ntp_misc(5) - phpMan

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 auto-
matically by the initial protocol exchanges between the client and server. In some
cases, the calibration procedure may fail due to network or server access con-
trols, 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 com-
mand linke option. If the file exists, it is read at startup in order to set the
initial frequency and then updated once per hour or more with the current fre-
quency 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.

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 multicastclient 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 available, 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 fur-
ther information. The default for this flag is disable.

includefile includefile
This command allows additional configuration commands to be included from a sepa-
rate file. Include files may be nested to a depth of five; upon reaching the end
of any include file, command 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[/pre-
fixlen]]
This command controls which network addresses ntpd opens, and whether input is
dropped without processing. The first parameter 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, pre-
fixlen 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. inter-
face 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 current 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 pre-
fixed 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 mes-
sages (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 mes-
sages 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 fol-
lowing minimum message configuration could be useful: logconfig =syncall +clockall
This configuration will list all clock information and synchronization informa-
tion. All other events and messages about peers, system events and so on is sup-
pressed.

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 num-
ber, 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 variables 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 variables
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 variables.

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 algo-
rithm. The default values of these variables have been carefully optimized for a
wide range of network speeds and reliability expectations. Very rarely is it nec-
essary 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 determines 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 disabled 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 cor-
rections.

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 stabilization after large slews it's not recom-
mended 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 com-
mand 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 system clock and is most useful in dynamic server discov-
ery schemes. The options are as follows:

beacon beacon
The manycast server sends packets at intervals of 64 s if less than max-
clock servers are available. Otherwise, it sends packets at the beacon
interval in seconds. The default is 3600 s. See the Automatic Server Dis-
covery 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 min-
imum 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 algo-
rithm. Larger values increase the tolerance for outliers; smaller values
increase the selectivity. 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 intersection interval is always nonempty.

minsane minsane
Specify the number of servers used by the selection algorithm as the mini-
mum to set the system clock. The default is 1 for legacy purposes; how-
ever, 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 further 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 num-
ber is unspecified, a value of 18447 is used. If the interface address is not
specified, the message is sent with a source address of the local interface the
message is sent through. Note that on a multihomed 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).