Cloudflare: DNS, SSL, Caching, WAF & Tunnels

DNS management, SSL/TLS modes, caching rules, firewall, WAF, rate limiting, page rules, origin certificates, and Cloudflare Tunnel.

OWASP Top 10: Vulnerabilities, Exploits & Fixes

SQL injection, XSS, CSRF, RCE, and the rest of the OWASP Top 10 — with vulnerable/fixed code examples and the security headers that stop them.

Linux File Permissions, Ownership & umask Explained

The rwx permission model, chmod symbolic vs. octal notation, chown/chgrp, setuid/setgid/sticky bits, and how umask sets your defaults.

SSH Hardening: Key-Based Auth, Fail2ban & Bastion Hosts

Disabling password auth, key-based login, sshd_config hardening, fail2ban jails, and bastion-host architecture for production access.

AWS IAM Fundamentals: Users, Roles, Policies & Least Privilege

Users vs. roles vs. groups, identity-based vs. resource-based policies, policy evaluation logic, and applying least privilege in practice.