# To create a 2048-bit private key:
openssl genrsa -out server.key 2048

# To create the Certificate Signing Request (CSR):
openssl req -new -key server.key -out server.csr

# To sign a certificate using a private key and CSR:
openssl x509 -req -days 365 -in server.csr -signkey server.key -out server.crt

# (The above commands may be run in sequence to generate a self-signed SSL certificate.)