sudo su
iptables -A INPUT -i wlan0 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
iptables -A INPUT -i wlan0 -p tcp -m tcp --dport 80 -j ACCEPT
iptables -A INPUT -i wlan0 -p udp -m udp --dport 53 -j ACCEPT
iptables -A INPUT -i wlan0 -p udp -m udp --dport 67:68 -j ACCEPT
iptables -A INPUT -i wlan0 -j DROP
iptables-save > /etc/iptables/iptables.rules