# http://www.zago.eti.br/modelos/ppp0-squid-compartilhar
    modprobe iptable_nat
    iptables -t nat -A PREROUTING -p tcp -m multiport -s 192.168.1.0/24 --dport 80,443 -j REDIRECT --to-ports 3128
    iptables -t nat -A POSTROUTING -o ppp0 -j MASQUERADE
    echo 1 > /proc/sys/net/ipv4/ip_forward