Firewall setup

Firewall setup

Introduction

This is a basic firewall it may not suit your needs, firewalling is an art so i recommend to read into it to improve on this basic one.

Basic config

Add these rules in your configuration file /etc/sysconfig/iptables

*raw
:PREROUTING ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
COMMIT

*nat
:PREROUTING ACCEPT [0:0]
:POSTROUTING ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
COMMIT

*mangle
:PREROUTING ACCEPT [0:0]
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
:POSTROUTING ACCEPT [0:0]
COMMIT

*filter
:FORWARD DROP [0:0]
:INPUT DROP [0:0]
:OUTPUT DROP [0:0]
-A INPUT -i lo -j ACCEPT
-A INPUT -p tcp -m tcp --dport 22 -j ACCEPT
-A INPUT -p tcp -m tcp --dport 21 -j ACCEPT
-A INPUT -p tcp -m multiport -j ACCEPT --dports 80,443,25,110,143,53
-A INPUT -p udp -m udp --dport 53 -j ACCEPT
-A INPUT -p icmp -m icmp -m limit --icmp-type 8 --limit 5/min -j ACCEPT
-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
-A OUTPUT -s 127.0.0.1 -j ACCEPT
-A OUTPUT -s 192.168.1.5 -j ACCEPT
-A OUTPUT -s 192.168.1.6 -j ACCEPT
COMMIT

Activate config

 # service iptables restart