Synchronizing a UNIX PC to a Time Server Through the Network
The second method of providing external time synchronization data from a time stamp is an NTP / SNTP (Network Time Protocol / Simple Network Time Protocol) time packet from a Time Server. The connection to the Time Server is either an Ethernet cable to an available HUB or switch on the network with a straight-thru network cable or a direct connection to a NIC card (Network Interface Card) on the UNIX machine with a cross-over network cable. In these two methods, the IP address of the Time Server is used instead of using the NTP Type 4 driver. In the NTP.conf file, add a line that states: server xxx.xxx.xxx.xxx (where x is the IP address of the NTP Time Server). The NTP.conf file should be located at /etc/ntp.conf (make sure all letters are lower-case).
For detailed information on installing and configuring the client software, refer to Dr. Mill's Building and Installing the Distribution page. Below is a very basic summary of the NTP4 software:
The main part of the program is known as NTPD or the NTP daemon. Involved with the main daemon are many utility programs that work in conjunction with the main daemon (either with the daemon running or with the daemon not running). These are listed and briefly described below :
| Command |
Description |
| ntpd |
A daemon process that is both, client and server. |
| ntpdate |
A utility to set the time once, similar to the popular rdate command. The NTP Daemon needs to be stopped for this utility to operate. |
| ntpquery (ntpq), ntpdc |
Monitoring and control programs that communicate via UDP with ntpd. |
| ntptrace |
A utility to back-trace the current system time, starting from the local server. |
| peers (pe command) |
Provides a list of all Time Servers that are available for synchronization. This command will display an "*" to show the best Time Server after about 300 queries (amount of time this takes depend on the query interval, such as every 4 seconds). |