Hi SerpentFly,
I found that the repetition starts after the final ack has been sent. I don’t know why its happening. for your reference, I am posting the log file here.
In the log, System-1 is the system where I am modifying the packet. and as I mentioned earlier, I am modifying only the packets with payload.
System-1 –>System-2
ip_len=40
Seq:19027, ack:28986
Type = FIN ACK
Identification:14987
System-2 –>System-1
ip_len=40
Seq:28986, ack:19027
Type = ACK
Identification:61538
System-2 –>System-1
ip_len=40
Seq:28986, ack:19027
Type = FIN ACK
Identification:61539
System-1 –>System-2
ip_len=40
Seq:19027, ack:28986
Type = ACK
Identification:14988
Repetition Starts here….
System-1 –>System-2
ip_len=40
Seq:19027, ack:28986
Type = ACK
Identification:14989
System-2 –>System-1
ip_len=40
Seq:28986, ack:19027
Type = ACK
Identification:61540
System-1 –>System-2
ip_len=40
Seq:19027, ack:28986
Type = ACK
Identification:14990
System-2 –>System-1
ip_len=40
Seq:28986, ack:19027
Type = ACK
Identification:61541
….
….