GL314 - Linux Troubleshooting

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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.

Current Version: A00

Prerequisites:

This course is designed for intermediate to advanced users. Students should have already taken the GL120, GL250 and GL275, or have equivalent knowledge. A short refresher for each topic will be presented, but will not be discussed in depth.

Supported Distributions:
Red Hat Enterprise Linux 8
SUSE Linux Enterprise 12
Recommended Class Length:
5 days
Detailed Course Outline:
  1. Troubleshooting Methodology
    1. The Troubleshooting Mindset
    2. Evaluating Possible Solutions
    3. Identifying and Implementing Change
    4. Define and Follow Policies
    5. Working with Others
    6. Finding Documentation
    7. Finding Help Online
  2. Troubleshooting Tools
    1. Common Troubleshooting Tools
    2. RPM Queries
    3. RPM Verification
    4. SRPM and spec Files
    5. Hardware Discovery Tools
    6. Configuring New Hardware with hwinfo
    7. strace and ltrace
    8. lsof and fuser
    9. ipcs and ipcrm
    10. iostat, mpstat, vmstat, and pidstat
    11. Using hdparm to Measure
    12. Troubleshooting with the ip command
    13. Name Resolution
    14. ss/netstat and rpcinfo
    15. nmap
    16. Netcat
    17. tcpdump and wireshark
    Lab Tasks
    1. Determining the System's Configuration
    2. Troubleshooting with rpm
    3. Process Related Tools
    4. Network Tools
  3. Rescue Environments
    1. Diagnostic/Recovery
    2. Rescue Procedures
    3. Recovery: mount & chroot
    4. Recovery Examples
    5. Recovery: Network Utilities
    Lab Tasks
    1. Recovery Runlevels
    2. Recovering Damaged MBR
    3. Recover from Deleted Critical Files
  4. Topic Group 1
    1. Linux Boot Process
    2. System Boot Method Overview
    3. systemd System and Service Manager
    4. Modifying systemd services
    5. Using systemd
    6. Booting Linux on PCs
    7. Troubleshooting With GRUB 2
    8. The Boot Loader Specification
    9. Boot Process Troubleshooting
    10. Troubleshooting: Linux and Init
    11. Process Management
    12. Process Management Tools
    13. Troubleshooting Processes: top
    14. Filesystem Concepts
    15. Filesystem Troubleshooting
    16. Backup Concepts
    17. Backup Troubleshooting
    18. Backup Troubleshooting
    Lab Tasks
    1. Troubleshooting Problems: Topic Group 1
  5. Topic Group 2
    1. Networking Tools
    2. Linux Network Interfaces
    3. Networking Commands Review
    4. NetworkManager
    5. Networking Troubleshooting
    6. Networking Troubleshooting
    7. Virtual Interfaces/IP Aliases
    8. Network Teaming
    9. Xinetd Concepts
    10. Xinetd Troubleshooting
    11. TCP Wrappers Concepts
    12. TCP Wrappers Concepts
    13. TCP Wrappers Troubleshooting
    14. Netfilter/iptables Concepts
    15. Netfilter/iptables Troubleshooting
    Lab Tasks
    1. Troubleshooting Problems: Topic Group 2
  6. Topic Group 3
    1. X11 Concepts
    2. X11 Server Operation
    3. X11 Troubleshooting
    4. System Logging
    5. Rsyslog Concepts
    6. systemd Journal
    7. systemd Journal's journalctl
    8. Secure Logging with Journal's Log Sealing
    9. Syslog Troubleshooting
    10. RPM Concepts
    11. RPM Troubleshooting
    12. Common Unix Printing System (CUPS)
    13. CUPS Troubleshooting
    14. CUPS Troubleshooting
    15. at & cron
    16. at & cron Usage
    17. at & cron Troubleshooting
    18. Systemd Timers
    19. Systemd Timer Troubleshooting
    Lab Tasks
    1. Troubleshooting Problems: Topic Group 3
  7. Topic Group 4
    1. Users and Groups
    2. Users and Groups Troubleshooting
    3. PAM Concepts
    4. PAM Troubleshooting
    5. Filesystem Quotas
    6. Quotas Troubleshooting
    7. File Access Control Lists
    8. FACL Troubleshooting
    9. SELinux Concepts
    10. SELinux Troubleshooting
    11. SELinux Troubleshooting Continued
    Lab Tasks
    1. Troubleshooting Problems: Topic Group 4
  8. Topic Group 5
    1. Kernel Modules
    2. Kernel Modules Troubleshooting
    3. Logical Volume Management
    4. Creating Logical Volumes
    5. LVM Deployment Issues
    6. VG Migration, PV Resizing & Troubleshooting
    7. Software RAID Overview
    8. RAID Troubleshooting
    9. Multipathing Overview
    10. SAN Multipathing
    11. Multipath Configuration
    12. Multipathing Best Practices
    13. LDAP and OpenLDAP
    14. Troubleshooting OpenLDAP
    15. LDAP and 389 Directory Server
    16. Troubleshooting 389 Directory Server
    17. NIS and NIS+ (YP)
    18. NIS Troubleshooting Aids
    Lab Tasks
    1. Troubleshooting Problems: Topic Group 5
  9. Topic Group 6
    1. DNS Concepts
    2. DNS Troubleshooting
    3. DNS Troubleshooting
    4. Apache Concepts
    5. Apache Troubleshooting
    6. Apache Troubleshooting
    7. FTP Concepts
    8. FTP Troubleshooting
    9. Squid Concepts
    10. Squid Troubleshooting
    Lab Tasks
    1. Troubleshooting Problems: Topic Group 6
  10. Topic Group 7
    1. Samba Concepts
    2. Samba Troubleshooting
    3. Postfix Concepts
    4. Postfix Troubleshooting
    5. Postfix Troubleshooting
    6. IMAP & POP Concepts
    7. IMAP/POP Troubleshooting
    8. MariaDB
    9. MariaDB Troubleshooting
    Lab Tasks
    1. Troubleshooting Problems: Topic Group 7