Multipurpose relay for bidirectional data transfer
http://www.dest-unreach.org/socat/

socat is a relay for bidirectional data transfer between two
independent data channels. Each of these data channels may be a file,
pipe, device (serial line etc. or a pseudo terminal), a socket (UNIX,
IP4, IP6 - raw, UDP, TCP), an SSL socket, proxy CONNECT connection, a
file descriptor (stdin etc.), the GNU line editor, a program, or a
combination of two of these.