Bash script to configure iptables for a web server. Some rules can be removed depending on used services.

iptables-config-script

#!/bin/sh

# Empty all rules
sudo iptables -t filter -F
sudo iptables -t filter -X

# Bloc everything by default
sudo iptables -t filter -P INPUT DROP
sudo iptables -t filter -P FORWARD DROP
sudo iptables -t filter -P OUTPUT DROP

# Authorize already established connexions
sudo iptables -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
sudo iptables -A OUTPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
sudo iptables -t filter -A INPUT -i lo -j ACCEPT
sudo iptables -t filter -A OUTPUT -o lo -j ACCEPT

# ICMP (Ping)
sudo iptables -t filter -A INPUT -p icmp -j ACCEPT
sudo iptables -t filter -A OUTPUT -p icmp -j ACCEPT

# SSH
sudo iptables -t filter -A INPUT -p tcp --dport 22 -j ACCEPT
sudo iptables -t filter -A OUTPUT -p tcp --dport 22 -j ACCEPT

# DNS
sudo iptables -t filter -A OUTPUT -p tcp --dport 53 -j ACCEPT
sudo iptables -t filter -A OUTPUT -p udp --dport 53 -j ACCEPT
sudo iptables -t filter -A INPUT -p tcp --dport 53 -j ACCEPT
sudo iptables -t filter -A INPUT -p udp --dport 53 -j ACCEPT

# HTTP
sudo iptables -t filter -A OUTPUT -p tcp --dport 80 -j ACCEPT
sudo iptables -t filter -A INPUT -p tcp --dport 80 -j ACCEPT

#HTTPS
sudo iptables -t filter -A OUTPUT -p tcp --dport 443 -j ACCEPT
sudo iptables -t filter -A INPUT -p tcp --dport 443 -j ACCEPT

# FTP
sudo iptables -t filter -A OUTPUT -p tcp --dport 20:21 -j ACCEPT
sudo iptables -t filter -A INPUT -p tcp --dport 20:21 -j ACCEPT

# Git
sudo iptables -t filter -A OUTPUT -p tcp --dport 9418 -j ACCEPT
sudo iptables -t filter -A INPUT -p tcp --dport 9418 -j ACCEPT

# Mail SMTP
iptables -t filter -A INPUT -p tcp --dport 25 -j ACCEPT
iptables -t filter -A OUTPUT -p tcp --dport 25 -j ACCEPT

# Mail POP3
iptables -t filter -A INPUT -p tcp --dport 110 -j ACCEPT
iptables -t filter -A OUTPUT -p tcp --dport 110 -j ACCEPT

# Mail IMAP
iptables -t filter -A INPUT -p tcp --dport 143 -j ACCEPT
iptables -t filter -A OUTPUT -p tcp --dport 143 -j ACCEPT

# NTP (server time)
sudo iptables -t filter -A OUTPUT -p udp --dport 123 -j ACCEPT

Very nice. Thanks.