Question How do I know if I have a safe version of NTP on a Linux server?
Background The United States Computer Emergency Readiness Team's website indicates that this many versions of NTP are susceptible to a denial-of-service attack.
Answer Run this command: ntpd --version
The output should look something like this:
If it is lower than that (e.g., ntpd 4.2.8p8), then you need to upgrade your ntp version.