TCP resets and why they happen
During a normal operation, TCP will open a connection with SYN signals, and close the connection with FIN signals. One of the characters of TCP is the possibility to close a connection faster due to a problem or just for better efficiency.
In this recipe we will describe these cases, and how to understand exactly what happens, and if it is a regular condition or something went wrong.
Getting ready
Connect Wireshark with a port mirror to the suspected link or server, and start capture. Keep track of every window message you will see on the capture window. TCP resets can be sent in several cases. Some point to the proper working of the protocol, and some suggest a failure or problem. In this recipe, we will get to the reasons for it, and try to point out the problems and how to solve them.
How to do it...
Reset is a TCP signal that is sent in order to tell the receiver to break the connection. Reset is sent by setting the RST flag to a value of 1.
