seq numbers and checksum in tcp

Ayman El-Khashab (ayman@ccwf.cc.utexas.edu)
Sun, 17 Jan 1999 23:51:41 -0600

for some research that i am working on, i am doing some experiments
with the linux kernel and some tcpip stuff in particular. In any
case, in the tcp_rcv function, i have been able to get most of the
information that i need. Now i need to modify the sequence number
of the packet and then recompute the checksum, but i am not sure
how to go about this. I have expermimented for a while and turned
up nothing.

basically, i want to just modify the th->seq and then recompute
the tcp checksum and i suspect the skb checksum.

Is there an easy way to check the tcp checksum and then make the
mod and then recompute a new checksum. any help is much appreciated.

for that matter, i will need to change fields in the tcp header in
the v_ip_queue_xmit function. how can i compute whatever checksums
are neccessary here.

thanks,
- ayman

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