57 lines
3.1 KiB
Bash
57 lines
3.1 KiB
Bash
#!/bin/sh
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### 1: Drop invalid packets ###
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/sbin/iptables -t mangle -A PREROUTING -m conntrack --ctstate INVALID -j DROP
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### 2: Drop TCP packets that are new and are not SYN ###
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/sbin/iptables -t mangle -A PREROUTING -p tcp ! --syn -m conntrack --ctstate NEW -j DROP
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### 3: Drop SYN packets with suspicious MSS value ###
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/sbin/iptables -t mangle -A PREROUTING -p tcp -m conntrack --ctstate NEW -m tcpmss ! --mss 536:65535 -j DROP
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### 4: Block packets with bogus TCP flags ###
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/sbin/iptables -t mangle -A PREROUTING -p tcp --tcp-flags FIN,SYN,RST,PSH,ACK,URG NONE -j DROP
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/sbin/iptables -t mangle -A PREROUTING -p tcp --tcp-flags FIN,SYN FIN,SYN -j DROP
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/sbin/iptables -t mangle -A PREROUTING -p tcp --tcp-flags SYN,RST SYN,RST -j DROP
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/sbin/iptables -t mangle -A PREROUTING -p tcp --tcp-flags FIN,RST FIN,RST -j DROP
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/sbin/iptables -t mangle -A PREROUTING -p tcp --tcp-flags FIN,ACK FIN -j DROP
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/sbin/iptables -t mangle -A PREROUTING -p tcp --tcp-flags ACK,URG URG -j DROP
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/sbin/iptables -t mangle -A PREROUTING -p tcp --tcp-flags ACK,FIN FIN -j DROP
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/sbin/iptables -t mangle -A PREROUTING -p tcp --tcp-flags ACK,PSH PSH -j DROP
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/sbin/iptables -t mangle -A PREROUTING -p tcp --tcp-flags ALL ALL -j DROP
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/sbin/iptables -t mangle -A PREROUTING -p tcp --tcp-flags ALL NONE -j DROP
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/sbin/iptables -t mangle -A PREROUTING -p tcp --tcp-flags ALL FIN,PSH,URG -j DROP
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/sbin/iptables -t mangle -A PREROUTING -p tcp --tcp-flags ALL SYN,FIN,PSH,URG -j DROP
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/sbin/iptables -t mangle -A PREROUTING -p tcp --tcp-flags ALL SYN,RST,ACK,FIN,URG -j DROP
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### 5: Block spoofed packets ###
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/sbin/iptables -t mangle -A PREROUTING -s 224.0.0.0/3 -j DROP
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/sbin/iptables -t mangle -A PREROUTING -s 169.254.0.0/16 -j DROP
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/sbin/iptables -t mangle -A PREROUTING -s 172.16.0.0/12 -j DROP
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/sbin/iptables -t mangle -A PREROUTING -s 192.0.2.0/24 -j DROP
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/sbin/iptables -t mangle -A PREROUTING -s 192.168.0.0/16 -j DROP
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/sbin/iptables -t mangle -A PREROUTING -s 10.0.0.0/8 -j DROP
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/sbin/iptables -t mangle -A PREROUTING -s 0.0.0.0/8 -j DROP
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/sbin/iptables -t mangle -A PREROUTING -s 240.0.0.0/5 -j DROP
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/sbin/iptables -t mangle -A PREROUTING -s 127.0.0.0/8 ! -i lo -j DROP
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### 6: Drop ICMP (you usually don't need this protocol) ###
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/sbin/iptables -t mangle -A PREROUTING -p icmp -j DROP
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### 7: Drop fragments in all chains ###
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/sbin/iptables -t mangle -A PREROUTING -f -j DROP
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### 8: Limit connections per source IP ###
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/sbin/iptables -A INPUT -p tcp -m connlimit --connlimit-above 111 -j REJECT --reject-with tcp-reset
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### 9: Limit RST packets ###
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/sbin/iptables -A INPUT -p tcp --tcp-flags RST RST -m limit --limit 2/s --limit-burst 2 -j ACCEPT
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/sbin/iptables -A INPUT -p tcp --tcp-flags RST RST -j DROP
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### 10: Limit new TCP connections per second per source IP ###
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/sbin/iptables -A INPUT -p tcp -m conntrack --ctstate NEW -m limit --limit 60/s --limit-burst 20 -j ACCEPT
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/sbin/iptables -A INPUT -p tcp -m conntrack --ctstate NEW -j DROP
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### 11: Use SYNPROXY on all ports (disables connection limiting rule) ###
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# Hidden - unlock content above in "Mitigating SYN Floods With SYNPROXY" section
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