http://arav.i2p/stuff/article/hardening_mikrotik?lang=en
To add a rule there is a command called add , and remove to remove a rule by its number. To see all rules and theirs numbers type print command. Next I will give you set of rules for input and forward chains for IPv4 and IPv6. Those are very basic rules that allows already established connections in, allows ping our router from the Internet, and drops any other traffic that comes from anywhere else but not our LAN.