# Performing post-installation checks
<a name="setting-up-installing-linux-checks"></a>

This topic provides some post-installation checks that you should perform after installing Amazon DCV to ensure that your Amazon DCV server is properly configured.

**Topics**
+ [Ensure the Amazon DCV Server is reachable](#checks-port)
+ [Ensure that the X server is accessible](#checks-xserver)
+ [Verify that DCV GL is properly installed](#checks-gl)
+ [Verify the Amazon DCV DEB package signature](#checks-deb)

## Ensure the Amazon DCV Server is reachable
<a name="checks-port"></a>

By default, the Amazon DCV server is configured to communicate over TCP port 8443. Ensure that the server is reachable over this port. If you have a firewall that prevents access over port 8443, you must change the port over which the Amazon DCV server communicates. For more information, see [Changing the Amazon DCV Server TCP/UDP ports and listen address](manage-port-addr.md).

Also, if you're setting up Amazon DCV on an EC2 instance, create a security group. This is to enable access to the port over which the Amazon DCV server communicates. For more information, see [how to configure security groups on EC2](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-network-security.html). 

## Ensure that the X server is accessible
<a name="checks-xserver"></a>

You must ensure that Amazon DCV console and virtual sessions can access the X server.

### Console Sessions
<a name="checks-xserver-console"></a>

When the Amazon DCV server is installed, a `dcv` user is created. Ensure that this user can access the X server.

**To verify that the `dcv` user can access the X server**  
Run the following command:

```
$ sudo DISPLAY=:0 XAUTHORITY=$(ps aux | grep "X.*\-auth" | grep -v Xdcv | grep -v grep | sed -n 's/.*-auth \([^ ]\+\).*/\1/p') xhost | grep "SI:localuser:dcv$"
```

If the command returns `SI:localuser:dcv`, the dcv user can access the X server.

If the command does not return `SI:localuser:dcv`, the dcv user doesn't have access to the X server. Run the following commands to restart the X server:
+ RHEL, Rocky, CentOS, Amazon Linux 2, Ubuntu, and SUSE Linux Enterprise

  ```
  $ sudo systemctl isolate multi-user.target
  ```

  ```
  $ sudo systemctl isolate graphical.target
  ```

### Virtual sessions
<a name="checks-xserver-virtual"></a>

If you installed the DCV GL package, you must ensure that local users can access the X server. This ensures that OpenGL hardware acceleration works correctly with virtual sessions.

**To verify that local users can access the X server**  
Run the following command:

```
$ sudo DISPLAY=:0 XAUTHORITY=$(ps aux | grep "X.*\-auth" | grep -v Xdcv | grep -v grep | sed -n 's/.*-auth \([^ ]\+\).*/\1/p') xhost | grep "LOCAL:$"
```

If the command returns `LOCAL:`, local users can access the X server.

If the command doesn't return `LOCAL:`, local users don't have access to the X server. Run the following commands to restart the X server, and to disable and re-enable DCV GL:
+ RHEL, Rocky, CentOS, Amazon Linux 2, Ubuntu, and SUSE Linux Enterprise

  ```
  $ sudo systemctl isolate multi-user.target
  ```

  ```
  $ sudo dcvgladmin disable
  ```

  ```
  $ sudo dcvgladmin enable
  ```

  ```
  $ sudo systemctl isolate graphical.target
  ```

## Verify that DCV GL is properly installed
<a name="checks-gl"></a>

The dcvgldiag utility is automatically installed when you install the DCV GL package. You can use this utility to check that the Linux server configuration meets the DCV GL requirements.

**To run the dcvgldiag utility**  
Use the following command:

```
$ sudo dcvgldiag
```

The utility returns a list of warnings and errors, along with the possible solutions.

## Verify the Amazon DCV DEB package signature
<a name="checks-deb"></a>

After Amazon DCV is installed, you can verify the signature on the Debian package (DEB). This verification process requires the use of GPG version 1.

**To verify the DEB package signature**  
Use the following command:

```
gpg1 --import NICE-GPG-KEY-SECRET
dpkg-sig --verify nice-dcv-server_2025.0.20103-1_amd64.deb
```

This will return a message that includes the term `GOODSIG` to confirm that the signature is verified. The following example shows a signature confirmation message. In place of *Example Key*, the key will be displayed.

```
Processing nice-dcv-server_2017.0.0-1_amd64.deb...
GOODSIG _gpgbuilder Example Key
```