www.nico.schottelius.org/blog/iptables-distribution-independent-powered-by-cdist-sponsored-by-panter.mdwn

[[!meta title="Linux distribution independent iptables setup powered by cdist sponsored by panter"]]

## Introduction

As a sysadmin, you may have encountered several different 
Linux distributions in your life. You may also have found
out that configuring [[!iptables]]
permanently differs from distribution to distribution.

Fortunately you can stop caring about this problem:
In the [[cdist|software/cdist]] source tree you find
two new types to handle this problem universally, independent
of the Linux distribution.

These types are a result of work done at [[!ungleich]] 
for our customer [[!panter]]. Panter does not only
allow us to publish the code freely, but also encourages
us to do so - many thanks!

## How to use it

First of all, ensure you have cdist installed on your source host.
Then create the directory ~/.cdist/manifest and then the file
~/.cdist/manifest/init with the following content:

    case "$__target_host" in
        insert-your-target-host-name-here)
            __iptables_rule policy-in   --rule "-P INPUT DROP"
            __iptables_rule policy-out  --rule "-P OUTPUT ACCEPT"
            __iptables_rule policy-fwd  --rule "-P FORWARD DROP"

            __iptables_rule established --rule "-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT"
            __iptables_rule http        --rule "-A INPUT -p tcp --dport 80 -j ACCEPT"
            __iptables_rule ssh         --rule "-A INPUT -p tcp --dport 22 -j ACCEPT"
        ;;
    esac

Running

    % cdist config insert-your-target-host-name-here

applies the configuration. That's it, really! Log on to your
server and do ***iptables -L -n*** to see the result!

## What did cdist do?

The cdist types \_\_iptables\_rule and \_\_iptables\_apply
take care of the necessary steps. In detail they

 * create the necessary files and directory
 * create and setup an init-script that loads / unloads the rules
 * apply the rules


[[!tag net unix foss ungleich panter]]