> 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/admin-area/radius.md).

# RADIUS

**Configure RADIUS auth** (`LAN_RADIUS_06`) — `radius_conf.php`

Authenticate against an external RADIUS server.

Help text: *"This authentication method is used with an external RADIUS server. It requires that PHP's RADIUS extension is enabled."* (`LAN_AUTHENTICATE_HELP`)

{% hint style="warning" %}
If PHP's `radius` extension is missing, the page shows a warning (`LAN_RADIUS_11`) and the method reports *"method not available"*. The extension is not bundled with most default PHP builds — you will usually have to install it yourself.
{% endhint %}

## Settings

| Field          | LAN key         | Notes                                                                                                                                     |
| -------------- | --------------- | ----------------------------------------------------------------------------------------------------------------------------------------- |
| Server address | `LAN_RADIUS_01` | Host name or IP of the RADIUS server.                                                                                                     |
| Shared secret  | `LAN_RADIUS_02` | The secret this site and the RADIUS server share. Stored in the site's database — see [Security](/alt-auth-plugin/reference/security.md). |

## Field transfer

The field table (`LAN_ALT_27`) is shown only if the RADIUS method exposes fields to copy. In practice RADIUS answers a yes/no question and returns little else, so most sites leave this empty and let e107 fill the local record from what the user enters at signup.

See [Field mapping](/alt-auth-plugin/reference/field-mapping.md).