ntp_misc(5) File Formats Manual ntp_misc(5)
NAME
ntp_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.
driftfile driftfile { 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 or more with the
current frequency computed by the daemon. If the file name is
specified, 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 parameter tolerance is the wander
threshold to skip writing the new value. If the value of wander
computed from recent frequency changes is greater than this
threshold the file will be updated once per hour. If below the
threshold, the file will not be written.
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.
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).
interface [listen | ignore | drop] [all | ipv4 | ipv6 | wildcard | name
| address[/prefixlen]]
This command controls which network addresses ntpd opens, and
whether input is dropped without processing. The first parame-
ter determines the action for addresses which match the second
parameter. That parameter specifies a class of addresses, or a
specific interface name, or an address. In the address case,
prefixlen determines how many bits must match for this rule to
apply. ignore prevents opening matching addresses, drop causes
ntpd to open the address and drop all received packets without
examination. Multiple interface commands can be used. The last
rule which matches a particular address determines the action
for it. interface commands are disabled if any -I, --interface,
-L, or --novirtualips command-line options are used. If none of
those options are used and no interface actions are specified
in the configuration file, all available network addresses are
opened. The nic command is an alias for interface.
leapfile leapfile
This command loads the NIST leapseconds file and initializes
the leapsecond values for the next leapsecond time, expiration
time and TAI offset. The file can be obtained directly from
NIST national time servers using ftp as the ASCII file
pub/leap-seconds. While not strictly a security function, the
Autokey protocol provides means to securely retrieve the cur-
rent or updated leapsecond values from a server.
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 =syncall +sysevents +sysstatus. 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 following minimum message configuration could be
useful: logconfig =syncall +clockall This configuration will
list all clock information and synchronization 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.
saveconfigdir directory_path
Specify the directory in which to write configuration snapshots
requested with ntpq's saveconfig command. If saveconfigdir does
not appear in the configuration file, saveconfig requests are
rejected by ntpd.
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 | stepback step | stepfwd step |
stepout stepout ]
This command alters certain system variables used by the clock
discipline algorithm. The default values of these variables
have been carefully optimized for a wide range of network
speeds and reliability expectations. Very rarely is it neces-
sary to change the default values; but, some folks can't resist
twisting the knobs. The options are as follows:
allan allan
Spedifies the Allan intercept, which is a parameter of
the PLL/FLL clock discipline algorithm, in seconds with
default 1500 s.
dispersion dispersion
Specifies the dispersion increase rate in parts-per-
million (PPM) with default 15 PPM.
freq freq
Spedifies the frequency offset in parts-per-million
(PPM) with default the value in the frequency file.
huffpuff huffpuff
Spedifies the huff-n'-puff filter span, which deter-
mines the most recent interval the algorithm will
search for a minimum delay. The lower limit is 900 s
(15 m), but a more reasonable value is 7200 (2 hours).
panic panic
Spedifies the panic threshold in seconds with default
1000 s. If set to zero, the panic sanity check is dis-
abled and a clock offset of any value will be accepted.
step step
Spedifies the step threshold in seconds. The default
without this command is 0.128 s. If set to zero, step
adjustments will never occur. Note: The kernel time
discipline is disabled if the step threshold is set to
zero or greater than 0.5 s and the threshold is applied
also to leap second corrections.
stepback step
Specifies the step threshold, but only in the backward
direction.
stepfwd step
Specifies the step threshold, but only in the forward
direction. To avoid problems with frequency stabiliza-
tion after large slews it's not recommended to set one
direction to a value greater than 0.5 s without setting
also the other direction to at least 0.5 s.
stepout stepout
Specifies the stepout threshold in seconds. The default
without this command is 900 s. If set to zero, popcorn
spikes will not be suppressed.
tos [ beacon beacon | ceiling ceiling | cohort {0 | 1} | floor floor |
maxclock maxclock | maxdist maxdist | minclock minclock | mindist
mindist | minsane minsane | orphan stratum ]
This command alters certain system variables used by the the
clock selection and clustering algorithms. The default values
of these variables have been carefully optimized for a wide
range of network speeds and reliability expectations. Very
rarely is it necessary to change the default values; but, some
folks can't resist twisting the knobs. It can be used to select
the quality and quantity of peers used to synchronize the sys-
tem clock and is most useful in dynamic server discovery
schemes. The options are as follows:
beacon beacon
The manycast server sends packets at intervals of 64 s
if less than maxclock servers are available. Otherwise,
it sends packets at the beacon interval in seconds. The
default is 3600 s. See the Automatic Server Discovery
page for further details.
ceiling ceiling
Specify the maximum stratum (exclusive) for acceptable
server packets. The default is 16. See the Automatic
Server Discovery page for further details.
cohort { 0 | 1 }
Specify whether (1) or whether not (0) a server packet
will be accepted for the same stratum as the client.
The default is 0. See the Automatic Server Discovery
page for further details.
floor floor
Specify the minimum stratum (inclusive) for acceptable
server packest. The default is 1. See the Automatic
Server Discovery page for further details.
maxclock maxclock
Specify the maximum number of servers retained by the
server discovery schemes. The default is 10. See the
Automatic Server Discovery page for further details.
maxdist maxdistance
Specify the synchronization distance threshold used by
the clock selection algorithm. The default is 1.5 s.
This determines both the minimum number of packets to
set the system clock and the maximum roundtrip delay.
It can be decreased to improve reliability or increased
to synchronize clocks on the Moon or planets.
minclock minclock
Specify the number of servers used by the clustering
algorithm as the minimum to include on the candidate
list. The default is 3. This is also the number of
servers to be averaged by the combining algorithm.
mindist mindistance
Specify the minimum distance used by the selection and
anticlockhop algorithm. Larger values increase the tol-
erance for outliers; smaller values increase the selec-
tivity. The default is .001 s. In some cases, such as
reference clocks with high jitter and a PPS signal, it
is useful to increase the value to insure the intersec-
tion interval is always nonempty.
minsane minsane
Specify the number of servers used by the selection
algorithm as the minimum to set the system clock. The
default is 1 for legacy purposes; however, for critical
applications the value should be somewhat higher but
less than minclock.
orphan stratum
Specify the orphan stratum with default 16. If less
than 16 this is the stratum assumed by the root
servers. See the Association Management page for fur-
ther details.
trap host_address [port port_number] [interface interfSace_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.
dscp dscp
This command specifies the Differentiated Services Code Point
(DSCP) value that is used in sent NTP packets. The default
value is 48 for Class Selector 6 (CS6).
SEE ALSO
ntp.conf(5)
The official HTML documentation.
This file was automatically generated from HTML source.
ntp_misc(5)
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