initiator                                                    listener
    |                                                           |
    |    S  0(1000) <MP_CAPABLE>, <TFO cookie>                  |
    | --------------------------------------------------------> |
    |                                                           |
    |    S. 0(0) ack 501 <MP_CAPABLE>                           |
    | <-------------------------------------------------------- |
    |                                                           |
    |    .  501(0) ack 1 <MP_CAPABLE>                           |
    | --------------------------------------------------------> |
    |                                                           |
    |    .  501(500) ack 1 <DSS ack=1 seq=1 ssn=1 dlen=500>     |
    | --------------------------------------------------------> |
    |                                                           |