::* Rules are applied to : '''chains ''' (e.g. ''input/output''), '''protocols ''' (e.g. ''tcp/udp/icmp''), and '''ports ''' (e.g. ''22, 80, 443'').*::# For the request the source port (sport) is 40112 and the destination port (dport) is 80*::# For the response the source port is 80 and the destination port is 40112* ::# Because we have the RELATED,ESTABLISHED rule we only care about controlling the incoming traffic on the server, which in our example on the server is INPUT TCP destination port 80.