Flash sockets via localhost

Is it possible to build both a flash client and a server in flash that communicate via sockets on the same PC/machine? In order to create a testing tool that will exercise our flash clients even when the network is absent, we’ve tried to create a socket server in flash that connects, via localhost:portno, to another flash client on the same machine. It doesn’t seem to work, and more surprizingly, we cannot find any examples of such a combo in any of the docs or boards. Help?