G
gcawood
Guest
Hello,
I have put together some basic iptables based firewall rules that I feel should apply to virtually any web server running cPanel/WHM that is connected to the internet. Please give me your feedback and improvements!
I popped the iptables rules into a bash script that can be easily commented and run in order to apply these rules.
I have put together some basic iptables based firewall rules that I feel should apply to virtually any web server running cPanel/WHM that is connected to the internet. Please give me your feedback and improvements!
I popped the iptables rules into a bash script that can be easily commented and run in order to apply these rules.
Code:
#!/bin/bash
#####################################################################
# 1) Clear old Rules
iptables -F # Delete all existing rules
# 2) Default Drop
iptables -P INPUT DROP # Set default chain policies to DROP
iptables -P FORWARD DROP # Set default chain policies to DROP
iptables -P OUTPUT DROP # Set default chain policies to DROP
# 3) Loopback
iptables -A INPUT -i lo -j ACCEPT # Allow loopback access from INPUT
iptables -A OUTPUT -o lo -j ACCEPT # Allow loopback access from Output
# 4) BLACKLIST IP's
# iptables -A INPUT -s "BLOCK_THIS_IP" -j DROP # Block a specific ip-address
# iptables -A INPUT -s "BLOCK_THIS_IP" -j DROP # Block a specific ip-address
# iptables -A INPUT -s "BLOCK_THIS_IP" -j DROP # Block a specific ip-address
# iptables -A INPUT -s "BLOCK_THIS_IP" -j DROP # Block a specific ip-address
# 5) WHITELIST IP's
iptables -A INPUT -s 127.0.0.1/32 -j ACCEPT # Allow Anything from localhost
iptables -A INPUT -s "ALLOW_THIS_IP"/32 -j ACCEPT # Allow Anything from KeyServer
# 6) ALLOWED SERVICES
iptables -A OUTPUT -o eth0 -p tcp --sport 25 -m state --state ESTABLISHED -j ACCEPT # PORT 25 SMTP - Allow connections to outbound
iptables -A OUTPUT -p udp -o eth0 --dport 53 -j ACCEPT # PORT 54 DNS - Allow connections to outbound
iptables -A INPUT -p tcp -m tcp --dport 80 -m state --state NEW,ESTABLISHED -j ACCEPT # PORT 80 httpd - Allow connections from anywhere
iptables -A INPUT -p tcp --dport 80 -m limit --limit 25/minute --limit-burst 100 -j ACCEPT # PORT 80 httpd - Rate Limit from outside
iptables -A INPUT -p tcp -m tcp --dport 443 -m state --state NEW,ESTABLISHED -j ACCEPT # PORT 443 SSL - Allow connections from anywhere
iptables -A INPUT -p tcp -m tcp --dport 2082 -m state --state NEW,ESTABLISHED -j ACCEPT # PORT 2082 cPanel - Allow connections to outbound
iptables -A INPUT -p tcp -m tcp --dport 2083 -m state --state NEW,ESTABLISHED -j ACCEPT # PORT 2083 cPanel - Allow connections to outbound
iptables -A INPUT -p tcp -m tcp --dport 2086 -m state --state NEW,ESTABLISHED -j ACCEPT # PORT 2086 WHM - Allow connections to outbound
iptables -A INPUT -p tcp -m tcp --dport 2087 -m state --state NEW,ESTABLISHED -j ACCEPT # PORT 2087 WHM - Allow connections to outbound
# 7) PING
iptables -A INPUT -p icmp -m icmp --icmp-type address-mask-request -j DROP # Drop Ping from address-mask-request
iptables -A INPUT -p icmp -m icmp --icmp-type timestamp-request -j DROP # Drop Ping from timestamp-request
iptables -A INPUT -p icmp -m icmp -m limit --limit 1/second -j ACCEPT # Rate Limit Ping from outside
# 8) Validate packets
iptables -A INPUT -m state --state INVALID -j DROP # Drop invalid packets
iptables -A FORWARD -m state --state INVALID -j DROP # Drop invalid packets
iptables -A OUTPUT -m state --state INVALID -j DROP # Drop invalid packets
iptables -A INPUT -p tcp -m tcp --tcp-flags SYN,FIN SYN,FIN -j DROP # Drop TCP - SYN,FIN packets
iptables -A INPUT -p tcp -m tcp --tcp-flags SYN,RST SYN,RST -j DROP # Drop TCP - SYN,RST packets
# 9) Reject Invalid networks (Spoof)
iptables -A INPUT -s 10.0.0.0/8 -j DROP # (Spoofed network)
iptables -a INPUT -s 192.0.0.1/24 -j DROP # (Spoofed network)
iptables -A INPUT -s 169.254.0.0/16 -j DROP # (Spoofed network)
iptables -A INPUT -s 172.16.0.0/12 -j DROP # (Spoofed network)
iptables -A INPUT -s 224.0.0.0/4 -j DROP # (Spoofed network)
iptables -A INPUT -d 224.0.0.0/4 -j DROP # (Spoofed network)
iptables -A INPUT -s 240.0.0.0/5 -j DROP # (Spoofed network)
iptables -A INPUT -d 240.0.0.0/5 -j DROP # (Spoofed network)
iptables -A INPUT -s 0.0.0.0/8 -j DROP # (Spoofed network)
iptables -A INPUT -d 0.0.0.0/8 -j DROP # (Spoofed network)
iptables -A INPUT -d 239.255.255.0/24 -j DROP # (Spoofed network)
iptables -A INPUT -d 255.255.255.255 -j DROP # (Spoofed network)
# 10) CHAINS
# FTP_BRUTE CHAIN
iptables -A INPUT -p tcp -m multiport --dports 20,21 -m state --state NEW -m recent --set --name FTP_BRUTE
iptables -A INPUT -p tcp -m multiport --dports 20,21 -m state --state NEW -m recent --update --seconds 60 --hitcount 4 --rttl --name FTP_BRUTE -j DROP
# SYNFLOOD CHAIN
iptables -A INPUT -m state --state NEW -p tcp -m tcp --syn -m recent --name SYNFLOOD--set
iptables -A INPUT -m state --state NEW -p tcp -m tcp --syn -m recent --name SYNFLOOD --update --seconds 1 --hitcount 60 -j DROP
# Logging CHAIN
iptables -N LOGGING # Create `LOGGING` chain for logging denied packets
iptables -A INPUT -j LOGGING # Create `LOGGING` chain for logging denied packets
iptables -A LOGGING -m limit --limit 2/min -j LOG --log-prefix "IPTables Packet Dropped: " --log-level 6 # Log denied packets to /var/log/messages
iptables -A LOGGING -j DROP # Drop everything
