if [ -x "${ipfw}" ] && ${ipfw} print >/dev/null 2>&1 ; then
firewall_tool="ipfw"
elif [ -x "${iptables}" -a -x "${ip6tables}" ] && ${iptables} -L -n >/dev/null 2>&1 ; then
firewall_tool="iptables"
else
echo "No firewall tool found! (Tried ipfw, iptables)" 1>&2
exit 1
fi