What are the available PHP extensions for TCP Socket Networking?

I'm looking for a PHP extension that allows me to connect, bind / listen, send and receive data on a TCP socket.

There is a PEAR Net_Socket package:

http://pear.php.net/package/Net_Socket

But this would require PEAR to be installed, which we would not want to do as it increases memory consumption.

Is there a pure C extension available for this?

Thanks, Kenneth