[ntp:questions] Synchronizing Linux clients with Windows Server 2003 NTP

george_joby kottayamachayen at gmail.com
Mon Jan 22 17:16:46 UTC 2007


Hi

Please see the requested information:

[root at txnaslload03 etc]# ntpq -pn
     remote           refid      st t when poll reach   delay   offset
jitter
==============================================================================
 16.74.32.162    .LOCL.           1 u   98  256  377    0.403  -11.752
 5.775
*127.127.1.0     LOCAL(0)        10 l   38   64  377    0.000    0.000
 0.001
[root at txnaslload03 etc]# ntpq
ntpq> as

ind assID status  conf reach auth condition  last_event cnt
===========================================================
  1 40372  9014   yes   yes  none    reject   reachable  1
  2 40373  9614   yes   yes  none  sys.peer   reachable  1

ntpq> rv 40372
assID=40372 status=9014 reach, conf, 1 event, event_reach,
srcadr=16.74.32.162, srcport=123, dstadr=16.74.35.185, dstport=123,
leap=00, stratum=1, precision=-6, rootdelay=0.000,
rootdispersion=10028.351, refid=LOCL, reach=377, unreach=0, hmode=3,
pmode=4, hpoll=8, ppoll=8, flash=00 ok, keyid=0, ttl=0, offset=-11.752,
delay=0.403, dispersion=23.991, jitter=5.775,
reftime=c95f68b3.04189374  Mon, Jan 22 2007 10:45:39.016,
org=c95f6cfe.e0000000  Mon, Jan 22 2007 11:03:58.875,
rec=c95f6cfe.e50bc7b4  Mon, Jan 22 2007 11:03:58.894,
xmt=c95f6cfe.e4e4ead0  Mon, Jan 22 2007 11:03:58.894,
filtdelay=     0.59    0.58    0.59    0.42    0.42    0.45    0.42
0.40,
filtoffset=  -19.41  -18.48  -18.53  -15.54   -7.28  -14.65   -5.35
-11.75,
filtdisp=     15.63   17.55   19.45   21.39   22.35   23.31   24.28
25.27

Please see the rootdispersion value itz too high. Is it the reason the
client not synchronising with the server?
Also see client "reject" the server .. in ntpq as command ...

I will give some more detail about our requirement. The environment
will be like this. We have 2-3 Linux box then many Non Stop systems and
a primary Windows 2003 server console and a backup console .. The Linux
box will be heavy loaded as all the request will be first coming into
that then to nonstop systems. So customer dont want to put the nonstop
or linux box as the server .. and the option is Windows 2003 server ...
Also we dont want to use any external time .. all these boxes should
sync up and have same time .. But i could see from all the mails and
from google that I cant use Windows SNTP as a server ... We are just
trying to figure out why it is not synching with Linux .. i mean the
real reason and also trying to contact Microsoft to get a confirmation
that it will not work. So our customer can think about some third party
NTP software.

Can some body help me from the above info why client reject the server
... is it coz of the high value in root dispertion or due to some other
issue ??

Thanks in advance ...

David L. Mills wrote:
> George,
>
> Have you noticed your Windows server is visible to your Linux client,
> but the offset shows -180 ms, which is larger than the step interval?
> Ordinarily, NTP steps the time after 900 s, but you show over this and
> the step has not occured. You need to look at the association billboard
> (rv <assocID>) and see the  flashcodes (flash=xxx). I suspect the
> Windows server packet has the usual casual disregard for the spec and
> says something illegal.
>
> Send the billboard in a message. There might be a simple workaround.
>
> I echo other commentators that, even if a workaround can be found, you
> will get terrible time and in particular are potential victim of
> unstable operation. The NTP clock discipline algorithm expects a stable
> clock source, either SNTP and a radio, or full NTP with clock discipline
> algorithm. It's much safer to use SNTP, rather than NTP, in you clients.
>
> Send the billboard se we can all have a good time bashing Windows.
>
> Dave
>
> george_joby wrote:
> > Our requirement is all our linux and nonstop systems synchronise to the
> > Windows 2003 server. We do not want Windows to syncronise with an
> > external clock and it should just synchronise with its internal clock.
> >
> > So what I am doing is just configuring with a client (Redhat Linux) and
> > server (windows 2003) to check whether Linux gets synchronise with
> > Windows server and that is not happening. Our customer need this setup.
> >
> > If i see the ntpq -pn in Linux it will show the correct offset and also
> > ntpdate works fine. But Linux not ready to synchronise with Server.
> >
> > [root at txnaslload03 ~]# ntpq -pn
> >      remote           refid      st t when poll reach   delay   offset
> > jitter
> > ==============================================================================
> >  16.74.32.162    .LOCL.           1 u  967 1024  377    0.355  -180.34
> >  5.407
> >
> > Thanks
> > George
> >
> > Ry wrote:
> >
> >>Richard B. Gilbert wrote:
> >>
> >>
> >>>Isn't port 123 UDP inbound required as well?
> >>
> >>Not on a stateful firewall, which are the most common type these days.
> >>In most firewall configuration tools, "allow UDP port 123 outbound"
> >>means that when a outbound packet is sent, the firewall will remember
> >>seeing it (that's the *stateful* part) allow a return UDP packet(s)
> >>from the destination IP and source port for a few seconds before
> >>closing things off again.
> >>
> >>This assumes all he is doing is configuring his NTP to act as a client
> >>to an internet-based NTP server. If he is going to be using
> >>symmetric/active or another mode, that's going to require allowing UDP
> >>port 123 inbound. But it doesn't seem to me that he would need to do
> >>anything like that.
> > 
> >




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