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 continuously, or run on a virtual machine. Two programs are included in chrony, chronyd is a daemon that is 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. Note 1: You must have the 'chrony' group and user to run this script: $ groupadd -g 354 chrony $ useradd -u 354 -d /var/lib/chrony -s /bin/false -g chrony chrony Feel free to use a different uid and gid if desired, but 354 is recommended to avoid conflicts with other stuff from SlackBuilds.org. Note 2: If you are upgrading from previous version, where the daemon was running under 'root' user as opposed to 'chrony' user, you need to ensure correct permissions for /var/run/chrony directory and files under /var/lib/chrony directory. If possible (i.e. you don't have any precious files there), before starting the daemon, remove /var/run/chrony directory (cronyd will recreate it) and remove files under /var/lib/chrony directory (cronyd will recreate them). Note 3: The provided configuration file sets up chrony to operate in the most common scenario, that is NTP client for synchronising local machine time with the remote NTP server(s) time (using pool.ntp.org by default). See the man pages for chronyd and chrony.conf (and the contrib and examples directories) for more details on possible configuration options. Note 4: The provided /etc/rc.d/rc.chrony script can be used to launch the daemon at boot and to stop it at shutdown.