I checked in a change (in rev 27351) to make the UDP dissector display
the checksum differently when this is the case. For example if the
packet is truncated it will now display:
Checksum: 0xc5ac [unchecked, not all data available]
[Good Checksum: False]
[Bad Checksum: False]
(The TCP and SCTP dissectors do that already, though SCTP uses different
words.)
HTH,
-Jeff
Jaap Keuter wrote:
> Hi,
>
> Then either the UDP packet was fragmented or the capture was limited to a
> certain length, not including all data. In these cases also Wireshark can't
> verify the checksum, hence can't say it's either good or bad.
>
> Thanx,
> Jaap
>
> Yuxin Zhuang wrote:
>> Hi, Jaap,
>>
>> Thanks for your reply!
>>
>> But the content of Checksum is not 0x0000. The output is as follows:
>> Checksum: 0xd87e
>> Good Checksum: False
>> Bad Checksum: False
>>
>> I can't figure out whether the checksum is correct or not. Lots of other packets' checksum are not zero either and the result is similar.
>>
>> Thanks,
>> Yuxin
>>
>> -----Original Message-----
>> From: wireshark-users-bounces@xxxxxxxxxxxxx [mailto:wireshark-users-bounces@xxxxxxxxxxxxx] On Behalf Of Jaap Keuter
>> Sent: 2009锟斤拷2锟斤拷2锟斤拷 14:00
>> To: Community support list for Wireshark
>> Subject: Re: [Wireshark-users] No indication about UDP checksum
>>
>> Hi,
>>
>> In UDP the checksum is optional. So if it's set to 0x0000 that means it's not calculated by the sender and cannot be checked by the receiver.
>> For Wireshark that results in "Checksum: 0x0000 (none)" and it can't be neither good or bad, since there's is no checksum.
>>
>> Thanx,
>> Jaap
>>
>> Yuxin Zhuang wrote:
>>> Hi,
>>>
>>> While i'm analyzing some captured pkts, i notice that lots of UDP pkts
>>> have no indication on 'checksum' and both good and bad checksum are
>>> 'false'. What does this mean?
>>>
>>> The output is as follows:
>>>
>>>
>>> Thanks a lot!
>>> Yuxin
>>>
>
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