From http://code.activestate.com/recipes/483732-asynchronous-port-forwarding/ with minor change

AsyncFowarder.py

import socket,asyncore

class forwarder(asyncore.dispatcher):
    def __init__(self, ip, port, remoteip,remoteport,backlog=5):
        asyncore.dispatcher.__init__(self)
        self.remoteip=remoteip
        self.remoteport=remoteport
        self.create_socket(socket.AF_INET,socket.SOCK_STREAM)
        self.set_reuse_addr()
        self.bind((ip,port))
        self.listen(backlog)

    def handle_accept(self):
        conn, addr = self.accept()
        # print '--- Connect --- '
        sender(receiver(conn),self.remoteip,self.remoteport)

class receiver(asyncore.dispatcher):
    def __init__(self,conn):
        asyncore.dispatcher.__init__(self,conn)
        self.from_remote_buffer=''
        self.to_remote_buffer=''
        self.sender=None

    def handle_connect(self):
        pass

    def handle_read(self):
        read = self.recv(4096)
        # print '%04i -->'%len(read)
        self.from_remote_buffer += read

    def writable(self):
        return (len(self.to_remote_buffer) > 0)

    def handle_write(self):
        sent = self.send(self.to_remote_buffer)
        # print '%04i <--'%sent
        self.to_remote_buffer = self.to_remote_buffer[sent:]

    def handle_close(self):
        self.close()
        if self.sender:
            self.sender.close()

class sender(asyncore.dispatcher):
    def __init__(self, receiver, remoteaddr,remoteport):
        asyncore.dispatcher.__init__(self)
        self.receiver=receiver
        receiver.sender=self
        self.create_socket(socket.AF_INET, socket.SOCK_STREAM)
        self.connect((remoteaddr, remoteport))

    def handle_connect(self):
        pass

    def handle_read(self):
        read = self.recv(4096)
        # print '<-- %04i'%len(read)
        self.receiver.to_remote_buffer += read

    def writable(self):
        return (len(self.receiver.from_remote_buffer) > 0)

    def handle_write(self):
        sent = self.send(self.receiver.from_remote_buffer)
        # print '--> %04i'%sent
        self.receiver.from_remote_buffer = self.receiver.from_remote_buffer[sent:]

    def handle_close(self):
        self.close()
        self.receiver.close()

if __name__=='__main__':
    import optparse
    parser = optparse.OptionParser()

    parser.add_option(
        '-l','--local-ip',
        dest='local_ip',default='127.0.0.1',
        help='Local IP address to bind to')
    parser.add_option(
        '-p','--local-port',
        type='int',dest='local_port',default=80,
        help='Local port to bind to')
    parser.add_option(
        '-r','--remote-ip',dest='remote_ip',
        help='Local IP address to bind to')
    parser.add_option(
        '-P','--remote-port',
        type='int',dest='remote_port',default=80,
        help='Remote port to bind to')
    options, args = parser.parse_args()

    forwarder(options.local_ip,options.local_port,options.remote_ip,options.remote_port)
    asyncore.loop(use_poll=True)