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Hi,

I am trying to port a web server from 8051 to ARM but found some problem after PC received an [SYN, ACK] packet (use web browser to test my server).

PC -> [SYN] My server-> [SYN, ACK] PC -> Can't see my sever response and just re-transmit the [SYN] again.

I look into the wireshark trace of both working (8051 server) and not working (ARM server) scenario. The reply packet from server is almost the same (except checksum, sequence number and identifier).

Can anyone give me a pointer?

Here is my trace. Both 8051 and ARM hardware addreess is the same. https://www.dropbox.com/sh/inu4urbdrgkb58x/VpXzdlSVZu

Thanks in advance. Imai

asked 19 Nov '13, 03:26

imai's gravatar image

imai
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accept rate: 0%


The TCP checksumm in the failing case is incorrect, so your client is validly discarding the SYN_ACK from the server. alt text

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answered 19 Nov '13, 07:50

mrEEde's gravatar image

mrEEde
3.9k152270
accept rate: 20%

Hi mrEEde, thank you very much. I found that the TCP checksum is not validated by default in Wireshark and need to enable it explicitly in the preference. After I changed the TCP checksum, everything goes well.

Thanks again! You save my life :-)

(20 Nov '13, 22:48) imai
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question asked: 19 Nov '13, 03:26

question was seen: 1,628 times

last updated: 20 Nov '13, 22:49

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