packet modify

[reta]

hi

I have linux router with 2 interface
eth0 connect to internet
eth1 connect to lan
and i want to capture all the packets that outgoing from eth1 (which connect to lan)
then modify all packets and then sent them to lan

i want to do that by using c lang

any one can help me please??????????

thanks

[jayasekar.k]

hi

I have linux router with 2 interface
eth0 connect to internet
eth1 connect to lan
and i want to capture all the packets that outgoing from eth1 (which connect to lan)
then modify all packets and then sent them to lan

i want to do that by using c lang

any one can help me please??????????

thanks

Hi, i dont know much about this.
You can access ethernet buffer to get raw packet's.
try to understand how tcpdump or wireshark is getting the raw packets from the ethernet buffer that may help you.

[reta]

HI jayasekar.k

I DON'T WANT TO CAPTURE PACKETS ONLY BUT WANT TO MODIFY IT AND THAT'S THE PROBLEM
IF I USE RAW SOCKET THEN I CAN'T STOP THE PACKETS IN KERNAL I JUST GET A COPY OF THE PACKETS AND WHEN I SEND MY MODIFICATION PACKET THEN THE PACKET WILL SEND TWICE :THE ORGINAL PACKET AND THE MODIFICATION PACKET

SO I NEED A WAY TO GET THE ORIGINAL PACKET NOT A COPY OF IT

HOW TO DO THAT ????

PLEASE HELP ME

[jayasekar.k]

hi reta, It look's like we have to do something with kernel.
Iam started working on this issue. i will let u know abt my result.
if you found the answer plz post it.

[reta]

hi reta, It look's like we have to do something with kernel.
Iam started working on this issue. i will let u know abt my result.
if you found the answer plz post it.

hi again

Iam pleased to hear that you start to work on this issue...
of course I will let you know if i get any result , and I will wait your result.

[gerrard_116]

Hi jayasekar.k and reta,
I am also working on packet modification. Additionally, I will have to check for specific packet format before packet modification. If any of you get any idea of how to do the modification then please do share.

Regards,
Kishwar.

[jayasekar.k]

Hi jayasekar.k and reta,
I am also working on packet modification. Additionally, I will have to check for specific packet format before packet modification. If any of you get any idea of how to do the modification then please do share.

Regards,
Kishwar.

Hi Kishwar, For packet modification, you should know the protocol format and checksum calculation for that protocol. if you are good in that you can modify any packet.

[jayasekar.k]

hi reta, hv u got any solutions.
Now iam started to analyse the kernel source code. on how it sends data to the network card. what about your status, ???

regards
jayasekar
jayasekar.k@gmail.com

[reta]

hi reta, hv u got any solutions.
Now iam started to analyse the kernel source code. on how it sends data to the network card. what about your status, ???

regards
jayasekar
jayasekar.k@gmail.com

Hi jayasekar.k

Finally I got this result ,You can capture >modify>reinject the packets using libipq library.

If you find diffrent result please post it.

Good luck
Reta

[jayasekar.k]

i know it is silly to ask you, i googled it , i dont get the proper result.
where can we download "libipq library for C", i found libipq for php but i cant found one for c