Advanced Topics in CompTIA Linux+

Key Concepts

• Advanced Shell Scripting
• Systemd Advanced Configuration
• SELinux Policy Management
• Network Configuration and Troubleshooting
• Advanced File System Management
• Performance Monitoring and Tuning
• Backup and Restore Strategies
• Security Hardening
• Virtualization and Containerization
• Advanced User and Group Management
• Kernel Tuning and Modification
• Automation with Ansible

Advanced Shell Scripting

Advanced shell scripting involves creating complex scripts that handle multiple tasks, error handling, and interact with system APIs. Techniques include using arrays, associative arrays, and advanced control structures.

Example: A script that monitors system resources and sends alerts if thresholds are exceeded.

#!/bin/bash
threshold=90
while true; do
    cpu_usage=$(top -bn1 | grep "Cpu(s)" | sed "s/.*, *\([0-9.]*\)%* id.*/\1/" | awk '{print 100 - $1}')
    if (( $(echo "$cpu_usage > $threshold" | bc -l) )); then
        echo "High CPU usage: $cpu_usage%" | mail -s "CPU Alert" admin@example.com
    fi
    sleep 60
done
    

Systemd Advanced Configuration

Systemd advanced configuration involves creating custom unit files, managing dependencies, and using advanced features like timers and slices. This ensures efficient system management and service control.

Example: Creating a custom service unit file for a web server.

[Unit]
Description=My Web Server
After=network.target

[Service]
ExecStart=/usr/bin/my_web_server
Restart=always

[Install]
WantedBy=multi-user.target
    

SELinux Policy Management

SELinux policy management involves creating and modifying security policies to enforce access controls. Techniques include labeling files, setting contexts, and using audit logs.

Example: Setting a custom SELinux context for a web server directory.

chcon -R -t httpd_sys_content_t /var/www/html
    

Network Configuration and Troubleshooting

Advanced network configuration involves setting up complex network topologies, configuring firewalls, and troubleshooting network issues. Tools like iptables, nftables, and tcpdump are essential.

Example: Configuring a firewall to allow SSH and HTTP traffic.

iptables -A INPUT -p tcp --dport 22 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j ACCEPT
iptables -A INPUT -j DROP
    

Advanced File System Management

Advanced file system management involves creating and managing file systems, setting up RAID arrays, and using advanced features like snapshots and quotas.

Example: Creating a RAID 1 array using mdadm.

mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sdb1 /dev/sdc1
mkfs.ext4 /dev/md0
mount /dev/md0 /mnt/raid1
    

Performance Monitoring and Tuning

Performance monitoring and tuning involve using tools like top, htop, and iostat to monitor system performance and making adjustments to optimize resource usage.

Example: Monitoring CPU and memory usage using top.

top
    

Backup and Restore Strategies

Advanced backup and restore strategies involve creating comprehensive backup plans, using incremental backups, and restoring data in disaster scenarios.

Example: Using rsync for incremental backups.

rsync -avz --delete /source/ /destination/
    

Security Hardening

Security hardening involves implementing best practices to protect the system from vulnerabilities. Techniques include disabling unnecessary services, using strong passwords, and configuring firewalls.

Example: Disabling unnecessary services using systemctl.

systemctl disable apache2
    

Virtualization and Containerization

Advanced virtualization and containerization involve creating and managing virtual machines and containers, setting up networks, and using advanced features like live migration and snapshots.

Example: Creating a Docker container for a web application.

docker run -d -p 80:80 my_web_app
    

Advanced User and Group Management

Advanced user and group management involves creating complex user accounts, managing permissions, and using advanced features like sudo and PAM.

Example: Configuring sudo for a specific user.

echo "user ALL=(ALL) NOPASSWD: /usr/bin/systemctl restart apache2" >> /etc/sudoers
    

Kernel Tuning and Modification

Kernel tuning and modification involve adjusting kernel parameters for performance and stability. Techniques include using sysctl and recompiling the kernel.

Example: Adjusting kernel parameters using sysctl.

sysctl -w net.ipv4.tcp_syncookies=1
    

Automation with Ansible

Automation with Ansible involves creating complex playbooks to automate system configuration, deployment, and management. Techniques include using roles, templates, and handlers.

Example: Creating an Ansible playbook to configure a web server.

- hosts: webservers
  tasks:
    - name: Install Apache
      apt:
        name: apache2
        state: present
    - name: Start Apache
      service:
        name: apache2
        state: started