsewhere in the world? Does anyone among the readership here know? Thx, Jan ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Distribution security
Harlan, Harlan Stenn wrote: Jan I really hate being sent from left to right in search of Jan documentation. This includes stub man pages pointing me at html or info Jan pages. Ideally I'd want to be able to select the documentation format Jan on a system I'm responsible for myself (i.e. as a policy decision on my Jan end). What you describe is my goal. I know and I thank you for it. My not-so-hidden agenda in writing the above message was to support you by showing that there is indeed demand for documentation on formats other than html, while ensuring consistency and an audit trail leading from the documentation in all formats to a single authoritative source. One obvious way progress toward this goal will be greatly improved will be for more people and institutions to join the NTP Forum. Please do what you can to get members to sign up for the forum - if you need more information to help make the decision please let me know. And if you decide not to join, it would also help to let me know why. Email is probably the best way to do these things. I have indeed sent you email about this. Happy to help you on this issue as well. Cheers, Jan ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Distribution security
Hal Murray wrote: When I wrote that I was unaware of the html page. I'm a Unix guy and I generally don't even consider looking for html docs - I am used to (and expect) man pages. Me too. Would it help to ship dummy man pages that just pointed to the html documentation? Can I just get my vote in (even though my non-membership of the ntpd development community puts me into the whiner-not-worker category)? I really hate being sent from left to right in search of documentation. This includes stub man pages pointing me at html or info pages. Ideally I'd want to be able to select the documentation format on a system I'm responsible for myself (i.e. as a policy decision on my end). This issue also goes beyond the mere format of the documentation, even in case I am forced to accept multiple document formats. Searching the documentation installed on a system gets more difficult in this case. For example, the apropos tool won't search anything but man pages. Cheers, Jan ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] quirky adjtimex behaviour
Hi Dean. Dean S. Messing wrote: Can I however suggest that you first try and eliminate CPU frequency scaling as a cause of the symptoms you're seeing: use cpufreq-set -g to select a policy that results in a constant CPU frequency and then check if this changes the behaviour (or renders it more predictable). ... analyzing CPU 0: no or unknown cpufreq driver is active on this CPU ... OK, this eliminates CPU frequency scaling as the cause of your problem. Sorry to have sent you off on a tangent; from recent experience this seemed like a promising low-hanhing fruit (but it turned out not to be). analyzing CPU 1: no or unknown cpufreq driver is active on this CPU analyzing CPU 2: no or unknown cpufreq driver is active on this CPU analyzing CPU 3: no or unknown cpufreq driver is active on this CPU ... If you or others wouldn't mind reading my whole original post (it's not _that_ long :-) maybe some other ideas might occur. Thanks. Sorry, I haven't a clue. Also note that I don't have any experience with SMP at all (let alone timekeeping on SMP machines). I'm very interested in this subject, but I've never been able to justify the hardware cost just so that I could play around with this. Cheers, Jan ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] quirky adjtimex behaviour
Dean, Dean S. Messing wrote: I am seeing strange behaviour on my _x86_64 Fedora 7 desktop workstation with regard to the system-cmos time that `adjtimex' reports. I've not read your whole post; it's clear that you've been wrestling with this problem for a while and have done quite a bit of work already. Can I however suggest that you first try and eliminate CPU frequency scaling as a cause of the symptoms you're seeing: use cpufreq-set -g to select a policy that results in a constant CPU frequency and then check if this changes the behaviour (or renders it more predictable). HTH. Jan ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Source address in response always the same as target address in request?
Richard B. Gilbert wrote: I believe that there is a solution to the DNS caching problem. Each DNS record can be given a Time To Live or TTL. If you are planning to change the record, set the TTL to seven days, then six, five, four, three, two, one. . . . All of those cached records should expire at more or less the same time. It's not perfect but it works. If you time it just right, you can minimize the amount of disruption. Still requires the clients to re-resolve the server address (something ntpd famously does not do currently; desparate attempt at getting back on-topic ;-) ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Any samples for NTP/SNTP client code?
Danny Mayer wrote: Jan Ceuleers wrote: This means that there is no need to allocate memory for constructing the reply packet, no need to copy data from received to transmitted packet, etc. This is also false. That's not what the code does. The recvbuf structure is not even the same size as the transmitbuf structure. I wasn't talking about the recvbuf and transmitbuf structures, but the socket receive and transmit buffers. Besides, transmitbuf appears to only exist in the Windows port. Jan ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Any samples for NTP/SNTP client code?
[EMAIL PROTECTED] wrote: Just look at the NTP/SNTP request format and for ***every*** field explain why would a client send it to a server. Do not pick just one field like MODE, explain for ***all*** fields. I believe that the principal reason for having the same format for the received and the transmitted packet is so that the server can reply simply by modifying the received packet and transmitting the result. This means that there is no need to allocate memory for constructing the reply packet, no need to copy data from received to transmitted packet, etc. This could conceivably be done very close to (or indeed in) the hardware, but even if it is done in user space (as is the case in ntpd) this saves precious time, which is important in a timing application. Optimising the packet format for conveying just enough information (i.e. optimising for bandwidth) is of secondary importance (particularly given the overhead that IP already represents), and is in fact counterproductive in the light of the above argument. Hope this helps. Cheers, Jan ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Reg: NTP accuracy
linux newbie wrote: HI, Need following clarification. Our Application needs to have two individual hardware (with DSP processor) to have same crystal clock freqency. Though individual boards are alike, due to environmental factors there might be drift after long run. This suggests that you need frequency synchronisation, not time-of-day synchronisation. Frequency synchronisation is used a lot in telecommunications networks (e.g. SDH/SONET). As the two boards are connected to local LAN through ethernet, we feel by comparing time at regular intervals can determine any drift in clock. (assuming one board as server and another as client). As telecommunications networks evolve from TDM to packet, there is also an increased need to transport synchronisation information across packet networks. Work is ongoing in the IETF (e.g. TICTOC) and elsewhere (e.g. IEEE 1588). But before choosing a solution, you need to be clear on what problem you are trying to solve. Cheers, Jan ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Any samples for NTP/SNTP client code?
[EMAIL PROTECTED] wrote: Does anybody know of any *practical* samples on how to implement NTP/SNTP client?. The goal is to provide accurate time for a program/client running on Windows Vista. Have you seen the sntp directory in the reference implementation tarball? ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] My ntpd stopped working
rasmus wrote: The _first_ rule in your INPUT chain needs to explicitly allow all traffic to 123/UDP. Something like this: Sorry, I was unclear. The rule I referred to was one that allowed udp/ 123 traffic. So I have a rule exactly matching what you wrote at the head of my INPUT chain. I can see traffic reach my nptd and I can log packets with sport 123 in my OUTPUT filter. You misunderstand. The rule only accepts packets that are related to an ongoing connection. You need to accept ALL packets destined to UDP port 123 (while retaining the stateful firewalling on all other traffic). So please do take Steve's advice and insert a -j ACCEPT rule matching only UDP port 123 traffic at the start of your INPUT chain. Cheers, Jan ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] My ntpd stopped working
rasmus wrote: This sounds as though your firewall is opening port 123/UDP in response to polls sent to remote time servers from your ntpd. That could indeed then explain the blinks in my availability as reported by the pool. How often does ntpd per default sync time with the configured servers? Do you have a rule like the following in your iptables setup: -A INPUT -i ppp0 -m state --state RELATED,ESTABLISHED -j ACCEPT If so, can you try and bypass it for 123/udp traffic? HTH, Jan ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Installing more stable oscillator?
Maarten Wiltink wrote: Keeping a room at a constant temperature might actually be easier than the other thing you could do - not run *any* other services on the computer. No cron at 3am. (Alternatively, make it run at 100% CPU always. Perhaps [EMAIL PROTECTED] would be _good_ for stability.) I used to do something like the following: I did not want setiathome to cause my server (which sits in a badly ventilated closet) to overheat. So I had written a C program that monitored the rate of the CPU fan (which is regulated by the CPU itself) and throttled the setiathome process (by sending it SIGSTOP/SIGCONT signals). The result was that the setiathome process kept the server at a constant temperature (and the CPU fan at around 3000 rpm). This ceased to work when the setiathome project changed their architecture, causing the work to be done by a load of sub-processes rather than the one I knew the pid of. So I dropped setiathome altogether. I haven't kept stats, but the clock now looks less stable (frantic attempt at remaining on-topic). Cheers, Jan ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
