I am demoing a product that will soon be sold, but during demos I have found that peoples internet is often more restrictive than I ever thought. In one particular area the internet provider does not allow the customer to access the router and open ports (this seems to be when the customer has cable through internet). This has got me thinking about how I am going to update and service the product, I originally assumed that I would be able to setup static IPs and port forwarding but this is not going to work. I also have found that many more people than I expected are on dynamic IPs. How do I overcome these problems?
I am running a very minimulistic linux with no gui, or X.