Chapter 24. The NTP Server

In This Chapter

• Download and Install the NTP Package

• The /etc/ntp.conf File

• How to Get NTP Started

• Testing and Troubleshooting NTP

• Configuring Cisco Devices to Use an NTP Server

• Firewalls and NTP

• Configuring a Windows NTP Client

• Conclusion

The Network Time Protocol (NTP) is a protocol used to help synchronize your Linux system's clock with an accurate time source. There are a number of sites that allow the general public to synchronize with them. They are divided into two types:

• Stratum 1: NTP sites using an atomic clock for timing

• Stratum 2: NTP sites with slightly less accurate time sources

It is good practice to have at least one server on your network be the local time server for all your other devices. This makes the correlation of system events on different systems much easier. It also reduces Internet bandwidth usage due to NTP traffic and reduces the need to manage firewall rules for each NTP client on your network. Sometimes, not all your servers will have Internet access; in such cases, you'll need a central server that all can access. For a list of available Stratum 1 and 2 servers, consult www.ntp.org.