def packOpen_direct_tcpip(destination, source):
    """
    Pack the data suitable for sending in a CHANNEL_OPEN packet.

    @type destination: L{tuple}
    @param destination: A tuple of the (host, port) of the destination host.

    @type source: L{tuple}
    @param source: A tuple of the (host, port) of the source host.
    """
    (connHost, connPort) = destination
    (origHost, origPort) = source
    if isinstance(connHost, unicode):
        connHost = connHost.encode("utf-8")
    if isinstance(origHost, unicode):
        origHost = origHost.encode("utf-8")
    conn = common.NS(connHost) + struct.pack('>L', connPort)
    orig = common.NS(origHost) + struct.pack('>L', origPort)
    return conn + orig

    Pack the data suitable for sending in a CHANNEL_OPEN packet.

    @type destination: L{tuple}
    @param destination: A tuple of the (host, port) of the destination host.

    @type source: L{tuple}
    @param source: A tuple of the (host, port) of the source host.
    
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/ssh/forwarding.py