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-4.2.8p7was released on 26 April 2016. It addresses 11 low- and medium-severity security issues, 16 bugfixes, and contains other improvements over 4.2.8p6.
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.
ntp.keysfile that specifies the list of IPs that are allowed to serve time. Note that this alone will not protect against time packets with forged source IP addresses, however other changes in ntp-4.2.8p6 provide significant mitigation against broadcast attacks. MITM attacks are a different story.