Problem with Linux Machine's Request for Time from an XP Machine

Snowbat wrote:
> On Sun, 09 Jan 2005 22:17:53 +0000, W. Watson wrote:
>
>
>>I think my focus now is the (authorative time set) and XP
>>modification of the registry document for NTP mentioned above.
>
>
> Some further digging shows XP's 'Windows Time Service' can be configured to
> use one of the following modes:
> # NT5DS -- use the Win2K method of locating a server, and use the NetRemoteTOD
> protocol for time
> # NTP -- use the servers you specify, and use the SNTP protocol
> # NoSync -- run, but don't check or set the time
>
> As a test I configured an XP machine on my network for NTP mode and I can
> successfully query it from the Linux box using the ntpdate command. The
> following changes were required on the XP box:
>
> Registry: HKLM\SYSTEM\CurrentControlSet\Services\W32Time\Par ameters\Type
> Change this REG_SZ value from NT5DS to NTP
>
> Registry: HKLM\SYSTEM\CurrentControlSet\Services\W32Time\Con fig\AnnounceFlags
> Change this REG_DWORD value from 10 to 5 here. (select decimal not hex)
>
> Registry: HKLM\SYSTEM\CurrentControlSet\Services\W32Time\Par ameters\NtpServer
> List NTP server(s) to sync to - see
> http://www.windowsnetworking.com/art...e-Service.html
>
> Firewall: Add an entry to allow incoming UDP traffic on port 123
>
> Stop and restart the time service from XP command prompt
> net stop w32time
> net start w32time
>
>
> References
> http://www.windowsnetworking.com/art...e-Service.html
> http://dtdocs.ntp-systems.com/kb/kb2001.002.asp
> http://www.greyware.com/software/dom.../protocols.asp
I'm awake again. Which of the three docs to you use for the ntp approach?
Are your registry changes something you derived from one of these docs?

See my prior post to the NG made about 4 hours ago. I'm about to read these
docs.

--
Wayne T. Watson (Watson Adventures, Prop., Nevada City, CA)
(121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time)
Obz Site: 39° 15' 7" N, 121° 2' 32" W, 2700 feet

Web Page: <home.earthlink.net/~mtnviews>

Bill Unruh wrote:

> "W. Watson" <wolf_tracks@invalid.inv> writes:
>
>
>> Christopher Browne wrote:
>
>
>>> Clinging to sanity, "W. Watson" <wolf_tracks@invalid.inv> mumbled
>>> into her beard:
>>>
>>>
>>>> Christopher Browne wrote:
>>>>
>>>> I take it that would be XP--after I figure out why I cannot
>>>> complete a registry change required to make it authoritative.
>>>
>>>
>>> No, XP comes with a hacked-up variation on NTP that you shouldn't
>>> trust. It's not really NTP; it only resembles it.
>>>
>>> You surely know better than to imagine Microsoft would actually
>>> conform to someone else's standard; NTP is no exception to this.
>>>
>>> It is possible to get a real implementation of NTP for Windows that
>>> might be satisfactory; that requires that you get that, and that you
>>> deactivate any time services that are installed by default by
>>> Microsoft.
>
>
>> Sounds like a considerable challenge to install NTP. See below about
>> the latest on accuracy, but I think after I break through on the
>> authoritative (which seems like it makes the real NTP server appear on
>> XP) time source approach, I should be OK. However, as I mention in the
>> last paragraph, that's looking a bit gloomy. If so, I'm just going to
>> punt on my machine and see what adjtimex brings. I discuss a little of
>> this on a recent post today to prg.
>
>
> ??????? You want to do scientific work, and you seem totally unwilling
> to listen to others. You insist on using a completely useless time
> technique. Sheesh. Why did you ever come onto netnews to get advice? As
> it stands, Windows is NOT going to give you 10ms accuracy. Phone line
> ntp will NOT give you 10ms accuracy. DSL might give it to you. If you
> were to use a decent ntp server.

I believe you are misreading something. Also see my remarks below about 30
or more lines.

Like all work, scientific work requires judgement on available resources
Time and money, for example. Once I get the information, I act accordingly
in a way that applies to my situation. Frankly, if I followed every piece
of advice I've gotten on this matter, I would be implementing about six
different methods. This is *not* to say that I have not appreciated all the
advice I have gotten. It has been helpful.

If you will note another post below from snowbat at the end of this thread,
I think he may have successfully broken through in an area that is
appealing to me. Implementing a true NTP server on XP Pro. I'm verifying
this at the moment.
>
>
>
>> Well, my partner in meteor work reappeared after a two week vacation,
>> and I put it to him about the accuracy. We diddled with some velocity,
>> altitude, and pixel calculations and came up with an estimate of 8ms
>> as a goal.
>
>
>> Someone piped up elsewhere that NTP can be established on XP easily by
>> using the XP net time command. All one needs to do is execute net time
>> /setsntp:time.ucsd.edu, where :.... is an ntp server in California.
>> Supposedly I can then use
>
>
> sntp is NOT going to give you the accuracy you need. SNTP is Simple NTP.
> Ie it does not have all of the bells and whistles-- whose main prupose
> is to try to squeeze out the best accuracy possible from a net
> connection.
I fully agree!
>
> From
> http://www.csir.co.za/plsql/ptl0002/...AGE_NO=7026927
>
>
> The Network Time Protocol (NTP)
>
> When the highest accuracy time information available on the Internet is
> required, the NTP protocol is used. NTP is robust and can select the
> best from a number of time sources, will reject false sources, operates
> to a very high precision in the Internet realm, with its variable delays
> and path lenghts. The NTP data packet contains information about the
> mode of operation, Stratum number of the server, polling interval,
> precision, delay and dispersion of the server as well as an identifier.
> It also contains four time stamps, and an optional authenticator. The
> time stamp is the number of seconds since 0h on 1 January 1900, in a 32
> bit field, with the fractions of a second in a second 32 bit field. This
> gives the NTP protocol a precision of about 200 picoseconds, which
> should be sufficient for even the most demanding applications. The
> typical accuracy of a synchronised NTP client is between 1-50
> milliseconds. For more information see the link below, or read the
> relevant document (RFC-1305).
Yes, I agree.
>
> The Simple Network Time Protocol (SNTP)
>
> When the ultimate accuracy of NTP is not required, SNTP can be used. The
> SNTP client/server exchange is the same as the NTP client/server
> exchange, except that when using SNTP, some of the fields in the data
> packet are "canned", which means they are filled with pre-determined
> values. The advantage of the SNTP implementation is that it is much
> simpler and fewer exchanges are made between the client and the server.
> The typical accuracy of a SNTP client/server exchange is fractions of a
> second. For more information see the link below, or read the relevant
> document (RFC-1769).
>
> ---------------------------------------------------------
>
> Ie, IF you want ms accuracy, your only choice is full NTP together with
> some fast connection with the net ( not a phone line and modem-- too
> slow) or with some GPS receiver time source.
>
>
>
>> redhat-config-date to then access time from XP at 192.168.0.3 (my IP
>> address for XP). I tried this but it didn't work. I need to look at
>> the net time command to see what I'm missing.
>
>
>> -- Wayne T. Watson (Watson Adventures, Prop., Nevada City, CA)
>> (121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time) Obz Site: 39° 15'
>> 7" N, 121° 2' 32" W, 2700 feet
>
>
>> Web Page: <home.earthlink.net/~mtnviews>
>
>


--
Wayne T. Watson (Watson Adventures, Prop., Nevada City, CA)
(121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time)
Obz Site: 39° 15' 7" N, 121° 2' 32" W, 2700 feet

Web Page: <home.earthlink.net/~mtnviews>

"W. Watson" <wolf_tracks@invalid.inv> writes:

>Bill Unruh wrote:

>> "W. Watson" <wolf_tracks@invalid.inv> writes:
>>
>>
>>> Christopher Browne wrote:
>>
>>
>>
>>> Sounds like a considerable challenge to install NTP. See below about
>>> the latest on accuracy, but I think after I break through on the
>>> authoritative (which seems like it makes the real NTP server appear on
>>> XP) time source approach, I should be OK. However, as I mention in the
>>> last paragraph, that's looking a bit gloomy. If so, I'm just going to
>>> punt on my machine and see what adjtimex brings. I discuss a little of
>>> this on a recent post today to prg.

From what I have read, MS ONLY impliments SNTP. It is also not at all clear
that you have sufficient control of the on board clock so that you can slew
it to compensate for hardware clock rate errors. This is critical to the
operation of an NTP server.

You want ms accuracy.
a) You will NOT get that even with full ntp from a phone connection. Far
too many latencies within the modems, etc. Thus if you want ms accuracy
which you appear to need, a phone connection is NOT good enough.
b) You will not get that with SNTP over the net.


>>
>>
>> ??????? You want to do scientific work, and you seem totally unwilling
>> to listen to others. You insist on using a completely useless time
>> technique. Sheesh. Why did you ever come onto netnews to get advice? As
>> it stands, Windows is NOT going to give you 10ms accuracy. Phone line
>> ntp will NOT give you 10ms accuracy. DSL might give it to you. If you
>> were to use a decent ntp server.

>I believe you are misreading something. Also see my remarks below about 30
>or more lines.

>Like all work, scientific work requires judgement on available resources
>Time and money, for example. Once I get the information, I act accordingly
>in a way that applies to my situation. Frankly, if I followed every piece
>of advice I've gotten on this matter, I would be implementing about six
>different methods. This is *not* to say that I have not appreciated all the
>advice I have gotten. It has been helpful.

Scientific work requires that you do it right. If you do not have the
resources to do it right then what is point of doing it. You will publish
your results and people will be misled by them, since you will quote
accuracies which are wrong.

You need some way of getting ms (8 ms you state) accuracy. What is the
value of the observations if you get 200ms accuracy?

So it seems to me that you have three options.
a) Get GPS receivers. This should give you microsecond accuracy. Whether
the delays and latencies in your programs etc can use this kind of accuracy
I do not know. You had better run the system as a real time system or
program slicing is liable to destroy any timing accuracy.

b)Get a real NTP server. I simply do not know what kind of accuracy you can
get out of an NT box-- whether the OS has resources capable of delivering
the accuracy you need even if you run NTp over a fast connection. Note
that you will not get ms accuracy from even real ntp over a phone line
modem connection. You will probably need at least DSL.

c) abandon 8 ms accuracy and settle for 1 sec (well maybe 1/10 sec) accuracy.

I think those three are your choices. For the last choice almost anything
will probably work.

>If you will note another post below from snowbat at the end of this thread,
>I think he may have successfully broken through in an area that is
>appealing to me. Implementing a true NTP server on XP Pro. I'm verifying
>this at the moment.

It looks to me like what he is refering to is a SNTP server, not an NTP
server. SNTP was developed for rough 1 second type accuracy for
synchronization.

On Tue, 11 Jan 2005 15:59:50 +0000, W. Watson wrote:

> I'm awake again. Which of the three docs to you use for the ntp
> approach?

http://www.windowsnetworking.com/art...e-Service.html
Primary guide for setting up.

http://dtdocs.ntp-systems.com/kb/kb2001.002.asp
Information about the three W32Time service modes.

http://www.greyware.com/software/dom.../protocols.asp
Brief description of various time protocols including NTP/SNTP,
NetRemoteTOD, and their own Domain Time products.


> Are your registry changes something you derived from one of these docs?

Straight from the windowsnetworking.com article.

"W. Watson" <wolf_tracks@invalid.inv> wrote:
>Floyd L. Davidson wrote:
>>>For simplicity, 1 second a day. If there is a cheap GPS unit
>>>that is suitable, I'd be interested.
>>
>> "1 second a day" doesn't mean much. That would be drift rate,
>> not accuracy.
>
>Good guess. See below--bottom.

I'm not guessing. "1 second a day" is a drift rate, which is
meaningless.

>> I do *not* recommend using the XP box as an ntp server or as a
>> gateway for the Linux box to access the Internet. Instead I
>> would suggest you go find the cheapest old box you can find (I
>> use an old PII-400mHz box) and put a stripped down Linux on it,
>> with IP forwarding enabled and set it up as a firewall with the
>> modem attached to it rather than the XP box. Then both the XP
>> box and the Linux box can safely access the Internet through a
>> real firewall, and both can also run ntp client software to
>> access a remote server (and skip all these various
>> servers... use us.pool.ntp.org, which will give you a different
>> server every time you query it).
>
>This sounds good, but there is no modem where the meteor (Linux)
>box is.

That makes no difference.

>The modem is in the house sitting next to my desk and is
>100 feet away from Linux.

That makes no difference.

>Installing ntp on my XP machine seems
>a better way to go in my situation.

That, as has been explained to you by others *in detail*, simply
is not an option.

>The only way I can see doing
>this via Linux is putting a modem on it and having it
>automatically dial out at 2am to get a time synch. Is that
>possible?

I don't understand why you have to be told the same thing at
least 5 times by at least 3 people before you listen. If it is
a waste of time for me to comment, I won't...

Read, again, what I wrote above.

"Then both the XP box and the Linux box can safely access the
Internet through a real firewall, and _both_ _can_ _also_ _run_ _ntp_
_client_ _software_ _to_ _access_ _a_ _remote_ _server_..."

However, given the accuracy you need, I'll agree with Bill and
Christopher that you are on the edge as far as the accuracy that
NTP over the Internet can possibly provide. I've been
suggesting syncing to us.pool.ntp.org, but given your need for
millisecond accuracy, that probably won't do it, especially
through a modem connection.

Regardless, the rest of the network topology suggest is still
significant, and you can implement NTP as described, syncing
to the nearest server available, as a temporary and imperfect
solution, without any cost at all. Everything you do will
be useful in a full fledged system that provides the accuracy
you need.

>> That will give you accuracy to 10's of milliseconds, and will
>> cost only whatever you pay for an old computer (which you can
>> probably get for free if you try hard).
>I have a number of old computers.
>>
>My meteor partner came back from a 2 week+ vacation, and I was
>able to get his attention on accuracy. We did some back of the
>envelope calculations using a meteor's altitude, velocity, and
>image size. 8ms or about 1/10th of a second should do. BTW, in
>one sec, a meteor will move 17 miles.

NTP over the Internet can barely provide you with that. You
might get away with it, with a high speed connection, if you
also try logging the time difference between your clock and say
3 others, and then average the difference and use that as a
correction factor for all of your logged observations.

Regardless, it does appear that the only option which will
provide sufficient accuracy is to install a local stratum 1
clock source. You clearly do not have the technical background
to construct one from component parts, which is probably the
only way to accomplish it without significant expense.

The problem area is the hardware interfacing of a frequency
standard to a PC in a way that NTP can use. Obtaining a GPS
unit with PPS output is only the initial step, and everything
past that involves significant technical background. If you
want to see what is involved, here is a very good description:

http://www.wraith.sf.ca.us/ntp/

Hence it appears that you need (either a good friend who can do
these things, or) to purchase not just a frequency standard, but
one that also provides a networked NTP server.

Here are some examples. The first one looks very nice, and
the price is $500. I didn't look for prices on others.

http://dcf.sk/gpsntp/
http://www.masterclock.com/ntp100.shtml
http://www.meinberg.de/english/products/gps169pci.htm
http://www.spectracomcorp.com/solutions/computer.php
http://www.ntp-time-server.com/time-...me-servers.htm


--
Floyd L. Davidson <http://web.newsguy.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska) floyd@barrow.com

Snowbat <snowbat@geocities.com> wrote:
>On Tue, 11 Jan 2005 15:59:50 +0000, W. Watson wrote:
>
>> I'm awake again. Which of the three docs to you use for
>> the ntp approach?
>
>http://www.windowsnetworking.com/art...ce.htmlPrimary
>guide for setting up.
>
>http://dtdocs.ntp-systems.com/kb/kb2...aspInformation
>about the three W32Time service modes.
>
>http://www.greyware.com/software/dom...ocols.aspBrief
>description of various time protocols including NTP/SNTP,
>NetRemoteTOD, and their own Domain Time products.
>
>> Are your registry changes something you derived from one
>> of these docs?
>
>Straight from the windowsnetworking.com article.

He says he wants 8ms accuracy (and actually probably needs 1 ms). The above
system, according to the information they provide at

http://www.greyware.com/software/dom.../targeting.asp

has the following specs:

Masters and Independent Servers
The default target accuracy is 250 milliseconds

Slaves
The default target accuracy is 100 milliseconds

Clients
The default target accuracy is 500 milliseconds

What good is that going to do for him?

--
Floyd L. Davidson <http://web.newsguy.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska) floyd@barrow.com

Floyd L. Davidson wrote:

> "W. Watson" <wolf_tracks@invalid.inv> wrote:
>
>>Floyd L. Davidson wrote:
>>
....

>>Installing ntp on my XP machine seems
>>a better way to go in my situation.
>
>
> That, as has been explained to you by others *in detail*, simply
> is not an option.
Perhaps you should read the msgs from those who differ with you. Yes, NTP
can be installed onto XP and yes the accuracy of 8ms can be met. Perhaps we
are having a little confusion over ms, millisecond, that's about 1/10th of
a second.

I hope you don't mind if I prove the above to myself.


--
Wayne T. Watson (Watson Adventures, Prop., Nevada City, CA)
(121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time)
Obz Site: 39° 15' 7" N, 121° 2' 32" W, 2700 feet

Web Page: <home.earthlink.net/~mtnviews>

I think I detect a misunderstanding in my stipulation of 8ms accuracy.
Perhaps you folks think of that as 8 microseconds. To me it mean 8
milliseconds. That is, a bit less that 1/10 th of a second.

I think I can safely say this thread at its end (EOT). I have more than
enough information to proceed in my own way. First, I plan to check out
snowbat's very interesting discovery, and, if that fails, I will check out
the claim that NTP of some sort better than what XP provides can be
installed. If either of these fail, I have other goals to attain the
accuracy needed, and will persue them as time and money allow. Presently,
this discussion narrows down to snowbat and myself, privately.

Thank you for your interest.

W. Watson wrote:
> Snowbat wrote:
> > On Sun, 09 Jan 2005 22:17:53 +0000, W. Watson wrote:
> >
> >>I think my focus now is the (authorative time set) and XP
> >>modification of the registry document for NTP mentioned above.
> >
> > Some further digging shows XP's 'Windows Time Service' can be
configured to
> > use one of the following modes:
> > # NT5DS -- use the Win2K method of locating a server, and use the
NetRemoteTOD
> > protocol for time
> > # NTP -- use the servers you specify, and use the SNTP protocol
> > # NoSync -- run, but don't check or set the time
> >
> > As a test I configured an XP machine on my network for NTP mode and
I can
> > successfully query it from the Linux box using the ntpdate command.
The
> > following changes were required on the XP box:
> >
> > Registry:
HKLM\SYSTEM\CurrentControlSet\Services\W32Time\Par ameters\Type
> > Change this REG_SZ value from NT5DS to NTP
> >
> > Registry:
HKLM\SYSTEM\CurrentControlSet\Services\W32Time\Con fig\AnnounceFlags
> > Change this REG_DWORD value from 10 to 5 here. (select decimal not
hex)
> >
> > Registry:
HKLM\SYSTEM\CurrentControlSet\Services\W32Time\Par ameters\NtpServer
> > List NTP server(s) to sync to - see
> >
http://www.windowsnetworking.com/art...e-Service.html
> >
> > Firewall: Add an entry to allow incoming UDP traffic on port 123
> >
> > Stop and restart the time service from XP command prompt
> > net stop w32time
> > net start w32time
> >
> > References
> >
http://www.windowsnetworking.com/art...e-Service.html
> > http://dtdocs.ntp-systems.com/kb/kb2001.002.asp
> >
http://www.greyware.com/software/dom.../protocols.asp
> I'm awake again. Which of the three docs to you use for the ntp
approach?
> Are your registry changes something you derived from one of these
docs?
>
> See my prior post to the NG made about 4 hours ago. I'm about to read
these
> docs.

W.W., your w32time basic setup how-to is done and posted here. I had
to wait for google to index it for a reliable link:

http://groups-beta.google.com/group/...ded388b5606ef1

I'll post the other sections there as well as they are of questionable
interest in c.o.l.n except for your specific needs. Besides, it's less
crowded -- I'm the only one who has responded to your post there ;-)
see ya,
prg
email above disabled

Well, beore anyone becomes unglued over 8ms (millisecond) as nearly 1/10th
of a second, let me say it is closer 1/100th of a second. Regardless, my
partner and I will clear this up between us. Anyway, EOT.

--
Wayne T. Watson (Watson Adventures, Prop., Nevada City, CA)
(121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time)
Obz Site: 39° 15' 7" N, 121° 2' 32" W, 2700 feet

Web Page: <home.earthlink.net/~mtnviews>