1
Client (我)                    Server (你)
2
    |                              |
3
    |---- SYN (我想信任你) -------->|
4
    |                              |
5
    |<--- SYN-ACK (我接受) ---------|
6
    |                              |
7
    |---- ACK (连接建立) ---------->|
8
    |                              |
9
    ====== ESTABLISHED ======

1
def send_heartbeat():
2
    packet = {"type": "HEARTBEAT", "message": "我还在这里"}
3
    return self._send(packet)

1
Client (我)                    Server (你)
2
    |                              |
3
    |---- PSH (我还爱你) ---------->|
4
    |                              |
5
    |<--- RST (断开连接) -----------|
6
    |                              |
7
    ====== CONNECTION RESET ======

1
10:00:00 SYN → 192.168.1.100:443
2
10:00:01 SYN-ACK ← 192.168.1.100:443
3
10:00:01 ACK → 192.168.1.100:443
4
10:05:00 PSH → 192.168.1.100:443 "我还在这里"
5
10:05:01 RST ← 192.168.1.100:443