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@@ -0,0 +1,239 @@ +This is the README for chrony. + +What is chrony? +=============== + +chrony is a versatile implementation of the Network Time Protocol (NTP). +It can synchronise the system clock with NTP servers, reference clocks +(e.g. GPS receiver), and manual input using wristwatch and keyboard. +It can also operate as an NTPv4 (RFC 5905) server and peer to provide +a time service to other computers in the network. + +It is designed to perform well in a wide range of conditions, including +intermittent network connections, heavily congested networks, changing +temperatures (ordinary computer clocks are sensitive to temperature), +and systems that do not run continuosly, or run on a virtual machine. + +Typical accuracy between two machines synchronised over the Internet is +within a few milliseconds; on a LAN, accuracy is typically in tens of +microseconds. With hardware timestamping, or a hardware reference clock, +sub-microsecond accuracy may be possible. + +Two programs are included in chrony, chronyd is a daemon that can be +started at boot time and chronyc is a command-line interface program +which can be used to monitor chronyd's performance and to change various +operating parameters whilst it is running. + +What will chrony run on? +======================== + +The software is known to work on Linux, FreeBSD, NetBSD, macOS and +Solaris. Closely related systems may work too. Any other system will +likely require a porting exercise. You would need to start from one +of the existing system-specific drivers and look into the quirks of +certain system calls and the kernel on your target system. + +How do I set it up? +=================== + +The file INSTALL gives instructions. On supported systems the +compilation process should be automatic. You will need a C compiler, +e.g. gcc or clang. + +What documentation is there? +============================ + +The distribution includes manual pages and a document containing +Frequently Asked Questions (FAQ). + +The documentation is also available on the chrony web pages, accessible +through the URL + + https://chrony.tuxfamily.org/ + +Where are new versions announced? +================================= + +There is a low volume mailing list where new versions and other +important news relating to chrony is announced. You can join this list +by sending mail with the subject "subscribe" to + +chrony-announce-request@chrony.tuxfamily.org + +These messages will be copied to chrony-users (see below). + +How can I get support for chrony? +and where can I discuss new features, possible bugs etc? +======================================================== + +There are 3 mailing lists relating to chrony. chrony-announce was +mentioned above. chrony-users is a users' discussion list, e.g. for +general questions and answers about using chrony. chrony-dev is a more +technical list, e.g. for discussing how new features should be +implemented, exchange of information between developers etc. To +subscribe to either of these lists, send a message with the subject +"subscribe" to + +chrony-users-request@chrony.tuxfamily.org +or +chrony-dev-request@chrony.tuxfamily.org + +as applicable. + +When you are reporting a bug, please send us all the information you can. +Unfortunately, chrony has proven to be one of those programs where it is very +difficult to reproduce bugs in a different environment. So we may have to +interact with you quite a lot to obtain enough extra logging and tracing to +pin-point the problem in some cases. Please be patient and plan for this! + +License +======= + +chrony is distributed under the GNU General Public License version 2. + +Authors +======= + +Richard P. Curnow <rc@rc0.org.uk> +Miroslav Lichvar <mlichvar@redhat.com> + +Acknowledgements +================ + +In writing the chronyd program, extensive use has been made of RFC 1305 +and RFC 5905, written by David Mills. The source code of the NTP reference +implementation has been used to check the details of the protocol. + +The following people have provided patches and other major contributions +to the program : + +Lonnie Abelbeck <lonnie@abelbeck.com> + Patch to add tab-completion to chronyc + +Benny Lyne Amorsen <benny@amorsen.dk> + Patch to add minstratum option + +Andrew Bishop <amb@gedanken.demon.co.uk> + Fixes for bugs in logging when in daemon mode + Fixes for compiler warnings + Robustness improvements for drift file + Improve installation (directory checking etc) + Entries in contrib directory + Improvements to 'sources' and 'sourcestats' output from chronyc + Improvements to documentation + Investigation of required dosynctodr behaviour for various Solaris + versions + +Stephan I. Boettcher <stephan@nevis1.columbia.edu> + Entries in contrib directory + +Erik Bryer <ebryer@spots.ab.ca> + Entries in contrib directory + +Bryan Christianson <bryan@whatroute.net> + Support for macOS + Support for privilege separation + Entries in contrib directory + +Juliusz Chroboczek <jch@pps.jussieu.fr> + Patch to fix install rule in Makefile if chronyd file is in use + +Christian Ehrhardt <christian.ehrhardt@canonical.com> + Patch to generate a warning message when CAP_SYS_TIME is missing + +Paul Elliott <pelliott@io.com> + Entries in contrib directory + +Mike Fleetwood <mike@rockover.demon.co.uk> + Fixes for compiler warnings + +Alexander Gretencord <arutha@gmx.de> + Changes to installation directory system to make it easier for + package builders + +Andrew Griffiths <agriffit@redhat.com> + Patch to add support for seccomp filter + +Walter Haidinger <walter.haidinger@gmx.at> + Access to a Linux installation where v1.12 wouldn't compile + Disc space for an independent backup of the sources + +Juergen Hannken-Illjes <hannken@eis.cs.tu-bs.de> + Port to NetBSD + +John Hasler <john@dhh.gt.org> + Project and website at tuxfamily.org + Changes to support 64 bit machines (i.e. those where + sizeof(unsigned long) > 4) + Bug fix to initstepslew directive + Fix to remove potential buffer overrun errors + Memory locking and real-time scheduler support + Fix fault where chronyd enters an endless loop + +Tjalling Hattink <t.hattink@fugro.nl> + Fix scheduler to allow stepping clock from timeout handler + Patch to take leap second in PPS refclock from locked source + Patch to make reading of RTC for initial trim more reliable + +Liam Hatton <me@liamhatton.com> + Advice on configuring for Linux on PPC + +Jachym Holecek <jakym@volny.cz> + Patch to make Linux real time clock work with devfs + +Håkan Johansson <f96hajo@chalmers.se> + Patch to avoid large values in sources and sourcestats output + +Jim Knoble <jmknoble@pobox.com> + Fixes for compiler warnings + +Antti Jrvinen <costello@iki.fi> + Advice on configuring for BSD/386 + +Victor Moroz <vim@prv.adlum.ru> + Patch to support Linux with HZ!=100 + +Kalle Olavi Niemitalo <tosi@stekt.oulu.fi> + Patch to add acquisitionport directive + +Frank Otto <sandwichmacher@web.de> + Handling arbitrary HZ values + +Denny Page <dennypage@me.com> + Advice on support for hardware timestamping + +Chris Perl <cperl@janestreet.com> + Patches to improve support for refclocks keeping time in TAI + +Gautier PHILIPPON <gautier.philippon@ensimag.grenoble-inp.fr> + Patch to add refresh command to chronyc + +Andreas Piesk <apiesk@virbus.de> + Patch to make chronyc use the readline library if available + +Andreas Steinmetz <ast@domdv.de> + Patch to make stratum of refclocks configurable + +Timo Teras <timo.teras@iki.fi> + Patch to reply correctly on multihomed hosts + +Bill Unruh <unruh@physics.ubc.ca> + Advice on statistics + +Stephen Wadeley <swadeley@redhat.com> + Improvements to man pages + +Wolfgang Weisselberg <weissel@netcologne.de> + Entries in contrib directory + +Ralf Wildenhues <Ralf.Wildenhues@gmx.de> + Many robustness and security improvements + +Ulrich Windl <ulrich.windl@rz.uni-regensburg.de> for the + Information about the Linux 2.2 kernel functionality compared to 2.0 + +Doug Woodward <dougw@whistler.com> + Advice on configuring for Solaris 2.8 on x86 + +Many other people have contributed bug reports and suggestions. We are sorry +we cannot identify all of you individually. |