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May 28, 2026

Understanding Communications Protocols

Note: Horizon Web Client is available with Horizon 8 versions 2412 and later. For Horizon 8 versions 2406 and earlier, Horizon Web Client is called "HTML Access." This documentation page uses the name "Horizon Web Client" to refer to both Horizon Web Client and HTML Access.

Horizon components use several different protocols to exchange messages.

The following table lists the default ports that each protocol uses. You can change the port numbers. For example, you might need to change the port numbers to comply with organization policies, or to avoid contention.

Default Ports

ProtocolPort
JMSTCP port 4001 TCP port 4002
HTTPTCP port 80
HTTPSTCP port 443
MMR/CDRTCP port 9427 The following features use this port.
  • Windows multimedia redirection
  • Client drive redirection
  • Microsoft Teams optimization
  • HTML multimedia redirection
  • Horizon printer redirection
  • USB redirection
RDPTCP port 3389
PCoIP TCP port 4172 UDP ports 4172, 50002, 55000
USB redirectionTCP port 32111. This port is also used for time zone synchronization.
Horizon Blast Extreme TCP ports 8443, 22443 UDP ports 443, 8443, 22443
Horizon Web ClientTCP ports 8443, 22443

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