> For the complete documentation index, see [llms.txt](https://playground.e107sk.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://playground.e107sk.com/alt-auth-plugin/getting-started/requirements.md).

# Requirements

|                        |                                                                         |
| ---------------------- | ----------------------------------------------------------------------- |
| e107                   | 2.4.0 or newer (`compatibility="2.4.0"` in `plugin.xml`)                |
| PHP                    | The version required by your e107 installation                          |
| PDO                    | **Required.** All database-backed methods open their own PDO connection |
| PHP `ldap` extension   | Only for the [LDAP](/alt-auth-plugin/admin-area/ldap.md) method         |
| PHP `radius` extension | Only for the [RADIUS](/alt-auth-plugin/admin-area/radius.md) method     |

## PDO

`e107db`, `otherdb` and the outbound sync all connect to a *foreign* database. e107's own `db` class always talks to the site's database, so it cannot be used for this — the plugin opens a separate `PDO` connection instead.

If PDO is not enabled, the main configuration page tells you so and the database methods will not work. Enable it by adding this line to `e107_config.php`:

```php
define('e_PDO', true);
```

{% hint style="warning" %}
If PDO is not correctly configured on your server, switching e107 to PDO may prevent the site from connecting to its own database at all. Check with your host first.
{% endhint %}

## Optional PHP extensions

The LDAP and RADIUS methods each need the matching PHP extension. If it is missing, the plugin does not crash — the configuration page shows a warning, and the method reports *"method not available"* instead of authenticating. Every other method keeps working.