NTP Network Time Protocol How To
Most of the text in this How to is taken from the massively documented NTP package.
The Network Time Protocol (NTP) is widely used to synchronize a computer to Internet time servers. It can also be used as a server for dependent clients. It provides accuracies typically less than a millisecond on LANs and up to a few milliseconds on WANs.
Client / Server Configuration
Client/server mode is the most common configuration in the Internet today. It operates in the classic remote-procedure-call (RPC) paradigm with stateless servers and stateful clients. In this mode a host sends a client (mode 3) request to the specified server and expects a server (mode 4) reply at some future time. In some contexts this would be described as a "pull" operation, in that the host pulls the time and related values from the server.
For a Ubuntu host acting as an NTP server, typically nothing needs to be done, beyond grabbing the IP address.
Do verify ntpd is running:
If a number is returned (the PID for the ntpd daemon), then your configuration is correct.
A target device is configured in client mode as follows
NTP_SERVER=10.111.0.3 echo "server $NTP_SERVER" > /etc/ntp.conf echo "statsdir /tmp/ntp_statistics" >> /etc/ntp.conf echo "driftfile /tmp/ntp_drift" >> /etc/ntp.conf echo "iburst" >> /etc/ntp.conf chmod ugo+r /etc/ntp.conf echo "ntp 123/tcp" >> /etc/services echo "ntp 123/udp >> /etc/services