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CHRONY(1)				  User's Manual 				CHRONY(1)

NAME
       chrony - programs for keeping computer clocks accurate

SYNOPSIS
       chronyc [OPTIONS]

       chronyd [OPTIONS]

DESCRIPTION
       chrony  is  a  pair  of programs for keeping computer clocks accurate.  chronyd is a back-
       ground (daemon) program and chronyc is a command-line  interface  to  it.  Time	reference
       sources	for  chronyd can be RFC1305 NTP servers, human (via keyboard and chronyc), or the
       computer's real-time clock at boot time (Linux only). chronyd can determine  the  rate  at
       which  the  computer gains or loses time and compensate for it while no external reference
       is present. Its use of NTP servers can be switched on and off (through chronyc) to support
       computers  with	dial-up/intermittent  access  to  the Internet, and it can also act as an
       RFC1305-compatible NTP server.

USAGE
       chronyc is a command-line interface program which can be used to monitor chronyd's perfor-
       mance and to change various operating parameters whilst it is running.

       chronyd's  main function is to obtain measurements of the true (UTC) time from one of sev-
       eral sources, and correct the system clock accordingly.	It also works  out  the  rate  at
       which  the  system clock gains or loses time and uses this information to keep it accurate
       between measurements from the reference.

       The reference time can be derived from either Network Time Protocol (NTP) servers,  refer-
       ence  clocks,  or  wristwatch-and-keyboard  (via chronyc).  The main source of information
       about the Network Time Protocol is http://www.ntp.org.

       It is designed so that it can work on computers which only  have  intermittent  access  to
       reference  sources, for example computers which use a dial-up account to access the Inter-
       net or laptops.	Of course, it will work well on computers with permanent connections too.

       In addition, on Linux it can monitor the system's real time clock performance, so the sys-
       tem can maintain accurate time even across reboots.

       Typical accuracies available between 2 machines are

       On  an  ethernet  LAN  : 100-200 microseconds, often much better On a V32bis dial-up modem
       connection : 10's of milliseconds (from one session to the next)

       With a good reference clock the accuracy can reach one microsecond.

       chronyd can also operate as an RFC1305-compatible NTP server and peer.

SEE ALSO
       chronyc(1), chrony(1)

       http://chrony.tuxfamily.org/

AUTHOR
       Richard Curnow <rc@rc0.org.uk>

       This man-page was written by Jan Schaumann <jschauma@netmeister.org> as part of "The Miss-
       ing  Man  Pages	Project".   Please see http://www.netmeister.org/misc/m2p2/index.html for
       details.

       The complete chrony documentation is supplied in texinfo format.

chrony @VERSION@			    @MAN_DATE@					CHRONY(1)
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