Re: Setting Up NTP for Time Sync

From: Bill Unruh (unruh_at_physics.ubc.ca)
Date: 01/09/05 

Date: Sun, 9 Jan 2005 09:21:27 -0800
To: "W. Watson" <wolf_tracks@invalid.inv>

On Sun, 9 Jan 2005, W. Watson wrote:

> Bill Unruh wrote:
>> I suspect Strongly that it does not. See the web page
>> http://geodsoft.com/howto/timesync/wininstall.htm
>> which a) suggests to me that windows does NOT support server, and b)
>> gives software that you can install which makes it into a server. Now,
>> whether (NetTime) SNTP will interoperate with NTP on the linux machines I
>> do
>> not know.
> I have two web pages that need examination that may tell the story. In the
> mean time,
> see tcpdump below.

What the tcp dump says is that the remote machine (0.3-- the windows
machine I assume) never replies. I suspect very strongly that it does
not support ntp as a server.

>
>> Again, I have no idea what your accuracy requirement is. If it is +- 1
>> sec, then sntp and your windows solution would be fine. If it is +- ms,
> I'm assuming that by sntp you are referring to the material I discovered with
> the net time command?

NetTime impliments sntp, the simple network time protocol. The linux
machine's ntp supports the full ntp protocol.I do not know if the linux
full protocol can use an sntp server to get the time.

> While time accuracy is of interest, I will put it aside until I really have
> this problem about NTP nailed to the wall.

Well, it would surely be best to impliment a strategy which will
ultimately give you what you need.

>>
>> I am still unclear what your topology is. You seems to say that the win
> I'm beginning to think it's a Klein bottle. :-)
>> machine has a direct connection to the net, but the Linux machine can
>> connect only via phone modem but it has a direct connection to the win
> The machine I'm currently using for Linux is a test bed. The *final* machine
> for my application will not have a modem.
>> machine. Why do you not switch them around. Have the Linux machine have
>

OK. I did not want to suggest a modem. So what you have is an ethernet
connection between your linux machine and your windows machine. What do
you use to to connect your Windows XP machine to the net? Is it a modem?
Is it a DSL connection via the phone company? Is it a cable modem?

Anyway, what you really want to do then is to make your windows machine
act as a router for your Linux machine. Ie the Windows machine will
accept the stuff from your linux machine, do address translation and
send the stuff onto the net. That way your Linux machine will be
directly connected to the net, whenever your Windows machine is, and can
use ntp directly from the net, and you can forget all about your windows
machine as an ntp server.

Looking up google, the web page
http://www.no-ip.com/tips.php/id/4
seems to give a guide to setting up the windows machine as a router for
the Linux machine.

Note that you say that you at present have your linux box as a test bed
and will be putting a different machine there. Why not use your test bed
as a router for the whole system-- Ie move it to the house and have it
distribute the internet to everything else?
Alternatively make your windows machine into a router for the linux
machine.

> I have no interest in putting a modem on the "final" Linux box. The machine
> is just a box that is operating 24/7 to trigger an all sky video camera to
> capture fireball (meteor) images it detect crossing the sky. I do not need it
> connected to the internet all day. I'm practically on the internet all day on
> the XP machine. Let it catch the time from the internet, and let Linux update
> its clock. If this doesn't work, then I'll try something else.
>
> Note all my linux machines are in my observatory 100' away from the XP. An
> ethernet cable runs to them from the house where the XP machine is located.
> These statements have no particular bearing on the above, but maybe it will
> help you understand some of the topology.

Yes, they do. Now how does your XP machine connect to the outside net?

>
>> a direct connection to the net and to the win machine, and then have it
>> do masquarading for the win machine so it too will have a direct
>> connection tot he net. Then it can easily act as a time standard for
>> the win machine, and you will know it is accurate to ms. And both will
>> have connections to the net.
>>
>>
>>
>>
> The results of tdpdump while requesting time via redhat-config-date are:
These just show that the Win machine never answers, making me suspect
strongly that there is no ntp server running on the Win machine.

Relevant Pages

  • Re: Setting Up NTP for Time Sync
    ... > not support ntp as a server. ... > connection between your linux machine and your windows machine. ... I do not need it connected to the internet all day. ...
    (comp.os.linux.networking)
  • Some network setup issues (Linux to internet via Windows)
    ... to the internet, and I've enabled sharing on that connection. ... the gateway to the ethernet IP of the windows machine. ... The other thing I would like to do is make the Linux machine ...
    (comp.os.linux.networking)
  • Re: Setting Up NTP for Time Sync
    ... >> OP probably does not have any man pages for ntp on RH9 as the docs were ... If your Linux machine can get onto the net somehow, ... then you must set up your windows machine as an ntp server. ...
    (comp.os.linux.networking)
  • Re: basic question about assigning ip address
    ... - boot the Windows machine only (Linux machine off). ... Is the Internet connection working ...
    (Fedora)
  • Re: Setting Up NTP for Time Sync
    ... > having one Linux machine with ntpd running continuously. ... > The algorithms in NTP act as a long-time PLL ... I now have ntp servers in California. ... I deliberately set the clock off by 15 seconds. ...
    (comp.os.linux.networking)