UDP packets are getting dropped because of invalied checksum though checksum offload is enabled in kernel-2.6.32

[Murali Annamneni]

Hi All,

I have written a kernel module using netfilter framework. In my code I'll do some modifications to the header & payload parts of UDP packet in pre & post hooks.
After modifying the udp packet, I'm computing ip & udp checksum. This computation is consuming some cpu cycles.
Now, I want to offload this computation to the Ethernet device. For this I have commented the checksum computation in my code and enabled the checksum offload parameters of my Ethernet device.
While testing, I found that kernel is dropping the packets because of invalid checksums for ip & udp packets.
I have few doubts regarding checksum offload

1)    Shall I need to do anything in my kernel code.

2)    I'm using the below command  to enable checksum offload

ethtool -K eth0 rx on tx on

Is there anything I need to do apart from this ?


I'm testing my kernel code in kernel-2.6.32.

Thanks & Regards
Murali Annamneni



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