important query on tcpdump header files and source codes

["Ignacio, Domingo Jr Ostria - igndo001" <DomingoJr.Ignacio () postgrads unisa edu au>]

Hi everyone,

I try to modify print-tcp.c and tcp.h source code and header file file
of tcpdump-3.9.8 to include a new option which is th_srtt, a variable I
added to my linux kernel protocol stacks. I added into the header(tcp.h
of tcpdump) my th_srtt variable and on print-tcp.c tcp options field. It
compiled. Once I run tcpdump I got the error message:

<[bad opt]>, <tcpdump bad hdr length 20 - too short, <28>

I increased the snaplen ( as seen on previous faq at tcpdump.org)and
still get a bad opt error.

Questions:

1. I successfully added and compiled the new variable th_srtt into the
tcp option field into my linux kernel (net/tcp.h, tcp_input.c) protocol
stacks. Since I want tcpdump to detect this added tcp option, how would
I go about this? Any suggestions anyone? 

2. Do I have to do modification as well on my tcpdump header file
(tcp.h, etc)and source code(print-tcp.c, etc)  to reflect this changes?
Note: I already tried modifying print_tcp.c and tcp.h of tcpdump and got
an error as specified above.

3. How would I go about using tcpdump to detect this new added tcp
option ( th_srtt) in the linux kernel?


Any help would be appreciated. Thanks. I'm getting confused now.

Cheers,
dom
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