[CentOS] How to know if packet is dropped by kernel for udp checksum mismatch

Fri Mar 16 12:11:17 UTC 2012
Arif Hossain <freefall1986 at gmail.com>

Hi all,

I have a netfilter_queue app which de-obfuscates a already obfuscated
udp packets. de-obfuscation process ends successfully but somehow packet
is not reaching to the udp daemon. i'm suspecting this is happening
because of a udp checksum mismatch. so i'm wondering how can i get logs
of packets which are dropped because of udp checksum mismatch?

i've heard linux by default dropps a packet if it does not have correct
checksum if checksum is present, this behavior can be modified by
recompiling the kernel. using a custom kernel is not in our agenda.

my platform :
Linux <hostname> 2.6.32-220.7.1.el6.x86_64 #1 SMP Wed Mar 7 00:52:02 GMT
2012 x86_64 x86_64 x86_64 GNU/Linux