+++
title = "iptables resource"
draft = false
gh_repo = "inspec"
platform = "linux"

[menu]
  [menu.inspec]
    title = "iptables"
    identifier = "inspec/resources/os/iptables.md iptables resource"
    parent = "inspec/resources/os"
+++

Use the `iptables` Chef InSpec audit resource to test rules that are defined in `iptables`, which maintains tables of IP packet filtering rules. There may be more than one table. Each table contains one (or more) chains (both built-in and custom). A chain is a list of rules that match packets. When the rule matches, the rule defines what target to assign to the packet.

## Availability

### Install

{{< readfile file="content/inspec/reusable/md/inspec_installation.md" >}}

### Version

This resource first became available in v1.0.0 of InSpec.

## Syntax

A `iptables` resource block declares tests for rules in IP tables:

    describe iptables(rule:'name', table:'name', chain: 'name', ignore_comments: true) do
      it { should have_rule('RULE') }
    end

where

- `iptables()` may specify any combination of `rule`, `table`, or `chain`
- `rule:'name'` is the name of a rule that matches a set of packets
- `table:'name'` is the packet matching table against which the test is run
- `chain: 'name'` is the name of a user-defined chain or one of `ACCEPT`, `DROP`, `QUEUE`, or `RETURN`
- `ignore_comments: true` is a boolean flag that ignores comments in a rule.
- `have_rule('RULE')` tests that rule in the iptables list. This must match the entire line taken from `iptables -S CHAIN`.

## Examples

The following examples show how to use this Chef InSpec audit resource.

### Test if the INPUT chain is in default ACCEPT mode

    describe iptables do
      it { should have_rule('-P INPUT ACCEPT') }
    end

### Test if the INPUT chain from the mangle table is in ACCEPT mode

    describe iptables(table:'mangle', chain: 'INPUT') do
      it { should have_rule('-P INPUT ACCEPT') }
    end

### Test if there is a rule allowing Postgres (5432/TCP) traffic

    describe iptables do
      it { should have_rule('-A INPUT -p tcp -m tcp -m multiport --dports 5432 -m comment --comment "postgres" -j ACCEPT') }
    end

### Test a rule without comments

    describe iptables(ignore_comments: true) do
      it { should have_rule('-A INPUT -p tcp -m tcp -m multiport --dports 5432 -j ACCEPT') }
    end

Note that the rule specification must exactly match what's in the output of `iptables -S INPUT`, which will depend on how you've built your rules.

## Matchers

{{< readfile file="content/inspec/reusable/md/inspec_matchers_link.md" >}}

This resource has the following special matchers.

### have_rule

The `have_rule` matcher tests the named rule against the information in the `iptables` file:

    it { should have_rule('RULE') }
