php as a Socket server

Hi all. Forgive me if I am being stupid, but I have\ am writing php stuff that uses sockets. As far as I have seen all the socket connection stuff in php seems to require a remote host. I am a little curious about how it can be made to act as a server. At first I thought that I could make it listen to itself, but supposing I didn't know the ip address and 127.0.0.1 didn't work, what would I do? I haven't seen a socket equivalent of ADDR_ANY for php. is there anyway of binding it as a listener socket type thing to act as a server without it having to connect anywhere? Thanks Darren