VPN and MySQL cluster

I need some thoughts about this: I have a web server, ... which uses the second Ethernet port to connect to a MySQL server. This server is a physical machine. I want to connect to the MySQL cluster there. The second port of the MySQL machine should use a VPN to different other MySQL machines world wide to complete more clusters. a. Which VPN software would fit for that? b. Which ports I have to open for that? All other ports will be closed. c. Has anybody on the list experience with MySQL cluster? bye Ronald Wiplinger