NTP users are strongly urged to take immediate action to ensure that their NTP daemons are not susceptible to use in a distributed denial-of-service (DDoS) attack. Please also take this opportunity to defeat denial-of-service attacks by implementing ingress and Egress filtering through BCP38.
A new set of mode 6 vulnerabilities has been discovered and, while these vulnerabilities can be reduced by making sure you have
restrict default … noquery in your
ntp.conf file, the best and most complete way to avoid these vulnerabilities is to install and deploy
ntp-4.2.8 which was released on 18 December 2014.
Are you using Autokey in production? If so, please contact Harlan - he's got some questions for you.
NTP Pool Time Servers
uses DNS round robin to make a random selection from a pool of time servers who have volunteered
to be in the pool. This is usually good enough for end-users. The minimal
configuration file (e.g.
) for using pool.ntp.org
Any questions about the pool.ntp.org server pool should be directed either to the pool mailing list
or to the comp.protocols.time.ntp usenet newsgroup.
Time server operators are encouraged to visit the NTP Pool
web-site to find out how they can join the NTP pool.
The NTP Pool DNS system automatically picks time servers which are geographically close for you, but if you want to choose explicitly, there are sub-zones of pool.ntp.org. The "continent" ones are:
There are also sub-zones for many countries. Click on your continent to see which country-zones are available there.
When using the by-country zones, be careful: some of them currently contain only one or two servers, so you are probably better off using either the zone of a nearby country, or using the continent or global zone (This is sometimes also valid if you live in a big country). In general though, just use the "global" zone as in the suggested configuration near the top of the page and let the system sort it out for you.
Related topics: RulesOfEngagement