I would like to access a Hard drive attached via USB to my Airport extreme.
It works fine within my LAN.
Special consideration: I have a VOIP router (Linksys SPA-2102) that must be first in line to the internet. The configuration is as follows:

Internet ----------> VOIP Router -----------> Airport Extreme
IP 216.106.nnn.nnn

I have a fixed IP address from my ISP

all internal devices have fixed IP addresses and access is controlled by mac address filtering (not really relevant).

My question is: what are the steps to set the AE so that I can access my hard drive via either afp or smb.

Any help is greatly appreciated