Fortytwo - Answer to the Ultimate Question of Life, the Universe, and Everything

This page is read only. You can view the source, but not change it. Ask your administrator if you think this is wrong.

====== Simple iptables Firewall ======
<code bash>
#!/bin/bash

# Set default policy
iptables -P INPUT DROP
iptables -P OUTPUT DROP
iptables -P FORWARD DROP

# Flush existing rules
iptables -F -t nat
iptables -F -t mangle
iptables -F -t filter
iptables -X

# Allow localhost traffic
iptables -A INPUT -i lo -j ACCEPT
iptables -A OUTPUT -o lo -j ACCEPT

# Allow related traffic
iptables -A INPUT -m conntrack --state ESTABLISHED -j ACCEPT
iptables -A OUTPUT -m conntrack --state ESTABLISHED -j ACCEPT

# Allow icmp traffic
iptables -A INPUT -p icmp -j ACCEPT
iptables -A OUTPUT -p icmp -j ACCEPT

# Allow outgoing traffic
iptables -A OUTPUT -j ACCEPT

# Log & Drop the rest
iptables -A INPUT -j LOG --log-prefix "INPUT "
iptables -A INPUT -j DROP
iptables -A FORWARD -j DROP
iptables -A FORWARD -j LOG --log-prefix "FORWARD "

# Show ruleset
iptables -L -vnx


</code>
{{tag>kb linux iptables firewall network}}