Wireshark-users: Re: [Wireshark-users] 12 bytes before the IP header
From: Aleksander Veksler <[email protected]>
Date: Sun, 23 Sep 2007 17:03:07 +0200
Yes, this worked,thanks!


Siterer "Small, James" <[email protected]>:


If I save the pcap file you sent and follow this procedure:
bittwiste -I http_packet.cap -O http-new.cap -M 147

Open http-new.cap in Wireshark 0.99.6

Click on Edit...
Click New
Leave encap at default of User 0 (DLT=147)
payload_proto - ip
header_size - 26 (12 for Ethernet + 12 for extra stuff + 2 for next
protocol field)
header_proto - eth_withoutfcs
trailer_size - leave blank
trailer_proto - leave blank
Click OK
Click OK

Now, the IP part and "below" of the packet decode correctly in

This doesn't work for you?

BTW - there does appear to be a bug in the DLT_User preferences where
you get gobbledygook - I should probably file a bug...

As to whether this should be automatically decoded I can't say - I would
have to defer to one of the developers.


-----Original Message-----
From: [email protected] [mailto:wireshark-users-
[email protected]] On Behalf Of Aleksander Veksler
Sent: Wednesday, September 19, 2007 7:23 PM
To: [email protected]
Subject: Re: [Wireshark-users] 12 bytes before the IP header

Hello again guys,

Sorry for the delay. The procedure Sake Block recommended didn't work.
I first thought it was because there was a trailer, so I tried with
trailer sized 1,2,3 and four (see the packet to see why), but this
didn't work.

There seem to be a bug in DLT_USER configuration page, which make
random characters appear in the "payload" field (it seem to me the
characters are coming from the capture, but I am not sure. I attach a
screenshot, can make more if you need it.

I also attached a sample http packet. I found a packet with as much
clear text as possible, tell me if you need more. This particlular
packet was not classified as LLC, but many others were.

Thank you again for your help.


Siterer Aleksander Veksler <[email protected]>:

> Siterer Joerg Mayer <[email protected]>:
>> On Fri, Sep 07, 2007 at 12:23:54AM +0200, Aleksander Veksler wrote:
>>> Anyone have tips on how you loose a few bytes? I get 12 bytes
>>> the Ethernet header and IP header. This means that wireshark does
>>> recognize the IP header as, and I can't use any of the wireshark's
>>> advanced features.
>>> Anyone know how to get rid of those bytes, or perhaps what they
>>> * My card is Intel Pro/Wireless 3945ABG
>>> * The wireless switch is D-Link DIR-635
>>> * The problem only happens in promiscuous mode, and only to the
>>> packets not directed to my computer
>>> * I attach picture of a window of a sample http packet
>>> * Please help :)
>> Actually it looks like this packet might have a third mac at the
>> Is the length of 02 d7 really correct? Sending a packet would have
>> helped more than the image you sent and have been smaller.
>> After the third mac it looks to me that there is an ordinary
>> header.
> The LLC dissector attempted to dissect the first 4 bytes, right
> ethernet length. Again, I will have to send full data on Monday.
> Thank you for the help!
>>  Ciao
>>        Joerg
>> --
>> Joerg Mayer
<[email protected]>
>> We are stuck with technology when what we really want is just stuff
>> works. Some say that should read Microsoft instead of technology.
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