What Is the Network Time Protocol?

Network Time Protocol, English name: Network Time Protocol (NTP) is a protocol used to synchronize computer time. It can enable a computer to synchronize its server or clock source (such as quartz clock, GPS, etc.). It can Provides highly accurate time correction (the difference between the LAN and the standard is less than 1 millisecond, and tens of milliseconds on the WAN), and can be used to prevent malicious protocol attacks through encryption and confirmation. The purpose of NTP is to provide accurate and robust time services in a disordered Internet environment.

NTP provides accurate time. First of all, there must be an accurate time source. This time should be

For many reasons it is important to maintain accurate time throughout the network. Even small time errors can cause big problems. For example, rely on coordinated time to ensure that the allocation process takes place in order. Security mechanisms rely on the coordinated time of the entire network. File system updates performed by multiple computers rely on time synchronization. The air control system provides descriptions of airspace images and also requires time synchronization. Since the flight path requires very precise time (think of it, what would happen if the air-controlled computer time was not synchronized).

UTC time is obtained using a number of different methods, including

The first implementation of the Network Time Protocol (NTP) is documented in the Internet Engineering Note, and its accuracy is hundreds of milliseconds. Later came the first time protocol specification, RFC-778, which was named DCNET Internet Time Service, and it provided this service by means of the Internet control Message Protocol (ICMP), which is

To adapt to the hierarchical structure of the Internet, NTP uses a hierarchical time distribution model. The network structure of the NTP system includes a master time server and a slave time.

Figure 2 shows the processing flow of NTP on a synchronization node. ^[3]

NTP was first implemented in 1980, when the synchronization accuracy was only a few hundred ms. In 1989, Dennis Fergusson of the University of Toronto developed an implementation based on NTP version 2 (RFC 1119) called xntp. xntp is a major implementation of NTP that is currently publicly available, and has now evolved to version 3.5. xntp supports most UNIX systems, such as: AIX, HP-UX, Irix, Linux, SCO UNIX, Solaris, etc. Currently the latest 3.5.93 version has started to support Windows 2000 / NT. Widnows2000 / NT itself also provides an SNTP-based time service. But Widnows2000 / NT's time service is only used to provide time reference for its authentication process, and its synchronization accuracy is only 2s. ^[3]

xntp has the following main features: (1) all the functions of NTP are realized; (2) even if the network connection is temporarily unavailable, xntp can use the past data to calculate the clock drift and automatically correct it; (3) xntp can obtain the local clock An estimate of quality; (4) xntp also includes a system interface and a variety of drivers for synchronizing the computer clock with an external clock (GPS receiver, Mode receiver, etc.). ^[3]

The configuration of xntp includes setting the working mode, setting the server address, whether to enable authentication, configuring frequency drift data files, and adjusting parameters used for the local clock. For specific methods and configuration procedures, see the xntp documentation. ^[3]