chrony 4.1 System clock synchronisation service that speaks NTP
Chrony keeps your system time accurate. It synchronises your computer's clock with NTP servers, reference clocks such as GPS receivers, or even manual input of the correct time from a wristwatch.
Chrony will determine the rate at which the computer gains or loses time, and compensate for it. It can also operate as an NTPv4 (RFC 5905) server and peer to tell time to other computers on the network.
It's designed to perform well even under adverse conditions: congested networks, unreliable clocks drifting with changes in temperature, and devices or virtual machines that are frequently turned off and connect to the Internet for only a few minutes at a time.
Typical accuracy when synchronised over the Internet is several milliseconds. On a local network this can reach tens of microseconds. With hardware time-stamping or reference clock, sub-microsecond accuracy is possible.