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The log command indicates that certain information is to be logged. Up to four optional arguments can be specified, the first is the maximum number of tries before giving up and returning a non-zero error code. The smoothing process is implemented with a quadratic spline function with two or three pieces. See Security with chronyc for more information. It limits the slew rate controlled by the correction time ratio see section corrtimeratio and is effective only on systems where chronyd is able to control the rate i. In the fifth form, the final byte is ignored. This directive, which takes no arguments, specifies that client accesses are not to be logged.

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A measurement is good if it passes chgony tests, for example, the round trip time to the source must be acceptable. The broadcast directive is used to declare a broadcast address to which chronyd should send packets in the NTP broadcast mode i.

The add server command allows a new NTP server to be added whilst chronyd is running.

Running chrony and rtc

If a computer can estimate its rate of drift it can keep itself closer to the ttc computers between updates by adjusting its clock every few seconds. The presend option cannot be used in the peer directive. When chronyd is slewing the system clock to correct an offset, the rate at which it is slewing adds to the frequency error of the clock.

The ratelimit directive supports a number of options which can be defined in any order:. An alternative is to enable the local directive to allow synchronisation with some unknown but constant offset.


c h r o n y

The value reported on this line is the difference due to this effect. The dump command is somewhat equivalent to the dumponexit directive in the chrony configuration file. The second form has three parameters: We protect your rights with two steps: You can only use the RTC facilities the rtcfile directive and the -s command-line option to chronyd if the following three conditions apply: However, your computer will keep trying to contact the servers to obtain timestamps, even whilst offline.

For example, maxdelay 0. It is recommended to find at least four good servers e. Mauro Post by Bill Unruh sorry, my mistype. This allows to use the RTC as accurate reference clock inside the guest, specifically if the host time is smoothly following an accurate external reference clock, e. To avoid excessive switching between sources, chronyd may stay synchronised to a source even when it is not currently the best one among the available sources.

Note that the chorny pair is expressed in UTC, not the local time zone. On other systems no extra library is needed. Therefore, it would be bad if chronyd had to work the value out each time it is restarted, because the system clock would not run so accurately whilst the determination is taking place. This means that whenever chronyd is ready to run it will run, interrupting whatever else is running unless it is a higher priority real-time process.


The password can be specified as a string of characters not containing white space with an optional ASCII: On most Unix systems it is not desirable to step the system clock, because many programs rely on time advancing monotonically forwards. The bindacqaddress directive sets cyrony network interface to which will chronyd bind its NTP client sockets. Real-time clocks are supported only on Linux.

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Configuring NTP Using the chrony Suite

Version-Release number of selected component if applicable: Some drivers do not listen for external events and try to produce samples in their own polling interval. This is the estimated residual frequency for the server, in parts per million.

Understanding chron and Its Configuration Understanding chronyd The chrony daemon, chronydrunning in user space, makes adjustments to the system clock which is running in the kernel.

It allows the RTC to drift without correcting it, so after booting up it can take several minutes for it to gradually correct the system clock. If not specified or zero, the value will not be checked. rtf

The stratum indicates how many hops away from a computer with an attached reference clock we are. The kernel is compiled with extended real-time clock support i.