port_knocking_firewall.xl

import "pkt_headers.xlh";

Stage port_knocking_on_the_heavens_door {
	//Register global incrementalCounter;

	setFlowKey(ipv4.src);

	// Initialized to 0

	State initial init {
		on (pktRcvd){
			if (tcp.dport == 2570) {
				setNextState(port1);    
			}
		}
	}

	State port1 {
		on (pktRcvd){
			if (tcp.dport == 2827) {
				setNextState(port2);
            }
		}
	}

	State port2 {
		on (pktRcvd){
			if (tcp.dport == 3084) {
				setNextState(port3);
            }
		}
    }

	State port3 {
		on (pktRcvd){
			if (tcp.dport == 5555) {
				setNextState(allowed);
            }
		}
    }


    State allowed {
		on (pktRcvd){
            if (tcp.dport == 22) {
			    sendPacket(255, 2);
		    }
        }
	}

    State any {
        on(pktRcvd) {
            if(pktRcvd.port == 2) {
                    sendPacket(255, 1);
            }
        }
    }
}