NTP: The Network Time Protocol

NTP users are strongly urged to take immediate action to ensure that their NTP daemons are not susceptible to being used in distributed denial-of-service (DDoS) attacks. Please also take this opportunity to defeat denial-of-service attacks by implementing Ingress and Egress filtering through BCP38.

ntp-4.2.8p15 was released on 23 June 2020.
It addresses 1 medium-severity security issue in ntpd, and provides 13 other non-security fixes improvements over 4.2.8p14.

Please see our NTP Security Notice page for vulnerability and mitigation details.

Welcome to, home of the Network Time Protocol project.

This page is home for the NTP Project (R&D). This web site, and all pages directly contained within, are in the public domain. Some portions of this site may be copyrighted by other authors. Please contact the webmaster with any questions regarding copyright. The NTP software distribution is copyrighted, as described in the NTP copyright page.

NTP is a protocol designed to synchronize the clocks of computers over a network.

NTP version 4, a significant revision of the previous NTP standard, is the current development version. It is formalized by RFCs released by the IETF.

The NTP Project (R&D)

The NTP Project conducts Research and Development in NTP and produces the Official Reference Implementation of NTP along with the Implementation Documentation. Background information about NTP, along with briefings and a bibliography, are available at the Network Time Synchronization Project Page.

The NTP Public Services Project

The NTP Public Services Project provides resources for the NTP software available here, which is the Official Reference Implementation of NTP. The available resources include:

Hosting resources for the NTP Public Services Project are provided by Internet Systems Consortium, Inc.

Please direct comments and questions about this web site to the NTP Project webmaster. To contact the NTP Public Services Project web maintainers or any member of the NTP developer team, please see the NTP Public Services Project Contact Page.