If no rxfilter is specified in the hwtimestamp directive and the NIC
doesn't support the all or ntp filter, enable TX-only HW timestamping
with the none filter.
If the -Q option is specified, disable by default pidfile, ntpport,
cmdport, Unix domain command socket, and clock control, in order to
allow starting chronyd without root privileges and/or when another
chronyd instance is already running.
Add an rxfilter option to the hwtimestamp directive to select which
received packets should be timestamped. It can be set to "none", "ntp",
or "all". The default value is ntp, which falls back to all when ntp is
not supported.
Always write the measurement history on exit when the dump directory is
specified and silently ignore the dumponexit directive. There doesn't
seem to be a good use case for dumpdir and -r without dumponexit as the
history would be invalidated by adjustments of the clock that happened
between the dump command and chronyd exit.
While the measurements log can be useful for debugging problems in NTP
configuration (e.g. authentication failures with symmetric keys), it
seems most users are interested only in valid measurements (e.g. for
producing graphs) and don't expect/handle entries where some of the RFC
5905 tests 1-7 failed. Modify the measurements log option to log only
valid measurements, and for debugging purposes add a new rawmeasurements
option.
This reverts commit 50022e9286.
Testing showed that ntpd as an NTP client performs poorly when it's
getting only 25% of responses. At least for now, disable rate limiting
by default again.
Change the default interval of both NTP and command rate limiting to -10
(1024 packets per second) and the burst to 16. The default NTP leak is 2
(rate limiting is enabled by default) and the default command leak is 0
(rate limiting is disabled by default).
The maxjitter directive sets the maximum allowed jitter of the sources
to not be rejected by the source selection algorithm. This prevents
synchronisation with sources that have a small root distance, but their
time is too variable. By default, the maximum jitter is 1 second.
Add a new directive to specify interfaces which should be used for HW
timestamping. Extend the Linux ntp_io initialization to enable HW
timestamping, configure the RX filter using the SIOCSHWTSTAMP ioctl,
open their PHC devices, and track them as hwclock instances. When
messages with HW timestamps are received, use the PTP_SYS_OFFSET ioctl
to make PHC samples for hwclock.
Add support for authenticating MS-SNTP responses in Samba (ntp_signd).
Supported is currently only the old MS-SNTP authenticator field. It's
disabled by default. It can be enabled with the --enable-ntp-signd
configure option and the ntpsigndsocket directive, which specifies the
location of the Samba ntp_signd socket.
Since the update to NTPv4, when the clock is in the synchronised state
and the clock updates stop (e.g. sources become unreachable), it doesn't
switch to the unsynchronised state and the local reference is never
activate. This can be a problem for clients that rely on the server to
always have root distance below some value (e.g. chronyd's maxdistance).
Add a timer that will activate the local reference when the root
distance reaches a specified threshold. It can be configured with the
distance option in the local directive (by default 1.0 second).
Add maxdrift directive to set the maximum assumed drift of the clock,
which sets the maximum frequency offset chronyd is allowed to use to
to correct the drift.
When the measured NTP or command request rate of a client exceeds
a threshold, reply only to a small fraction of the requests to reduce
the network traffic. Clients are allowed to send a burst of requests.
Try to detect broken clients which increase the request rate when not
getting replies and suppress the rate limiting for them.
Add ratelimit and cmdratelimit directives to configure the thresholds,
bursts and leak rates independently for NTP and command response rate
limiting. Both are disabled by default. Commands from localhost are
never limited.
Add maxdistance directive to set the maximum root distance the sources
are allowed to have to be selected. This is useful to reject NTPv4
sources that are no longer synchronized and report large dispersion.
The default value is 3 seconds.
Create logdir and dumpdir before dropping root. Set their uid/gid to the
user chronyd will switch to. This allows chronyd to create the
directories in a directory where the user won't have write permissions
(e.g. /var/lib).
In addition to the IPv4/IPv6 command sockets, create also a Unix domain
socket to process cmdmon requests. For now, there is no difference for
authorized commands, packets from all sockets need to be authenticated.
The default path of the socket is /var/run/chrony/chronyd.sock. It can
be configured with the bindcmdaddress directive with an address starting
with /.
The leaponly option can be used to enable a mode where only leap seconds
are smoothed out and normal offset/frequency changes are ignored. This
is useful to make the interval in which a leap second is smoothed out
constant and allow an NTP client to use multiple leap smearing servers
safely.
Time smoothing determines an offset that needs to be applied to the
cooked time to make it smooth for external observers. Observed offset
and frequency change slowly and there are no discontinuities. This can
be used on an NTP server to make it easier for the clients to track the
time and keep their clocks close together even when large offset or
frequency corrections are applied to the server's clock (e.g. after
being offline for longer time).
Accumulated offset and frequency are smoothed out in three stages. In
the first stage, the frequency is changed at a constant rate (wander) up
to a maximum, in the second stage the frequency stays at the maximum for
as long as needed and in the third stage the frequency is brought back
to zero.
Time smoothing is configured by the smoothtime directive. It takes two
arguments, maximum frequency offset and maximum wander. It's disabled by
default.
In addition to the system driver handling add new modes to slew or step
the system clock for leap second, or ignore it completely. This can be
configured with leapsecmode directive.
In addition to the quadratic function, allow configuration of the
compensation with a file containing list of (temperature, compensation)
points used for linear interpolation and extrapolation.
This should reduce the number of possible memory leaks reported by
valgrind. The remaining reported leaks are sched tqe allocation, async
DNS instance allocation, cmdmon response/timestamp cell allocation, and
clientlog subnet allocation.
Since the kernel USER_HZ constant was introduced and the internal HZ
can't be reliably detected in user-space, the frequency scaling constant
used with older kernels is just a random guess.
Remove the scaling completely and let the closed loop compensate for the
error. To prevent thrashing between two states when the system's
frequency error is close to a multiple of USER_HZ, stick to the current
tick value if it's next to the new required tick. This is used only on
archs where USER_HZ is 100 as the frequency adjustment is limited to 500
ppm.
The linux_hz and linux_freq_scale directives are no longer supported,
but allowed by the config parser.
With the generic driver, the maxslewrate directive sets the maximum
frequency offset that the driver is allowed to use to slew the time. By
default, it's set to 83333.333 (1/12). This is identical to what Linux
fast slewing used to use.
The initstepslew code has its own minimal NTP implementation. Drop the
code, add a new initstepslew mode to the reference updating code and
use regular NTP sources with iburst flag for initstepslew addresses
instead. When an update is made or a source is found unreachable, log a
message, remove the initstepslew sources and switch to normal mode.
This reduces code duplication and makes initstepslew use features
implemented only in the main code like source combining or SO_TIMESTAMP
support.
Combine only sources whose distance is shorter than distance of the
selected source multiplied by the value of combinelimit and their
estimated frequencies are close to the frequency of the selected source.
Add outlyer status for sources which are selectable, but not included in
the combining. The status is displayed as '-' in the chronyc sources
output.
When chronyd is started with -R, the initstepslew directive and the
makestep directive with a positive limit will be ignored. This is useful
when restarting chronyd to avoid unnecessary clock adjustments. It can
be used with -r.
leapsectz directive is used to set the name of the timezone in the
system tz database which chronyd can use to find out when will the next
leap second occur. It will periodically check if dates Jun 30 23:59:60
and Dec 31 23:59:60 are valid in that timezone. This is mainly useful
with reference clocks which don't provide the leap second information.
It is not necessary to restart chronyd if the tz database is updated
with a new leap second at least 12 hours before the event.
This directive sets the maximum allowed offset corrected on a clock
update. The check is performed only after the specified number of
updates to allow a large initial adjustment of the system clock. When
an offset larger than the specified maximum occurs, it will be ignored
for the specified number of times and then chronyd will give up
and exit (a negative value can be used to never exit). In both cases
a message is sent to syslog.
