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README.md

iptables Cookbook

This cookbook will install and configure iptables for IPv4.

WARNING: Without setting any iptable rules, this cookbook will fail by default. This is to prohibit iptables from locking us out. Ensure you can access the node after a Chef run by adding some rules to use. See the first example under Usage.

NOTE: The rules template for this cookbook does not block outbound traffic. Only inbound. If you require blocking outbound traffic, you will need to create a rule for it.

If you require further documentation:

Requirements

Platforms

  • ubuntu/xenial64
  • ubuntu/trusty64
  • centos/7
  • centos/6
  • debian/jessie64
  • debian/wheezy64

Chef

  • Chef '>= 12.5'

Attributes

You can set custom rules via the rules attribute.

default['iptables']['rules']

Usage

Including the cop_iptables cookbook in the run_list ensures that iptables will be installed. Use the default['iptables']['rules'] attribute to merge your rules with the cookbook template.

Here's a general iptables role that will install and configure iptables. It will also allow all traffic on all interfaces.

WARNING: This is generally considered bad practice, you should be strict in what is allowed and on which interface(s). See the next example.

name 'iptables'
description 'iptables'

override_attributes(
    'iptables' => {
        'rules' => [
            '-A INPUT -j ACCEPT',
        ]
    }
)

run_list(
    'recipe[cop_iptables::default]'
)

In this example these two rules are allowing any traffic over port 22/tcp and 80/tcp on all interfaces.

Here's a list of ports by service https://en.wikipedia.org/wiki/List_of_TCP_and_UDP_port_numbers

NOTE: Use these types of rules at the very least. However, it's better to lock things down by interfaces. See the next example.

override_attributes(
    'iptables' => {
        'rules' => [
            '-A INPUT -p tcp -m tcp --dport 22 -j ACCEPT',
            '-A INPUT -p tcp -m tcp --dport 80 -j ACCEPT',
        ]
    }
)

In this example the first rule will allow all traffic on the eth0 interface, which is usually the LAN interface. The second and third rules are allowing traffic over port 22/tcp and 80/tcp on the eth1 or WAN interface. Interfaces can be different depending on which host you use.

You can get a list of interfaces by using the $ ifconfig command on your host.

NOTE: When you specify an interface with -i <interface>, that rule will only apply to that interface. You will need to think about how traffic is coming in and out of your network and on which interface.

override_attributes(
    'iptables' => {
        'rules' => [
            '-A INPUT -i eth0 -j ACCEPT',
            '-A INPUT -i eth1 -p tcp -m tcp --dport 22 -j ACCEPT',
            '-A INPUT -i eth1 -p tcp -m tcp --dport 80 -j ACCEPT',
        ]
    }
)

Testing

Testing is handled with ServerSpec, via Test Kitchen, which uses Vagrant to spin up VMs.

ServerSpec and Test Kitchen are bundled in the ChefDK package.

Dependencies

$ brew cask install chefdk

Running

Get a listing of your instances with:

$ kitchen list

Run Chef on an instance, in this case default-ubuntu-1204, with:

$ kitchen converge default-ubuntu-1204

Destroy all instances with:

$ kitchen destroy

Run through and test all the instances in serial by running:

$ kitchen test

Notes

  • The Berksfile.lock file has been purposely omitted, as we don't care about upstream dependencies.