2014-10-30 79 views
0

這取決於iphdr.saddr字段。 當它被設置爲我自己的地址或隨機組播地址時,我可以看到服務器使用syn/ack數據包進行回覆。 如果設置爲其他ips,服務器沒有回覆。 如何解釋?當我嘗試通過原始套接字連接時,爲什麼tcp服務器不回覆syn包?

多播地址的情況下: 13:55:08.242535 IP 240.151.224.61.13579 > localhost.5223: Flags [S], seq 123456, win 4096, length 0 E..([email protected][email protected]$X.. 13:55:14.906511 IP 239.151.224.61.13579 > localhost.5223: Flags [S], seq 123456, win 4096, length 0 E..([email protected][email protected]%X.. 13:55:14.906549 IP localhost.5223 > 239.151.224.61.13579: Flags [S.], seq 3502093187, ack 123457, win 43690, options [mss 65495], length 0 E..,[email protected]@..........=.g5........A ... N ....... 13:55:15.904599 IP localhost.5223> 239.151.224.61.13579:旗[S.],SEQ 3502093187,ACK 123457 ,贏得43690,選項[MSS 65495],長度爲0

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我自己的地址情況: 14:14:22.989225 IP slave1.domain.com.13579 > localhost.5223: Flags [S], seq 123456, win 4096, length 0 E..([email protected]@....P...3... 14:14:22.989236 IP localhost.5223 > slave1.domain.com.13579: Flags [S.], seq 3228604881, ack 123457, win 43690, options [mss 65495], length 0 E..,[email protected]@..........m.g5..p.....A ... A5 ...... 14:14:22.989259 IP slave1.domain.com .13579> localhost.5223:Flags [。],ack 3228604882,win 4096,length 0 E ..(.. @。@ ...... m .... 5..g ... Ap。 P ....... `

無SYN/ACK應答的情況下: 14:16:18.719629 IP 223.151.224.61.13579 > localhost.5223: Flags [S], seq 123456, win 4096, length 0 E..([email protected][email protected] 14:16:46.511299 IP 240.151.224.61.13579 > localhost.5223: Flags [S], seq 123456, win 4096, length 0 E..([email protected][email protected]$X..

回答

0

iphdr.saddr表示IP分組的源地址。我假設您的SYN數據包的接收端會嘗試以ACK響應您在IP數據包中提供的任何源地址。

+0

服務器沒有回覆我,除非iphdr.saddr被設置爲多播類型地址 – qingfeng 2014-10-31 07:11:51

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