tun-sql

echo "Connecting to bastion via SSH..."
ssh -nNf bastion
 
echo "Connecting to MySQL..."
mysql -ugabe -pPaS$w0rD -h127.0.0.1 my_database
 
echo "MySQL client terminated, closing SSH connection..."
ssh -O exit bastion
 
echo "Done."

tun-sql-config

# put this in ~/.ssh/config
Host bastion
    HostName bastion.example.com
    IdentityFile ~/.ssh/my-private-key
    LocalForward 3306 db-server.local:3306
    User gabe
    ControlMaster auto
    ControlPath /tmp/ssh-%r@%h:%p