/ip firewall filter
add action=accept chain=forward comment="allow already established connections" \
    connection-state=established
add action=accept chain=input connection-state=established in-interface=WAN
add action=accept chain=forward comment="allow related connections" \
    connection-state=related
add action=add-src-to-address-list address-list="port scanners" \
    address-list-timeout=2w chain=input comment="NMAP NULL scan" protocol=tcp \
    tcp-flags=!fin,!syn,!rst,!psh,!ack,!urg
add action=add-src-to-address-list address-list="port scanners" \
    address-list-timeout=2w chain=input comment="Port scanners to list " \
    protocol=tcp psd=21,3s,3,1
add action=add-src-to-address-list address-list="port scanners" \
    address-list-timeout=2w chain=input comment="NMAP FIN Stealth scan" \
    protocol=tcp tcp-flags=fin,!syn,!rst,!psh,!ack,!urg
add action=add-src-to-address-list address-list="port scanners" \
    address-list-timeout=2w chain=input comment="SYN/FIN scan" protocol=tcp \
    tcp-flags=fin,syn
add action=add-src-to-address-list address-list="port scanners" \
    address-list-timeout=2w chain=input comment="SYN/RST scan" protocol=tcp \
    tcp-flags=syn,rst
add action=add-src-to-address-list address-list="port scanners" \
    address-list-timeout=2w chain=input comment="FIN/PSH/URG scan" protocol=tcp \
    tcp-flags=fin,psh,urg,!syn,!rst,!ack
add action=add-src-to-address-list address-list="port scanners" \
    address-list-timeout=2w chain=input comment="ALL/ALL scan" protocol=tcp \
    tcp-flags=fin,syn,rst,psh,ack,urg
add action=drop chain=forward comment="drop invalid connections" \
    connection-state="" disabled=yes
add action=drop chain=input comment="Drop Invalid connections" \
    connection-state="" disabled=yes
add action=drop chain=input comment="dropping port scanners" src-address-list=\
    "port scanners"
add action=drop chain=forward comment="Block Bogon IP addresses" src-address=\
    0.0.0.0/8
add action=drop chain=forward dst-address=0.0.0.0/8
add action=drop chain=forward src-address=127.0.0.0/8
add action=drop chain=forward dst-address=127.0.0.0/8
add action=drop chain=forward src-address=224.0.0.0/3
add action=drop chain=forward dst-address=224.0.0.0/3
add action=drop chain=input in-interface=WAN