How to block certain IP/MAC Address that access your WiFi Network ? I can see people access into my Wifi by going into AirportUtility
Here is a list of people that are connected to Wifi at the moment. 

There're 2 of them in there that I'm not sure - how they get in there ?



Goals


I would like to both of them out.
I also want to block a certain MAC Address for future access.


What I have tried

I've been playing around with the AirPort Utility, and all I can do is restrict the time access to a certain MAC address.

I also came across an app called Little Snitch, but that not exactly what I want.

Is there any Mac App that let me block/allow a certain IP address ?
On your airport extreme you can block certain mac address for good with "No Access".

In your airports configuration go to the "Network" tab and check "Enable Access Control", then click on "Timed Access Control".



Then on the top add the mac address you want to prohibit and give it a description.  Towards the bottom, On the "Wireless Access Time" drop down select "No Access" and save.



Confirmed this works on a 5th generation airport running version 7.6.4