openwrt/target/default/target_skeleton/etc/init.d/S45firewall

   1 #!/bin/sh
   2 . /etc/functions.sh
   3
   4 WAN=$(nvram get wan_ifname)
   5
   6 IPT=/usr/sbin/iptables
   7
   8 for T in filter nat mangle ; do
   9   $IPT -t $T -F
  10   $IPT -t $T -X
  11 done
  12
  13 $IPT -t filter -A INPUT -m state --state INVALID -j DROP
  14 $IPT -t filter -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
  15 $IPT -t filter -A INPUT -p icmp -j ACCEPT
  16 $IPT -t filter -A INPUT -p 47 -j ACCEPT         # allow GRE
  17 $IPT -t filter -A INPUT -i $WAN -p tcp -j REJECT --reject-with tcp-reset
  18 $IPT -t filter -A INPUT -i $WAN -j REJECT --reject-with icmp-port-unreachable
  19 $IPT -t filter -A FORWARD -m state --state INVALID -j DROP
  20 $IPT -t filter -A FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT
  21 $IPT -t filter -A FORWARD -i $WAN -m state --state NEW,INVALID -j DROP
  22 $IPT -t filter -A FORWARD -o $WAN -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --clamp-mss-to-pmtu
  23
  24 $IPT -t nat -A POSTROUTING -o $WAN -j MASQUERADE