Essential Linux Security

Explore defense in depth across administrative, physical, network, and application layers to strengthen Linux security. Implement firewall and host protections and understand attacker perspectives to secure your system.

Encrypt data against physical access by scrambling files or entire disks with a password, using gpg symmetric and Linux unified key setup for full disk encryption on Linux systems.

Learn how host-based Linux firewalls protect systems by filtering network packets with Netfilter, ufw, and iptables, enabling your chosen ports (22, 21, 23) and blocking others to reduce attack surfaces.

Discover remote Linux administration with SSH over the network, log in from the command line to perform administrative tasks, and recognize password-guessing attacks from hackers using Kali Linux.

Demonstrates a brute force attack using Hydra on Kali Linux to test SSH access with the rockyou password list, showing how passwords are found and login gained, underscoring strong passwords.

Learn to disable unused Linux accounts to prevent remote login via SSH by editing /etc/passwd as root and setting no login, then re-enable if needed.

Enforce strong password quality using the pwquality.conf policy, enable it by uncommenting the lines, and set min length, min class, and bad word checks to deter brute-force and dictionary attacks.

Update and upgrade your Ubuntu system with sudo apt update and sudo apt upgrade, enable automatic updates, and consider long-term support releases that provide five years of security updates.

Explore /var/log directory and how Linux uses log files such as output log, utmp, current log, kernel log, and boot log to track login attempts and system events across distributions.