說明
A TCP reset basically kills a TCP connection instantly.
headers contains a bit known as the "reset" (RST) flag.
it indicates to the receiving computer that the computer should immediately stop using the TCP connection;
it should not send any more packets using the connection's identifying numbers, called ports, and discard any further packets it receives with headers indicating they belong to that connection.
Example
<1>
A 'router' could be doing anything - particularly NAT
One reason a device will send a RST is in response to receiving a packet for a closed socket.
<2>
an application makes lots of short-lived TCP connections and we don't want to leave the connection on the server in a Time Wait state