ssh -N -f -i ~/.ssh/ssh_private_key -L 5901:localhost:5901 user@remote.host
- -N means no commands
- -f means go to background
- change identity key, remote username and host
openssl req -x509 -key ~/.ssh/private_key.rsa -nodes -days 365 -newkey rsa:2048 -out public_key.pem
In this example private key is in RSA format. Example came from SO post so I can't vouch for its security. For example only!