How to disable TCP's checksum

How to disable TCP's checksum

[Zhu Ying Jie]

Hi,
  I am currently using kernel version 2.4.2 and trying to disable
tcp_input's checksum function. However, even I comment all the csum_error
in the file tcp_input.c, the packet (with wrong checksum) seems still will
be dropped. Can anyone tell me how to do the work? 

Zhu Ying jie
Department of Computer Science,
School of Computing, 
National University of Singapore


SS****************************SS***********************************SS
+           From little town of far land we came,                   + 
+           to save our honor from a world of flame.                +
+           By little town of far land we sleep,                    + 
+           and trust that world will be won for you to keep.       +
SS****************************SS***********************************SS

Re: How to disable TCP's checksum

[Roberto Nibali]

Hello,

Zhu Ying Jie wrote:
> Hi,
>   I am currently using kernel version 2.4.2 and trying to disable
> tcp_input's checksum function. However, even I comment all the csum_error
> in the file tcp_input.c, the packet (with wrong checksum) seems still will
> be dropped. Can anyone tell me how to do the work? 

You can try to set skb->ip_summed=CHECKSUM_UNNECESSARY. But read the 
comments in ../include/linux/skbuff.h to see if you really want that.

HTH,
Roberto Nibali, ratz

Re: How to disable TCP's checksum

[bert hubert]

On Wed, Feb 27, 2002 at 02:20:11PM +0000, Zhu Ying Jie wrote:
> Hi,
>   I am currently using kernel version 2.4.2 and trying to disable
> tcp_input's checksum function. However, even I comment all the csum_error
> in the file tcp_input.c, the packet (with wrong checksum) seems still will
> be dropped. Can anyone tell me how to do the work? 

Perhaps the ip checksum is also incorrect?

Regards,

bert

-- 
http://www.PowerDNS.com          Versatile DNS Software & Services
http://www.tk                              the dot in .tk
http://lartc.org           Linux Advanced Routing & Traffic Control HOWTO

Re: How to disable TCP's checksum

[Nivedita Singhvi]

> I am currently using kernel version 2.4.2 and trying to
> disable tcp_input's checksum function. However, even
> I comment all the csum_error in the file tcp_input.c, the
> packet (with wrong checksum) seems still will be dropped.

If the checksum field is the only one thats incorrect or messed
up, then disabling the checksum will suffice.  But if any other part
of the packet is also corrupted or altered in some way, it
might fail the many other checks both IP and TCP perform.

(Sorry, I know thats fairly obvious, but its easy to miss a check
or two. :) )

> Zhu Ying jie

thanks,
Nivedita