Re: IP cheksum and libnet_pblock_coalesce

Hi jarppe

> Hello everybody,
> 
> Should libnet_pblock_coalesce() set the IP checksum correctly? I'm using libnet 1.1.2.1, compiled with GCC 3.2.2 20030222 on Linux.
> 
> When I create packet using libnet_build_[udp|tcp]() + libnet_build_ip(), then get the packet using libnet_pblock_coalesce() and then call libnet_ip_check() over the returned buffer, I get non-zero reply, indicating wrong IP checksum.
> 
> Interestingly enough, if I create the packet with libnet_build_icmpv4_echo() + libnet_build_ip(), then libnet_ip_check() returns zero (checksum ok).
> 
> Am I doing something wrong, or is there a bug?
> 
> -jarppe

I had something similar situation. I'm also using libnet 1.1.2.1 with
GCC (Redhat9).

I also found some wrong checksum packets created by libnet.
So, I replace the function libnet_in_checksum() (libnet_checksum.c) with
the same name function of libnet-1.0.2a, there is no wrong packet.

-Kenichi