Hi all. I need help with FCS re-computing. I added an extra header in outgoing packets, between layer 2 and 3 for my own needs. Now when the packet is forwarded Wireshark software on receiving machine tells the FCS is incorrect.

How can I recompute FCS after adding the extra header? I thought I could disable hardware checksumming setting skb->ip_summed = CHECKSUM_NONE and then call skb_checksum on socket buffer, but it seems not to be working.

Thanks in advance