How to block Minecraft on pfSense?

I am playing around with pfSense at home and I also installed the pfBlockerNG. My son is secretly playing Minecraft when he's supposed to doing online class. So I want to block the Minecraft client from connecting outside private or public Minecraft servers. Any idea on howto? Thanks!

Like other posters said, most MC servers are on port 25565, but not all, and there are many ways children can innovate to workaround a simple port block.

However, if you'd like to test this, in pfSense go to Firewall > Rules > LAN. Click the Top Add button (green up arrow), then just choose the options:

1. Action: Block
2. Interface: LAN
3. Address Family: IPv4+IPv6
4. Protocol: TCP/UDP
5. Source: any
6. Destination: any
7. Port Range (only the first custom box): 25565
8. Description: Minecraft Port 25565 Styrofoam Vault Door

Save and reload your firewall