Your book says it doesn't send back anything in response to FIN

hi

On page 225 of Building open network... you wrote that when FIN scan sends out TCP packet with FIN flag set to a port,and if that port is open,it ussually ignores the packet.
 But as far as I've read,when FIN (for unexisting connection)arrives on open port,it sends back RST packet

So which is it?

PS:I'd appreciate if my previous (i.e. Blocking mode) would also be answered.I received some email,but with only header and no text in the body of message

thank you and sorry for the trouble