ntp_misc(5)ntp_misc(5)NAMEntp_misc - Miscellaneous Options
broadcastdelay seconds
The broadcast and multicast modes require a special calibration
to determine the network delay between the local and remote
servers. Ordinarily, this is done automatically by the initial
protocol exchanges between the client and server. In some
cases, the calibration procedure may fail due to network or
server access controls, for example. This command specifies the
default delay to be used under these circumstances. Typically
(for Ethernet), a number between 0.003 and 0.007 seconds is
appropriate. The default when this command is not used is 0.004
seconds.
calldelay delay
This option controls the delay in seconds between the first and
second packets sent in burst or iburst mode to allow additional
time for a modem or ISDN call to complete.
driftfile driftfile [ minutes [ tolerance ] ]
This command specifies the complete path and name of the file
used to record the frequency of the local clock oscillator.
This is the same operation as the -f command linke option. If
the file exists, it is read at startup in order to set the ini‐
tial frequency and then updated once per hour with the current
frequency computed by the daemon. If the file name is speci‐
fied, but the file itself does not exist, the starts with an
initial frequency of zero and creates the file when writing it
for the first time. If this command is not given, the daemon
will always start with an initial frequency of zero. The file
format consists of a single line containing a single floating
point number, which records the frequency offset measured in
parts-per-million (PPM). The file is updated by first writing
the current drift value into a temporary file and then renaming
this file to replace the old version. This implies that ntpd
must have write permission for the directory the drift file is
located in, and that file system links, symbolic or otherwise,
should be avoided.
The two optional values determine how often the file is writ‐
ten, and are particuarly useful when is it desirable to avoid
spinning up the disk unnecessarily. The parameter minutes is
how often the file will be written. If omitted or less than 1,
the interval will be 60 minutes (one hour). The parameter tol‐
erance is the threshold to skip writing the new value. If the
new value is within tolerance percent of the last value written
(compared out to 3 decimal places), the write will be skipped.
The default is 0.0, which means that the write will occur
unless the current and previous values are the same. A toler‐
ance of .1 equates roughly to a difference in the 2nd decimal
place.
enable [ auth | bclient | calibrate | kernel | monitor | ntp | pps |
stats]
disable [ auth | bclient | calibrate | kernel | monitor | ntp | pps |
stats ]
Provides a way to enable or disable various system options.
Flags not mentioned are unaffected. Note that all of these
flags can be controlled remotely using the ntpdc utility pro‐
gram.
auth Enables the server to synchronize with unconfigured
peers only if the peer has been correctly authenticated
using either public key or private key cryptography.
The default for this flag is enable.
bclient Enables the server to listen for a message from a
broadcast or multicast server, as in the multicast‐
client command with default address. The default for
this flag is disable.
calibrate
Enables the calibrate feature for reference clocks. The
default for this flag is disable.
kernel Enables the kernel time discipline, if available. The
default for this flag is enable if support is avail‐
able, otherwise disable.
monitor Enables the monitoring facility. See the ntpdc program
and the monlist command or further information. The
default for this flag is enable.
ntp Enables time and frequency discipline. In effect, this
switch opens and closes the feedback loop, which is
useful for testing. The default for this flag is
enable.
pps Enables the pulse-per-second (PPS) signal when fre‐
quency and time is disciplined by the precision time
kernel modifications. See the A Kernel Model for Preci‐
sion Timekeeping page for further information. The
default for this flag is disable.
stats Enables the statistics facility. See the Monitoring
Options page for further information. The default for
this flag is disable
includefile includefile
This command allows additional configuration commands to be
included from a separate file. Include files may be nested to a
depth of five; upon reaching the end of any include file, com‐
mand processing resumes in the previous configuration file.
This option is useful for sites that run ntpd on multiple
hosts, with (mostly) common options (e.g., a restriction list).
logconfig configkeyword
This command controls the amount and type of output written to
the system syslog facility or the alternate logfile log file.
All configkeyword keywords can be prefixed with =, + and -,
where = sets the syslogmask, + adds and - removes messages.
syslog messages can be controlled in four classes (clock, peer,
sys and sync). Within these classes four types of messages can
be controlled: informational messages (info), event messages
(events), statistics messages (statistics) and status messages
(status). Configuration keywords are formed by concatenating
the message class with the event class. The all prefix can be
used instead of a message class. A message class may also be
followed by the all keyword to enable/disable all messages of
the respective message class. By default, logconfig output is
set to allsync. Thus, a minimal log configuration could look
like this:
logconfig=syncstatus +sysevents
This would just list the synchronizations state of ntpd and the
major system events. For a simple reference server, the follow‐
ing minimum message configuration could be useful:
logconfig=allsync +allclock
This configuration will list all clock information and synchro‐
nization information. All other events and messages about
peers, system events and so on is suppressed.
logfile logfile
This command specifies the location of an alternate log file to
be used instead of the default system syslog facility. This is
the same operation as the -l command line option.
phone dial1 dial2 ...
This command is used in conjunction with the ACTS modem driver
(type 18). The arguments consist of a maximum of 10 telephone
numbers used to dial USNO, NIST or European time services. The
Hayes command ATDT is normally prepended to the number, which
can contain other modem control codes as well.
setvar variable [default]
This command adds an additional system variable. These vari‐
ables can be used to distribute additional information such as
the access policy. If the variable of the form name = value is
followed by the default keyword, the variable will be listed as
part of the default system variables (ntpq rv command). These
additional variables serve informational purposes only. They
are not related to the protocol other that they can be listed.
The known protocol variables will always override any variables
defined via the setvar mechanism. There are three special vari‐
ables that contain the names of all variable of the same group.
The sys_var_list holds the names of all system variables. The
peer_var_list holds the names of all peer variables and the
clock_var_list holds the names of the reference clock vari‐
ables.
tinker [ allan allan | dispersion dispersion | freq freq | huffpuff
huffpuff | panic panic | step step | stepout stepout ]
This command can be used to alter several system variables in
very exceptional circumstances. It should occur in the configu‐
ration file before any other configuration options. The default
values of these variables have been carefully optimized for a
wide range of network speeds and reliability expectations. In
general, they interact in intricate ways that are hard to pre‐
dict and some combinations can result in some very nasty behav‐
ior. Very rarely is it necessary to change the default values;
but, some folks can't resist twisting the knobs anyway and this
command is for them. Emphasis added: twisters are on their own
and can expect no help from the support group. The variables
operate as follows:
allan allan
The argument becomes the new value for the Allan inter‐
cept, which is a parameter of the PLL/FLL clock disci‐
pline algorithm. The value is in seconds with default
1500 s, which is appropriate for most computer clocks.
dispersion dispersion
The argument becomes the new value for the dispersion
increase rate, normally .000015 s/s.
freq freq
The argument becomes the initial value of the frequency
offset in parts-per-million. This overrides the value
in the frequency file, if present, and avoids the ini‐
tial training state if it is not.
huffpuff huffpuff
The argument becomes the new value for the experimental
huff-n'-puff filter span, which determines the most
recent interval the algorithm will search for a minimum
delay. The lower limit is 900 s (15 m), but a more rea‐
sonable value is 7200 (2 hours). There is no default,
since the filter is not enabled unless this command is
given.
panic panic
The argument is the panic threshold, by default 1000 s.
If set to zero, the panic sanity check is disabled and
a clock offset of any value will be accepted.
step step
The argument is the step threshold, by default 0.128 s.
It can be set to any positive number in seconds. If set
to zero, step adjustments will never occur. Note: The
kernel time discipline is disabled if the step thresh‐
old is set to zero or greater than the default.
stepout stepout
The argument is the stepout timeout, by default 900 s.
It can be set to any positive number in seconds. If set
to zero, the stepout pulses will not be suppressed.
trap host_address [port port_number] [interface interface_address]
This command configures a trap receiver at the given host
address and port number for sending messages with the specified
local interface address. If the port number is unspecified, a
value of 18447 is used. If the interface address is not speci‐
fied, the message is sent with a source address of the local
interface the message is sent through. Note that on a multi‐
homed host the interface used may vary from time to time with
routing changes. The trap receiver will generally log event
messages and other information from the server in a log file.
While such monitor programs may also request their own trap
dynamically, configuring a trap receiver will ensure that no
messages are lost when the server is started.
ttl hop ...
This command specifies a list of TTL values in increasing
order. up to 8 values can be specified. In manycast mode these
values are used in turn in an expanding-ring search. The
default is eight multiples of 32 starting at 31.
FILES
ntp.drift frequency compensation (PPM)
SEE ALSOntp.conf(5)
Primary source of documentation: /usr/share/doc/ntp-*
This file was automatically generated from HTML source.
ntp_misc(5)