Recently, I built a computer running Ubuntu and gave it away to a relative. I'm willing to give them IT support for free, but they live 50 miles away. The Solution? A NX Server. I setup the Node, Client and Server on her computer, with the client only on my computer. It's working out fine, but the only fear I have is other people accessing the server. I want only a few computers to be able to access the NX server, and nobody else. How do I go about doing this? By the way, both computers (relative's computer and my computer) are running 12.04, with a few computers that may access running CentOS 5.