* `allow_origin_regex` - A regex string to match against origins that should be permitted to make cross-origin requests. e.g. `'https://.*\.example\.org'`.
* `allow_methods` - A list of HTTP methods that should be allowed for cross-origin requests. Defaults to `['GET']`. You can use `['*']` to allow all standard methods.

///

### Enable Proxy Forwarded Headers { #enable-proxy-forwarded-headers }

You can start FastAPI CLI with the *CLI Option* `--forwarded-allow-ips` and pass the IP addresses that should be trusted to read those forwarded headers.

If you set it to `--forwarded-allow-ips="*"` it would trust all the incoming IPs.

The next sections assume you already read the main [Tutorial - User Guide: Security](../../tutorial/security/index.md){.internal-link target=_blank}.

# Cookie Parameter Models { #cookie-parameter-models }

If you have a group of **cookies** that are related, you can create a **Pydantic model** to declare them. 🍪

This would allow you to **re-use the model** in **multiple places** and also to declare validations and metadata for all the parameters at once. 😎

/// note

This is supported since FastAPI version `0.115.0`. 🤓

///

/// tip

# Query Parameter Models { #query-parameter-models }

If you have a group of **query parameters** that are related, you can create a **Pydantic model** to declare them.

This would allow you to **re-use the model** in **multiple places** and also to declare validations and metadata for all the parameters at once. 😎

/// note

This is supported since FastAPI version `0.115.0`. 🤓

///

     * @see DialectVersion
     * @return minimum protocol version to use/allow
     * @since 2.1
     */
    DialectVersion getMinimumVersion();

    /**
     * Maximum protocol version
     *
     * Property {@code jcifs.smb.client.maxVersion} (string, default SMB210)
     *
     * @see DialectVersion
     * @return maximum protocol version to use/allow
     * @since 2.1
     */
    DialectVersion getMaximumVersion();

# Header Parameter Models { #header-parameter-models }

If you have a group of related **header parameters**, you can create a **Pydantic model** to declare them.

This would allow you to **re-use the model** in **multiple places** and also to declare validations and metadata for all the parameters at once. 😎

/// note

This is supported since FastAPI version `0.115.0`. 🤓

///

For example, if the **application server** is only receiving communication from the trusted **proxy**, you can set it to `--forwarded-allow-ips="*"` to make it trust all incoming IPs, as it will only receive requests from whatever is the IP used by the **proxy**.

/// note

FastAPI will know that the value of `q` is not required because of the default value `= None`.

Having `str | None` will allow your editor to give you better support and detect errors.

///

## Additional validation { #additional-validation }

The following arguments are supported:

* `allowed_hosts` - A list of domain names that should be allowed as hostnames. Wildcard domains such as `*.example.com` are supported for matching subdomains. To allow any hostname either use `allowed_hosts=["*"]` or omit the middleware.
* `www_redirect` - If set to True, requests to non-www versions of the allowed hosts will be redirected to their www counterparts. Defaults to `True`.