Book Image

Ubuntu 20.04 Essentials

By : Neil Smyth
Book Image

Ubuntu 20.04 Essentials

By: Neil Smyth

Overview of this book

Ubuntu is undeniably one of the most highly regarded and widely used Debian-based Linux distributions available today. Thanks to its ease of use and reliability, Ubuntu has a loyal following of Linux users and an active community of developers. Ubuntu 20.04 Essentials is designed to take you through the installation, use, and administration of the Ubuntu 20.04 distribution in detail. For beginners, the book covers topics such as operating system installation, the basics of the GNOME desktop environment, configuring email and web servers, and installing packages and system updates. Additional installation topics such as dual booting with Microsoft Windows are also covered along with crucial security topics such as configuring a firewall and user and group administration. For the experienced user, the book delves into topics such as remote desktop access, the Cockpit web interface, logical volume management (LVM), disk partitioning, and swap management. Further, it also explores KVM virtualization, Secure Shell (SSH), Linux containers, and file sharing using both Samba and NFS to provide a thorough overview of this enterprise-class operating system.
Table of Contents (38 chapters)
38
Index

17.3 Configuring Firewall Rules with firewall-cmd

The firewall-cmd command-line utility allows information about the firewalld configuration to be viewed and changes to be made to zones and rules from within a terminal window.

When making changes to the firewall settings, it is important to be aware of the concepts of runtime and permanent configurations. By default, any rule changes are considered to be runtime configuration changes. This means that while the changes will take effect immediately, they will be lost next time the system restarts or the firewalld service reloads, for example by issuing the following command:

# firewall-cmd --reload

To make a change permanent, the --permanent command-line option must be used. Permanent changes do not take effect until the firewalld service reloads but will remain in place until manually changed.

17.3.1 Identifying and Changing the Default Zone

To identify the default zone (in other words the zone to which all interfaces...