What firewall settings do I need to use NTP (Network Time Protocol)?

To use a Network Time Protocol (NTP) client or server on your system you need to have access to port 123 both incoming and outgoing between any client and the server that it is communicating with. The startup script for the NTP service should create the firewall holes on your machine automatically. You will have to ensure that all points along the route between the client and the server will a...