Playing with an RB493G and wanted to allow only a certain list of mac addresses to be able to connect. We all know this type of security is in no way fool proof. The 493G has 2 switch chips in it and ports 2-5 are on switch2 and ports 1 and 6-9 are on switch1 Much like /ip firewall filter rules, switch rules are checked chronologically (top down). And like /ip firewall filter rules, you must specify a deny rule. Although there is no 'deny' rule as such, you can just specify a redirect to null (specify no port) which achieves the same result.