I have a few servers with public Internet IP addresses like
A.B.C.x. One of my hosts (
A.B.C.10) runs ntpd and I have it syncing it's time from europe.pool.ntp.org.
Now I only want to allow hosts from my subnet (
A.B.C.x) to be able to sync to
A.B.C.10. By default the whole world can sync to my NTP server. How do I accomplish this?
All examples I can find assume that I'm syncing to specific IP addresses but I sync to DNS names and as far as I can tell the IP addresses that the DNS names
x.europe.pool.ntp.org point to are variable. So I can't setup exceptions in my firewall and I can't use the
restrict option in ntp.conf because it too only accepts IP addresses and not DNS names (Oh! and
restrict applies both to clients and to servers as firewall rules do!)