Bug 186133 - [patch] tcpdump(1): zero checksums are invalid for UDP over IPv6
Summary: [patch] tcpdump(1): zero checksums are invalid for UDP over IPv6
Status: Open
Alias: None
Product: Base System
Classification: Unclassified
Component: bin (show other bugs)
Version: 10.0-PRERELEASE
Hardware: Any Any
: Normal Affects Only Me
Assignee: freebsd-bugs mailing list
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2014-01-26 18:40 UTC by Christian Weisgerber
Modified: 2017-12-31 22:27 UTC (History)
0 users

See Also:


Attachments
patch-print-udp.c (696 bytes, text/plain)
2014-01-26 18:40 UTC, Christian Weisgerber
no flags Details
zerocksum.pcap (18.86 KB, text/plain)
2014-01-26 18:40 UTC, Christian Weisgerber
no flags Details

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Description Christian Weisgerber freebsd_committer 2014-01-26 18:40:00 UTC
As per RFC 2460, section 8.1, UDP packets over IPv6 *must* have a
non-zero checksum.  Currently tcpdump ignores this and will print
"udp sum ok".  Maybe the author didn't understand how the Internet
checksum works and thought the checksum calculation would catch
this.

This bug and the fix should be reported upstream, but that requires
registration and whatnot.

How-To-Repeat: 
$ tcpdump -nvr zerocksum.pcap

An example zerocksum.pcap file is attached.
Comment 1 Eitan Adler freebsd_committer freebsd_triage 2017-12-31 07:59:01 UTC
For bugs matching the following criteria:

Status: In Progress Changed: (is less than) 2014-06-01

Reset to default assignee and clear in-progress tags.

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