Even basic networking is complex, so don't fret if you don't understand it all immediately. That article is providing steps to take to help you identify the traffic that the Sonicwall believes is a flood and is logging as such. That article will not provide you an answer, you have to determine the answer yourself.
That being said traffic identified as a FIN FLOOD isn't always bad, it may just be an instance of a half-open TCP connection. Again, you have to determine that.
Answers
The server is waiting for the client to close the connection. The Sonicwall identified the packets as a possible flood.
Read up on TCP handshaking.
server is "source" ?
https://en.wikipedia.org/wiki/Client%E2%80%93server_model
In this instance yes.
Read up on the client-server model.
I read.
I'm studyng this article:
but it's no easy for me.
Even basic networking is complex, so don't fret if you don't understand it all immediately. That article is providing steps to take to help you identify the traffic that the Sonicwall believes is a flood and is logging as such. That article will not provide you an answer, you have to determine the answer yourself.
That being said traffic identified as a FIN FLOOD isn't always bad, it may just be an instance of a half-open TCP connection. Again, you have to determine that.