1.\" Copyright (c) 1980, 1991 Regents of the University of California. 2.\" All rights reserved. 3.\" 4.\" %sccs.include.redist.roff% 5.\" 6.\" @(#)timed.8 6.6 (Berkeley) 04/27/91 7.\" 8.Dd 9.Dt TIMED 8 10.Os BSD 4.3 11.Sh NAME 12.Nm timed 13.Nd time server daemon 14.Sh SYNOPSIS 15.Nm timed 16.Op Fl M 17.Op Fl t 18.Op Fl i Ar network 19.Op Fl n Ar network 20.Sh DESCRIPTION 21This 22is the time server daemon and is normally invoked 23at boot time from the 24.Xr rc 8 25file. 26It synchronizes the host's time with the time of other 27machines in a local area network running 28.Nm timed 8 . 29These time servers will slow down the clocks of some machines 30and speed up the clocks of others to bring them to the average network time. 31The average network time is computed from measurements of clock differences 32using the 33.Tn ICMP 34timestamp request message. 35.Pp 36The service provided by 37.Nm timed 38is based on a master-slave 39scheme. 40When 41.Nm timed 8 42is started on a machine, it asks the master for the network time 43and sets the host's clock to that time. 44After that, it accepts synchronization messages periodically sent by 45the master and calls 46.Xr adjtime 2 47to perform the needed corrections on the host's clock. 48.Pp 49It also communicates with 50.Xr date 1 51in order to set the date globally, 52and with 53.Xr timedc 8 , 54a timed control program. 55If the machine running the master crashes, then the slaves will elect 56a new master from among slaves running with the 57.Fl M 58flag. 59A 60.Nm timed 61running without the 62.Fl M 63flag will remain a slave. 64The 65.Fl t 66flag enables 67.Nm timed 68to trace the messages it receives in the 69file 70.Pa /var/log/timed.log . 71Tracing can be turned on or off by the program 72.Xr timedc 8 . 73Normally 74.Nm timed 75checks for a master time server on each network to which 76it is connected, except as modified by the options described below. 77It will request synchronization service from the first master server 78located. 79If permitted by the 80.Fl M 81flag, it will provide synchronization service on any attached networks 82on which no current master server was detected. 83Such a server propagates the time computed by the top-level master. 84The 85.Fl n 86flag, followed by the name of a network which the host is connected to 87(see 88.Xr networks 5 ) , 89overrides the default choice of the 90network addresses made by the program. 91Each time the 92.Fl n 93flag appears, that network name is added to a list of valid networks. 94All other networks are ignored. 95The 96.Fl i 97flag, followed by the name of a network to which the host is connected 98(see 99.Xr networks 5 ) , 100overrides the default choice of the network addresses made by the program. 101Each time the 102.Fl i 103flag appears, that network name is added to a list of networks to ignore. 104All other networks are used by the time daemon. 105The 106.Fl n 107and 108.Fl i 109flags are meaningless if used together. 110.Sh FILES 111.Bl -tag -width /var/log/timed.masterlog -compact 112.It Pa /var/log/timed.log 113tracing file for timed 114.It Pa /var/log/timed.masterlog 115log file for master timed 116.El 117.Sh SEE ALSO 118.Xr date 1 , 119.Xr adjtime 2 , 120.Xr gettimeofday 2 , 121.Xr icmp 4 , 122.Xr timedc 8 , 123.Rs 124.%T "TSP: The Time Synchronization Protocol for UNIX 4.3BSD" 125.%A R. Gusella 126.%A S. Zatti 127.Re 128.Sh HISTORY 129The 130.Nm 131daemon appeared in 132.Bx 4.3 . 133