step | Action | Server | direction | client -----+--------+--------+-----------+------- 1 | Listen | 8020 | | -----+--------+--------+-----------+------- 2 | h'beat | 8020 | <-------- | 53036 Client 53036 originates; Server 8020 receives. -----+--------+--------+-----------+------- 3 | resp | 8020 | --------> | 53036 Server 8020 originates; client 53036 receives. -----+--------+--------+-----------+------- 4 | data | 8020 | --------> | 53036 Server 8020 originates; client 53036 receives. -----+--------+--------+-----------+-------