#!/bin/bash
mc_port=25565

regex="^([[:digit:]\.]+):[[:digit:]]+$"
ips=()
while read -r line ; do
    if [[ $line =~ $regex ]] ; then
        ips+=(${BASH_REMATCH[1]})
    fi
done < <(netstat -n --protocol inet | grep ':22022' | awk '{print $5}')

#flush existing rules
/sbin/iptables -F
for i in "${!ips[@]}" ; do
    #allow connection for ip ${ips[$i]}
    /sbin/iptables -A INPUT -p tcp --destination-port $mc_port -s ${ips[$i]} -j ACCEPT
done

#disallow all other connections
/sbin/iptables -A INPUT -p tcp --destination-port $mc_port -j DROP