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UDP 3391

ProtocolUDP
Port3391
Labels

Synopsis

  • UDP port 3391 is used by Microsoft Remote Desktop Gateway (RD Gateway) for the RDP-UDP transport introduced with RDP 8 and later.
  • Windows Server Remote Desktop Services with the RD Gateway role (e.g., Windows Server 2012, 2016, 2019, 2022) listens on UDP 3391 by default to carry RDP traffic over UDP when clients connect through the gateway.
  • Microsoft Remote Desktop clients (Windows 8/10/11, macOS, iOS, Android) use UDP 3391 to the RD Gateway for better performance; if unavailable, they fall back to TCP over 443.
  • Organizations using Remote Desktop Services/RemoteApp via RD Gateway commonly enable UDP 3391 to improve graphics and multimedia performance over WAN links.
  • RD Gateway has been targeted by exploits (e.g., CVE-2020-0609 and CVE-2020-0610 remote code execution), so UDP 3391 is often restricted to trusted sources in hardened deployments.

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