Mimicking TCP connection

Hi there,

I try to use libpcap and libnet to write a program that will mimic a TCP connection. In other words, my program performs TCP-handshake with a remote machine, sends out some data, analyzes the data it receives from the remote machine, and ends the TCP connection (i.e., FIN sequence). 

While I can capture and send packets, it seems that the Linux kernel interfere with my program. For example, in the TCP-handshake procedure, this is what happens:
1.	I send a syn
2.	I get back a synack.
3.	I send the next ack, but the kernel sends out a reset (RST) packet too (which ruin my handshake).


It seems to me that the kernel “does not know” about the connection I’m trying to establish. This seems logical to me because I never use the “legal” interface (e.g., TCP-sockets) to establish this connection. 

How can I prevent the kernel from interfering with my program?

Thanks,

Shai Rubin