Book Image

Mastering CentOS 7 Linux Server

By : Mohamed Alibi, BHASKARJYOTI ROY
Book Image

Mastering CentOS 7 Linux Server

By: Mohamed Alibi, BHASKARJYOTI ROY

Overview of this book

Most server infrastructures are equipped with at least one Linux server that provides many essential services, both for a user's demands and for the infrastructure itself. Setting up a sustainable Linux server is one of the most demanding tasks for a system administrator to perform. However, learning multiple, new technologies to meet all of their needs is time-consuming. CentOS 7 is the brand new version of the CentOS Linux system under the RPM (Red Hat) family. It is one of the most widely-used operating systems, being the choice of many organizations across the world. With the help of this book, you will explore the best practices and administration tools of CentOS 7 Linux server along with implementing some of the most common Linux services. We start by explaining the initial steps you need to carry out after installing CentOS 7 by briefly explaining the concepts related to users, groups, and right management, along with some basic system security measures. Next, you will be introduced to the most commonly used services and shown in detail how to implement and deploy them so they can be used by internal or external users. Soon enough, you will be shown how to monitor the server. We will then move on to master the virtualization and cloud computing techniques. Finally, the book wraps up by explaining configuration management and some security tweaks. All these topics and more are covered in this comprehensive guide, which briefly demonstrates the latest changes to all of the services and tools with the recent shift from CentOS 6 to CentOS 7.
Table of Contents (16 chapters)
Mastering CentOS 7 Linux Server
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Preface
Index

Restricting access to su or sudo


We can restrict a user from running the su or sudo commands by changing the user's SELinux user mapping like this:

semanage login -a -s user_u test

The preceding command will change the Linux test user's mapping to user_u and will not allow the su or sudo commands access.

Note

This will only take effect when the user is not logged in.

Restricting permissions to run scripts

To restrict the Linux test user's ability to run scripts we have to do two things. First, we change the user's mapping to guest_u, the same way as we did previously:

semanage login -a -s guest_u test

By default, SELinux allows users mapped to guest_t to execute scripts from their home directories. We can confirm the same using the following command:

getsebool allow_guest_exec_content

It will show that guest_exec_content is on. So, the second step is that we disable the guest_exec_content using this:

setsebool allow_guest_exec_content off

Now, the test user for whom we changed the mapping won...