I recently came across an excellent article on the topic of TCP resets. TCP is a connection-oriented protocol as opposed to the connectionless nature of UDP. So, if there are TCP resets on your network, this is not a bad thing and is just inherent in the protocol. Without TCP resets, a host could have a lot of partial connections established which are in the wait state awaiting further transmissions. This can exhaust the number of available sockets and cause the host to become unresponsive. This is what happened several years back with the TCP SYN flood and LAND denial of service attacks. Another reset type includes the ACK/RST. This is where a client attempts to connect to a service that is not available on that destination host.
If you manage a network and have taken packet captures to work on a problem and have seen RST packets or if you need to do this at some point in your career, you need to understand the purpose and source of the RST packets. Take a few minutes, read this excellent article that is the best explanation that I have seen on this topic. You will become better informed and better able to understand the nature of the network beast.
Thanks for reading and let’s continue to be good network citizens.