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TIMED(8)                    System Manager's Manual                   TIMED(8)

     timed - time server daemon

     timed [-dMt] [-F host ...] [-G netgroup] [-i network | -n network]

     The timed utility is a time server daemon which is normally invoked at
     boot time from the rc(8) file.  It synchronizes the host's time with the
     time of other machines, which are also running timed, in a local area
     network.  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 ICMP timestamp request message.

     The following options are available:

     -d      Enable debugging mode; do not detach from the terminal.

     -F host ...
             Create a list of trusted hosts.  The timed utility will only
             accept trusted hosts as masters.  If it finds an untrusted host
             claiming to be master, timed will suppress incoming messages from
             that host and call for a new election.  This option implies the
             -M option.  If this option is not specified, all hosts on the
             connected networks are treated as trustworthy.

     -G netgroup
             Specify a netgroup of trustworthy hosts, in addition to any
             masters specified with the -M flag.  This option may only be
             specified once.

     -i network
             Add network to the list of networks to ignore.  All other
             networks to which the machine is directly connected are used by
             timed.  This option may be specified multiple times to add more
             than one network to the list.

     -M      Allow this host to become a timed master if necessary.

     -n network
             Add network to the list of allowed networks.  All other networks
             to which the machine is directly connected are ignored by timed.
             This option may be specified multiple times to add more than one
             network to the list.

     -t      Enable tracing of received messages and log to the file
             /var/log/timed.log.  Tracing can be turned on or off while timed
             is running with the timedc(8) utility.

     The -n and -i flags are mutually exclusive and require as arguments real
     networks to which the host is connected (see networks(5)).  If neither
     flag is specified, timed will listen on all connected networks.

     A timed running without the -M nor -F flags will always remain a slave.
     If the -F flag is not used, timed will treat all machines as trustworthy.

     The timed utility is based on a master-slave scheme.  When timed 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 adjtime(2) to perform
     the needed corrections on the host's clock.

     It also communicates with date(1) in order to set the date globally, and
     with timedc(8), a timed control utility.  If the machine running the
     master becomes unreachable, the slaves will elect a new master from among
     those slaves which are running with at least one of the -M and -F flags.

     At startup timed normally checks for a master time server on each network
     to which it is connected, except as modified by the -n and -i options
     described above.  It will request synchronization service from the first
     master server located.  If permitted by the -M or -F flags, it will
     provide synchronization service on any attached networks on which no
     trusted master server was detected.  Such a server propagates the time
     computed by the top-level master.  The timed utility will periodically
     check for the presence of a master on those networks for which it is
     operating as a slave.  If it finds that there are no trusted masters on a
     network, it will begin the election process on that network.

     One way to synchronize a group of machines is to use ntpd(8) to
     synchronize the clock of one machine to a distant standard or a radio
     receiver and -F hostname to tell its timed to trust only itself.

     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.

     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

     Temporal chaos will result if two or more time daemons attempt to adjust
     the same clock.  If both timed and another time daemon are run on the
     same machine, ensure that the -F flag is used, so that timed never
     attempts to adjust the local clock.

     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 -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.

     /var/log/timed.log        tracing file for timed
     /var/log/timed.masterlog  log file for master timed

     date(1), adjtime(2), gettimeofday(2), icmp(4), netgroup(5), networks(5),
     ntpd(8), timedc(8)

     R. Gusella and S. Zatti, TSP: The Time Synchronization Protocol for UNIX

     The timed utility appeared in 4.3BSD.

NetBSD 10.99                     May 11, 1993                     NetBSD 10.99