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

Setting up and configuring of Postfix mail server


As we all know, Postfix as an MTA acts, as an SMTP server. It accepts incoming mail and passes it to the service responsible for retrieving mails. Then it forwards outgoing mails to the next responsible SMTP server. For the SMTP service, we need to have the port 25/TCP open in the system's firewall. Postfix is very easy to set up and configure. We only need to make sure that some pre-installation steps have been done in order to have a clean setup.

First, we need to open the required port at the firewall for all the needed services for a mail server, using Firewalld. The ports we are going to open are from the following services:

  • Simple Mail Transfer Protocol (SMTP): 25 on TCP

  • Secure SMTP (SMTPS): 465 on TCP

  • Mail Submission Agent (MSA): 587 on TCP

  • Post Office Protocol 3 (POP3): 110 on TCP

  • Secure POP3: 995 on TCP

  • Internet Message Access Protocol (IMAP): 143 on TCP

  • Secure IMAP (IMAP SSL): 993 on TCP

    This is how to apply the change in the system...