openwrt/package/base-files/default/etc/init.d/S45firewall

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