Ethereal-dev: [Ethereal-dev] Potential bug decoding a UDP packet (it thinks it's TFTP, it's no

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From: Ben Greear <greearb@xxxxxxxxxxxxxxx>
Date: Sat, 20 Apr 2002 15:34:10 -0700
I'm working on a kernel packet generator that can, among other things,
generate UDP packets to an ever-increasing port number.  (I can provide
this source if anyone wants it, but it's not completely
finished/debugged yet.)

I'm using ethereal to diagnose my module, and I noticed an wierd
thing.  After the destination port got to TFTP's port number, every
packet after that was decoded as TFTP too, even though the ports
kept increasing.

In case it helps, the machine running ethereal was receiving about 100,000
or more packets-per-second.  The "be 9b e9 55" is the start of my
custom packet.  After that is a time stamp and a sequence number, and
then random crap that was in the skb when allocated...

Here is the capture of one packet that seems to exhibit the problem:

0000  00 80 5f a7 80 b1 00 80  c8 b9 35 c6 08 00 45 00   .._�.�.. ȹ5�..E.
0010  00 2e c0 00 00 00 03 11  9d 53 ac 01 01 65 ac 01   ..�..... .S�..e�.
0020  01 04 00 09 00 6e 00 1a  00 00 be 9b e9 55 00 00   .....n.. ..�.�U..
0030  00 64 3c c1 e8 ae 00 04  43 b1 01 00               .d<��.. C�..

I've attached a screen-capture of the decoded frame.

The ethereal version is: 0.8.18.

Please let me know if there is any more information I can get for you
to make it easier to figure out what is going on here...

Thanks,
Ben

--
Ben Greear <greearb@xxxxxxxxxxxxxxx>       <Ben_Greear AT excite.com>
President of Candela Technologies Inc      http://www.candelatech.com
ScryMUD:  http://scry.wanfear.com     http://scry.wanfear.com/~greear

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