stratum 1 and stratum 2 servers. You should find one or more servers
that are near to you --- check that their access policy allows you to
use their facilities.
+
+@item Use public servers from
+@uref{http://www.pool.ntp.org/, the pool.ntp.org project}.
@end itemize
Assuming that you have found some servers, you need to set up a
server g.h.i
keyfile @SYSCONFDIR@/chrony.keys
commandkey 1
-driftfile @SYSCONFDIR@/chrony.drift
+driftfile @CHRONYVARDIR@/drift
@end example
@c }}}
@c {{{ S:Infrequent connection
server g.h.i
@end example
-However, the following issues need to be addressed:
-
-@enumerate 1
-@item
-Your computer probably doesn't have DNS access whilst offline to turn
-the machine names into IP addresses.
-@item
-Your computer will keep trying to contact the servers to obtain
+However, your computer will keep trying to contact the servers to obtain
timestamps, even whilst offline. If you operate a dial-on-demand
system, things are even worse, because the link to the internet will
keep getting established.
-@end enumerate
For this reason, it would be better to specify this part of your
configuration file in the following way:
@example
-server 1.2.3.4 offline
-server 5.6.7.8 offline
-server 9.10.11.12 offline
+server a.b.c offline
+server d.e.f offline
+server g.h.i offline
@end example
-Because numeric IP addresses have been used, the first problem is
-overcome. The @code{offline} keyword indicates that the servers start
+The @code{offline} keyword indicates that the servers start
in an offline state, and that they should not be contacted until @code{chronyd}
receives notification that the link to the internet is present.
-An alternative is to use the names of the NTP servers, and put entries for them
-into your @file{/etc/hosts} file. This will be OK as long as @samp{files}
-comes before @samp{dns} in the @samp{hosts} line of the
-@file{/etc/nsswitch.conf} file.
-
In order to notify @code{chronyd} of the presence of the link, you will need to
be able to log in to it with the program chronyc. To do this, @code{chronyd}
needs to be configured with an administrator password. To set up an
containing a single line
@example
-1 xyzzy
+1 ALongAndRandomPassword
@end example
and add the following line to @file{@SYSCONFDIR@/chrony.conf} (the order of the
The smallest useful configuration file would look something like
@example
-server 1.2.3.4 offline
-server 5.6.7.8 offline
-server 9.10.11.12 offline
+server a.b.c offline
+server d.e.f offline
+server g.h.i offline
keyfile @SYSCONFDIR@/chrony.keys
commandkey 1
-driftfile @SYSCONFDIR@/chrony.drift
+driftfile @CHRONYVARDIR@/drift
@end example
The next section describes how to tell @code{chronyd} when the internet link
master's address is 192.168.169.170)
@example
-driftfile @SYSCONFDIR@/chrony.drift
+driftfile @CHRONYVARDIR@/drift
commandkey 25
keyfile @SYSCONFDIR@/chrony.keys
initstepslew 10 client1 client3 client6
@example
server master
-driftfile @SYSCONFDIR@/chrony.drift
+driftfile @CHRONYVARDIR@/drift
logdir /var/log/chrony
log measurements statistics tracking
keyfile @SYSCONFDIR@/chrony.keys
configuration files are shown in this section.
For the @file{@SYSCONFDIR@/chrony.conf} file, the following can be used as an
-example. @emph{NOTE : The @code{server} directives are only applicable
-to customers of Demon Internet; users of other ISPs will need to use
-their own ISP's NTP servers or public NTP servers.}
+example.
@example
-server 158.152.1.65 minpoll 5 maxpoll 10 maxdelay 0.4 offline
-server 158.152.1.76 minpoll 5 maxpoll 10 maxdelay 0.4 offline
-server 194.159.253.2 minpoll 5 maxpoll 10 maxdelay 0.4 offline
+server 0.pool.ntp.org minpoll 5 maxpoll 10 maxdelay 0.4 offline
+server 1.pool.ntp.org minpoll 5 maxpoll 10 maxdelay 0.4 offline
+server 2.pool.ntp.org minpoll 5 maxpoll 10 maxdelay 0.4 offline
logdir /var/log/chrony
log statistics measurements tracking
-driftfile @SYSCONFDIR@/chrony.drift
+driftfile @CHRONYVARDIR@/drift
keyfile @SYSCONFDIR@/chrony.keys
commandkey 25
maxupdateskew 100.0
dumponexit
-dumpdir /var/log/chrony
-rtcfile @SYSCONFDIR@/chrony.rtc
-@end example
-
-With Freeserve as the ISP, the following server lines can be used:
-
-@example
-server 194.152.64.68 minpoll 5 maxpoll 10 maxdelay 0.4 offline
-server 194.152.64.35 minpoll 5 maxpoll 10 maxdelay 0.4 offline
-server 194.152.64.34 minpoll 5 maxpoll 10 maxdelay 0.4 offline
+dumpdir @CHRONYVARDIR@
+rtcfile @CHRONYVARDIR@/rtc
@end example
-@code{pppd} is used for connecting to my ISP. This runs two scripts
+@code{pppd} is used for connecting to the internet. This runs two scripts
@file{/etc/ppp/ip-up} and @file{/etc/ppp/ip-down} when the link goes
online and offline respectively.
and the relevant part of the @file{/etc/ppp/ip-down} script is
@example
-@BINDIR@/chronyc -a <<EOF
-offline
-dump
-writertc
-EOF
+@BINDIR@/chronyc -a -m offline dump writertc
@end example
-(Because they have to contain the administrator password, it would be
-desirable to make the files readable only by root on a multiuser
-machine).
-
To start @code{chronyd} during the boot sequence, the following
is in @file{/etc/rc.d/rc.local} (this is a Slackware system)
@end example
The placement of this command may be important on some systems. In
-particular, @code{chronyd} may need to be started several seconds (about
-10 as a minimum) before any software that depends on the system clock
-not jumping or moving backwards, depending on the directives in
-@code{chronyd's} configuration file.
+particular, @code{chronyd} may need to be started before any software
+that depends on the system clock not jumping or moving backwards,
+depending on the directives in @code{chronyd's} configuration file.
For the system shutdown, @code{chronyd} should receive a SIGTERM several
seconds before the final SIGKILL; the SIGTERM causes the measurement
-histories and RTC information to be saved out. There should be no need
-to add anything to the shutdown sequence, unless (as my system had)
-there is no pause between the SIGTERM and SIGKILL being delivered to the
-remaining processes. So if you find something like
-
-@example
-killall5 -15
-killall5 -9
-@end example
-
-in your @code{/etc/rc.d/rc.0} script, you will need to insert a sleep, e.g.
-
-@example
-killall5 -15
-sleep 5
-killall5 -9
-@end example
-
-Otherwise, @code{chronyd} will not always save information on shutdown,
-which could be a problem if you don't use @code{dump} and
-@code{writertc} when you go offline.
+histories and RTC information to be saved out.
@c }}}
@c {{{ S:Other config options
@node Configuration options overview
To avoid this problem, @code{chronyd} allows the gain or loss rate to be
stored in a file, which can be read back in when the program is
restarted. This file is called the drift file, and might typically be
-stored in @file{@SYSCONFDIR@/chrony.drift}. By specifying an option like the
+stored in @file{@CHRONYVARDIR@/drift}. By specifying an option like the
following
@example
-driftfile @SYSCONFDIR@/chrony.drift
+driftfile @CHRONYVARDIR@/drift
@end example
in the configuration file (@file{@SYSCONFDIR@/chrony.conf}), the drift file
On systems that support an @file{/etc/rc.local} file for starting
programs at boot time, @code{chronyd} can be started from there.
-On systems with a System V style initialisation (e.g. Solaris), a
+On systems with a System V style initialisation, a
suitable start/stop script might be as shown below. This might be
placed in the file @file{/etc/rc2.d/S83chrony}.
You can have more than 1 @code{broadcast} directive if you have more than 1
network interface onto which you wish to send NTP broadcast packets.
-Chronyd itself cannot currently act as a broadcast client; it must always be
+@code{chronyd} itself cannot currently act as a broadcast client; it must always be
configured as a point-to-point client by defining specific NTP servers and
peers. This broadcast server feature is intended for providing a time source
to other NTP software (e.g. various MS Windows clients).
An example of the driftfile command is
@example
-driftfile @SYSCONFDIR@/chrony.drift
+driftfile @CHRONYVARDIR@/drift
@end example
@c }}}
@c {{{ dumpdir
An example of the command is
@example
-dumpdir /var/log/chrony
+dumpdir @CHRONYVARDIR@
@end example
A source whose reference id (the IP address for IPv4 sources) is
1.2.3.4 would have its measurement history saved in the file
-@file{/var/log/chrony/1.2.3.4.dat}.
+@file{/var/lib/chrony/1.2.3.4.dat}.
@c }}}
@c {{{ dumponexit
@node dumponexit directive
The syntax is illustrated in the following example
@example
-rtcfile @SYSCONFDIR@/chrony.rtc
+rtcfile @CHRONYVARDIR@/rtc
@end example
@code{chronyd} saves information in this file when it exits and when the
This directive uses the Linux sched_setscheduler() system call to
instruct the kernel to use the SCHED_FIFO first-in, first-out
-real-time scheduling policy for Chronyd with the specified priority.
-This means that whenever Chronyd is ready to run it will run,
+real-time scheduling policy for @code{chronyd} with the specified priority.
+This means that whenever @code{chronyd} is ready to run it will run,
interrupting whatever else is running unless it is a higher priority
-real-time process. This should not impact performance as Chronyd's
+real-time process. This should not impact performance as @code{chronyd's}
resource requirements are modest, but it should result in lower and
-more consistent latency since Chronyd will not need to wait for the
+more consistent latency since @code{chronyd} will not need to wait for the
scheduler to get around to running it. You should not use this unless
you really need it. The sched_setscheduler man page has more details.
@c }}}
The @code{lock_all} directive will lock chronyd into RAM so that it
will never be paged out. This mode is only supported on Linux. This
-directive uses the Linux mlockall() system call to prevent Chronyd
+directive uses the Linux mlockall() system call to prevent @code{chronyd}
from ever being swapped out. This should result in lower and more
consistent latency. It should not have significant impact on
-performance as Chronyd's memory usage is modest. The mlockall man
+performance as @code{chronyd's} memory usage is modest. The mlockall man
page has more details.
@c }}}
@c {{{ server
@example
% mv /var/log/chrony/measurements.log /var/log/chrony/measurements1.log
-% chronyc
-chronyc> password aardvark
-200 OK
-chronyc> cyclelogs
-200 OK
-chronyc> exit
+% chronyc -a cyclelogs
% ls -l /var/log/chrony
-rw-r--r-- 1 root root 0 Jun 8 18:17 measurements.log
-rw-r--r-- 1 root root 12345 Jun 8 18:17 measurements1.log
projects / thirdparty / chrony.git / commitdiff
