long time ago i found an wiki article for method that protect your network from unwanted access.
method was something like:
attacker need to know 2, 3 or more exact ports which are open to access the network.
in the case of 3 ports, one of them can be closed at certain time "port1", and other two can be open, after a time "port1" opens and "port3" closes, so in that way it confuses port scanners
i forgot how this method was called so i can find the article and find information how to do it my self.
i remember that this was some kind of methot that network admins protect their network.
Can someone help me, telling me what was the name of that method or give me some articles about this type of protection or something similar?