The VMware Blast ADMX template file (vdm_blast.admx) contains policy settings for the VMware Blast display protocol. After the policy is applied, the settings are stored in the registry key HKLM\Software\Policies\VMware, Inc.\VMware Blast\config.

These settings apply to HTML Access and all Horizon Client platforms.

Table 1. VMware Blast Policy Settings
Setting Description
Audio playback Specifies whether audio playback is enabled for remote desktops. This setting is to enable audio playback.
Clipboard memory size on server Specifies the server's clipboard memory size value in bytes or kilobytes, as selected. The memory size is in kilobytes if it is not configured.

The client also has a value for the clipboard memory size, which is always in kilobytes. After the session is set up, the server sends its clipboard memory size value to the client. The effective clipboard memory size value is the lesser of the client and server clipboard memory size values.

For Windows clients, agent machine to client machine clipboard auditing is supported in Horizon Client 4.9 and later. For all clients, client machine to agent machine clipboard auditing is supported in Horizon Client 4.10 and later.

Note: Only the Windows client supports agent machine to client machine clipboard auditing.
Configure clipboard audit Specifies whether the clipboard audit feature is enabled on the agent machine. When this setting is enabled, the options are as follows:
  • Disabled in both directions - information about clipboard data is not recorded.
  • Enabled client to server only - information about clipboard data that is copied from the client to machine to the agent machine is recorded in an event log on the agent machine.
  • Enabled in both directions - information about clipboard data that is copied from the client machine to the agent machine, and from the agent machine to the client machine, is recorded in an event log on the agent machine.
  • Enabled server to client only - information about clipboard data that is copied from the agent machine to the client machine is recorded in an event log on the agent machine.

When this setting is disabled or not configured, the default value is Disabled in both directions.

Note: Only the Windows client supports agent machine to client machine clipboard auditing. All other clients support only client machine to agent machine clipboard auditing.

You can use the Windows event viewer on the agent machine to view the event log. The log name is VMware Horizon RX Audit. To view the event log in a centralized location, you can configure VMware Log Insight or Windows Event Collector.

Configure clipboard redirection Specifies the permissible behavior for clipboard redirection. The options are as follows:
  • Enabled in both directions
  • Disabled in both directions
  • Enabled client to server only
  • Enabled server to client only

The default is Enabled client to server only.

Configure drag and drop direction

Specifies the direction in which drag and drop is allowed. When this setting is enabled, the options are as follows:

  • Disabled in both directions
  • Enabled client to agent only. Allows drag and drop only from the client system to the agent.
  • Enabled agent to client only. Allows drag and drop only from the agent to the client system.
  • Enabled in both directions

When this setting is disabled or not configured, the default value is Enabled client to agent only.

This setting applies to the agent only.

Configure drag and drop formats Determines which drag and drop direction (Disabled in both directions, Enabled agent to client only, Enabled client to agent only, or Enabled in both directions) is allowed for each data format. When this setting is enabled, the options are as follows:
  • Option for file format
  • Option for text format
  • Option for Rich Text format
  • Option for Image format
  • Option for HTML format
  • Option for File Content format

When this setting is disabled or not configured, the default value for all formats is Enabled in both directions.

This setting applies to the agent only.

Configure drag and drop size threshold Determines the size limit for dragging common data types other than files and folders.

When this setting is enabled, select the unit of the drag data size from the Choose the unit of the drag and drop size drop-down menu. You can select Bytes, Kilobytes, or Megabytes. Select or enter the drag data size in the Drag and drop size threshold text box. The effective data range for each unit is as follows:

  • Bytes: 1 to 1023
  • Kilobytes: 1 to 1023
  • Megabytes: 1 to 16 (the maximum data size to drag and drop is 16 megabytes)

When this setting is disabled or not configured, a default threshold of 1 megabytes is set.

This setting applies to the agent only.

Configure file transfer Specifies the permissible behavior for file transfer between a remote desktop and the HTML Access client. You can select one of the following values:
  • Disabled both upload and download
  • Enabled both upload and download
  • Enabled file upload only (Users can upload files from the client system to the remote desktop only.)
  • Enabled file download only (Users can download files from the remote desktop to the client system only.)

The default is Enabled file upload only.

This setting applies only to HTML Access 4.1 and later.

Cookie Cleanup Interval Determines how often, in milliseconds, cookies associated with inactive sessions are deleted. The default is 100 ms.
DSCP Marking When enabled or not configured, this setting allows Differentiated Services Code Point (DSCP) values to be established in outgoing Blast network traffic, as specified by the various individual settings for each network hop. When disabled, DSCP values are not established in Blast network traffic.

When enabled, you can set a numeric value in the range 0-63 for the following network connections:

  • DSCP from Agent, TCP/IPv4
  • DSCP from Agent, TCP/IPv6
  • DSCP from Agent, UDP/IPv4
  • DSCP from Agent, UDP/IPv6
  • DSCP from BSG to Client, TCP/IPv4
  • DSCP from BSG to Client, TCP/IPv6
  • DSCP from BSG to Client, UDP/IPv4
  • DSCP from BSG to Client, UDP/IPv6
  • DSCP from BSG to Agent, TCP/IPv4
  • DSCP from BSG to Agent, TCP/IPv6
  • DSCP from BSG to Agent, UDP/IPv4
  • DSCP from BSG to Agent, UDP/IPv6
  • DSCP from Client, TCP/IPv4
  • DSCP from Client, TCP/IPv6
  • DSCP from Client, UDP/IPv4
  • DSCP from Client, UDP/IPv6
Filter images out of the incoming clipboard data Specifies whether image data is filtered out of the clipboard data coming from the client to the agent. When this setting is enabled and the check box is selected, the data is filtered out. When this setting is disabled or not configured, the data is allowed.
Filter images out of the outgoing clipboard data Specifies whether image data is filtered out of the clipboard data sent from the agent to the client. When this setting is enabled and the check box is selected, the data is filtered out. When this setting is disabled or not configured, the data is allowed.
Filter Microsoft Chart and Smart Art data out of the incoming clipboard data Specifies whether Microsoft Office Chart and Smart Art data (Art::GVML ClipFormat) is filtered out of the clipboard data coming from the client to the agent. When this setting is enabled and the check box is selected, the data is filtered out. When this setting is disabled or not configured, the data is allowed.
Filter Microsoft Chart and Smart Art data out of the outgoing clipboard data Specifies whether Microsoft Office Chart and Smart Art data (Art::GVML ClipFormat) is filtered out of the clipboard data sent from the agent to the client. When this setting is enabled and the check box is selected, the data is filtered out. When this setting is disabled or not configured, the data is allowed.
Filter Microsoft Office text data out of the incoming clipboard data Specifies whether Microsoft Office text format data (BIFF12 format) is filtered out of the clipboard data coming from the client to the agent. When this setting is enabled and the check box is selected, the data is filtered out. When this setting is disabled or not configured, the data is allowed.
Filter Microsoft Office text data out of the outgoing clipboard data Specifies whether Microsoft Office text format data (BIFF12 format) is filtered out of the clipboard data sent from the agent to the client. When this setting is enabled and the check box is selected, the data is filtered out. When this setting is disabled or not configured, the data is allowed.
Filter Microsoft Text Effects data out of the incoming clipboard data Specifies whether Microsoft Office text effects data (HTML Format) is filtered out of the clipboard data coming from the client to the agent. When this setting is enabled and the check box is selected, the data is filtered out. When this setting is disabled or not configured, the data is allowed.
Filter Microsoft Text Effects data out of the outgoing clipboard data Specifies whether Microsoft Office text effects data (HTML Format) is filtered out of the clipboard data sent from the agent to the client. When this setting is enabled and the check box is selected, the data is filtered out. When this setting is disabled or not configured, the data is allowed.
Filter Rich Text Format data out of the incoming clipboard data Specifies whether Rich Text Format data is filtered out of the clipboard data coming from the client to the agent. When this setting is enabled and the check box is selected, the data is filtered out. When this setting is disabled or not configured, the data is allowed.
Filter Rich Text Format data out of the outgoing clipboard data Specifies whether Rich Text Format data is filtered out of the clipboard data sent from the agent to the client. When this setting is enabled and the check box is selected, the data is filtered out. When this setting is disabled or not configured, the data is allowed.
Filter text out of the incoming clipboard data Specifies whether textual data is filtered out of the clipboard data coming from the client to the agent. When this setting is enabled and the check box is selected, the data is filtered out. When this setting is disabled or not configured, the data is allowed.
Filter text out of the outgoing clipboard data Specifies whether textual data is filtered out of the clipboard data sent from the agent to the client. When this setting is enabled and the check box is selected, the data is filtered out. When this setting is disabled or not configured, the data is allowed.
H264 Specifies whether to use H.264 encoding or JPEG/PNG encoding. The default is to use H.264 encoding.
H264 High Color Accuracy Increases color accuracy when using H.264 encoding by using the YUV 4:4:4 colorspace instead of 4:2:0.

This setting might result in degraded performance at very high resolutions or with multiple monitors.

H.264 Quality Specifies the image quality for the remote display configured to use H.264 encoding. You can specify the minimum and maximum quantization values that determine how much an image is controlled for lossless compression. You can specify a minimum quantization value for the best image quality. You can specify a maximum quantization value for the lowest image quality. You can specify the following settings:
  • H264maxQP (available range of values: 0-51, default: 36)
  • H264minQP (available range of values: 0-51, default: 10)

For the best image quality, set the quantization parameter (QP) values to within +5 or -5 of the available range of values. These parameters determine the amount of data that is discarded, so a lower value results in higher image quality.

HTTP Service Specifies the port that is used for secure communication (HTTPS) between the security server or Access Point appliance and a desktop. The firewall must be configured to have this port open. The default is 22443.
Image Quality Specifies the image quality of the remote display. You can specify two low-quality settings, two high-quality settings, and a mid-quality setting. The low-quality settings are for areas of the screen that change often, for example, when scrolling occurs. The high-quality settings are for areas of the screen that are more static, resulting in a better image quality. You can specify the following settings:
  • Low JPEG Quality (available range of values: 10 - 100, default: 25)
  • Mid JPEG Quality (available range of values: 10- 100, default: 35)
  • High JPEG Quality (available range of values: 10 - 100, default: 90)
Keyboard locale synchronization Specifies whether to synchronize a client's keyboard locale list and default keyboard locale to the remote desktop or application. If this setting is enabled, synchronization occurs. This setting applies to Horizon Agent only.
Note: This feature is supported only for Horizon Client for Windows.
Max Frame Rate Specifies the maximum rate of screen updates. Use this setting to manage the average bandwidth that users consume. The default is 30 updates per second.
Max Session Bandwidth Specifies the maximum bandwidth, in kilobits per second (kbps), for a VMware Blast session. The bandwidth includes all imaging, audio, virtual channel, USB, and VMware Blast control traffic. The default is 1 Gbps.
Max Session Bandwidth kbit/s Megapixel Slope Specifies the maximum bandwidth slope, in kilobits per second (kbps), that is reserved for a VMware Blast session. The minimum value is 100. The maximum value is 100000. The default value is 6200.
Min Session Bandwidth Specifies the minimum bandwidth, in kilobits per second (kbps), that is reserved for a VMware Blast session. The default is 256 kbps.
PNG If you enable or do not configure this setting, PNG encoding is available for remote sessions. If you disable this setting, only JPEG encoding is used for encoding in JPEG/PNG mode. This policy does not apply when the H.264 encoder is active. This setting is not configured by default.
Screen Blanking Specifies whether to have the desktop VM's console show the actual desktop that the user sees or to show a blank screen when the desktop has an active session. The default is to show a blank screen.
UDP Protocol Specifies whether to use the UDP or the TCP protocol. The default is to use the UDP protocol. This setting requires a reboot of the Horizon Agent machine on which the registry key exists. This setting does not apply to HTML Access, which always uses the TCP protocol.
Whether block clipboard redirection to client side when client doesn't support audit Determines whether to block clipboard redirection to client machines that do not support the clipboard audit feature.

When this setting is enabled, you must select one of the following values.

  • Block - blocks agent-to-client clipboard redirection if the clipboard audit feature is supported on the agent machine but is not supported on the client machine.
  • Passthrough - allows agent-to-client clipboard redirection if the clipboard audit feature is supported on the agent machine but is not supported on the client machine.

When this setting is disabled or not configured, the default value is Block.

You must enable the Configure clipboard audit group policy setting for this setting to take effect.

Applying VMware Blast Policy Settings

If the following VMware Blast policies change during a client session, Horizon Client detects the change and immediately applies the new setting.

  • H264
  • Audio Playback
  • Max Session Bandwidth
  • Min Session Bandwidth
  • Max Frame Rate
  • Image Quality

For all other VMware Blast policies, Microsoft GPO update rules apply. GPOs can be updated manually or by restarting the Horizon Agent machine. For more information, see the Microsoft documentation.