HTTPS & SSL/TLS Basics

# Protocol versions
SSL 2.0 # deprecated, insecure
SSL 3.0 # deprecated, insecure
TLS 1.0 # deprecated
TLS 1.1 # deprecated
TLS 1.2 # minimum recommended
TLS 1.3 # current standard, fastest

# Domain Validation (DV)
Free, automated, basic validation

# Organization Validation (OV)
Verifies organization identity

# Extended Validation (EV)
Highest validation, shows company name

# Wildcard Certificate
*.example.com # covers all subdomains

# Generate private key
openssl genrsa -out private.key 2048

# Generate CSR
openssl req -new -key private.key -out cert.csr

# View certificate
openssl x509 -in cert.crt -text -noout

# Test SSL connection
openssl s_client -connect example.com:443

# Install certbot
sudo apt install certbot python3-certbot-nginx

# Get certificate
sudo certbot --nginx -d example.com

# Renew certificates
sudo certbot renew

# Auto-renewal
0 0 * * * certbot renew --quiet