On Feb 2, 2004, at 8:28 PM, Jonty Ray wrote:
Have Ethereal 0.10.1 and The h225 setup msg appears as unreassembled
packet ( incorrect TCP check sum )
You're probably capturing traffic being sent by the machine running
Ethereal, and the machine probably has a network interface that does
checksum offloading. Packets sent on an interface that does checksum
offloading, when they're captured by the machine sending the packet,
don't have a valid checksum - the host hasn't given the packet a
checksum, as it's letting the network interface do that.
Select "Preferences" from the "Edit" menu, open up the "Protocols"
list, select "TCP", turn off the "Check the validity of the TCP
checksum when possible" option, and click "OK" (click "Save" before you
click "OK" if you want this to be your default setting).
That causes Ethereal not to check whether the TCP checksum is valid on
a packet, so that it'll be willing to reassemble higher-level packets
across TCP segment boundaries even if the checksum appears to be bad.
All other msgs like call proceeding and alerting appear fine.
Those messages are probably small enough that they don't cross TCP
segment boundaries.