| TIMED(8) | System Manager's Manual | TIMED(8) | 
timed —
| timed | [ -dMt] [-Fhost ...] [-Gnetgroup] [-inetwork |-nnetwork] | 
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-F
    host ...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-M flag. This option may only
      be specified once.-i
    networktimed. This option may be specified multiple times
      to add more than one network to the list.-Mtimed master if
      necessary.-n
    networktimed. This option may be specified multiple times
      to add more than one network to the list.-ttimed 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 network.
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.
timedtimedR. Gusella and S. Zatti, TSP: The Time Synchronization Protocol for UNIX 4.3BSD.
timed utility appeared in
  4.3BSD.
| May 11, 1993 | NetBSD 10.0 |