[ntp:questions] Local clock question with dialup connection

Nigel Henry cave.dnb at tiscali.fr
Thu Apr 19 18:07:49 UTC 2007


On Thursday 19 April 2007 19:11, Danny Mayer wrote:
> Nigel Henry wrote:
> > On Thursday 19 April 2007 05:12, Danny Mayer wrote:
> >> Harlan Stenn wrote:
> >>>>>> In article <200704162309.24517.cave.dnb at tiscali.fr>,
> >>>>>> cave.dnb at tiscali.fr (Nigel Henry) writes:
> >>>
> >>> Nigel> djmons at localhost djmons]$ /usr/sbin/ntpq
> >>> ntpq> pe
> >>> Nigel> localhost.localdomain: timed out, nothing received ***Request
> >>> timed Nigel> out
> >>>
> >>> This looks like ntpd is not running at the time you did this.
> >>
> >> No, you would not get Request timed out, you would get connection
> >> refused. It may be that the server is just dropping your queries.
> >>
> >> Danny
> >
> > FC5 isn't giving me this problem using 4.2.4p0-1.fc6. I do have the 2
> > local clock lines (server, and fudge) uncommented, and when I boot the
> > machine with no Internet connection, then after connecting to the
> > Internet (dialup) , I run ntpq> pe, it shows local as a system peer, and
> > 3 servers from fedora.pool.ntp.org dynamic. It does take ages before one
> > of the servers is set as system peer, but it's working.
> >
> > On FC2 using 4.2.0-7, I am using 3 specific stratum2 servers, rather than
> > a pool. Could it be that because I only have 3 specific servers, that
> > they are being tried once while there is no initial Internet connection
> > on bootup, are failing to be found, and ntpd is not trying them again.  I
> > presume a server pool has many available servers, so if I have a server
> > pool in /etc/ntp.conf, does ntpd just keep on trying to get a response in
> > this case, like it tries the pool, doesn't get a response, tries again,
> > no response, tries again, and so on, by which time I have made the
> > Internet connection, and it's still trying to find a pool server, and now
> > with an active Internet connection it gets a response, and sets up 3
> > available Internet servers?
> >
> > As I'm having problems installing 4.2.4p0 from the tarball on FC2, I
> > think I'll try reinstalling 4.2.0-7, put a server pool in /etc/ntp.conf,
> > and see just for hell of it, if it works.
> >
> > All in a days work.
> >
> > Nigel.
>
> That's not the issue. The question really is what you have in your
> ntp.conf file. If you have restrict statements in the file ntpd may just
> drop queries like you are making and therefore ntpq will just time out.
> It's hard to know without seeing the config file.
>
> If it takes a long time to get a preferred server, you are probably not
> using the iburst option on the server lines. It speeds up
> synchronization considerably.
>
> Danny

I havn't used iburst before, but bear in mind that when I boot up there is no 
Internet connection. As I mentioned above, I've reinstalled 4.2.0-7, and used 
the servers from FC6's /etc/ntp.conf file for 4.2.4p0. /etc/ntp.conf is very 
basic, and I removed "dynamic" from the end of the server lines, as otherwise 
there were problems using the file with 4.2.0-7 on FC2. See below.

# Use public servers from the pool.ntp.org project.
# Please consider joining the pool (http://www.pool.ntp.org/join.html).
server 0.fedora.pool.ntp.org
server 1.fedora.pool.ntp.org
server 2.fedora.pool.ntp.org

# Undisciplined Local Clock. This is a fake driver intended for backup
# and when no outside source of synchronized time is available. 
#server 127.127.1.0 # local clock
#fudge 127.127.1.0 stratum 10

# Drift file.  Put this in a directory which the daemon can write to.
# No symbolic links allowed, either, since the daemon updates the file
# by creating a temporary in the same directory and then rename()'ing
# it to the file.
driftfile /var/lib/ntp/drift

It's getting better, and booting up with no Internet connection, then 
connecting to the Internet, then running ntpq< pe gives me just one available 
server, and that is one using an IP address rather than a hostname, so there 
appears to perhaps be a slight DNS problem.

 ntpq> pe
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
 192.33.214.57   .INIT.          16 u    -   64    0    0.000    0.000 4000.00
ntpq> pe
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
 192.33.214.57   192.33.214.12    2 u   31   64    1  148.565  -1745.9   0.001
ntpq> pe
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
 192.33.214.57   192.33.214.12    2 u   40   64    3  148.565  -1745.9  21.924
ntpq> pe
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
 192.33.214.57   192.33.214.12    2 u   49  128    7  148.565  -1745.9  15.573
ntpq> pe
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
*192.33.214.57   192.33.214.12    2 u  319  512   37  148.565  -1745.9  15.685
ntpq>

Stopping and then starting ntpd, and running ntpq> pe now gives me the 
expected 3 Internet servers from the pool.

ntpq> pe
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
 dedibox.ebzao.i 195.220.94.163   2 u   26   64    1  140.115  -14.301   0.001
 chime6.surfnet. .PPS.            1 u   25   64    1  139.069  -16.197   0.001
 i216-58-31-84.c 199.212.17.22    3 u   23   64    1  258.237    0.795   0.001
ntpq>

It looks like I need to delay ntpd being started at bootup, or at least delay 
the polling of the servers. I see there is a script for this in the 4.2.4p0 
version, but can't see such a workaround on a rpm installed version as the 
4.2.0-7 version is on FC2.

I think ideally what I need is a script that will detect when the Internet 
connection is up, and then start ntpd. I can't see there being any problems 
then.  If you can suggest a suitable script that would be great, otherwise 
I'll ask on some other lists. I've little experience on writing scripts.

Someway or other this is going to be fixed.

Nigel.






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