# coarse time ref-clock, not really needed here as we have LAN & WAN servers
server 127.127.28.0 minpoll 4 maxpoll 4
fudge 127.127.28.0 time1 +0.350 refid GPS stratum 15
# Kernel-mode PPS ref-clock for the precise seconds
server 127.127.22.0 minpoll 4 maxpoll 4
fudge 127.127.22.0 refid PPS
# LAN servers
server 192.168.0.3 minpoll 5 maxpoll 5 iburst prefer
server 192.168.0.2 minpoll 5 maxpoll 5 iburst
server 192.168.0.7 minpoll 5 maxpoll 5 iburst
remote refid st t when poll reach delay offset jitter
*127.127.20.1 .GPS. 0 l 16 16 377 0.000 0.002 0.001
127.127.1.0 .LCK. 0 l - 16 377 0.000 0.000 0.001
NTP-SERVER:/#cat /etc/ntp.conf|grep -v "^#"|grep '[a-z]'
server 127.127.20.1 prefer mode 17 minpoll 4
fudge 127.127.20.1 stratum 0 refid GPS flag2 1 flag3 1
server 127.127.1.0 minpoll 4 maxpoll 4
fudge 127.127.1.0 stratum 0 refid LCK
logconfig =clockevents +syncevents +sysevents +clockall +syncall +sysall
The fudge command is used to provide additional information for individual clock drivers and normally follows immediately after the server command. The address
argument specifies the clock address. The refid and stratum options control can be used to override the defaults for the device. There are two optional device-
dependent time offsets and four flags that can be included in the fudge command as well.
The stratum number of a reference clock is by default zero. Since the ntpd daemon adds one to the stratum of each peer, a primary server ordinarily displays an
external stratum of one. In order to provide engineered backups, it is often useful to specify the reference clock stratum as greater than zero. The stratum option
is used for this purpose. Also, in cases involving both a reference clock and a pulse-per-second (PPS) discipline signal, it is useful to specify the reference
clock identifier as other than the default, depending on the driver. The refid option is used for this purpose. Except where noted, these options apply to all clock
REFERENCE CLOCK COMMANDS
server 127.127.t.u [prefer] [mode int] [minpoll int] [maxpoll int]
This command can be used to configure reference clocks in special ways. The options are interpreted as follows:
prefer Marks the reference clock as preferred. All other things being equal, this host will be chosen for synchronization among a set of correctly operat‐
ing hosts. See the Mitigation Rules and the prefer Keyword page for further information.
Specifies a mode number which is interpreted in a device-specific fashion. For instance, it selects a dialing protocol in the ACTS driver and a
device subtype in the parse drivers.
These options specify the minimum and maximum polling interval for reference clock messages in seconds, interpreted as dual logarithms (2 ^ x). For
most directly connected reference clocks, both minpoll and maxpoll default to 6 (2^16 = 64 s). For modem reference clocks, minpoll defaults to 10
(2^10 = 1024 s = 17.1 m) and maxpoll defaults to 14 (2^14 = 16384 s = 4.5 h). The allowable range is 4 (16 s) to 17 (36.4 h) inclusive.
fudge 127.127.t.u [time1 sec] [time2 sec] [stratum int] [refid string] [flag1 0|1] [flag2 0|1] [flag3 0|1] [flag4 0|1]
This command can be used to configure reference clocks in special ways. It must immediately follow the server command which configures the driver. Note that
the same capability is possible at run time using the ntpdc program. The options are interpreted as follows:
Specifies a constant to be added to the time offset produced by the driver, a fixed-point decimal number in seconds. This is used as a calibration
constant to adjust the nominal time offset of a particular clock to agree with an external standard, such as a precision PPS signal. It also pro‐
vides a way to correct a systematic error or bias due to serial port or operating system latencies, different cable lengths or receiver internal
delay. The specified offset is in addition to the propagation delay provided by other means, such as internal DIPswitches. Where a calibration for
an individual system and driver is available, an approximate correction is noted in the driver documentation pages. Note: in order to facilitate
calibration when more than one radio clock or PPS signal is supported, a special calibration feature is available. It takes the form of an argument
to the enable command described in the Miscellaneous Options page and operates as described in the Reference Clock Drivers page.
Specifies a fixed-point decimal number in seconds, which is interpreted in a driver-dependent way. See the descriptions of specific drivers in the
reference clock drivers page.
Specifies the stratum number assigned to the driver, an integer between 0 and 15. This number overrides the default stratum number ordinarily
assigned by the driver itself, usually zero.
Specifies an ASCII string of from one to four characters which defines the reference identifier used by the driver. This string overrides the
default identifier ordinarily assigned by the driver itself.
flag1 flag2 flag3 flag4
These four flags are used for customizing the clock driver. The interpretation of these values, and whether they are used at all, is a function of
the particular clock driver. However, by convention flag4 is used to enable recording monitoring data to the clockstats file configured with the
filegen command. Further information on the filegen command can be found in the Monitoring Options page.