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99 lines
2.8 KiB
Bash
99 lines
2.8 KiB
Bash
#!/bin/sh
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## Please make changes in /etc/firewall.user
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${FAILSAFE:+exit}
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. /etc/functions.sh
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. /etc/network.overrides
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[ "$FAILSAFE" != "true" -a -e /etc/config/network ] && . /etc/config/network
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WAN=$(nvram get wan_ifname)
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LAN=$(nvram get lan_ifname)
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## CLEAR TABLES
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for T in filter nat; do
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iptables -t $T -F
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iptables -t $T -X
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done
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iptables -N input_rule
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iptables -N output_rule
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iptables -N forwarding_rule
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iptables -t nat -N prerouting_rule
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iptables -t nat -N postrouting_rule
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### INPUT
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### (connections with the router as destination)
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# base case
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iptables -P INPUT DROP
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iptables -A INPUT -m state --state INVALID -j DROP
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iptables -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
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iptables -A INPUT -p tcp --tcp-flags SYN SYN --tcp-option \! 2 -j DROP
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#
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# insert accept rule or to jump to new accept-check table here
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#
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iptables -A INPUT -j input_rule
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# allow
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iptables -A INPUT ${WAN:+-i \! $WAN} -j ACCEPT # allow from lan/wifi interfaces
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iptables -A INPUT -p icmp -j ACCEPT # allow ICMP
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iptables -A INPUT -p gre -j ACCEPT # allow GRE
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# reject (what to do with anything not allowed earlier)
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iptables -A INPUT -p tcp -j REJECT --reject-with tcp-reset
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iptables -A INPUT -j REJECT --reject-with icmp-port-unreachable
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### OUTPUT
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### (connections with the router as source)
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# base case
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iptables -P OUTPUT DROP
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iptables -A OUTPUT -m state --state INVALID -j DROP
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iptables -A OUTPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
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#
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# insert accept rule or to jump to new accept-check table here
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#
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iptables -A OUTPUT -j output_rule
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# allow
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iptables -A OUTPUT -j ACCEPT #allow everything out
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# reject (what to do with anything not allowed earlier)
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iptables -A OUTPUT -p tcp -j REJECT --reject-with tcp-reset
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iptables -A OUTPUT -j REJECT --reject-with icmp-port-unreachable
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### FORWARDING
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### (connections routed through the router)
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# base case
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iptables -P FORWARD DROP
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iptables -A FORWARD -m state --state INVALID -j DROP
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iptables -A FORWARD -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --clamp-mss-to-pmtu
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iptables -A FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT
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#
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# insert accept rule or to jump to new accept-check table here
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#
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iptables -A FORWARD -j forwarding_rule
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# allow
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# if there is bridge splitting this workaround works too
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for iface in $LAN; do
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iptables -A FORWARD -i $iface -o $iface -j ACCEPT
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[ -z "$WAN" ] || iptables -A FORWARD -i $iface -o $WAN -j ACCEPT
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done
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# reject (what to do with anything not allowed earlier)
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# uses the default -P DROP
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### MASQ
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iptables -t nat -A PREROUTING -j prerouting_rule
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iptables -t nat -A POSTROUTING -j postrouting_rule
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[ -z "$WAN" ] || iptables -t nat -A POSTROUTING -o $WAN -j MASQUERADE
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## USER RULES
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[ -f /etc/firewall.user ] && . /etc/firewall.user
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