#!/bin/bash
while true
do
echo "
______ ___________ _____ _    _  ___  _     _
|  ___|_   _| ___ |  ___| |  | |/ _ \| |   | |
| |_    | | | |_/ | |__ | |  | / /_\ | |   | |
|  _|   | | |    /|  __|| |/\| |  _  | |   | |
| |    _| |_| |\ \| |___\  /\  | | | | |___| |____
\_|    \___/\_| \_\____/ \/  \/\_| |_\_____\_____/
"

# Deny all access
sudo iptables -t filter -P INPUT DROP
sudo iptables -t filter -P FORWARD DROP
sudo iptables -t filter -P OUTPUT DROP

# Ready accept
sudo iptables -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
sudo iptables -A OUTPUT -m state --state RELATED,ESTABLISHED -j ACCEPT

# loop-back (localhost)
sudo iptables -t filter -A INPUT -i lo -j ACCEPT
sudo iptables -t filter -A OUTPUT -o lo -j ACCEPT

# Anti DDoS.
sudo iptables -A FORWARD -p tcp --syn -m limit --limit 1/second -j ACCEPT
sudo iptables -A FORWARD -p udp -m limit --limit 1/second -j ACCEPT
sudo iptables -A FORWARD -p icmp --icmp-type echo-request -m limit --limit 1/second -j ACCEPT
sudo iptables -A FORWARD -p tcp --tcp-flags SYN,ACK,FIN,RST RST -m limit --limit 1/s -j ACCEPT
sudo iptables -A INPUT -p tcp -m tcp --tcp-flags RST RST -m limit --limit 2/second --limit-burst 2 -j ACCEPT

# Anti DDoS Config 2.
sudo iptables -A INPUT -p tcp --syn -m limit --limit 2/s --limit-burst 30 -j ACCEPT
sudo iptables -A INPUT -p icmp --icmp-type echo-request -m limit --limit 1/s -j ACCEPT
sudo iptables -A INPUT -p tcp --tcp-flags ALL NONE -m limit --limit 1/h -j ACCEPT
sudo iptables -A INPUT -p tcp --tcp-flags ALL ALL -m limit --limit 1/h -j ACCEPT

# Reject spoofed packets.
sudo iptables -t mangle -A PREROUTING -s 224.0.0.0/3 -j DROP
sudo iptables -t mangle -A PREROUTING -s 240.0.0.0/5 -j DROP
sudo iptables -t mangle -A PREROUTING -s 169.254.0.0/16 -j DROP
sudo iptables -t mangle -A PREROUTING -s 172.16.0.0/12 -j DROP
sudo iptables -t mangle -A PREROUTING -s 192.0.2.0/24 -j DROP
sudo iptables -t mangle -A PREROUTING -s 100.64.0.0/10 -j DROP
sudo iptables -t mangle -A PREROUTING -s 239.0.0.0/8 -j DROP
sudo iptables -t mangle -A PREROUTING -s 192.168.2.0/24 -j DROP
sudo iptables -t mangle -A PREROUTING -s 192.168.10.0/24 -j DROP
sudo iptables -t mangle -A PREROUTING -s 192.168.0.0/16 -j DROP
sudo iptables -t mangle -A PREROUTING -s 192.0.0.0/16 -j DROP
sudo iptables -t mangle -A PREROUTING -s 192.88.99.0/24 -j DROP
sudo iptables -t mangle -A PREROUTING -s 10.0.0.0/8 -j DROP
sudo iptables -t mangle -A PREROUTING -s 127.0.0.0/8 -j DROP
sudo iptables -t mangle -A PREROUTING -s 203.0.113.0/24 -j DROP
sudo iptables -t mangle -A PREROUTING -s 198.51.100.0/24 -j DROP
sudo iptables -t mangle -A PREROUTING -s 198.18.0.0/15 -j DROP
sudo iptables -t mangle -A PREROUTING -s 0.0.0.0/8 -j DROP
sudo iptables -t mangle -A PREROUTING -s 239.255.255.0/24 -j DROP
sudo iptables -t mangle -A PREROUTING -s 255.0.0.0/8 -j DROP
sudo iptables -t mangle -A PREROUTING -d 255.255.255.255 -j DROP

# Block packets with bogus TCP flags.
sudo iptables -t mangle -A PREROUTING -p tcp -m tcp --tcp-flags FIN,SYN,RST,PSH,ACK,URG FIN,SYN,RST,PSH,ACK,URG -j DROP
sudo iptables -t mangle -A PREROUTING -p tcp -m tcp ! --tcp-flags FIN,SYN,RST,ACK SYN -m state --state NEW -j DROP
sudo iptables -t mangle -A PREROUTING -p tcp -m tcp --tcp-flags FIN,SYN,RST,PSH,ACK,URG NONE -j DROP
sudo iptables -t mangle -A PREROUTING -p tcp --tcp-flags FIN,SYN,RST,PSH,ACK,URG NONE -j DROP
sudo iptables -t mangle -A PREROUTING -p tcp --tcp-flags FIN,SYN FIN,SYN -j DROP
sudo iptables -t mangle -A PREROUTING -p tcp --tcp-flags SYN,RST SYN,RST -j DROP
sudo iptables -t mangle -A PREROUTING -p tcp --tcp-flags FIN,RST FIN,RST -j DROP
sudo iptables -t mangle -A PREROUTING -p tcp --tcp-flags FIN,ACK FIN -j DROP
sudo iptables -t mangle -A PREROUTING -p tcp --tcp-flags ACK,URG URG -j DROP
sudo iptables -t mangle -A PREROUTING -p tcp --tcp-flags ACK,FIN FIN -j DROP
sudo iptables -t mangle -A PREROUTING -p tcp --tcp-flags ACK,PSH PSH -j DROP
sudo iptables -t mangle -A PREROUTING -p tcp --tcp-flags ALL ALL -j DROP
sudo iptables -t mangle -A PREROUTING -p tcp --tcp-flags ALL NONE -j DROP
sudo iptables -t mangle -A PREROUTING -p tcp --tcp-flags ALL FIN,PSH,URG -j DROP
sudo iptables -t mangle -A PREROUTING -p tcp --tcp-flags ALL SYN,FIN,PSH,URG -j DROP
sudo iptables -t mangle -A PREROUTING -p tcp --tcp-flags ALL SYN,RST,ACK,FIN,URG -j DROP

# Drop TCP packets that are new and are not SYN.
sudo iptables -t mangle -A PREROUTING -p tcp ! --syn -m conntrack --ctstate NEW -j DROP

# Limit connections per source IP.
sudo iptables -A INPUT -p tcp -m connlimit --connlimit-above 111 -j REJECT --reject-with tcp-reset

# Drop SYN packets with suspicious MSS value.
sudo iptables -t mangle -A PREROUTING -p tcp -m conntrack --ctstate NEW -m tcpmss ! --mss 536:65535 -j DROP

# Drop fragments in all chains.
sudo iptables -t mangle -A PREROUTING -f -j DROP

# Drop all invalid packets.
sudo iptables -t mangle -A PREROUTING -m conntrack --ctstate INVALID -j DROP
sudo iptables -A INPUT -m state --state INVALID -j DROP
sudo iptables -A FORWARD -m state --state INVALID -j DROP
sudo iptables -A OUTPUT -m state --state INVALID -j DROP

# Drop excessive RST packets to avoid smurf attacks.
sudo iptables -A INPUT -p tcp -m tcp --tcp-flags RST RST -m limit --limit 2/second --limit-burst 2 -j ACCEPT

# Limit new TCP connections per second per source IP.
sudo iptables -A INPUT -p tcp -m conntrack --ctstate NEW -m limit --limit 60/s --limit-burst 20 -j ACCEPT
sudo iptables -A INPUT -p tcp -m conntrack --ctstate NEW -j DROP

#Port protection
sudo iptables -A INPUT -p tcp -m tcp --dport 80 --tcp-flags FIN,SYN,RST,ACK SYN -m connlimit --connlimit-above 10 --connlimit-mask 32 -j REJECT --reject-with icmp-port-unreachable
sudo iptables -I INPUT -p tcp --dport 80 -m state --state NEW -m recent --set
sudo iptables -I INPUT -p tcp --dport 80 -m state --state NEW -m recent --update --seconds 20 --hitcount 10 -j DROP
sudo iptables -A INPUT -p tcp -m tcp --dport 22 --tcp-flags FIN,SYN,RST,ACK SYN -m connlimit --connlimit-above 10 --connlimit-mask 32 -j REJECT --reject-with icmp-port-unreachable
sudo iptables -A INPUT -p tcp -m tcp --dport 443 --tcp-flags FIN,SYN,RST,ACK SYN -m connlimit --connlimit-above 10 --connlimit-mask 32 -j REJECT --reject-with icmp-port-unreachable
sudo iptables -A INPUT -p tcp -m tcp --dport 25565 --tcp-flags FIN,SYN,RST,ACK SYN -m connlimit --connlimit-above 3 --connlimit-mask 32 --connlimit-saddr -j REJECT --reject-with icmp-port-unreachable

#Anti DDoS Server Web.
sudo iptables -t filter -N syn-flood
sudo iptables -t filter -A INPUT -i eth0 -p tcp --syn -j syn-flood
sudo iptables -t filter -A syn-flood -m limit --limit 1/sec --limit-burst 4 -j RETURN
sudo iptables -t filter -A syn-flood -j LOG --log-prefix "IPTABLES SYN-FLOOD:"
sudo iptables -t filter -A syn-flood -j DROP
sudo iptables -A INPUT -p tcp -m connlimit --connlimit-above 80 -j REJECT --reject-with tcp-reset
sudo iptables -A INPUT -p tcp -m conntrack --ctstate NEW -m limit --limit 60/s --limit-burst 20 -j ACCEPT
sudo iptables -A INPUT -p tcp -m conntrack --ctstate NEW -j DROP
sudo iptables -t mangle -A PREROUTING -f -j DROP
sudo iptables -A INPUT -p tcp --tcp-flags RST RST -m limit --limit 2/s --limit-burst 2 -j ACCEPT
sudo iptables -A INPUT -p tcp --tcp-flags RST RST -j DROP
#
sleep 1
done
echo "Firewall was successfully installed!"
done