Specifically, using iptables somehow? I have my router/server using a specific port but this rule is not blocking all content even though I see a few packets hitting the rule
iptables -I INPUT -p tcp -s ! 192.168.1.*** -m mac --mac-source ! 11:22:33:44:55:66 --dport 12250 -j DROP
iptables -I INPUT -p tcp -s ! 192.168.1.*** -m mac --mac-source ! 11:22:33:44:55:66 --dport 12250 -j DROP