Unwanted RST TCP packet with Scapy

Question

In order to understand how TCP works, I tried to forge my own TCP SYN/SYN-ACK/ACK (based on the tutorial: http://www.thice.nl/creating-ack-get-packets-with-scapy/ ).

Answer 1

I don't have a non-iptables answer, but one can fix the reset issue. Instead of trying to filter the outgoing reset in the filter table, filter all of the incoming packets from the target in the raw table instead. This prevents the return packets from the target from even being processed by the kernel, though scapy still sees them. I used the following syntax:

iptables -t raw -A PREROUTING -p tcp --dport  -j DROP

This solution does force me to use the same source port for my traffic; feel free to use your own iptables-fu to identify your target's return packets.