# Security

You can allow or deny user access to a gateway based on a MAC address. This can be accomplished using the **Security** tab in the **RAS Secure Gateway Properties** dialog.

To use Site default settings, click the **Inherit default settings** option. To specify your own settings, clear the option.

To configure a list of allowed or denied MAC addresses, click the **Security** tab and select one of the following options:

* **Allow all except.** All devices on the network will be allowed to connect to the gateway except those included in this list. Click **Tasks** > **Add** to select a device or to specify a MAC address.
* **Allow only**. Only the devices with the MAC addresses included in the list are allowed to connect to the gateway. Click **Tasks** > **Add** to select a device or to specify a MAC address.

Please note that the Gateway MAC address filtering is based on ARP, so client and server must be on the same network for the filtering to work. It does not work across network boundaries.


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.parallels.com/landing/ras-mp-guide/infrastructure/gateways/configure-a-gateway/security.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.