What this book covers
Chapter 1, Basics of Troubleshooting CentOS, serves as an introduction to the book, in general, by giving you the low-down on gathering hardware information, dmesg, working with log files, and learning how to manipulate these log files using an array of command-line tools.
Chapter 2, Troubleshooting Active Processes, takes up the running and dives into the world of tuning server performance, swap, memory management, system load, monitoring disk I/O, a tour of the system, guidance on issuing the kill signal, and running additional performance checks using many more tools associated with the command line.
Chapter 3, Troubleshooting the Network Environment, walks you through the process of diagnosing a variety of issues related to the network environment. ping, dig, host, traceroute, mtr, ss, and tcpdump are just some of the tools that will be discussed when highlighting a whole host of network-related problems.
Chapter 4, Troubleshooting Package Management and System Upgrades, puts yum (Yellowdog Updater, Modified) in the spotlight with the intention of showing you how to manage plugins, add additional repositories, download RPM packages, restore the RPM database, and gather generalized software information.
Chapter 5, Troubleshooting Users, Directories, and Files, takes a stance on on-going maintenance and provides the information you need to prepare you for a variety of issues that the professional troubleshooter may face. From user management to login.defs, utmpdump to general file and directory audits. This chapter also builds on your existing knowledge related to the XFS filesystem and shows you how to recover the lost data with Scalpel.
Chapter 6, Troubleshooting Shared Resources, takes a magnifying glass to NFS on CentOS 7 and shows you how to provide shares, manage exports, and access them via a client workstation while simultaneously approaching the subject of CIFS and autofs to deliver an all round problem solving guide.
Chapter 7, Troubleshooting Security Issues, builds on the momentum and discusses why you need to keep SELinux by showing you how to generate audit reports with aureport. From this point onward, you will discover a comprehensive review on FirewallD and an installation guide for Tripwire so that you can develop your very own intrusion detection system.
Chapter 8, Troubleshooting Database Services, lends a hand to troubleshooters and system administrators alike by taking the key points regarding MariaDB, MySQL, and PostgreSQL to provide a birds eye view of how to deal with a lost root password, database tuning, database metrics, and how to install MySQL server on CentOS 7.
Chapter 9, Troubleshooting Web Services, takes a step back from recovery and examines the need to improve a system, website, or web application. Taking you through the art of cURL, you will not only discover how to audit your server and access FTP, but you will also learn how to validate your Akamai headers and manage Varnish with the overall intention to illustrate the fine line between Dev/Ops and troubleshooting.
Chapter 10, Troubleshooting DNS Services, completes our journey with an investigation into a variety of domain name service issues. Hostnames, FQDNs, BIND, and iftop are all under the knife as we navigate to a number of issues related to bandwidth, cache flushing, and how to make a DNS health check.
