Update documentation
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Miroslav Lichvar
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6 changed files with 63 additions and 128 deletions
12
INSTALL
12
INSTALL
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@ -81,12 +81,14 @@ Now that the software is successfully installed, the next step is to
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set up a configuration file. The contents of this depend on the
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network environment in which the computer operates. Typical scenarios
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are described in the manual. The simplest case is for a computer with
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a permanent Internet connection - suppose you want to use the NTP
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server ntp1.foobar.com as your time reference. You would create an
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/etc/chrony.conf file containing
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a permanent Internet connection - suppose you want to use public NTP
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servers from the pool.ntp.org project as your time reference. You would
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create an /etc/chrony.conf file containing
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server ntp1.foobar.com
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driftfile /etc/chrony.drift
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server 0.pool.ntp.org
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server 1.pool.ntp.org
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server 2.pool.ntp.org
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driftfile /var/lib/chrony/drift
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and then run /usr/local/sbin/chronyd.
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19
README
19
README
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@ -21,12 +21,12 @@ between measurements from the reference.
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The reference time can be derived from Network Time Protocol (NTP)
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servers, reference clocks, or wristwatch-and-keyboard (via chronyc).
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The main source of information about the Network Time Protocol is
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http://www.eecis.udel.edu/~ntp.
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http://www.ntp.org.
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It is designed so that it can work on computers which only have
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intermittent access to reference sources, for example computers which
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use a dial-up account to access the Internet. Of course, it will work
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on computers with permanent connections too.
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use a dial-up account to access the Internet or laptops. Of course, it
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will work well on computers with permanent connections too.
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In addition, on Linux it can monitor the system's real time clock
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performance, so the system can maintain accurate time even across
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@ -48,10 +48,7 @@ What will chrony run on?
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Chrony can be successfully built and run on
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1. Linux v1.2.13, v2.0.x, 2.1.x (partially), 2.2.x, 2.3.x, 2.4.x, 2.6.x.
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Real time clock support is limited to 2.0.32 onwards and to 2.2, 2.3,
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2.4 and 2.6 series only. i386, x86_64, PowerPC are known to be
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supported.
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1. Linux 2.2.x, 2.3.x, 2.4.x, 2.6.x, 3.x
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2. Solaris 2.5/2.5.1/2.6/2.7/2.8 (various platforms)
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@ -88,12 +85,6 @@ through the URL
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http://chrony.tuxfamily.org/
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What can chrony not do?
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=======================
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Compared to the `reference' RFC1305 implementation xntpd, chronyd does
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not support broadcast modes.
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Where are new versions announced?
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=================================
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@ -252,5 +243,3 @@ Doug Woodward <dougw@whistler.com>
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Many other people have contributed bug reports and suggestions. I'm
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sorry I can't identify all of you individually.
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vim:tw=72
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12
chrony.1
12
chrony.1
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@ -32,16 +32,16 @@ between measurements from the reference.
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The reference time can be derived from either Network Time Protocol
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(NTP) servers, reference clocks, or wristwatch-and-keyboard (via \fIchronyc\fR).
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The main source of information about the Network Time Protocol is
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\fIhttp://www.eecis.udel.edu/~ntp\fR.
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\fIhttp://www.ntp.org\fR.
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It is designed so that it can work on computers which only have
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intermittent access to reference sources, for example computers which
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use a dial-up account to access the Internet. Of course, it will work
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on computers with permanent connections too.
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use a dial-up account to access the Internet or laptops. Of course, it
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will work well on computers with permanent connections too.
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In addition, for Linux 2.0.x (for x >= 32) or 2.2 onwards, chronyd can monitor
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the system's real time clock performance, so the system can maintain accurate
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time even across reboots.
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In addition, on Linux it can monitor the system's real time clock
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performance, so the system can maintain accurate time even across
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reboots.
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Typical accuracies available between 2 machines are
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@ -31,7 +31,7 @@ useful configuration file would look something like
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server g.h.i
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keyfile @SYSCONFDIR@/chrony.keys
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commandkey 1
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driftfile @SYSCONFDIR@/chrony.drift
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driftfile @CHRONYVARDIR@/drift
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.SH "SEE ALSO"
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143
chrony.texi.in
143
chrony.texi.in
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@ -570,6 +570,9 @@ customers.
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stratum 1 and stratum 2 servers. You should find one or more servers
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that are near to you --- check that their access policy allows you to
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use their facilities.
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@item Use public servers from
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@uref{http://www.pool.ntp.org/, the pool.ntp.org project}.
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@end itemize
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Assuming that you have found some servers, you need to set up a
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@ -595,7 +598,7 @@ server d.e.f
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server g.h.i
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keyfile @SYSCONFDIR@/chrony.keys
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commandkey 1
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driftfile @SYSCONFDIR@/chrony.drift
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driftfile @CHRONYVARDIR@/drift
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@end example
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@c }}}
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@c {{{ S:Infrequent connection
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@ -629,38 +632,24 @@ server d.e.f
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server g.h.i
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@end example
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However, the following issues need to be addressed:
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@enumerate 1
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@item
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Your computer probably doesn't have DNS access whilst offline to turn
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the machine names into IP addresses.
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@item
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Your computer will keep trying to contact the servers to obtain
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However, your computer will keep trying to contact the servers to obtain
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timestamps, even whilst offline. If you operate a dial-on-demand
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system, things are even worse, because the link to the internet will
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keep getting established.
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@end enumerate
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For this reason, it would be better to specify this part of your
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configuration file in the following way:
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@example
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server 1.2.3.4 offline
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server 5.6.7.8 offline
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server 9.10.11.12 offline
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server a.b.c offline
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server d.e.f offline
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server g.h.i offline
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@end example
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Because numeric IP addresses have been used, the first problem is
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overcome. The @code{offline} keyword indicates that the servers start
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The @code{offline} keyword indicates that the servers start
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in an offline state, and that they should not be contacted until @code{chronyd}
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receives notification that the link to the internet is present.
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An alternative is to use the names of the NTP servers, and put entries for them
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into your @file{/etc/hosts} file. This will be OK as long as @samp{files}
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comes before @samp{dns} in the @samp{hosts} line of the
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@file{/etc/nsswitch.conf} file.
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In order to notify @code{chronyd} of the presence of the link, you will need to
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be able to log in to it with the program chronyc. To do this, @code{chronyd}
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needs to be configured with an administrator password. To set up an
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@ -668,7 +657,7 @@ administrator password, you can create a file @file{@SYSCONFDIR@/chrony.keys}
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containing a single line
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@example
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1 xyzzy
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1 ALongAndRandomPassword
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@end example
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and add the following line to @file{@SYSCONFDIR@/chrony.conf} (the order of the
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@ -681,12 +670,12 @@ commandkey 1
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The smallest useful configuration file would look something like
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@example
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server 1.2.3.4 offline
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server 5.6.7.8 offline
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server 9.10.11.12 offline
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server a.b.c offline
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server d.e.f offline
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server g.h.i offline
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keyfile @SYSCONFDIR@/chrony.keys
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commandkey 1
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driftfile @SYSCONFDIR@/chrony.drift
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driftfile @CHRONYVARDIR@/drift
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@end example
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The next section describes how to tell @code{chronyd} when the internet link
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@ -750,7 +739,7 @@ be (assuming the clients are in the 192.168.165.x subnet and that the
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master's address is 192.168.169.170)
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@example
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driftfile @SYSCONFDIR@/chrony.drift
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driftfile @CHRONYVARDIR@/drift
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commandkey 25
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keyfile @SYSCONFDIR@/chrony.keys
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initstepslew 10 client1 client3 client6
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@ -764,7 +753,7 @@ the configuration file might be
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@example
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server master
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driftfile @SYSCONFDIR@/chrony.drift
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driftfile @CHRONYVARDIR@/drift
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logdir /var/log/chrony
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log measurements statistics tracking
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keyfile @SYSCONFDIR@/chrony.keys
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@ -900,34 +889,24 @@ To illustrate how a dial-up home computer might be configured, example
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configuration files are shown in this section.
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For the @file{@SYSCONFDIR@/chrony.conf} file, the following can be used as an
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example. @emph{NOTE : The @code{server} directives are only applicable
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to customers of Demon Internet; users of other ISPs will need to use
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their own ISP's NTP servers or public NTP servers.}
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example.
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@example
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server 158.152.1.65 minpoll 5 maxpoll 10 maxdelay 0.4 offline
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server 158.152.1.76 minpoll 5 maxpoll 10 maxdelay 0.4 offline
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server 194.159.253.2 minpoll 5 maxpoll 10 maxdelay 0.4 offline
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server 0.pool.ntp.org minpoll 5 maxpoll 10 maxdelay 0.4 offline
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server 1.pool.ntp.org minpoll 5 maxpoll 10 maxdelay 0.4 offline
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server 2.pool.ntp.org minpoll 5 maxpoll 10 maxdelay 0.4 offline
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logdir /var/log/chrony
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log statistics measurements tracking
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driftfile @SYSCONFDIR@/chrony.drift
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driftfile @CHRONYVARDIR@/drift
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keyfile @SYSCONFDIR@/chrony.keys
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commandkey 25
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maxupdateskew 100.0
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dumponexit
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dumpdir /var/log/chrony
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rtcfile @SYSCONFDIR@/chrony.rtc
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dumpdir @CHRONYVARDIR@
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rtcfile @CHRONYVARDIR@/rtc
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@end example
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With Freeserve as the ISP, the following server lines can be used:
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@example
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server 194.152.64.68 minpoll 5 maxpoll 10 maxdelay 0.4 offline
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server 194.152.64.35 minpoll 5 maxpoll 10 maxdelay 0.4 offline
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server 194.152.64.34 minpoll 5 maxpoll 10 maxdelay 0.4 offline
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@end example
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@code{pppd} is used for connecting to my ISP. This runs two scripts
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@code{pppd} is used for connecting to the internet. This runs two scripts
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@file{/etc/ppp/ip-up} and @file{/etc/ppp/ip-down} when the link goes
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online and offline respectively.
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@ -940,17 +919,9 @@ The relevant part of the @file{/etc/ppp/ip-up} file is
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and the relevant part of the @file{/etc/ppp/ip-down} script is
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@example
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@BINDIR@/chronyc -a <<EOF
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offline
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dump
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writertc
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EOF
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@BINDIR@/chronyc -a -m offline dump writertc
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@end example
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(Because they have to contain the administrator password, it would be
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desirable to make the files readable only by root on a multiuser
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machine).
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To start @code{chronyd} during the boot sequence, the following
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is in @file{/etc/rc.d/rc.local} (this is a Slackware system)
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@ -962,34 +933,13 @@ fi
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@end example
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The placement of this command may be important on some systems. In
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particular, @code{chronyd} may need to be started several seconds (about
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10 as a minimum) before any software that depends on the system clock
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not jumping or moving backwards, depending on the directives in
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@code{chronyd's} configuration file.
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particular, @code{chronyd} may need to be started before any software
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that depends on the system clock not jumping or moving backwards,
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depending on the directives in @code{chronyd's} configuration file.
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For the system shutdown, @code{chronyd} should receive a SIGTERM several
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seconds before the final SIGKILL; the SIGTERM causes the measurement
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histories and RTC information to be saved out. There should be no need
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to add anything to the shutdown sequence, unless (as my system had)
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there is no pause between the SIGTERM and SIGKILL being delivered to the
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remaining processes. So if you find something like
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@example
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killall5 -15
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killall5 -9
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@end example
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in your @code{/etc/rc.d/rc.0} script, you will need to insert a sleep, e.g.
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@example
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killall5 -15
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sleep 5
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killall5 -9
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@end example
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Otherwise, @code{chronyd} will not always save information on shutdown,
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which could be a problem if you don't use @code{dump} and
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@code{writertc} when you go offline.
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histories and RTC information to be saved out.
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@c }}}
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@c {{{ S:Other config options
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@node Configuration options overview
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@ -1007,11 +957,11 @@ determination is taking place.
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To avoid this problem, @code{chronyd} allows the gain or loss rate to be
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stored in a file, which can be read back in when the program is
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restarted. This file is called the drift file, and might typically be
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stored in @file{@SYSCONFDIR@/chrony.drift}. By specifying an option like the
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stored in @file{@CHRONYVARDIR@/drift}. By specifying an option like the
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following
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@example
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driftfile @SYSCONFDIR@/chrony.drift
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driftfile @CHRONYVARDIR@/drift
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@end example
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in the configuration file (@file{@SYSCONFDIR@/chrony.conf}), the drift file
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@ -1117,7 +1067,7 @@ IPv6 sockets will be created.
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On systems that support an @file{/etc/rc.local} file for starting
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programs at boot time, @code{chronyd} can be started from there.
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On systems with a System V style initialisation (e.g. Solaris), a
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On systems with a System V style initialisation, a
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suitable start/stop script might be as shown below. This might be
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placed in the file @file{/etc/rc2.d/S83chrony}.
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@ -1422,7 +1372,7 @@ chronyd is running.
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You can have more than 1 @code{broadcast} directive if you have more than 1
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network interface onto which you wish to send NTP broadcast packets.
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Chronyd itself cannot currently act as a broadcast client; it must always be
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@code{chronyd} itself cannot currently act as a broadcast client; it must always be
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configured as a point-to-point client by defining specific NTP servers and
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peers. This broadcast server feature is intended for providing a time source
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to other NTP software (e.g. various MS Windows clients).
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@ -1608,7 +1558,7 @@ which the true rate actually lies.
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An example of the driftfile command is
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@example
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driftfile @SYSCONFDIR@/chrony.drift
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driftfile @CHRONYVARDIR@/drift
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@end example
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@c }}}
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@c {{{ dumpdir
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@ -1634,12 +1584,12 @@ directory where the measurement histories are saved.
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An example of the command is
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@example
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dumpdir /var/log/chrony
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dumpdir @CHRONYVARDIR@
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@end example
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A source whose reference id (the IP address for IPv4 sources) is
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1.2.3.4 would have its measurement history saved in the file
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@file{/var/log/chrony/1.2.3.4.dat}.
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@file{/var/lib/chrony/1.2.3.4.dat}.
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@c }}}
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@c {{{ dumponexit
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@node dumponexit directive
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@ -2670,7 +2620,7 @@ of the system's real-time clock (RTC).
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The syntax is illustrated in the following example
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@example
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rtcfile @SYSCONFDIR@/chrony.rtc
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rtcfile @CHRONYVARDIR@/rtc
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@end example
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@code{chronyd} saves information in this file when it exits and when the
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@ -2741,12 +2691,12 @@ This mode is supported only on Linux.
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This directive uses the Linux sched_setscheduler() system call to
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instruct the kernel to use the SCHED_FIFO first-in, first-out
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real-time scheduling policy for Chronyd with the specified priority.
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This means that whenever Chronyd is ready to run it will run,
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real-time scheduling policy for @code{chronyd} with the specified priority.
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This means that whenever @code{chronyd} is ready to run it will run,
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interrupting whatever else is running unless it is a higher priority
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real-time process. This should not impact performance as Chronyd's
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real-time process. This should not impact performance as @code{chronyd's}
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resource requirements are modest, but it should result in lower and
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more consistent latency since Chronyd will not need to wait for the
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more consistent latency since @code{chronyd} will not need to wait for the
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scheduler to get around to running it. You should not use this unless
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you really need it. The sched_setscheduler man page has more details.
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@c }}}
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@ -2776,10 +2726,10 @@ ignore stratum when selecting the source.
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The @code{lock_all} directive will lock chronyd into RAM so that it
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will never be paged out. This mode is only supported on Linux. This
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directive uses the Linux mlockall() system call to prevent Chronyd
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directive uses the Linux mlockall() system call to prevent @code{chronyd}
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from ever being swapped out. This should result in lower and more
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consistent latency. It should not have significant impact on
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performance as Chronyd's memory usage is modest. The mlockall man
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performance as @code{chronyd's} memory usage is modest. The mlockall man
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page has more details.
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@c }}}
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@c {{{ server
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@ -3472,12 +3422,7 @@ periodically purged. An example of how to do this is shown below.
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@example
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% mv /var/log/chrony/measurements.log /var/log/chrony/measurements1.log
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% chronyc
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chronyc> password aardvark
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200 OK
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chronyc> cyclelogs
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200 OK
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chronyc> exit
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% chronyc -a cyclelogs
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% ls -l /var/log/chrony
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-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
|
||||
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|||
|
|
@ -125,8 +125,7 @@ from \fIhttp://go.to/chrony\fR
|
|||
.BR chrony(1),
|
||||
.BR chronyc(1),
|
||||
.BR chrony.conf(5),
|
||||
.BR clock(8),
|
||||
.BR xntpd(8),
|
||||
.BR hwclock(8),
|
||||
.BR ntpd(8)
|
||||
|
||||
.SH AUTHOR
|
||||
|
|
|
|||
Loading…
Reference in a new issue