I've been asked to create a couple of very simple POS (Point of Sale) systems for a couple of clients, they are very basic and are to be built for the use on a laptop which are connected to the internet in stalls.

They all will need to connect to a master server where product prices etc are controlled.

Is this as simple as connecting to a sql server on a remote site?

How can I ensure port forwarding, firewalls etc aren't an issue?