Im just curious about the access w/ samba...
I use a linux to route my network (as well as for the ipchains firewall rules)
I have two NIC's in the box,

eth0 -- connected to my cable modem w/ a public IP address
eth1 -- connected to my LAN w/ a private IP address

I have samba running, but if i scan my eth0 i don't see the netbios ports open, but obviosuly if i scan eth1 they're open there. How could someone outside the LAN somehow 'break in' to my file sharing if the port is open on an internal interface?