I have a client workstation that is in a private network (172 range) that wants to access my network through my Sidewinder firewall. He gave me his private address. Of course this will not work since it is a private address. He could give me the external interface of his internet facing firewall but this would allow every body in from his LAN or WAN and of course I do not want that. How do I tie it down to his workstation only??