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 bug and the fix should be reported upstream, but that requires
registration and whatnot.
$ tcpdump -nvr zerocksum.pcap
An example zerocksum.pcap file is attached.
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.
Mail being skipped
RFC 6935 allows 0 checksum for IPv6 in tunnel applications. If you still think this issue is relevant please create a bug with upstream, tcpdump no longer requires registration for changes.