Bug 135889 - TCP checksums incorrect
Summary: TCP checksums incorrect
Status: RESOLVED INVALID
Alias: None
Product: SUSE Linux 10.1
Classification: openSUSE
Component: Kernel (show other bugs)
Version: unspecified
Hardware: Other Other
: P5 - None : Normal (vote)
Target Milestone: ---
Assignee: E-mail List
QA Contact: E-mail List
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Reported: 2005-11-29 16:33 UTC by Dirk Mueller
Modified: 2005-11-29 17:58 UTC (History)
0 users

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Found By: Other
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pcap (600 bytes, application/octet-stream)
2005-11-29 16:33 UTC, Dirk Mueller 		Details
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Description Dirk Mueller 2005-11-29 16:33:11 UTC 
Hi, 

it seems current STABLE kernel emits packages with incorrect tcp checksums. the checksum seems to be always the value "0x19da2" instead of the correct one. 

See pcap trace I'll attach shortly.
Comment 1 Dirk Mueller 2005-11-29 16:33:46 UTC 
Created attachment 59009 [details]
pcap
Comment 2 Dirk Mueller 2005-11-29 16:34:28 UTC 
0x19da, not 0x19da2.
Comment 3 Olaf Kirch 2005-11-29 17:02:55 UTC 
If it really did, you wouldn't be able to do any TCP at all.

More likely what you're seeing is a side effect of TSO or TX checksums.
The kernel simply doesn't fill in a valid checksum but leaves it to
the hardware.

On the wire, these packets should look good.
Comment 4 Dirk Mueller 2005-11-29 17:58:00 UTC 
hmm, indeed. dumping on the other side doesn't show that. so my actual issue is something different.