How is my VM firewalled on the Cloud server?

The firewall is an IP Tables based firewall which resides on the XEN hypervisor. It is controlled by the customised web interface we provide with the control panel.

Default firewalling in front of the VM allows the opening of common ports such as HTTP / FTP etc. however for more advanced firewalling requirements (VPN)  it is recommended that this is managed via the VM's own firewall (windows firewall / Linux IPtables etc.) 
The firewall can be considered stand alone to the virtual machine as it operates in front of the bridge device that the virtual machine is assigned to when it boots.