Name

timed − time server daemon

Syntax

/usr/etc/timed [ −i | −n network ][ −E ][ −M ][ −t ]

Description

The timed daemon synchronizes a host’s time with the time of other machines in a local area network running timed. It is normally invoked at boot time from the /etc/rc.local file.

Servers running timed slow down the clocks of some machines and speed up the clocks of others to bring them all to the average network time. The average network time is computed from measurements of clock differences with the Internet Communication Message Protocol (ICMP) timestamp request message.

The service provided by timed 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 the adjtime or settimeofday routine to perform any corrections on the host’s clock.

It also communicates with the date command to set the date globally, and with the timed control program, timedc. If the machine running the master crashes, then the slaves elect a new master from among slaves running with the −M flag set.  The −M flag provides time synchronization on any attached networks where no current master server is detected. Such a server propagates the time computed by the top-level master. At least one timed daemon on each network must run with the −M option set to allow it to become a timed master.

Options

−EOverrides the input of slaves.  Use the −E flag in conjunction with the −M flag.  It specifies that a master timed should not average the times of the slaves to calculate the network time but should distribute the time of its local host as the network time.  This flag allows a master timed to distribute time to a network while the network time is controlled by an outside agent such as the Network Time Protocol.

[−i | −n] network

−iSpecifies a network to ignore.  Each network that appears as an argument to the −i flag is added to the list of networks that timed will ignore.  If the −i flag is used, timed accesses all networks to which the host is connected except for those networks specified as arguments to the −i flag.

−nSpecifies a network to use.  When the timed is started, it gathers information about all the network devices connected to the local host.  If neither the −n flag nor the −i flag is used, timed tries to access all the network devices connected to the local host. The network argument to the −n flag is the name of a network that timed should access.

If the −n switch is used, only those networks specified by the −n flag are accessed.

Do not use the −i and −n flags together.

−MAllows a slave time server to become a master time server if the master server crashes.  A system running the timed daemon without the −M flag set remains a slave. The timed daemon checks for a master time server on each network to which it is connected.  It requests synchronization service from the first master server it locates.

−tEnables timed to trace the messages it receives in the file /usr/adm/timed.log. Tracing can be enabled or disabled with the timedc program.

Restrictions

Any system running timed with the −E and −M options set is eligible to become the timed master, and distribute its local time to all systems running timed on its network.  Run the Network Time Protocol daemon, ntpd, instead of timed to prevent this behavior.

Files

/etc/rc.local Invokes the timed daemon each time the system boots

/usr/adm/timed.log Tracing file for timed

/usr/adm/timed.masterlog Log file for master timed

See Also

date(1), adjtime(2), gettimeofday(2), networks(5), ntpd(8), timedc(8)
Introduction to Networking and Distributed System Services