NTP users are strongly urged to take immediate action to ensure that their NTP daemon is not susceptible to use in a reflected denial-of-service (DRDoS) attack. Please see the NTP Security Notice for vulnerability and mitigation details, and the Network Time Foundation Blog for more information. (January 2014)
The Official NTP documentation is distributed as HTML only. Manpages, or other forms of documentation, are maintained by third parties.
Information on time and frequency services - Links to NTP servers and reference clocks, NTP software and documentation, time and frequency standard stations operated by U.S. and other countries, and time and frequency standard station transmission data are available here.