Drop port scanners

To protect the Router from port scanners, we can record the IPs of hackers who try to scan your box. Using this address list we can drop connection from those IP

in /ip firewall filter

/ip firewall filter add action=add-src-to-address-list address-list="port scanners"

   address-list-timeout=2w chain=input comment="Port scanners to list"
   disabled=no 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"
   disabled=no 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" disabled=no
   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" disabled=no
   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" disabled=
   no 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" disabled=no
   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="NMAP NULL scan" disabled=no
   protocol=tcp tcp-flags=!fin,!syn,!rst,!psh,!ack,!urg

Then you can drop those IPs:

add chain=input src-address-list="port scanners" action=drop comment="dropping port scanners" disabled=no

Similarly, you can drop these port scanners in the forward chain, but using the above rules with "chain=forward".