Kernel sender module in post routing hook causing ethernet fcs error at receiver
coded netfilter module and in a post routing hook i have modified the data. the data reaches the wireshark packet capture at receiver but fails to reach up the application . rather the complete data that reaches receiver. part of it shows up in ethernet trailer with ethernet fcs error.
is there a point to be taken care of while sending skbuff finally..
i have done following:-
calculated tcp checksum
ip checksum - not calculated
header pointers - not re-setted
csum - initialised using csum_partial . but not sure
data put in skbuff using skb_put.
modified data seen by putting prints as well as on reciever packet capture, but not in receiving application..
As soon as the module is removed ( rmmod) the original packet shows up in application... how can i handle this data modification in netfilter hook. what all do i need to cater for step wise.. can any one please please guide