243 lines
7.2 KiB
Groff
243 lines
7.2 KiB
Groff
.\" $NetBSD: ntpd.8,v 1.3 2000/07/23 14:34:14 simonb Exp $
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.\" Converted from HTML to mandoc by html-to-mdoc.pl
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.\"
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.Dd Mar 29, 2000
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.Dt NTPD 8
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.Os
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.Sh NAME
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.Nm ntpd
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.Nd Network Time Protocol (NTP) daemon
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.Sh SYNOPSIS
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.Nm
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.Op Fl aAbdm
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.Op Fl c Ar conffile
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.Op Fl f Ar driftfile
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.Op Fl g
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.Op Fl k Ar keyfile
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.Op Fl l Ar logfile
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.Op Fl p Ar pidfile
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.Op Fl r Ar broadcastdelay
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.Op Fl s Ar statsdir
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.Op Fl t Ar key
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.Op Fl v Ar variable
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.Op Fl V Ar variable
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.Op Fl x
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.Sh DESCRIPTION
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.Nm
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is an operating system daemon which sets and maintains the
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system time-of-day in synchronism with Internet standard time servers.
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.Nm
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is a complete implementation of the Network Time Protocol
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(NTP) version 4, but also retains compatibility with version 3, as
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defined by RFC-1305, and version 1 and 2, as defined by RFC-1059 and
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RFC-1119, respectively.
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.Nm
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does most computations in 64-bit
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floating point arithmetic and does relatively clumsy 64-bit fixed point
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operations only when necessary to preserve the unltimate precision,
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about 232 picoseconds. While the ultimate precision, is not achievable
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with ordinary workstations and networks of today, it may be required
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with future nanosecond CPU clocks and gigabit LANs.
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.Pp
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The daemon can operate in any of several modes, including symmetric
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active/passive, client/server broadcast/multicast and manycast. A
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broadcast/multicast or manycast client can discover remote servers,
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compute server-client propagation delay correction factors and configure
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itself automatically. This makes it possible to deploy a fleet of
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workstations without specifying configuration details specific to the
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local environment.
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.Pp
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Ordinarily,
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.Nm
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reads the
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.Pa ntp.conf
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configuration
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file at startup time in order to determine the synchronization sources
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and operating modes. It is also possible to specify a working, although
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limited, configuration entirely on the command line, obviating the need
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for a configuration file. This may be particularly appropriate when the
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local host is to be configured as a broadcast/multicast client or
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manycast client, with all peers being determined by listening to
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broadcasts at run time.
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.Pp
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If NetInfo support is built into
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.Nm "" ,
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then
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.Nm
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will attempt to read its configuration from the NetInfo if the default
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ntp.conf file cannot be read and no file is specified by the
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.Fl c
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option.
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.Pp
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Various internal
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.Nm
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variables can be displayed and
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configuration options altered while the daemon is running using the
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.Xr ntpq 8
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and
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.Xr ntpdc 8
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utility programs.
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.Pp
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When
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.Nm
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starts it looks at the value of
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.Pa umask
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,
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and if it's zero
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.Nm
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will set the
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.Pa umask
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to
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.Pa 022
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.
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.Sh COMMAND LINE OPTIONS
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.Bl -tag -width indent
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.It Fl a
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Enable authentication mode (default).
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.It Fl A
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Disable authentication mode.
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.It Fl b
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Synchronize using NTP broadcast messages.
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.It Fl c Ar conffile
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Specify the name and path of the configuration file.
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.It Fl d
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Specify debugging mode. This flag may occur multiple times, with
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each occurrence indicating greater detail of display.
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.It Fl D Ar level
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Specify debugging level directly.
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.It Fl f Ar driftfile
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Specify the name and path of the drift file.
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.It Fl g
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Normally, the daemon exits if the offset exceeds a 1000-s sanity
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limit. This option overrides this limit and allows the time to be set to
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any value without restriction; however, this can happen only once. After
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that, the daemon will exit of the limit is exceeded.
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.It Fl k Ar keyfile
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Specify the name and path of the file containing the NTP
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authentication keys.
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.It Fl l Ar logfile
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Specify the name and path of the log file. The default is the system
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log facility.
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.It Fl m
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Synchronize using NTP multicast messages on the IP multicast group
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address 224.0.1.1 (requires multicast kernel).
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.It Fl p Ar pidfile
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Specify the name and path to record the daemon's process ID.
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.It Fl P
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Override the priority limit set by the operating system. Not
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recommended for sissies.
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.It Fl r Ar broadcastdelay
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Specify the default propagation delay from the broadcast/multicast
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server and this computer. This is necessary only if the delay cannot be
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computed automatically by the protocol.
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.It Fl s Ar statsdir
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Specify the directory path for files created by the statistics
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facility.
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.It Fl t Ar key
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Add a key number to the trusted key list.
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.It Fl v Ar variable
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.It Fl V Ar variable
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Add a system variable listed by default.
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.It Fl x
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Ordinarily, if the time is to be adjusted more than 128 ms, it is
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stepped, not gradually slewed. This option forces the time to be slewed
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in all cases. Note: Since the slew rate is limited to 0.5 ms/s, each
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second of adjustment requires an amortization interval of 2000 s. Thus,
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an adjustment of many seconds can take hours or days to amortize.
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.El
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.Sh THE CONFIGURATION FILE
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The
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.Nm
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configuration file is read at initial startup in order
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to specify the synchronization sources, modes and other related
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information. Usually, it is installed in the
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.Pa /etc
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directory,
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but could be installed elsewhere (see the
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.Fl c
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.Ar conffile
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command line option). The file format is similar to other Unix
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configuration files - comments begin with a
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.Pa #
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character and
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extend to the end of the line; blank lines are ignored. Configuration
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commands consist of an initial keyword followed by a list of arguments,
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some of which may be optional, separated by whitespace. Commands may not
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be continued over multiple lines. Arguments may be host names, host
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addresses written in numeric, dotted-quad form, integers, floating
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point numbers (when specifying times in seconds) and text strings.
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Optional arguments are delimited by
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.Pa [ ]
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in the following
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descriptions, while alternatives are separated by
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.Pa | .
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The
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notation
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.Pa [ ... ]
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means an optional, indefinite repetition of
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the last item before the
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.Pa [ ... ]
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.
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.Pp
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See the following pages for configuration and control options. While
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there is a rich set of options available, the only required option is
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one or more
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.Pa server, peer,
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.Pa broadcast
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or
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.Pa manycastclient
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commands described in the Configuration Options
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page. The
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.%T "Notes on Configuring NTP and Setting up a NTP Subnet"
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page in
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.Pa /usr/share/doc/html/ntp/notes.htm
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contains an extended discussion of these options.
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For
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.%T "Configuration Options" ,
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refer to
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.Pa /usr/share/doc/html/ntp/confopt.htm .
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.Pp
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For
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.%T "Authentication Options" ,
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refer to
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.Pa /usr/share/doc/html/ntp/authopt.htm .
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.Pp
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For
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.%T "Monitoring Options" ,
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refer to
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.Pa /usr/share/doc/html/ntp/monopt.htm .
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.Pp
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For
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.%T "Access Control Options" ,
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refer to
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.Pa /usr/share/doc/html/ntp/accopt.htm .
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.Pp
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For
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.%T "Reference Clock Options" ,
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refer to
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.Pa /usr/share/doc/html/ntp/clockopt.htm .
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.Pp
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For
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.%T "Miscellaneous Options" ,
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refer to
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.Pa /usr/share/doc/html/ntp/miscopt.htm .
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.Pp
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.Sh FILES
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.Bl -tag -width /etc/ntp.drift -compact
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.It Pa /etc/ntp.conf
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the default name of the configuration file
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.It Pa /etc/ntp.drift
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the default name of the drift file
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.It Pa /etc/ntp.keys
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the default name of the key file
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.El
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.Sh BUGS
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.Nm
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has gotten rather fat. While not huge, it has gotten
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larger than might be desireable for an elevated-priority daemon running
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on a workstation, particularly since many of the fancy features which
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consume the space were designed more with a busy primary server, rather
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than a high stratum workstation, in mind.
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.Sh AUTHOR
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David L. Mills <mills@udel.edu>
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