how do I target a specific machine - not ip address?

[sean]

I want to connect from travel to my server. Since I'm 
connecting through hot-spots or hotel connections, my ip 
address will be all over the place.

I thought about putting the laptop's MAC address in the 
packet, and using mac-source, but I've it seems to MAC 
address is stripped out over the internet.

So, how do I set it up so the server will know my laptop 
from whatever ip address I happen to have.

BTW, the laptop is linux, so I can mangle POSTROUTING if 
that helps.

I can ssh, but what I want to do is set up an NFS mount.

sean