Bug 163470 - bad cksum in tcpdump(1) output
Summary: bad cksum in tcpdump(1) output
Status: Closed Not A Bug
Alias: None
Product: Base System
Classification: Unclassified
Component: bin (show other bugs)
Version: 9.0-CURRENT
Hardware: Any Any
: Normal Affects Only Me
Assignee: freebsd-net (Nobody)
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2011-12-20 08:50 UTC by kes-kes
Modified: 2017-01-07 23:54 UTC (History)
1 user (show)

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Description kes-kes 2011-12-20 08:50:04 UTC 
tcpdump -n -i vlan492 -vv
10:40:47.679077 IP (tos 0x0, ttl 1, id 60569, offset 0, flags [DF], proto TCP (6), length 40, bad cksum 0 (->8a69)!)
    77.93.52.10.179 > 77.93.52.9.20224: Flags [.], cksum 0x02e8 (incorrect -> 0xc4f9), seq 23, ack 55, win 8759, length 0
10:41:06.339857 IP (tos 0xc0, ttl 1, id 46979, offset 0, flags [DF], proto TCP (6), length 59, bad cksum 0 (->bea8)!)
    77.93.52.14.24404 > 77.93.52.9.179: Flags [P.], cksum 0x02ff (incorrect -> 0x25e0), seq 20:39, ack 219, win 8760, length 19: BGP, length: 19

is it right behaviour?
Comment 1 Hiren Panchasara freebsd_committer freebsd_triage 2017-01-07 23:54:06 UTC 
Yes it is expected when doing offloading. If thats not the case, please reopen the bug.