System Security

Minimizing Attack Surface

Disabling Unused Services

Applying Security Updates

Secure Configuration Practices

Concepts of Firewalls

Managing Rules with iptables

Using firewalld

Using ufw (Uncomplicated Firewall)

Opening and Closing Ports

Saving and Restoring Rules

Host-Based Intrusion Detection Systems (HIDS)

Monitoring Suspicious Activity

Security Auditing Tools

SELinux Concepts

AppArmor Concepts

Basic Policy Management

System Logs in /var/log

Syslog and Rsyslog

Monitoring and Analyzing Logs