NTP users are strongly urged to take immediate action to ensure that their NTP daemons are not susceptible to being used in distributed denial-of-service (DDoS) attacks. Please also take this opportunity to defeat denial-of-service attacks by implementing Ingress and Egress filtering through BCP38.
ntp-4.2.8p15 was released on 23 June 2020. It addresses 1 medium-severity security issue in ntpd, and provides 13 non-security bugfixes over 4.2.8p13.
Are you using Autokey in production? If so, please contact Harlan - he's got some questions for you.
Reading the System Clock
There are two interesting numbers here, the precision of the clock and the time it takes to read the clock. These serve as a floor to the jitter component. This also helps to make sure we don't divide by zero...
DLM says that the next leap forward on lowering the floor will happen when it takes less than 100nsec to read the clock.
is the time it takes to read the clock in nanoseconds (it's an integer type), and
is the same thing in a floating type but in usec.
is log2 of
Some systems have
and it behaves differently on different OSes. NTP generally uses
for its operations, but on some OSes that value will not give use the information we want: