r2 - 2008-08-30 - 01:40:36 - HarlanStennYou are here: NTP >  Dev Web > DevelopmentIssues > NtpdsSyncStatus
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.

Please see the NTP Security Notice for vulnerability and mitigation details.

Are you using Autokey in production? If so, please contact Harlan - he's got some questions for you.

The Synchronization Status of ntpd

There is a need to be able to easily and consistently determine if system clock and/or ntpd 's idea of its internal state and the system clock are "correct" (for some definition of correct).

To offer this ability, it seems to me that the first thing we need to nail down is the definition and specification of "correct".

The definition of 'correct' time

How about the following:

  • The decoded system status bits contain sync_ntp
  • (obsolete) ntpd is in state S_SYNC (which Dave is renaming to EVNT_SYNC)
  • any slew adjustment in-process is under X (where X is configurable)

  • Do we care about the root dispersion?
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