---
title: About the shadow Resource
platform: linux
---

# shadow

Use the `shadow` InSpec audit resource to test the contents of `/etc/shadow`, which contains password details that are only readable by the `root` user. The format for `/etc/shadow` includes:

* A username
* The password for that user (on newer systems passwords should be stored in `/etc/shadow` )
* The last time a password was changed
* The minimum number of days a password must exist, before it may be changed
* The maximum number of days after which a password must be changed
* The number of days a user is warned about an expiring password
* The number of days a user must be inactive before the user account is disabled
* The number of days a user account has been disabled

These entries are defined as a colon-delimited row in the file, one row per user:

    dannos:Gb7crrO5CDF.:10063:0:99999:7:::

<br>

## Syntax

A `shadow` resource block declares one (or more) users and associated user information to be tested:

    describe shadow do
      its('users') { should_not include 'forbidden_user' }
    end

or with a single query:

    describe shadow.users('root') do
      its('count') { should eq 1 }
    end

or with a filter:

    describe shadow.filter(min_days: '0', max_days: '99999') do
      its('count') { should eq 1 }
    end

The following properties are available:

* `users`
* `passwords`
* `last_changes`
* `min_days`
* `max_days`
* `warn_days`
* `inactive_days`
* `expiry_date`
* `reserved`

Properties can be used as a single query or can be joined together with the `.filter` method.

<br>

## Examples

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

### Test for a forbidden user

    describe shadow do
      its('users') { should_not include 'forbidden_user' }
    end

### Test that a user appears one time

    describe shadow.users('bin') do
      its('passwords') { should cmp 'x' }
      its('count') { should eq 1 }
    end

<br>

## Matchers

For a full list of available matchers, please visit our [matchers page](https://www.inspec.io/docs/reference/matchers/).

### count

The `count` matcher tests the number of times the named user appears in `/etc/shadow`:

    its('count') { should eq 1 }

This matcher is best used in conjunction with filters. For example:

    describe shadow.users('dannos') do
       its('count') { should eq 1 }
    end

### expiry_dates

The `expiry_dates` matcher tests the number of days a user account has been disabled:

    its('expiry_dates') { should eq '' }

### inactive_days

The `inactive_days` matcher tests the number of days a user must be inactive before the user account is disabled:

    its('inactive_days') { should eq '' }

### last_changes

The `last_changes` matcher tests the last time a password was changed:

    its('last_changes') { should eq '' }

### max_days

The `max_days` matcher tests the maximum number of days after which a password must be changed:

    its('max_days') { should eq 90 }

### min_days

The `min_days` matcher tests the minimum number of days a password must exist, before it may be changed:

    its('min_days') { should eq 0 }

### passwords

The `passwords` matcher returns the encrypted password string from the shadow file. The returned string may not be an encrypted password, but rather a `*` or similar which indicates that direct logins are not allowed.

For example:

    its('passwords') { should cmp '*' }

### users

The `users` matcher tests if the user name exists `/etc/shadow`:

    its('users') { should eq 'root' }

### warn_days

The `warn_days` matcher tests the number of days a user is warned about an expiring password:

    its('warn_days') { should eq 7 }