Articles & Guides
Useful resources for web developers and system administrators
SSL/TLS
TLS 1.3 vs TLS 1.2: What Changed and How to Migrate Correctly
TLS 1.3 vs TLS 1.2 — detailed comparison: speed, security, compatibility. Step-by-step nginx migration guide with backward compatibility notes.
SSL/TLS
SSL Certificate Chain: How It Works, How to Verify It and How to Fix an Incomplete Chain
How an SSL certificate chain works: leaf, intermediate and root certs, trust stores and path building, plus verification commands and incomplete-chain fixes.
SSL/TLS
Wildcard vs SAN Certificate: Which to Choose in 2026
Wildcard vs SAN certificates — differences, pricing, security, automation. Which cert type to pick for different architectures and how many domains to cover.
SSL/TLS
Self-Signed Certificates: When to Use Them and How to Avoid Warnings
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.
SSL/TLS
Mixed Content: How to Find and Fix HTTP Resources on HTTPS Sites
Mixed content blocks scripts, styles and iframes on HTTPS pages. Active vs passive, finding every http URL in code and database, CSP reports, regression control.
SSL/TLS
SSL Handshake Failed: Root Causes and Step-by-Step Diagnosis
SSL handshake failed — deep dive into causes and diagnosis: protocols, SNI, cipher suites, client certs. openssl and curl examples for debugging.
SSL/TLS
Expired SSL Certificate: How to Fix NET::ERR_CERT_DATE_INVALID
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.
Security
SQL Injection Prevention: Prepared Statements and ORM
SQL injection types, prepared statements, PDO, ORM safety, least privilege DB users, WAF. Examples in PHP, Node.js, Python.
Security
WAF (Web Application Firewall): A Practical Guide
Web Application Firewall basics: mod_security, cloud WAFs (Cloudflare, AWS), OWASP CRS, when you need one, and avoiding false positives.
Security
Subresource Integrity (SRI): Protecting CDN Scripts
Subresource Integrity (SRI) — integrity attribute for <script> and <link>. CDN compromise protection, hash generation, CSP require-sri-for.