Linux Troubleshooting

Course Description

The GL314 is designed to give Linux administrators experience with both common and uncommon system problems. The course is based on the idea that the best way to learn troubleshooting is to perform troubleshooting. Approximately 25% of class time is spent on lecture, leaving 75% for intensive lab content. Class starts with a discussion of effective troubleshooting technique. Tools and topics are gradually introduced over the course of the week. Students practice applying these tools and techniques in self-paced labs. Students can choose from over 120 scenarios organized by topic and difficulty. Because each scenarios is independent of the others, students can choose scenarios according to their interests and experience. Each scenario is designed to help students develop deeper understanding while exploring the problem. All scenarios includes optional hints designed to reflect a realistic troubleshooting process while only gradually revealing the solution. Students find the flexibility and challenge of this course very rewarding.

Training Objectives

At the end of the training participants:

• Apply an effective troubleshooting methodology and mindset: evaluate possible solutions, identify and implement change, follow policies, work with others and find documentation and help online.
• Use the common Linux troubleshooting tools, including RPM queries and verification, hardware discovery tools, strace, ltrace, lsof, fuser, iostat, mpstat, vmstat, ip, ss, nmap, netcat, tcpdump and wireshark.
• Work in rescue environments: use diagnostic and recovery runlevels, mount and chroot recovery procedures and recover a damaged MBR or deleted critical files.
• Troubleshoot the Linux boot process, systemd, process management, filesystems and backups.
• Troubleshoot networking, NetworkManager, virtual interfaces, network teaming, xinetd, TCP wrappers and Netfilter/iptables.
• Troubleshoot X11, system logging with rsyslog and the systemd journal, RPM, CUPS printing as well as at, cron and systemd timers.
• Troubleshoot users and groups, PAM, filesystem quotas, file access control lists and SELinux.
• Troubleshoot kernel modules, LVM, software RAID, SAN multipathing, OpenLDAP, the 389 Directory Server and NIS.
• Troubleshoot network services including DNS, Apache, FTP, Squid, Samba, Postfix, IMAP/POP and MariaDB.

Target Audience

Intermediate to advanced users

Prerequisites

Students should have already taken the GL-120: Linux Fundamentals, GL-250: Linux Systems Administration, GL-275: Linux Network Services, or have equivalent knowledge. A short refresher for each topic will be presented, but will not be discussed in depth.

Distributions

Red Hat Enterprise Linux 8