f3llps · August 23, 2020 17:29 · Jun 14, 2011
diff --git a/iptables_rules.sh b/iptables_rules.sh
@@ -0,0 +1,118 @@
+# Modify this file accordingly for your specific requirement.
+# http://www.thegeekstuff.com
+# 1. Delete all existing rules
+iptables -F
+
+# 2. Set default chain policies
+iptables -P INPUT DROP
+iptables -P FORWARD DROP
+iptables -P OUTPUT DROP
+
+# 3. Block a specific ip-address
+#BLOCK_THIS_IP="x.x.x.x"
+#iptables -A INPUT -s "$BLOCK_THIS_IP" -j DROP
+
+# 4. Allow ALL incoming SSH
+iptables -A INPUT -i eth0 -p tcp --dport 22 -m state --state NEW,ESTABLISHED -j ACCEPT
+iptables -A OUTPUT -o eth0 -p tcp --sport 22 -m state --state ESTABLISHED -j ACCEPT
+
+# 5. Allow incoming SSH only from a specific network
+#iptables -A INPUT -i eth0 -p tcp -s 192.168.200.0/24 --dport 22 -m state --state NEW,ESTABLISHED -j ACCEPT
+#iptables -A OUTPUT -o eth0 -p tcp --sport 22 -m state --state ESTABLISHED -j ACCEPT
+
+# 6. Allow incoming HTTP
+iptables -A INPUT -i eth0 -p tcp --dport 80 -m state --state NEW,ESTABLISHED -j ACCEPT
+iptables -A OUTPUT -o eth0 -p tcp --sport 80 -m state --state ESTABLISHED -j ACCEPT
+
+# Allow incoming HTTPS
+iptables -A INPUT -i eth0 -p tcp --dport 443 -m state --state NEW,ESTABLISHED -j ACCEPT
+iptables -A OUTPUT -o eth0 -p tcp --sport 443 -m state --state ESTABLISHED -j ACCEPT
+
+# 7. MultiPorts (Allow incoming SSH, HTTP, and HTTPS)
+iptables -A INPUT -i eth0 -p tcp -m multiport --dports 22,80,443 -m state --state NEW,ESTABLISHED -j ACCEPT
+iptables -A OUTPUT -o eth0 -p tcp -m multiport --sports 22,80,443 -m state --state ESTABLISHED -j ACCEPT
+
+# 8. Allow outgoing SSH
+iptables -A OUTPUT -o eth0 -p tcp --dport 22 -m state --state NEW,ESTABLISHED -j ACCEPT
+iptables -A INPUT -i eth0 -p tcp --sport 22 -m state --state ESTABLISHED -j ACCEPT
+
+# 9. Allow outgoing SSH only to a specific network
+#iptables -A OUTPUT -o eth0 -p tcp -d 192.168.101.0/24 --dport 22 -m state --state NEW,ESTABLISHED -j ACCEPT
+#iptables -A INPUT -i eth0 -p tcp --sport 22 -m state --state ESTABLISHED -j ACCEPT
+
+# 10. Allow outgoing HTTPS
+iptables -A OUTPUT -o eth0 -p tcp --dport 443 -m state --state NEW,ESTABLISHED -j ACCEPT
+iptables -A INPUT -i eth0 -p tcp --sport 443 -m state --state ESTABLISHED -j ACCEPT
+
+# 11. Load balance incoming HTTPS traffic
+#iptables -A PREROUTING -i eth0 -p tcp --dport 443 -m state --state NEW -m nth --counter 0 --every 3 --packet 0 -j DNAT --to-destination 192.168.1.101:443
+#iptables -A PREROUTING -i eth0 -p tcp --dport 443 -m state --state NEW -m nth --counter 0 --every 3 --packet 1 -j DNAT --to-destination 192.168.1.102:443
+#iptables -A PREROUTING -i eth0 -p tcp --dport 443 -m state --state NEW -m nth --counter 0 --every 3 --packet 2 -j DNAT --to-destination 192.168.1.103:443
+
+# 12. Ping from inside to outside
+iptables -A OUTPUT -p icmp --icmp-type echo-request -j ACCEPT
+iptables -A INPUT -p icmp --icmp-type echo-reply -j ACCEPT
+
+# 13. Ping from outside to inside
+iptables -A INPUT -p icmp --icmp-type echo-request -j ACCEPT
+iptables -A OUTPUT -p icmp --icmp-type echo-reply -j ACCEPT
+
+# 14. Allow loopback access
+iptables -A INPUT -i lo -j ACCEPT
+iptables -A OUTPUT -o lo -j ACCEPT
+
+# 15. Allow packets from internal network to reach external network.
+# if eth1 is connected to external network (internet)
+# if eth0 is connected to internal network (192.168.1.x)
+iptables -A FORWARD -i eth0 -o eth1 -j ACCEPT
+
+# 16. Allow outbound DNS
+iptables -A OUTPUT -p udp -o eth0 --dport 53 -j ACCEPT
+iptables -A INPUT -p udp -i eth0 --sport 53 -j ACCEPT
+
+# 17. Allow NIS Connections
+# rpcinfo -p | grep ypbind ; This port is 853 and 850
+#iptables -A INPUT -p tcp --dport 111 -j ACCEPT
+#iptables -A INPUT -p udp --dport 111 -j ACCEPT
+#iptables -A INPUT -p tcp --dport 853 -j ACCEPT
+#iptables -A INPUT -p udp --dport 853 -j ACCEPT
+#iptables -A INPUT -p tcp --dport 850 -j ACCEPT
+#iptables -A INPUT -p udp --dport 850 -j ACCEPT
+
+# 18. Allow rsync from a specific network
+#iptables -A INPUT -i eth0 -p tcp -s 192.168.101.0/24 --dport 873 -m state --state NEW,ESTABLISHED -j ACCEPT
+#iptables -A OUTPUT -o eth0 -p tcp --sport 873 -m state --state ESTABLISHED -j ACCEPT
+
+# 19. Allow MySQL connection only from a specific network
+#iptables -A INPUT -i eth0 -p tcp -s 192.168.200.0/24 --dport 3306 -m state --state NEW,ESTABLISHED -j ACCEPT
+#iptables -A OUTPUT -o eth0 -p tcp --sport 3306 -m state --state ESTABLISHED -j ACCEPT
+
+# 20. Allow Sendmail or Postfix
+iptables -A INPUT -i eth0 -p tcp --dport 25 -m state --state NEW,ESTABLISHED -j ACCEPT
+iptables -A OUTPUT -o eth0 -p tcp --sport 25 -m state --state ESTABLISHED -j ACCEPT
+
+# 21. Allow IMAP and IMAPS
+#iptables -A INPUT -i eth0 -p tcp --dport 143 -m state --state NEW,ESTABLISHED -j ACCEPT
+#iptables -A OUTPUT -o eth0 -p tcp --sport 143 -m state --state ESTABLISHED -j ACCEPT
+#iptables -A INPUT -i eth0 -p tcp --dport 993 -m state --state NEW,ESTABLISHED -j ACCEPT
+#iptables -A OUTPUT -o eth0 -p tcp --sport 993 -m state --state ESTABLISHED -j ACCEPT
+
+# 22. Allow POP3 and POP3S
+#iptables -A INPUT -i eth0 -p tcp --dport 110 -m state --state NEW,ESTABLISHED -j ACCEPT
+#iptables -A OUTPUT -o eth0 -p tcp --sport 110 -m state --state ESTABLISHED -j ACCEPT
+#iptables -A INPUT -i eth0 -p tcp --dport 995 -m state --state NEW,ESTABLISHED -j ACCEPT
+#iptables -A OUTPUT -o eth0 -p tcp --sport 995 -m state --state ESTABLISHED -j ACCEPT
+
+# 23. Prevent DoS attack
+iptables -A INPUT -p tcp --dport 80 -m limit --limit 25/minute --limit-burst 100 -j ACCEPT
+
+# 24. Port forwarding 422 to 22
+#iptables -t nat -A PREROUTING -p tcp -d 192.168.102.37 --dport 422 -j DNAT --to 192.168.102.37:22
+#iptables -A INPUT -i eth0 -p tcp --dport 422 -m state --state NEW,ESTABLISHED -j ACCEPT
+#iptables -A OUTPUT -o eth0 -p tcp --sport 422 -m state --state ESTABLISHED -j ACCEPT
+
+# 25. Log dropped packets
+iptables -N LOGGING
+iptables -A INPUT -j LOGGING
+iptables -A LOGGING -m limit --limit 2/min -j LOG --log-prefix "IPTables Packet Dropped: " --log-level 7
+iptables -A LOGGING -j DROP