Question about programming with ip_queue

[lam wai wm]

Mr. Chapman,

I've tried to create a new payload with the original header, 
but new payload.  I've found that it keeps sending the encrypt 
packet, but the data inside, is the output of the encrypted 
"encrypted content".  (It means it keep sending an encrypted 
"encrypted data content").  But it didn't reach the point of 
the destination.  I mean in the destination side, it didn't 
reach hook point of the program.  So how can I solve the 
problem?  Is it because I didn't change the checksum in the 
sending side?  And the kernel will silently discard modified 
packets with invalid checksums.  And honestly, I don't want to 
change the original checksum.  Would you mind telling me how 
can I rememdy this?  

Thanks, thanks so much.


Very respectfully,
marco.


Brad Chapman <kakadu_croc@yahoo.com> wrote:
>
> --- lam wai wm <00028911@brookes.ac.uk> wrote:
> > Dear Mr James Morris,
> > 
> > Thanks for your reply.  And I'm implementing a system, 
which 
> > will encrypt, decrypt the packet.  And I've encrypted the 
> > payload, but the size is bigger than the original size.  
> > Although I've passed the new size in the function of 
> > ipq_set_verdict, but it can just transmit the original 
size's 
> > payload.  I mean it will discard the byte afterward.  So I 
> > tried the other approach that I clone the payload (Header 
> > information), and place a encrypted payload.  But it seems 
it 
> > didn't work, too.
> > 
> > Could you please tell me how can I transmit the packet 
(with 
> > bigger size of payload) to the network.
> > 
> > Thanks, thanks a lot.
> > 
> > Very respectfully,
> > marco.
> 
> Mr. marco,
> 
>  If you were doing this in the kernel, you would simply 
clone/expand
> the skb and recalculate the checksum. In userspace, though, 
you need to
> pass your expanded payload and payload length to 
ipq_set_verdict(). See the
> libipq man pages.
> 
> Brad
> 
> 
> =====
> Brad Chapman
> 
> Permanent e-mail: kakadu_croc@yahoo.com
> Current e-mail: kakadu@adelphia.net
> 
> Reply to the address I used in the message to you,
> please!
> 
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