原文
1. SYN: Client sends its sequence number (seq=1000) to open a connection.
2. SYN-ACK: Server acknowledges the packet by adding its own sequence number (seq=5000) and acknowledging the client sequence number by incrementing it by 1 (ack=1001).
3. ACK: Client confirms the server number by incrementing it by 1 (ack=5001) and the connection is ready.