Accessing asterisk behind a NAT

Hi,

I have an PBXinaflash box behind a NAT.

I’d like to send AMI and AGI requests from a box on the outside, what would be the best way to go about it? Which ports should I use by defaults? What caveats should I be aware of?

I don’t have much networking experience so I just have no idea how to proceed.

For security reasons, I would definitly recommend using a VPN connection.