Posted by: Anonymous Coward
on September 17, 2004 07:15 AM
Port knocking is using uncompleted connections to transmit information. The client has no idea if the server got the SYN packet or not. The server is blocking the packet and isn't going to tell them either way. If it gets dropped somewhere between the two computers neither will ever know.
So UDP is no different, and it allows sending more information more reliably. Either the whole thing arrives or the whole thing is lost. That way the client can retry is the port doesn't open. With port knocking you wouldn't know which port was dropped and the server would then be out of sync with the client.