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

   1 #!/bin/sh
   2
   3 ## Please make changes in /etc/firewall.user
   4
   5 . /etc/functions.sh
   6 WAN=$(nvram get wan_ifname)
   7 LAN=$(nvram get lan_ifname)
   8
   9 ## CLEAR TABLES
  10 for T in filter nat mangle; do
  11   iptables -t $T -F
  12   iptables -t $T -X
  13 done
  14
  15 iptables -N input_rule
  16 iptables -N output_rule
  17 iptables -N forwarding_rule
  18
  19 iptables -t nat -N prerouting_rule
  20 iptables -t nat -N postrouting_rule
  21
  22 ### INPUT
  23 ###  (connections with the router as destination)
  24
  25   # base case
  26   iptables -P INPUT DROP
  27   iptables -A INPUT -m state --state INVALID -j DROP
  28   iptables -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
  29   iptables -A INPUT -p tcp --syn --tcp-option \! 2 -j  DROP
  30
  31   #
  32   # insert accept rule or to jump to new accept-check table here
  33   #
  34   iptables -A INPUT -j input_rule
  35
  36   # allow
  37   iptables -A INPUT -i \! $WAN  -j ACCEPT       # allow from lan/wifi interfaces
  38   iptables -A INPUT -p icmp     -j ACCEPT       # allow ICMP
  39   iptables -A INPUT -p gre      -j ACCEPT       # allow GRE
  40
  41   # reject (what to do with anything not allowed earlier)
  42   iptables -A INPUT -p tcp -j REJECT --reject-with tcp-reset
  43   iptables -A INPUT -j REJECT --reject-with icmp-port-unreachable
  44
  45 ### OUTPUT
  46 ### (connections with the router as source)
  47
  48   # base case
  49   iptables -P OUTPUT DROP
  50   iptables -A OUTPUT -m state --state INVALID -j DROP
  51   iptables -A OUTPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
  52
  53   #
  54   # insert accept rule or to jump to new accept-check table here
  55   #
  56   iptables -A OUTPUT -j output_rule
  57
  58   # allow
  59   iptables -A OUTPUT -j ACCEPT          #allow everything out
  60
  61   # reject (what to do with anything not allowed earlier)
  62   iptables -A OUTPUT -p tcp -j REJECT --reject-with tcp-reset
  63   iptables -A OUTPUT -j REJECT --reject-with icmp-port-unreachable
  64
  65 ### FORWARDING
  66 ### (connections routed through the router)
  67
  68   # base case
  69   iptables -P FORWARD DROP
  70   iptables -A FORWARD -m state --state INVALID -j DROP
  71   iptables -A FORWARD -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --clamp-mss-to-pmtu
  72   iptables -A FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT
  73
  74   #
  75   # insert accept rule or to jump to new accept-check table here
  76   #
  77   iptables -A FORWARD -j forwarding_rule
  78
  79   # allow
  80   iptables -A FORWARD -i br0 -o br0 -j ACCEPT
  81   iptables -A FORWARD -i $LAN -o $WAN -j ACCEPT
  82
  83   # reject (what to do with anything not allowed earlier)
  84   # uses the default -P DROP
  85
  86 ### MASQ
  87   iptables -t nat -A PREROUTING -j prerouting_rule
  88   iptables -t nat -A POSTROUTING -j postrouting_rule
  89   iptables -t nat -A POSTROUTING -o $WAN -j MASQUERADE
  90
  91 ## USER RULES
  92 [ -f /etc/firewall.user ] && . /etc/firewall.user