Or potentially even socat (http://www.dest-unreach.org/socat/ http://www.dest-unreach.org/socat/), which could be used (among many other things) to model the us

Or potentially even socat (http://www.dest-unreach.org/socat/ http://www.dest-unreach.org/socat/), which could be used (among many other things) to model the use case of GP, forwarding a socket to a pipe.