inspec/docs/resources/iptables.md.erb
Sean Walberg a0ebc43132 Update iptables docs (#1968)
* Update iptables docs

* Correct nomenclature and be a bit more specific for existing exampls
* Provide an example of allowing a specified port in.

* Update iptables.md.erb
2017-06-28 03:17:24 -07:00

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Text

---
title: About the iptables Resource
---
# iptables
Use the `iptables` 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.
## Syntax
A `iptables` resource block declares tests for rules in IP tables:
describe iptables(rule:'name', table:'name', chain: 'name') 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`
* `have_rule('RULE')` tests that rule in the iptables list. This must match the entire line taken from `iptables -S CHAIN`.
## Matchers
This InSpec audit resource has the following matchers:
### be
<%= partial "/shared/matcher_be" %>
### cmp
<%= partial "/shared/matcher_cmp" %>
### eq
<%= partial "/shared/matcher_eq" %>
### have_rule
The `have_rule` matcher tests the named rule against the information in the `iptables` file:
it { should have_rule('RULE') }
### include
<%= partial "/shared/matcher_include" %>
### match
<%= partial "/shared/matcher_match" %>
## Examples
The following examples show how to use this 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
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.