

Use of options not listed may not be caught as an error, but may result in some weird and even destructive behavior. Note that only those options applicable to each command are listed below. Addresses are classed by type as s a remote server or peer (IPv4 class A, B and C), b the broadcast address of a local interface, m a multicast address (IPv4 class D), or r a reference clock address (.x). The various modes are determined by the command keyword and the type of the required IP address. There are two classes of commands, configuration commands that configure a persistent association with a remote server or peer or reference clock, and auxiliary commands that specify environmental variables that control various related operations. These commands have the same basic functions as in NTPv3 and in some cases new functions and new arguments. While there is a rich set of options available, the only required option is one or more pool, server, peer, broadcast, or manycastclient commands.įollowing is a description of the configuration commands in NTPv4. The rest of this page describes the configuration and control options. Arguments may be host names, host addresses written in numeric, dotted-quad form, integers, floating point numbers (when specifying times in seconds) and text strings. Commands may not be continued over multiple lines. Configuration commands consist of an initial keyword followed by a list of arguments, some of which may be optional, separated by whitespace. Comments begin with a # character and extend to the end of the line blank lines are ignored. The file format is similar to other UNIX configuration files. Usually, it is installed in the /etc directory, but could be installed elsewhere (see the daemon’s -c command line option). The ntp.conf configuration file is read at initial startup by the ntpd daemon in order to specify the synchronization sources, modes and other related information. The behavior of ntpd can be changed by a configuration file, by default ntp.conf. This software is released under the NTP license. This document describes the configuration file for the NTP Project’s ntpd program.
