OpenSSL

gistfile1.txt

// create CA key
openssl genrsa -out ca.key 2048

// create CA cert
openssl req -x509 -sha256 -new -nodes -key ca.key -days 365 -out ca.pem

// create client key
openssl genrsa -out client.key 2048

// create client csr
openssl req -new -key client.key -out client.csr

// create openssl extension file and fill in DNS entry for client
subjectAltName = @alt_names
[alt_names]
DNS.1 = client
IP.1  = 127.0.0.1

// create client cert
openssl x509 -req -in client.csr -CA ca.pem -CAkey ca.key -CAcreateserial -out client.pem -days 365 -sha256 -extfile client.conf