I think I found the problem. Sebek header reports datalen*2 because of this:
uiPacketLen += DataLength;
When uiPacketLen already contains the DataLength. Weird that it works fine
for me here though.
I will repackage a new sebek and get it up to the site later tonight.
Thanks,
Michael A. Davis
Chief Executive Officer
Savid Technologies, Inc.
Main: 708.243.2850
http://www.savidtech.com
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> -----Original Message-----
> From: Edward Balas [mailto:ebalas_at_iu.edu]
> Sent: Wednesday, October 19, 2005 10:38 AM
> To: Truong, Thanh V.
> Cc: Michael A. Davis; Compton, Rich; honeypots_at_securityfocus.com
> Subject: Re: Problems capturing sebek win32 3.0.3 traffic on
> roo honeywall
>
> Truong, Thanh V. wrote:
>
> >Michael,
> >I have the same problem. After a little debugging, I found that
> >pcapheader->caplen is always equal to [(datlen*2) +
> pkt_head_sz] but in
> >your "if" statement (in sbk_extract.c) you check to see if
> >pcapheader->caplen = datlen + pkt_head_sz. That will fail. So, it
> >will complain about the malformed package.
> >
> >After putting that in, it seems to work fine. But I haven't fully
> >tested to see if all functions work.
> >
> >I'm running sebekd-3.0.3 on Fedora 4. I hope that and pcap
> output from
> >Rich Compton will help you looking into it.
> >
> >
> >
> Hey all,
>
> This a not the recomended way to work around this.
> datalen+pkt_head_sz should equal caplen, if it does not then
> the client is sending malformed records.
>
> Looking at Rich's data, we see the following for the first packet.
>
> rectype=0
> caplen=176
> len=39
> discrepancy=39
> data*2=0x4d6963726f736f66742057696e646f7773205850205b566572736
96f6e20352e312e323630305d000000000000000000000000000000000000000
>
> Firing up this same packet into ethereal or other sniffer
> here is what we see.
>
> caplength of 176
> ip total length of 123
>
> Ethernet header shows a trailer which should not be there of
> 35 bytes and another 4 bytes which should be the frame check
> sequence are also null. So at the tail end of the frame we
> see 39 null bytes, same as the length of the data.
>
> This is a malformed packet. Can you provide details on the
> client system?
>
>
> Edward
>
>
>
Received on Oct 19 2005
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