hping3 --syn -c 1 -p 80 vi4nn4network.blogspot.com
set --syn to receive destinet answer
set -c 1 to define how many packet that you want received
set -p 80 to define the port
set the site that you want test
when you request with the parameter set --syn you must wait the answer syn ACK, that answer that the service is available on your destiny.
After the command run see the target flags=SA = SYN ACK
That is when the service is available.
If you start the command see the target flags=RA = RESET ACK
That is when the service is not available.
POSSIBLE ANSWER WHEN YOU START THE SWEEP FURTIVELY:
flags = RA (close)
flags = SA (open)
ACK = AcknowledgementSYN = Synchronize