Re: Setting Up NTP for Time Sync

From: W. Watson (wolf_tracks_at_invalid.inv)
Date: 01/09/05


Date: Sun, 09 Jan 2005 14:41:03 GMT

Marius wrote:

> W. Watson <wolf_tracks@invalid.inv> wrote:
>
>>Here's my total focus right now.
>>Why can't I synch off of the NTP machine from linux?
>
>
> But you can... See your text below.
>
>
>>I can specify a location for the ntp server.
>>One of them [...] is 192.168.0.3, which is my XP machine.
>>Another, provided by RH, is clock1.redhat.com.
>
>
> OK. So you specified two possible time sources for testing. Good.
>
>
>>I deliberately set the clock off by 15 seconds.
>>If I specify 192.xxxx, I do not get any correction.
>
>
> So you observe, that you don't get time corrections from your XP.
> Non conclusive yet.
>
>
>>I then dial into my ISP from the Linux machine [...]
>>I now use the tool again, but specify the clock1 entry.
>>It resets the clock to the correct time.
>
>
> So here you observe, that using another time source you _do_ get
> time corrected on your Linux box. Good.
> Conclusion 1: NTP synch _works_ for your Linux box _with_ _a_
> _working_ _time_ _server_.
>
>
>>I again set the clock off by 10 seconds or so, and do the
>>same with 192.xxxxx. Nothing.
>
>
> Here you repeat your first test, but this time with an
> added knowledge of NTP sync working with another source.
> Non conclusive yet, but your following assertions:
>
>
>>Either XP isn't set up to deal with NTP or the request
>>never makes it to XP.
>
>
> are valid.
>
>
>>The question remains, why doesn't this work?
>
>
> 1) check networking:
> - can you ping your XP box from your Linux box?
Yes, no trouble at all
> - other way round as well?
Yes, easily done.

> - using names as well as IP numbers?
I just tried ping \\astropc2004 (the Linux box). couldn't find it, but that may not
be an acceptable command. Maybe only 192.168.0.1.
The net view (cmd line op) command shows both computers with their \\ names.
> - can you transfer some data between both boxes?
> (Samba, www, etc.?)
I can connect to the internet with either machine and download. I haven't quite
figured out how to use Samba yet. If I boot up on the alternate OS, Win2k, on the
Linux box, I can easily transfer data between W2k and XP.
>
> Only after you positively verified each step from '1'
> do:
>
> 2) Is NTP _server_ installed and configured on XP?
> (how to check this one is up to you. I don't do windows).
Good question. I was just beginning to look into this at the request of another
posterer, and found via Help a command called net time.
(
Net timeSynchronizes the computer's clock with that of another computer or domain.
Used without parameters, net time displays the time for another computer or domain.
...
/querysntp
Displays the name of the Network Time Protocol (NTP) server currently configured for
the local computer or the one specified in ComputerName.
)

Executing net time /querysntp produces the result:
The current sntp value is time.windows.com, 0x1

Another bit of help from XP:
Your personal or network firewall prevents clock synchronization. Most corporate and
organizational firewalls will block time synchronization, as do some personal
firewalls. Home users should read the firewall documentation for information about
unblocking network time protocol (NTP). You should be able to synchronize your clock
if you switch to Windows Firewall.

I updated with SP2 recently, which has the new MS firewall. I had to remove McAfee in
the process, so use MS at the moment. A few days ago, I just disabled it for about 10
minutes, but got the same results as above. No time set from XP. Otherwise, I really
do not know how (yet) to just open a hole to NTP on XP when the firewall is up.
>
> HTH.
> Marius
>
Yes, definitely one of the better jokes around. BTW, the need for time is driven by
astronomy. See my URL below and go to the reference near the bottom of the page to
"meteor".

I think I'm going to trim the branches of this thread later today but re-opening it
on the topic of current interest.

> PS: Reading this veeery lengthy thread reminded me of an
> old joke. Disclaimer: absolutely no offence meant.
>
> Holmes and Watson went for a night out camping.
> They went to sleep in their tent.
> In the middle of the night Holmes silently wakes up Watson
> and asks him to look up and describe what he sees.
> Watson looks up and begins to describe how beautiful the
> starlit night sky is, and how many stars there are and how
> romantic and scientific the wiew is...
> Holmes impatiently interrupts him saying "you fool! don't you
> _see_ that someone stole our tent?" :-)
>

-- 
              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>


Relevant Pages

  • Re: Reference clock driver for /dev/rtc
    ... The Linux kernel discipline code adapted from my Alpha code of the 1990s does not account for the frequency gain at other than a 100-Hz clock. ... This makes NTP unstable at the larger poll intervals when the kernel discipline is not in use. ... I have no trouble with that as long as whatever modifications are required in NTP to make the RTC driver work remain proprietary to Linux and never leak to other systems. ...
    (comp.protocols.time.ntp)
  • Re: Clock drift problems
    ... > only as a client of a couple of web-based applications and as a file ... I know almost nothing about Linux, ... the real-time clock has gotten 7 hours slow. ... NTP is NOT capable of coping with such a gross correction over time; ...
    (comp.os.linux.misc)
  • Re: Setting Up NTP for Time Sync
    ... the XP boot and the ntp restart didn't change a thing. ... It changes the rate of the clock so that it will ... I want my linux box, astropc, to get its time from ...
    (comp.os.linux.networking)
  • Problem with Linux Machines Request for Time from an XP Machine
    ... The Linux modem is only there to conduct tests regarding the problem I present ... I believe this is time kept by NTP (see comment just above ... I deliberately set the clock off by 15 seconds in Linux. ... Your personal or network firewall prevents clock synchronization. ...
    (comp.os.linux.networking)
  • Re: sync clock on PC with time on internet
    ... > looked at ntp but ... > cannot figure it out (ntpd starts fine but clock is unaffected). ... Also make sure port 123 is not blocked at your firewall if you are using a ...
    (comp.os.linux.misc)