Network Firewall Tools on CentOS

Provides quick descriptions on 3 major network firewall tools, 'firewalld/fireall-cmd', 'nftables/nft', and 'iptables' on CentOS 8 systems.

After connecting your CentOS system to the Internet, you need to review and revise firewall settings to protect your system.

CentOS system uses a number tools to manage the network firewall. Here are 3 major ones:

1. "firewalld" and "fireall-cmd" - A firewall daemon and a CLI (Command Line Interface) works together as a frontend tool to manage the network firewall. "firewalld" uses "nftables/iptables" as the backend engine.

2. "nftables" and "nft" - A firewall daemon and a CLI (Cammand Line Interface) works together as a backend engine for packet filtering and classification. "nftables" uses "/etc/nftables" directory to store its rules. "nftables" is installed on CentOS 8 by default to replace "iptables".

3. "iptables" - A basic administration tool for IPv4/IPv6 packet filtering and NAT (Network Address Translation) in the Linux kernel. "iptables" uses "/usr/sbin/iptables" to store its rules. "iptables" is now replaced by "nftables" on CentOS 8 systems.

Here is diagram that shows how firewalld, nftables/iptables and other tools are related to each other (source: https://firewalld.org).

CentOS Firewall Tools - firewalld and nftables/iptables
CentOS Firewall Tools - firewalld and nftables/iptables

Table of Contents

 About This Book

 Introduction to Linux Systems

 Cockpit - Web Portal for Administrator

 Process Management

 Files and Directories

 Users and Groups

 File Systems

 Block Devices and Partitions

 LVM (Logical Volume Manager)

 Installing CentOS

 SELinux - Security-Enhanced Linux

Network Connection on CentOS

 Setup Ethernet Connection on CentOS

Network Firewall Tools on CentOS

 "firewalld" and "firewall-cmd" on CentOS

 Manage Multiple Firewall Zones

 "nftables" and "nft" on CentOS

 "iptables" Command on CentOS

 "nmap" - Network Mapper on CentOS

 Monitor Network Services on CentOS

 Software Package Manager on CentOS - DNF and YUM

 Running Apache Web Server (httpd) on Linux Systems

 Running PHP Scripts on Linux Systems

 Running MySQL Database Server on Linux Systems

 Running Python Scripts on Linux Systems

 vsftpd - Very Secure FTP Daemon

 Postfix - Mail Transport Agent (MTA)

 Dovecot - IMAP and POP3 Server

 Email Client Tools - Mail User Agents (MUA)

 LDAP (Lightweight Directory Access Protocol)

 GCC - C/C++ Compiler

 Conda - Environment and Package Manager

 Tools and Utilities

 Administrative Tasks

 References

 Full Version in PDF/EPUB