/ip firewall filter add chain=forward src-address=10.50.0.0/20 dst-address=!10.50.0.0/20 action=drop
/ip firewall filter add chain=forward src-address=192.168.100.0/24 dst-address=!192.168.100.0/24 action=drop
/ip firewall filter add chain=forward src-address=192.168.200.0/24 dst-address=!192.168.200.0/24 action=drop
/ip firewall filter add chain=forward src-address=172.18.0.0/24 dst-address=!172.18.0.0/24 action=drop
/ip firewall filter add chain=forward src-address=172.16.0.0/24 dst-address=!172.16.0.0/24 action=drop