Book Image

Red Hat Enterprise Linux Troubleshooting Guide

By : Benjamin Cane
Book Image

Red Hat Enterprise Linux Troubleshooting Guide

By: Benjamin Cane

Overview of this book

Red Hat Enterprise Linux is an operating system that allows you to modernize your infrastructure, boost efficiency through virtualization, and finally prepare your data center for an open, hybrid cloud IT architecture. It provides the stability to take on today's challenges and the flexibility to adapt to tomorrow's demands. In this book, you begin with simple troubleshooting best practices and get an overview of the Linux commands used for troubleshooting. The book will cover the troubleshooting methods for web applications and services such as Apache and MySQL. Then, you will learn to identify system performance bottlenecks and troubleshoot network issues; all while learning about vital troubleshooting steps such as understanding the problem statement, establishing a hypothesis, and understanding trial, error, and documentation. Next, the book will show you how to capture and analyze network traffic, use advanced system troubleshooting tools such as strace, tcpdump & dmesg, and discover common issues with system defaults. Finally, the book will take you through a detailed root cause analysis of an unexpected reboot where you will learn to recover a downed system.
Table of Contents (14 chapters)
13
Index

Managing the Linux firewall with iptables


When it comes to managing the firewall service within Linux, there are many options, the most popular being iptables and ufw. For Ubuntu distributions, ufw is the default firewall management tool; however, overall, iptables is by far the most popular across multiple Linux distributions. Both of these, however, in themselves, are simply user interfaces to Netfilter.

Netfilter is a framework within the Linux kernel that allows for packet filtering as well as network and port translation. Tools such as the iptables command are simply interacting with the netfilter framework to apply these rules.

For this book, we will concentrate on utilizing the iptables command and service to manage our firewall rules. Not only is it the most popular firewall tool, it has also been the default firewall service for Red Hat based operating systems for quite a while. Even with the newer firewalld service arriving in Red Hat Enterprise Linux 7, this is simply a service...