Patch NTP against DoS, again

The Network Time Protocol (NTP) organisation pushed out a bunch of patches last Thursday, including one high-severity bug. The vulnerabilities in question are CVE-2016-4957 (another vulnerability in Crypto-NAK found by Cisco), and from Red Hat there's CVE-2016-4953 (an authentication bug), CVE-2016-4954 (server packet spoofing …