Articles & Guides

Free SSL certificate via Let's Encrypt and certbot: step-by-step install for nginx, Apache, auto-renewal, and gotchas. Works on any Linux.

TLS 1.3 vs TLS 1.2 — detailed comparison: speed, security, compatibility. Step-by-step nginx migration guide with backward compatibility notes.

Incomplete SSL chain causes errors on mobile and API clients. Learn how to assemble fullchain.pem, add intermediates, and verify the chain.

Wildcard vs SAN certificates — differences, pricing, security, automation. Which cert type to pick for different architectures and how many domains to cover.

Self-signed SSL certificates: when they're appropriate, how to create them with openssl, trust them system-wide, and when to use Let's Encrypt or internal PKI instead.

Mixed content breaks scripts and styles on HTTPS. Learn how to find HTTP resources, fix them with CSP and upgrade-insecure-requests automatically.

SSL handshake failed — deep dive into causes and diagnosis: protocols, SNI, cipher suites, client certs. openssl and curl examples for debugging.

Expired SSL certificate? Learn how to quickly diagnose and fix NET::ERR_CERT_DATE_INVALID, renew the certificate, and set up monitoring to prevent it.

SQL injection types, prepared statements, PDO, ORM safety, least privilege DB users, WAF. Examples in PHP, Node.js, Python.

Web Application Firewall basics: mod_security, cloud WAFs (Cloudflare, AWS), OWASP CRS, when you need one, and avoiding false positives.