#!/bin/sh . /etc/functions.sh export WAN=$(nvram get wan_ifname) export LAN=$(nvram get lan_ifname) ## CLEAR TABLES for T in filter nat mangle; do iptables -t $T -F iptables -t $T -X done iptables -N input_rule iptables -N output_rule iptables -N forwarding_rule iptables -t nat -N prerouting_rule iptables -t nat -N postrouting_rule ### Port forwarding # iptables -t nat -A prerouting_rule -p tcp --dport 22 -j DNAT --to 192.168.1.2 # iptables -A forwarding_rule -p tcp --dport 22 -d 192.168.1.2 -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 # allow iptables -A INPUT -i \! $WAN -j ACCEPT # allow from lan/wifi interfaces iptables -A INPUT -p icmp -j ACCEPT # allow ICMP iptables -A INPUT -p 47 -j ACCEPT # allow GRE iptables -A INPUT -p tcp --syn --tcp-option \! 2 -j DROP # # insert accept rule or to jump to new accept-check table here # iptables -A INPUT -j input_rule # 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 # allow iptables -A OUTPUT -j ACCEPT #allow everything out # # insert accept rule or to jump to new accept-check table here # iptables -A OUTPUT -j output_rule # 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 -m state --state RELATED,ESTABLISHED -j ACCEPT iptables -A FORWARD -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --clamp-mss-to-pmtu # allow iptables -A FORWARD -i br0 -o br0 -j ACCEPT iptables -A FORWARD -i $LAN -o $WAN -j ACCEPT # # insert accept rule or to jump to new accept-check table here # iptables -A FORWARD -j forwarding_rule # reject (what to do with anything not allowed earlier) # uses the default -P DROP ### MASQ iptables -t nat -A PREROUTING -j prerouting_rule iptables -t nat -A POSTROUTING -j postrouting_rule iptables -t nat -A POSTROUTING -o $WAN -j MASQUERADE