PSH

发送数据长度4:
02:08:50.824408 IP node2.56683 > node1.webcache: Flags [P.], seq 4188428378:4188428382, ack 3144228973, win 20, options [nop,nop,TS val 228065193 ecr 228168524], length 4
02:08:50.825350 IP node1.webcache > node2.56683: Flags [.], ack 4188428382, win 27, options [nop,nop,TS val 228168528 ecr 228065193], length 0

返回数据长度13：
02:08:52.827214 IP node1.webcache > node2.56683: Flags [P.], seq 3144228973:3144228986, ack 4188428382, win 27, options [nop,nop,TS val 228170531 ecr 228065193], length 13
02:08:52.827280 IP node2.56683 > node1.webcache: Flags [.], ack 3144228986, win 20, options [nop,nop,TS val 228067196 ecr 228170531], length 0