Course Description

Linux Diagnostics And Troubleshooting

Introduction

• What is troubleshooting?

• Troubleshooting a login issue

• Collecting Information

• System Journal

• Troubleshoot a web server issue using the log files

• Using Red Hat Resources

• Collecting Information with SOSREPORT

• Practice Lab Session

• Troubleshoot a FTP Connectivity Issue

Monitoring Systems

• System Monitoring with Cockpit

• Performance Co-Pilot or pcp

• Centralized log server using rsyslog

• Practice Lab Session

• Intrusion detection software to monitor changes

• Advanced Intrusion Detection Environment (AIDE)

• Practice Lab Session

• System Auditing with auditd

• 
  

Identifying Hardware Issues

• Identify various harwdare and their problems

• Hardware Error Reporting using mcelog and rasdaemon

• Memory Testing using memtest86+ package

• Manging Kernel Modules

• Loading and unloading modules

• Managing module options

• Troubleshooting to disable MSI-X interrupt handling in the driver

Troubleshooting Storage Issues

• Overview of Linux Storage Stack

• Virtual File System

• Filesystems & Device Manager

• Device Mapper Multipath

• Recovering from File System Corruption

• Checking & Repairing ext3/ext4 fs using e2fsck

• Checking & Repairing xfs fs using xfs_repair

• Recovering LVM Issues

• Practice Lab Session - using vgcfgrestore

• Migrating a Volume Group from one system to another

• Recovering Metadata in LVM

• Practice Lab Session

• Configuration of Iscsi target & Initiator

• Practice Lab Session on iscsi target & initiator - 1

• Practice Lab Session on iscsi target & initiator - 2

Troubleshooting RPM Issues

• Resolve package management dependency issues

• Identify & fix dependency issue

• Recover a corrupted RPM Database

• Working with transaction history using Yum command

• Reverting & repeating transaction using yum command

• Practice Lab Session

Troubleshooting a Network Issues

• Check Network Connectivity

• Scanning Network Ports using nmap

• Communicating with a remote service using nc command

• Monitoring Network traffic using iptraf-ng

• Troubleshooting a network issue (One network interface is not working properly)

• Troubleshooting tips related with device names of ethernet interface

• Disable consistent network device naming

• Overview NetworkManager

• Practice Lab Session

• Capturing Packets with tcpdump

• Practice Lab Sessions

Troubleshooting a Boot Issues

• Linux Boot process

• Booting of RHEL 7 with systemd

• Overview of Grub2

• Grub2 features

• Booting into Grub Menu

• Protect Grub by appying a password

• Labon Basic System Recovery (Initramfs file missing/Corrupted)

• Labon Basic System Recovery (Grub related issues like grub is missing)

• Labon Basic System Recovery (Master Boot Record missing/corrupted)

• Rescue Modue in RHEL 7

• Practice Lab Session

• Reset the root passwd using installation disk

• Reset the root passwd using rd.break

• Repairing File System Issues at boot

• Fix issues at /etc/fstab at boot - Lab Session

Troubleshooting a Security Issues

• Troubleshooting a SELinux Issue

• Changing SELinux context

• troubleshooting ftp connectivity issue using booleans

• SELinux Audit Logs & Troubleshooting

• Overview of PAM Security

• Concepts of PAM

• PAM Modules & Configurations

• PAM Module Groups

• Control Flags in PAM

• PAM Modules

• last lecture