Log Message:
Update ntp4 to 4.2.8p9.

Here is quote from NEWS file and please refer it in detail.

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NTP 4.2.8p9 (Harlan Stenn <stenn@ntp.org>, 2016/11/21)

Focus: Security, Bug fixes, enhancements.

Severity: HIGH

In addition to bug fixes and enhancements, this release fixes the
following 1 high- (Windows only), 2 medium-, 2 medium-/low, and
5 low-severity vulnerabilities, and provides 28 other non-security
fixes and improvements: