THE SMART TRICK OF WINBOX THAT NO ONE IS DISCUSSING

/ip firewall filter incorporate chain=enter connection-state=set up,related action=accept remark="acknowledge recognized,connected"; incorporate chain=input link-point out=invalid motion=fall; add chain=enter in-interface=ether1 protocol=icmp action=acknowledge remark="make it possible for ICMP"; include chain=input in-interface=ether1 protocol=tcp