ssh -f -N -L 9906:127.0.0.1:3306 user@database.example.com
Host tunnel HostName database.example.comm IdentityFile ~/.ssh/id_rsa LocalForward 9906 127.0.0.1:3306 User root
$ ssh -f -N tunnel
ssh -f -N -L 9906:127.0.0.1:3306 user@database.example.com
Host tunnel HostName database.example.comm IdentityFile ~/.ssh/id_rsa LocalForward 9906 127.0.0.1:3306 User root
$ ssh -f -N tunnel