Book Image

Ubuntu Server Cookbook

By : Uday Sawant
Book Image

Ubuntu Server Cookbook

By: Uday Sawant

Overview of this book

Ubuntu is one of the most secure operating systems and defines the highest level of security as compared other operating system. Ubuntu server is a popular Linux distribution and the first choice when deploying a Linux server. It can be used with a $35 Raspberry Pi to top-notch, thousand-dollar-per-month cloud hardware. Built with lists that there are 4 million + websites built using Ubuntu. With its easy-to-use package management tools and availability of well-known packages, we can quickly set up our own services such as web servers and database servers using Ubuntu. This book will help you develop the skills required to set up high performance and secure services with open source tools. Starting from user management and an in-depth look at networking, we then move on to cover the installation and management of web servers and database servers, as well as load balancing various services. You will quickly learn to set up your own cloud and minimize costs and efforts with application containers. Next, you will get to grips with setting up a secure real-time communication system. Finally, we’ll explore source code hosting and various collaboration tools. By the end of this book, you will be able to make the most of Ubuntu’s advanced functionalities.
Table of Contents (20 chapters)
Ubuntu Server Cookbook
Credits
About the Author
www.PacktPub.com
Preface
Index

Being on time with NTP


Network Time Protocol (NTP) is a TCP/IP protocol for synchronizing time over a network. Although Ubuntu has a built-in clock that is helpful for keeping track of local events, it may create issues when the server is connected over a network and provides time-critical services to the clients. This problem can be solved with the help of NTP time synchronization. NTP works by synchronizing time across all servers on the Internet.

NTP uses hierarchies of servers with top-level servers synchronizing time with atomic clocks. This hierarchy levels are known as stratum, and the level can range between 1 and 15, both inclusive. The highest stratum level is 1 and is determined by the accuracy of the clock the server synchronizes with. If a server synchronizes with other NTP server with stratum level 3, then the stratum level for this server is automatically set to 4.

Another time synchronization tool provided by Ubuntu is ntpdate, which comes preinstalled with Ubuntu. It executes...