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#!/bin/sh /etc/rc.common
# Copyright (C) 2006 OpenWrt.org
## Please make changes in /etc/firewall.user
START=45
start() {
include /lib/network
scan_interfaces
config_get WAN wan ifname
config_get WANDEV wan device
config_get LAN lan ifname
## CLEAR TABLES
for T in filter nat; do
iptables -t $T -F
iptables -t $T -X
done
iptables -N input_rule
iptables -N input_wan
iptables -N output_rule
iptables -N forwarding_rule
iptables -N forwarding_wan
iptables -t nat -N prerouting_rule
iptables -t nat -N prerouting_wan
iptables -t nat -N postrouting_rule
iptables -N LAN_ACCEPT
[ -z "$WAN" ] || iptables -A LAN_ACCEPT -i "$WAN" -j RETURN
[ -z "$WANDEV" -o "$WANDEV" = "$WAN" ] || iptables -A LAN_ACCEPT -i "$WANDEV" -j RETURN
iptables -A LAN_ACCEPT -j ACCEPT
### INPUT
### (connections with the router as destination)
# base case
iptables -P INPUT DROP
iptables -A INPUT -m state --state INVALID -j DROP
iptables -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
iptables -A INPUT -p tcp --tcp-flags SYN SYN --tcp-option \! 2 -j DROP
#
# insert accept rule or to jump to new accept-check table here
#
iptables -A INPUT -j input_rule
[ -z "$WAN" ] || iptables -A INPUT -i $WAN -j input_wan
# allow
iptables -A INPUT -j LAN_ACCEPT # allow from lan/wifi interfaces
iptables -A INPUT -p icmp -j ACCEPT # allow ICMP
iptables -A INPUT -p gre -j ACCEPT # allow GRE
# reject (what to do with anything not allowed earlier)
iptables -A INPUT -p tcp -j REJECT --reject-with tcp-reset
iptables -A INPUT -j REJECT --reject-with icmp-port-unreachable
### OUTPUT
### (connections with the router as source)
# base case
iptables -P OUTPUT DROP
iptables -A OUTPUT -m state --state INVALID -j DROP
iptables -A OUTPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
#
# insert accept rule or to jump to new accept-check table here
#
iptables -A OUTPUT -j output_rule
# allow
iptables -A OUTPUT -j ACCEPT #allow everything out
# reject (what to do with anything not allowed earlier)
iptables -A OUTPUT -p tcp -j REJECT --reject-with tcp-reset
iptables -A OUTPUT -j REJECT --reject-with icmp-port-unreachable
### FORWARDING
### (connections routed through the router)
# base case
iptables -P FORWARD DROP
iptables -A FORWARD -m state --state INVALID -j DROP
iptables -A FORWARD -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --clamp-mss-to-pmtu
iptables -A FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT
#
# insert accept rule or to jump to new accept-check table here
#
iptables -A FORWARD -j forwarding_rule
[ -z "$WAN" ] || iptables -A FORWARD -i $WAN -j forwarding_wan
# allow
iptables -A FORWARD -i $LAN -o $LAN -j ACCEPT
[ -z "$WAN" ] || iptables -A FORWARD -i $LAN -o $WAN -j ACCEPT
# reject (what to do with anything not allowed earlier)
# uses the default -P DROP
### MASQ
iptables -t nat -A PREROUTING -j prerouting_rule
[ -z "$WAN" ] || iptables -t nat -A PREROUTING -i "$WAN" -j prerouting_wan
iptables -t nat -A POSTROUTING -j postrouting_rule
[ -z "$WAN" ] || iptables -t nat -A POSTROUTING -o $WAN -j MASQUERADE
## USER RULES
[ -f /etc/firewall.user ] && . /etc/firewall.user
[ -n "$WAN" -a -e /etc/config/firewall ] && {
export WAN
awk -f /usr/lib/common.awk -f /usr/lib/firewall.awk /etc/config/firewall | ash
}
}
stop() {
iptables -P INPUT ACCEPT
iptables -P OUTPUT ACCEPT
iptables -P FORWARD ACCEPT
iptables -F
iptables -X
iptables -t nat -P PREROUTING ACCEPT
iptables -t nat -P POSTROUTING ACCEPT
iptables -t nat -P OUTPUT ACCEPT
iptables -t nat -F
iptables -t nat -X
}
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