# `[dcv]` section
<a name="dcv-section"></a>

Defines configuration settings for the Amazon DCV server running on the head node.

To create and configure a Amazon DCV server, specify the cluster [`dcv_settings`](cluster-definition.md#dcv-settings) with the name you define in the `dcv` section, and set [`enable`](#dcv-section-enable) to `master`, and [`base_os`](cluster-definition.md#base-os) to `alinux2`, `centos7`, `ubuntu1804` or `ubuntu2004`. If the head node is an ARM instance, set [`base_os`](cluster-definition.md#base-os) to `alinux2`, `centos7`, or `ubuntu1804`.

The format is `[dcv dcv-name]`. *dcv-name* must start with a letter, contain no more than 30 characters, and only contain letters, numbers, hyphens (-), and underscores (\$1).

```
[dcv custom-dcv]
enable = master
port = 8443
access_from = 0.0.0.0/0
```

For more information, see [Connect to the head node through Amazon DCV](dcv.md)

**Important**  
By default the Amazon DCV port setup by AWS ParallelCluster is open to all IPv4 addresses. However, you can connect to a Amazon DCV port only if you have the URL for the Amazon DCV session and connect to the Amazon DCV session within 30 seconds of when the URL is returned from `pcluster dcv connect`. Use the [`access_from`](#dcv-section-access-from) setting to further restrict access to the Amazon DCV port with a CIDR-formatted IP range, and use the [`port`](#dcv-section-port) setting to set a nonstandard port.

**Note**  
Support for the [`[dcv]` section](#dcv-section)on `centos8` was removed in AWS ParallelCluster version 2.10.4. Support for the [`[dcv]` section](#dcv-section) on `centos8` was added in AWS ParallelCluster version 2.10.0. Support for the [`[dcv]` section](#dcv-section) on AWS Graviton-based instances was added in AWS ParallelCluster version 2.9.0. Support for the [`[dcv]` section](#dcv-section) on `alinux2` and `ubuntu1804` was added in AWS ParallelCluster version 2.6.0. Support for the [`[dcv]` section](#dcv-section)on `centos7` was added in AWS ParallelCluster version 2.5.0.

## `access_from`
<a name="dcv-section-access-from"></a>

 **(Optional, Recommended)** Specifies the CIDR-formatted IP range for connections to Amazon DCV. This setting is used only when AWS ParallelCluster creates the security group.

The default value is `0.0.0.0/0`, which allows access from any internet address.

```
access_from = 0.0.0.0/0
```

[Update policy: This setting can be changed during an update.](using-pcluster-update.md#update-policy-setting-supported)

## `enable`
<a name="dcv-section-enable"></a>

 **(Required)** Indicates whether Amazon DCV is enabled on the head node. To enable Amazon DCV on the head node and configure the required security group rule, set the `enable` setting to `master`.

The following example enables Amazon DCV on the head node.

```
enable = master
```

**Note**  
Amazon DCV automatically generates a self-signed certificate that's used to secure traffic between the Amazon DCV client and Amazon DCV server running on the head node. To configure your own certificate, see [Amazon DCV HTTPS certificate](dcv.md#dcv-certificate).

[Update policy: If this setting is changed, the update is not allowed.](using-pcluster-update.md#update-policy-fail)

## `port`
<a name="dcv-section-port"></a>

 **(Optional)** Specifies the port for Amazon DCV.

The default value is `8443`.

```
port = 8443
```

[Update policy: If this setting is changed, the update is not allowed.](using-pcluster-update.md#update-policy-fail)