NTP Security

NTP security uses "restrict ..." lines in the NTP configuration file to allow you to restrict, by IP address range, which NTP features hosts (including your own host) can use or access. That means that if you want to restrict remote access to features that you wish to use locally, you must also include the following configuration line (since no restrictions are listed, the local host has unrestricted access; see the NTP documentation):

	restrict  127.0.0.1

You can also control access to other hosts or subnets. E.g., to give unrestricted access to all hosts on the 192.168.0 subnet:

	restrict  192.168.0.0  mask  255.255.255.0

Then, you can set the default access restrictions for all other hosts. We recommend the following configuration line:

	restrict  default  nomodify  nopeer

To see the restriction list at run-time, use the following commands to the ntpdc program (note that there are additional entries which you should not delete):

	> ntpdc
	ntpdc>  reslist
	ntpdc>  quit