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.
Instead of a worst-case delay use a mean value and relate it to the
source's time. This makes it more stable in the interleaved and
symmetric modes, which should improve the weighting and asymmetry
correction. Modify the test A and B to work with a minimum estimated
delay (delay - dispersion).
Change default minsamples to 6 and polltarget to 8. This should improve
stability with extremely small jitters (e.g. HW timestamping) and not
decrease time accuracy at minimum polling interval too much.
This option sets a timeout (in seconds) after which chronyd will exit.
If the clock is not synchronised, it will exit with a non-zero status.
This is useful with the -q or -Q option to shorten the maximum time
waiting for measurements, or with the -r option to limit the time when
chronyd is running, but still allow it to adjust the frequency of the
system clock.
If the MAC in NTPv4 requests would be truncated, use version 3 by
default to avoid the truncation. This is necessary for compatibility
with older chronyd servers, which do not respond to messages with
truncated MACs.
In order to allow deterministic parsing of NTPv4 extension fields, the
MAC must not be longer than 192 bits (RFC 7822). One way to get around
this limitation when using symmetric keys which produce longer MACs is
to truncate them to 192 bits (32-bit key ID and 160-bit hash).
Modify the code to accept NTPv4 packets with MACs truncated to 192
bits, but still allow long MACs in NTPv4 packets to not break
compatibility with older chrony clients.
This is an incompatible change in the output of the tracking command,
which may break some scripts, but it's necessary to avoid confusion with
IPv4 addresses when synchronised to an IPv6 server or reference clock.
In a burst of three requests (two presend + one normal) the server can
detect the client is using the interleaved mode and save the transmit
timestamp of the second response for the third response. This shortens
the interval in which the server has to keep the state.
Rework the code to make a real request for presend and process the
response, but don't accumulate the sample. This allows presend to work
in the interleaved client mode.
In unauthenticated interleaved symmetric NTP mode we should be now
careful with the reference timestamp as it may be useful with the peer
delay for estimating the local receive timestamp and increasing the
chance of spoofing a valid response from the peer.
When updating the reference time, add a random error of up to one second
to make it less sensitive when disclosed to NTP and cmdmon clients.
