Captive_portal in Shell
How can i block/pass client's mac address in captive_portal using shell command?
It's not supported.
You could play around with ipfw commands (the technology used by the captive portal to allow/block users) but you will face a lot of issues (such as your MACs not being displayed in the GUI, being wiped at each captive portal change, etc).
If this feature ever existed, it would not be implemented in shell...but using an HTTP API
Netgate had plans to implement an API for pfsense....then dropped it. More info here : https://www.netgate.com/blog/more-on-aes-ni.html