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网络服务器响应挂起

tag-icon • tag-icon nat blackhole
网络服务器响应挂起

从某些网络请求我们的 Web 服务器上的某些图像非常不稳定。我查看了两端的 tcpdump，服务器发回了文件的一部分，客户端确认了 TCP 数据包，但服务器从未收到确认。

服务器视图：

41  19.941136   212.169.34.114  209.20.73.85    TCP 52456 > http [SYN] Seq=0 Win=8192 Len=0 MSS=1460 WS=2
42  19.941136   209.20.73.85    212.169.34.114  TCP http > 52456 [SYN, ACK] Seq=0 Ack=1 Win=5440 Len=0 MSS=1360
46  20.041142   212.169.34.114  209.20.73.85    TCP 52456 > http [ACK] Seq=1 Ack=1 Win=65280 Len=0
47  20.045142   212.169.34.114  209.20.73.85    HTTP    GET /map/map/s+74-WBkWk0aR28Yy-YjXA== HTTP/1.1
48  20.045142   209.20.73.85    212.169.34.114  TCP http > 52456 [ACK] Seq=1 Ack=522 Win=6432 Len=0
49  20.045142   209.20.73.85    212.169.34.114  TCP [TCP segment of a reassembled PDU] (Part of the content of the image 2720 bytes. i assume it is reassembled in tcpdump and it is fragmented over the wire.)
** never receives the ACK sent in frame 282 and will eventually resend the tcp segment **

客户观点：

274 26.161773   10.0.16.67  209.20.73.85    TCP 52456 > http [SYN] Seq=0 Win=8192 Len=0 MSS=1460 WS=2
276 26.262867   209.20.73.85    10.0.16.67  TCP http > 52456 [SYN, ACK] Seq=0 Ack=1 Win=5440 Len=0 MSS=1360
277 26.263255   10.0.16.67  209.20.73.85    TCP 52456 > http [ACK] Seq=1 Ack=1 Win=65280 Len=0
278 26.265193   10.0.16.67  209.20.73.85    HTTP    GET /map/map/s+74-WBkWk0aR28Yy-YjXA== HTTP/1.1 
279 26.365562   209.20.73.85    10.0.16.67  TCP http > 52456 [ACK] Seq=1 Ack=522 Win=6432 Len=0
280 26.368002   209.20.73.85    10.0.16.67  TCP [TCP segment of a reassembled PDU] (Part of the content of the image. Only 1400 bytes.)
282 26.571380   10.0.16.67  209.20.73.85    TCP 52456 > http [ACK] Seq=522 Ack=1361 Win=65280 Len=0

我们遇到问题的网络是 NATd。这种奇怪的现象有什么解释吗？

答案1

检查路由器、防火墙和端点的 MTU 设置。

还要检查两个网络之间是否存在不稳定的路由。

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