Forward packet from wlan0 to eth0

sharenet.sh

function sharenet()
{
    if [ $# -eq 0 ]; then
        echo "usage: sharenet <on/off>"
        return 0
    fi

    local if_from=wlan0
    local if_to=eth0
    # check command-line commands
    cmd=$1
    case $cmd in
        on )
            sudo su -c "echo 1 > /proc/sys/net/ipv4/ip_forward"
            echo "Enable sharing internet from $if_from to $if_to"
            sudo /sbin/iptables -A FORWARD -i $if_to -o $if_from -j ACCEPT
            sudo /sbin/iptables -A FORWARD -i $if_from -o $if_to -m state --state RELATED,ESTABLISHED -j ACCEPT
            sudo /sbin/iptables -t nat -A POSTROUTING -o $if_from -j MASQUERADE
            ;;
        off )
            sudo su -c "echo 0 > /proc/sys/net/ipv4/ip_forward"
            echo "Disable sharing internet from $if_from to $if_to"
            ;;
        * )
            echo "sharenet: $1: invalid command"
            echo "usage: sharenet <on/off>"
            ;;
    esac
}