These Security guides come from the same library as the rest of How7o Learn: each one documents a real task or a real failure, and the exact steps that resolved it.
Security Tutorials
Security guides for developers and self-hosters — hardening, certificates, keys and access.
29 tutorials
Server Management
How to Install Tailscale on Ubuntu (Zero-Config Mesh VPN for Self-Hosters)
Server Management
How to Install Cloudflare Tunnel on Ubuntu (Expose Local Services, No Port Forwarding)
Server Management
How to Set Up WireGuard VPN on Ubuntu (Server, Linux Client, and iOS)
Server Management
How to Install fail2ban on Ubuntu (SSH, nginx, and WordPress Filters)
Server Management
How to Set Up SSH Key Authentication on Ubuntu (Without Locking Yourself Out)
Server Management
How to Harden a Fresh Ubuntu VPS: UFW + Fail2Ban + SSH Key Auth
Web Development
Securely Hash Passwords in PHP (password_hash, Argon2id)
Web Development
How to Validate an Email Address in PHP
Web Development
How to Upload Only Image Files Using PHP
Server Management
How to Change the Default SSH Port on Linux
Server Management
How to Add and Delete Users on a Linux Server from the Terminal
Server Management