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Diffstat (limited to 'usr.sbin/timed/timed/timed.8')
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diff --git a/usr.sbin/timed/timed/timed.8 b/usr.sbin/timed/timed/timed.8 new file mode 100644 index 0000000..8f8798d --- /dev/null +++ b/usr.sbin/timed/timed/timed.8 @@ -0,0 +1,219 @@ +.\" Copyright (c) 1980, 1991, 1993 +.\" The Regents of the University of California. All rights reserved. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" 3. All advertising materials mentioning features or use of this software +.\" must display the following acknowledgement: +.\" This product includes software developed by the University of +.\" California, Berkeley and its contributors. +.\" 4. Neither the name of the University nor the names of its contributors +.\" may be used to endorse or promote products derived from this software +.\" without specific prior written permission. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND +.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE +.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS +.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY +.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +.\" SUCH DAMAGE. +.\" +.\" @(#)timed.8 8.1 (Berkeley) 6/6/93 +.\" +.Dd June 6, 1993 +.Dt TIMED 8 +.Os BSD 4.3 +.Sh NAME +.Nm timed +.Nd time server daemon +.Sh SYNOPSIS +.Nm timed +.Op Fl M +.Op Fl t +.Op Fl d +.Op Fl i Ar network +.Op Fl n Ar network +.Op Fl F Ar host1 host2 ... +.Sh DESCRIPTION +This +is a time server daemon and is normally invoked +at boot time from the +.Xr rc 8 +file. +It synchronizes the host's time with the time of other +machines in a local area network running +.Nm timed 8 . +These time servers will slow down the clocks of some machines +and speed up the clocks of others to bring them to the average network time. +The average network time is computed from measurements of clock differences +using the +.Tn ICMP +timestamp request message. +.Pp +The service provided by +.Nm timed +is based on a master-slave +scheme. +When +.Nm timed 8 +is started on a machine, it asks the master for the network time +and sets the host's clock to that time. +After that, it accepts synchronization messages periodically sent by +the master and calls +.Xr adjtime 2 +to perform the needed corrections on the host's clock. +.Pp +It also communicates with +.Xr date 1 +in order to set the date globally, +and with +.Xr timedc 8 , +a timed control program. +If the machine running the master crashes, then the slaves will elect +a new master from among slaves running with the +.Fl M +flag. +A +.Nm timed +running without the +.Fl M +or +.Fl F +flags will remain a slave. +The +.Fl t +flag enables +.Nm timed +to trace the messages it receives in the +file +.Pa /var/log/timed.log . +Tracing can be turned on or off by the program +.Xr timedc 8 . +The +.Fl d +flag is for debugging the daemon. +It causes the program to not put itself into the background. +Normally +.Nm timed +checks for a master time server on each network to which +it is connected, except as modified by the options described below. +It will request synchronization service from the first master server +located. +If permitted by the +.Fl M +flag, it will provide synchronization service on any attached networks +on which no current master server was detected. +Such a server propagates the time computed by the top-level master. +The +.Fl n +flag, followed by the name of a network which the host is connected to +(see +.Xr networks 5 ) , +overrides the default choice of the +network addresses made by the program. +Each time the +.Fl n +flag appears, that network name is added to a list of valid networks. +All other networks are ignored. +The +.Fl i +flag, followed by the name of a network to which the host is connected +(see +.Xr networks 5 ) , +overrides the default choice of the network addresses made by the program. +Each time the +.Fl i +flag appears, that network name is added to a list of networks to ignore. +All other networks are used by the time daemon. +The +.Fl n +and +.Fl i +flags are meaningless if used together. +.Pp +.Nm Timed +checks for a master time server on each network to which +it is connected, except as modified by the +.Fl n +and +.Fl i +options described above. +If it finds masters on more than one network, it chooses one network +on which to be a "slave," and then periodically checks the other +networks to see if the masters there have disappeared. +.Pp +One way to synchronize a group of machines is to use an NTP daemon to +synchronize the clock of one machine to a distant standard or a radio +receiver and +.Fl F Ar hostname +to tell its timed daemon to trust only itself. +.Pp +Messages printed by the kernel on the system console occur with +interrupts disabled. +This means that the clock stops while they are printing. +A machine with many disk or network hardware problems and consequent +messages cannot keep good time by itself. Each message typically causes +the clock to lose a dozen milliseconds. A time daemon can +correct the result. +.Pp +Messages in the system log about machines that failed to respond +usually indicate machines that crashed or were turned off. +Complaints about machines that failed to respond to initial time +settings are often associated with "multi-homed" machines +that looked for time masters on more than one network and eventually +chose to become a slave on the other network. +.SH WARNING +If two or more time daemons, whether +.Nm timed , +.Xr NTP , +try to adjust the same clock, temporal chaos will result. +If both +.Nm +and another time daemon are run on the same machine, +ensure that the +.Fl F +flag is used, so that +.Nm timed +never attempts to adjust the local clock. +.Pp +The protocol is based on UDP/IP broadcasts. All machines within +the range of a broadcast that are using the TSP protocol must cooperate. +There cannot be more than a single administrative domain using the +.Fl F +flag among all machines reached by a broadcast packet. +Failure to follow this rule is usually indicated by complaints concerning +"untrusted" machines in the system log. +.Sh FILES +.Bl -tag -width /var/log/timed.masterlog -compact +.It Pa /var/log/timed.log +tracing file for timed +.It Pa /var/log/timed.masterlog +log file for master timed +.El +.Sh SEE ALSO +.Xr date 1 , +.Xr adjtime 2 , +.Xr gettimeofday 2 , +.Xr icmp 4 , +.Xr timedc 8 , +.Rs +.%T "TSP: The Time Synchronization Protocol for UNIX 4.3BSD" +.%A R. Gusella +.%A S. Zatti +.Re +.Sh HISTORY +The +.Nm +daemon appeared in +.Bx 4.3 . |